The Increasing Disastrous Global Drought Situation
Due to Global Warming
This report is a collection of recent news posts covering the impacts of the increasing
disastrous global drought situation due to global warming
Researched and Compiled by Dr.Tamanna Afrin, Bangladesh
The Shape Of Droughts To Come: 2012 Versus The 1930s Dust Bowl
By Joe Romm
Date: Aug 17, 2012
The United States will suffer a series of severe droughts in the next two decades,
according to a new study published in the journal Nature Climate Change. Moreover,
global warming will play an increasingly important role in their abundance and
severity, claims Aiguo Dai, the study’s author.
Page # 1
His findings bolster conclusions from climate models used by researchers around the
globe that have predicted severe and widespread droughts in coming decades over
many land areas…
“We can now be more confident that the models are correct,” Dai said, “but
unfortunately, their predictions are dire.”
What follows is an update on the Dust Bowl of 2012 from Meteorologist Dr. Jeff
Masters.
August 14, 2012 drought conditions showed historic levels of drought across the U.S.,
with 62% of the contiguous U.S. experiencing moderate or greater drought, and 46% of
the county experiencing severe or greater drought. Image credit: U.S. Drought Monitor.
The great U.S. drought of 2012 remained about the same size and intensity over the past week,
said NOAA in their weekly U.S. Drought Monitor report issued Thursday, August 16. The area of
the contiguous U.S. covered by drought remained constant at 62%, and the area covered by
severe or greater drought also remained constant at 46%. However, the area covered by the
highest level of drought–exceptional–increased by 50%, from 4% to 6%.
Large expansions of exceptional drought occurred over the heart of America’s grain producing
areas, in Kansas, Nebraska, Oklahoma, and Missouri. The new NOAA State of the Climate
Drought report for July 2012 shows that the 2012 drought is 5th greatest in U.S. history, and the
worst in 56 years. The top five years for area of the contiguous U.S. covered by moderate or
greater drought:
1. Jul 1934, 80%
Page # 2
2.
3.
4.
5.
Dec 1939, 60%
Jul 1954, 60%
Dec 1956, 58%
Jul 2012, 57%
The top five years for the area of the contiguous U.S. covered by severe or greater
drought:
1.
2.
3.
4.
5.
Jul 1934, 63%
Sep 1954, 50%
Dec 1956, 46%
Aug 1936, 43%
Jul 2012, 38%
Comparison with the great Dust Bowl droughts of the 1930s
An important fact to remember is that the 2012 drought is–so far–only a one-year
drought. Recall that 2011 saw record rains that led to unprecedented flooding on the
Mississippi, Ohio, and Missouri Rivers. In contrast, the great droughts of the 1950s and
1930s were multi-year droughts. The Dust Bowl drought of the 1930s lasted up to eight
years in some places, with the peak years being 1934, 1936, and 1939 – 1940. Once
the deep soil dries out, it maintains a memory of past drought years. This makes is
easier to have a string of severe drought years. Since the deep soil this summer still
maintains the memory of the very wet year of 2011, the 2012 drought will be easier to
break than the Dust Bowl droughts of the 1930s were.
In addition, a repeat of the dust storms of the 1930s Dust Bowl is much less likely now,
due to improved farming practices. In a 2009 paper titled, Amplification of the North
American “Dust Bowl” drought through human-induced land degradation, a team of
scientists led by Benjamin Cook of the Lamont-Doherty Earth Observatory explained the
situation:
During the 1920s, agriculture in the United States expanded into the central Great
Plains. Much of the original, drought-resistant prairie grass was replaced with droughtsensitive wheat. With no drought plan and few erosion-control measures in place, this
led to large-scale crop failures at the initiation of the drought, leaving fields devegetated
and barren, exposing easily eroded soil to the winds. This was the source of the major
dust storms and atmospheric dust loading of the period on a level unprecedented in the
historical record.
Page # 3
Figure 2. Black Sunday: On April 14, 1935 a “Black Blizzard” hit Oklahoma and Texas
with 60 mph winds, sweeping up topsoil loosened by the great Dust Bowl drought that
began in 1934.
The Dust Bowl drought and heat of the 1930s: partially human-caused
Using computer models of the climate, the scientists found that the Dust Bowl drought
was primarily caused by below-average ocean temperatures in the tropical Pacific and
warmer than average ocean temperatures in the Atlantic, which acted together to alter
the path of the jet stream and bring fewer precipitation-bearing storms to the Central
U.S. However, the full intensity of the drought and its spatial extent could not be
explained by ocean temperature patterns alone.
Only when their model included the impact of losing huge amounts of vegetation in the
Plains due to poor farming practices could the full warmth of the 1930s be simulated. In
addition, only by including the impact of the dust kicked up by the great dust storms of
the Dust Bowl, which blocked sunlight and created high pressure zones of sinking air
that discouraged precipitation, could the very low levels of precipitation be explained.
The Dust Bowl drought had natural roots, but human-caused effects made the drought
worse and longer-lasting.
The fact that we are experiencing a drought in 2012 comparable to the great Dust Bowl
drought of the 1930s–without poor farming practices being partially to blame–bodes ill
for the future of drought in the U.S. With human-caused global warming expected to
greatly increase the intensity and frequency of great droughts like the 2012 drought in
coming decades, we can expect drought to cause an increasing amount of damage and
economic hardship for the U.S. Since the U.S. is the world’s largest food exporter, this
will also create an increasing amount of hardship and unrest in developing countries
that rely on food imports.
Page # 4
How droughts will reshape the United States
By Brad Plumer
Date: July 17, 2012
More than half of the continental United States is currently suffering through the worst
drought in 50 years, with heat and a lack of rain rippling through the middle of the
country. Crops are wilting, soils are cracked, and some dried-out forests are catching
fire. U.S. corn production in particular is dwindling.
Things look bad for the corn harvest (Scott Olson/Getty)
So is this a glimpse at our hotter, drier future? It might be. While severe dry spells can
and do occur naturally, a few recent U.S. droughts have been tentatively linked to the
broad-scale warming of the planet. And if greenhouse gas emissions keep rising and
temperatures keep ticking upward, scientists say, we can likely expect more serious and
persistent droughts in the years ahead. Here’s what we know about our potentially
parched future:
1) The current drought isn’t at Dust Bowl levels, though it’s large from a historical
standpoint. The worst drought month in recorded U.S. history came in July of 1934, the
dessicated peak of the Dust Bowl, when 79.9 percent of the country experienced
drought conditions (and 63 percent of the country was suffering from extreme drought).
Last month’s drought isn’t nearly at that level—and it hasn’t persisted for years the way
the multi-year Dust Bowl droughts did. But it’s still in the top 10 for the past century,
according to a Weather Channel analysis of the Palmer Drought Severity Index:
Page # 5
As it happens, the current drought is also more widespread than the infamous 1936
heat wave, when more than 5,000 Americans died and farmers endured widespread
crop failures. So why the difference in impact? A great deal of credit goes to modern
agricultural practices. Back in the 1930s, overgrazing led to erosion and dust storms
that caked the Plains and worsened the drought. Modern erosion control and droughtresistant hybrid crops have averted some of that damage. Though not all…
2) Current droughts may be hurting U.S. corn yields, but they’re not yet causing a
global food crisis. The United States is the world’s largest exporter of corn and a key
supplier of soybeans. And right now, U.S. corn and soy production appear to be wilting
under the heat—the Department of Agriculture has cut its corn-production estimate by
12 percent. If output ends up falling, that would raise the price for corn, for biofuels, as
well as for beef (since corn is used to feed livestock).
More broadly, however, analysts still don’t think we’re facing a situation like 2007 and
2008, when skyrocketing food prices triggered riots in dozens of countries from Haiti to
Egypt. That’s because global wheat and rice supplies are holding fairly steady, at least
for now.
3) Climate change may already be making some U.S. droughts more likely. Given
that the United States experienced even more severe droughts in the 1930s and 1950s,
when carbon emissions were lower than they are today, one might assume that the
current U.S. drought has little to do with global warming. Tree-ring data, after
all, suggest that droughts in North America have been part of a natural cycle in the past,
often tied to strong La Niña events.
Yet scientists wonder whether rising global temperatures might be making present-day
droughts more common than natural conditions would otherwise suggest. One recent
attribution study (pdf) from researchers at NOAA and the Met Office estimated that
rising global temperatures may have made last year’s severe drought in Texas more
likely to occur. That is, if it weren’t for human-driven climate change, seasonal
conditions in Texas should have looked more like they did in the 1960s, when rainfall
was higher. That’s one early, albeit tentative piece of evidence that the impacts of global
Page # 6
warming are already being felt. (The NOAA study concedes, however, that “attribution
of single extreme events to anthropogenic climate change remains challenging.”)
4) And future global warming could seriously dry out the United States. There’s
more research, however, on what the future could hold. Keep in mind that human
activity has already warmed the planet about 0.8°C above pre-industrial levels.
According to the International Energy Agency, we’re on pace to warm the planet by 6°C
by the end of the century. And a growing body of scientific evidence suggests that level
of warming could drastically increase droughts around the world, including in North
America.
This 2011 review paper (pdf) by Aiguo Dai of the National Center for Atmospheric
Research summarizes much of what’s known about climate change and drought.
Computer models suggest that in North America, the rain won’t go away. But warmer air
temperatures and increased evaporation will dry out soils and make persistent droughts
more likely in the next 20 to 50 years. (Again, these droughts aren’t unprecedented, but
they’re expected to become more frequent.) Here’s one projection of what the world
could look like mid-century under a “moderate” emissions scenario:
The Palmer Drought Severity Index mid-century under a moderate emissions scenario.
Under the PDSI, "a reading of -4 or below is considered extreme drought." (Source:
National Center for Atmospheric Research.)
That’s a model of predicted Palmer Drought Severity Index around the world by midcentury. Take a look at the United States, where the PDSI ranges from -4 to -8 in the
Plains. As Joe Romm notes, the PDSI briefly spiked to -6 in the Plains during the Dust
Bowl, but it rarely exceeded -3 for the rest of the 1930s. In other words, it’s a forecast of
drought conditions more severe than they were during the Dust Bowl.
5) Farmers can take steps to adapt, though a drier world could prove tough to
navigate. Given that climate change might already be making drought more likely, U.S.
farmers will likely need to adapt no matter what else is done. A 2009 paper by John
Page # 7
Antle of Montana State University went through the research on this. By 2030, farmers
in the U.S. corn belt and Southwest are expected to see significant losses, which could
be partly offset by gains up North. (Antle estimated the overall drop in U.S. agricultural
production to be quite modest, between 4 percent to 13 percent.) Keep in mind,
however, that drought projections seem to be growing more severe in recent years. So
the economic impacts could be higher.
Better farming techniques can soften some of the damage, the way erosion control has
prevented Dust Bowl-type storms. Antle’s paper suggests that the U.S. government may
need to change some policies—for instance, subsidies for corn and soy can prevent
adaptation by locking in current farming patterns. Meanwhile, Tom Philpott argues that
organic farming may need to play a larger role in the future. While the practice often
produces lower yields than industrial farming, a recent Nature paper found that soils
managed with organic techniques tend to hold more water and perform better in
droughts. And droughts are looking increasingly tough to avoid.
James Hansen Is Correct About Catastrophic Projections For U.S.
Drought If We Don’t Act Now
By Joe Romm
Date: May 13, 2012
Page # 8
The response by NOAA’s Martin Hoerling to James Hansen’s recent op-ed does not
reflect the scientific literature.
I’m traveling, so let me focus first on Hoerling’s incorrect statements — posted on this
blog and Dot Earth — about drought. As readers know, the journal Nature asked me to
write a Comment piece on the threat posed by drought after they read one of my posts
examining the latest science on prolonged drought and “Dust-Bowlification.”
The research I did for that article — along with the comments of the expert reviewers I
sent it to — is why I know Hoerling is quite wrong. Hoerling begins by quoting Hansen’s
recent New York Times Op-Ed piece:
“Over the next several decades, the Western United States and the semi-arid region
from North Dakota to Texas will develop semi-permanent drought, with rain, when it
does come, occurring in extreme events with heavy flooding. Economic losses would be
incalculable. More and more of the Midwest would be a dust bowl. California’s Central
Valley could no longer be irrigated. Food prices would rise to unprecedented levels.”
Hoerling then asserts:
He doesn’t define “several decades,” but a reasonable assumption is that he refers to a
period from today through mid-century. I am unaware of any projection for “semipermanent” drought in this time frame over the expansive region of the Central
Page # 9
Great Plains. He implies the drought will be due to a lack of rain (except for the brief,
and ineffective downpours)….
But facts should, and do, matter to some. The vision of a Midwest Dustbowl is a
scary one, and the author appears intent to instill fear rather than reason.
That’s a very serious attack on Hansen — if it were true. But it isn’t, and it should be
retracted.
The fact is that the recent literature examining warming-driven drought in America could
not be clearer in warning about a “semi-permanent” (or worse) drought in both the
South West and the Central Great Plains and “More and more of the Midwest.” Here are
two studies that lay things out starkly:


Aiguo Dai of the National Center for Atmospheric Research, “Drought under global
warming: a review” (2010)
Michael Wehner et al., “Projections of Future Drought in the Continental United States
and Mexico” (2011)
I would also add the 2010, Environmental Research Letters article “Characterizing
changes in drought risk for the United States from climate change.”
And that’s not even counting the Journal of Geophysical Research study that Hansen
himself co-authored in 1990, “Potential evapo transpiration and the likelihood of future
drought,” which projected that severe to extreme drought in the United States, then
occurring every 20 years or so, could become an every-other-year phenomenon by midcentury.
As an important aside, contrary to what Hoerling states, Hansen was not implying the
drought will be due to lack of rain (by itself). Everyone seriously writing about warmingdriven drought knows we are talking about a combination of factors, ones that I laid out
in my Nature article:
Precipitation patterns are expected to shift, expanding the dry subtropics. What
precipitation there is will probably come in extreme deluges, resulting in runoff rather
than drought alleviation. Warming causes greater evaporation and, once the ground is
dry, the Sun’s energy goes into baking the soil, leading to a further increase in air
temperature. That is why, for instance, so many temperature records were set for the
United States in the 1930s Dust Bowl; and why, in 2011, drought-stricken Texas saw
the hottest summer ever recorded for a US state. Finally, many regions are expected to
see earlier snowmelt, so less water will be stored on mountain tops for the summer dry
season.
Obviously, since Hansen coauthored an article titled, “Potential evapotranspiration
and the likelihood of future drought,” we know he understands the drought conditions
are driven by more than precipitation changes. The whole point of that 1990 paper was
to examine the impact of warming-driven evaporation on soil moisture and drought.
Page # 10
It is quite surprising that Hoerling doesn’t appear to know the drought literature given
that, as Revkin notes, he “runs an effort by the National Oceanic and Atmospheric
Administration to assess the forces contributing to extreme weather events!”
Hoerling says it is reasonable to assume Hansen means “a period from today through
mid-century.” Hansen says the “semi-permanent drought” will develop “over the next
several decades.” That would clearly seem to mean that these conditions will evolve by
just after mid-century, the 2050s and 2060s. This is also the first period of time where
aggressive action to reduce emissions today could substantially change the projected
climate.
Dai’s analysis does indeed project drought conditions over the Great Plains and
Midwest. He is in the process of revising his analysis, but the figure below (which had
been his 2030s projection in his original version) is a rough representation of where his
analysis projects things will be in Hansen’s time frame for the U.S.
The PDSI [Palmer Drought Severity Index] in the Great Plains during the Dust Bowl
apparently spiked very briefly to -6, but otherwise rarely exceeded -3 for the
decade
Of course, just because several models project this future doesn’t make it a
certainty. As I note in the article, “drought models need to be improved. They
successfully chart the hydrological changes seen in the US Southwest and the drying
seen at the global level7, but regional predictions can be disturbingly variable.”
On the other hand, these models most certainly are not the worst-case scenario. Dai is
modeling A1B (720 ppm), whereas we are on track for worse than that. A plausible
worst-case scenario is here (and below): Royal Society Special Issue on Global
Warming Details ‘Hellish Vision’ of 7°F (4°C) World — Which We May Face in the
2060s!
Hansen’s use of the term “Dust Bowl” is justified since that is the term widely used in the
drought literature (see below). We are talking conditions that become as bad as the
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original Dust Bowl by mid-century and then get much, much worse for a long, long time.
The Nature editors made repeated use of the term “Dust-Bowlification,” and I was
particularly delighted that one of the leading experts in the field that I sent the piece to,
Jonathan Overpeck, also liked the term.
Indeed, Hoerling’s critique is really only about whether the semi-permanent drought
conditions will extend outside the U.S. SW to include most of Northern U.S. Great
Plains. The literature is very clear that the Southwest is very likely headed for Dust Bowl
conditions:


In 2007, Science (subs. req’d) published research that “predicted a permanent
drought by 2050 throughout the Southwest” — levels of aridity comparable to the
1930s Dust Bowl would stretch from Kansas to California. And they were also only
looking at a 720 ppm case.
In December 2008, the Bush Administration quietly released a US Geological Survey
stunner: SW faces “permanent drying” by 2050, which found:
The serious hydrological changes and impacts known to have occurred in both historic
and prehistoric times over North America reflect large-scale changes in the climate
system that can develop in a matter of years and, in the case of the more severe past
megadroughts, persist for decades. Such hydrological changes fit the definition of
abrupt change because they occur faster than the time scales needed for human and
natural systems to adapt, leading to substantial disruptions in those systems. In the
Southwest, for example, the models project a permanent drying by the mid-21st
century that reaches the level of aridity seen in historical droughts, and a quarter
of the projections may reach this level of aridity much earlier.

NOAA: Climate change “largely irreversible for 1000 years,” with permanent Dust Bowls
in Southwest and around the globe. This January 2009 PNAS paper finds
… the climate change that is taking place because of increases in carbon dioxide
concentration is largely irreversible for 1,000 years after emissions stop…. Among
illustrative irreversible impacts that should be expected if atmospheric carbon dioxide
concentrations increase from current levels near 385 parts per million by volume (ppmv)
to a peak of 450-600 ppmv over the coming century are irreversible dry-season
rainfall reductions in several regions comparable to those of the “dust bowl” era
So again, the ‘debate’ such as it is, is how far into the northern US Great Plains and
Midwest these Dust Bowl conditions will extend — and that’s without even considering
the impact of the increasingly early loss of the winter snowpack, which most of these
studies don’t even model. Since the recent literature suggests the droughts will extend
that far, Hansen’s warning is justified by the literature.
And Hansen’s use of the phrase “semi-permanent” is fully warranted. Given that the
drought conditions just keep getting worse and worse as long as we keep warming –
and are “largely irreversible for 1000 years” (according to a NOAA-led paper), “semipermanent” seems like a rather mild word.
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Bottom Line: Given how catastrophic it would be to the nation and the world if our
breadbasket were indeed hit by these conditions, Hansen’s warning seems fully justified
and Hoerling’s response does not.
Finally, it’s always worth repeating that much of human behavior and government
policy is driven by the desire to avoid it worst-case scenarios, which is why we have fire
insurance and catastrophic health insurance — and a military budget equal to that of the
next 16 countries combined.
If we look at the plausible worst case for climate, we get both continuing high levels of
emissions and high carbon-cycle feedbacks. That possibility was discussed in a Royal
Society Special Issue on a 7°F (4°C) World, which notes “In such a 4°C world, the limits
for human adaptation are likely to be exceeded in many parts of the world, while the
limits for adaptation for natural systems would largely be exceeded throughout the
world.”
This would be the worst-case for the 2060s, but is in any case, close to business as
usual for 2090s:
This is 13-18°F over most of U.S. and 27°F in the Arctic. The drought conditions
that would be created by such warming over most of the central and western U.S. are
beyond imagining.
And there is every reason to believe that the earth would just keep getting hotter and
hotter:

Science stunner — On our current emissions path, CO2 levels in 2100 will hit levels last
seen when the Earth was 29°F (16°C) hotter: Paleoclimate data suggests CO2 “may
have at least twice the effect on global temperatures than currently projected by
computer models”
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Indeed, Steve Easterbrook’s post “A first glimpse at model results for the next IPCC
assessment” shows that for the scenario where there is 9°F warming by 2100, you get another
7°F warming by 2300. Of course, folks that aren’t motivated to avoid the civilization-destroying
9°F by 2100 won’t be moved by whatever happens after that.
So if folks want to quibble about whether the semi-permanent Dust Bowl that the U.S.
Southwest is headed to by mid-century might not spread to the northern U.S. Great Plains for,
say, another few decades after that, well, I must say they are rearranging deck chairs on the
Titanic.
Extreme Weather and Climate Change Understanding the Link,
Managing the Risk
By Daniel G. Huber and Jay Gulledge, Ph.D.
Dated December 2011
Executive Summary:
Page # 14
Thousands of record-breaking weather events worldwide bolster long-term trends of
increasing heat waves, heavy precipitation, droughts and wildfires. A combination of
observed trends, theoretical understanding of the climate system, and numerical
modeling demonstrates that global warming is increasing the risk of these types of
events today. Debates about whether single events are “caused” by climate change are
illogical, but individual events offer important lessons about society’s vulnerabilities to
climate change. Reducing the future risk of extreme weather requires reducing
greenhouse gas emissions and adapting to changes that are already unavoidable.
Introduction:
Typically, climate change is described in
terms of average changes in temperature
or precipitation, but most of the social and
economic costs associated with climate
change will result from shifts in the
frequency and severity of extreme events.
This fact is illustrated by a large number of
costly weather disasters in 2010, which
tied 2005 as the warmest year globally
since 1880. Incidentally, both years were
noted for exceptionally damaging weather
events, such as Hurricane Katrina in 2005
and the deadly Russian heat wave in
2010. Other remarkable events of 2010
include Pakistan’s biggest flood, Canada’s
warmest year, and Southwest Australia’s
driest year. 2011 continued in similar form,
with “biblical” flooding in Australia, the
second hottest summer in U.S. history,
devastating drought and wildfires in Texas,
New Mexico and Arizona as well as
historic flooding in North Dakota, the
Lower Mississippi and in the Northeast.
Box 1. Why can’t scientists say whether
climate change “caused” a given weather
event?
Climate is the average of many weather
events over of a span of years. By
definition, therefore, an isolated event lacks
useful information about climate trends.
Consider a hypothetical example: Prior to
any change in the climate, there was one
category 5 hurricane per year, but after the
climate warmed for some decades, there
were two category 5 hurricanes per year. In
a given year, which of the two hurricanes
was caused by climate change? Since the
two events are indistinguishable, this
question is nonsense. It is not the
occurrence of either of the two events that
matters. The two events together – or more
accurately, the average of two events per
year – define the change in the climate.
Munich Re, the world’s largest reinsurance company, has compiled global disaster for
1980-2010. In its analysis, 2010 had the second-largest (after 2007) number of
recorded natural disasters and the fifth-greatest economic losses. Although there were
far more deaths from geological disasters—almost entirely from the Haiti earthquake—
more than 90 percent of all disasters and 65 percent of associated economic damages
were weather and climate related (i.e. high winds, flooding, heavy snowfall, heat waves,
droughts, wildfires). In all, 874 weather and climate-related disasters resulted in 68,000
deaths and $99 billion in damages worldwide in 2010.
The fact that 2010 was one of the warmest years on record as well as one of the most
disastrous, begs the question: Is global warming causing more extreme weather? The
Page # 15
short and simple answer is yes, at least for heat waves and heavy precipitation. But
much of the public discussion of this relationship obscures the link behind a misplaced
focus on causation of individual weather events. The questions we ask of science are
critical: When we ask whether climate change “caused” a particular event, we pose a
fundamentally unanswerable question (see Box 1). This fallacy assures that we will
often fail to draw connections between individual weather events and climate change,
leading us to disregard the real risks of more extreme weather due to global warming.
Climate change is defined by changes in mean climate conditions—that is, the average
of hundreds or thousands events over the span of decades. Over the past 30 years, for
example, any single weather event could be omitted or added to the record without
altering the long-term trend in weather extremes and the statistical relationship between
that trend and the rise in global temperatures. Hence, it is illogical to debate the direct
climatological link between a single event and the long-term rise in the global average
surface temperature.
What about
tornadoes?
climate
change
and
Scientists are unsure if tornadoes will
become stronger or more frequent, but
with increased temperatures changing
the weather in unexpected ways, the
risk is real that tornado outbreaks will
become more damaging in the
future. The lack of certainty in the state
of the science does not equate with a
lack of risk, since risk is based on
possibility.
The lack of scientific
consensus is a risk factor itself, and we
must prepare for a future that could
possibly include increased tornado
damage.
Nonetheless, individual weather events offer
important lessons about social and
economic vulnerabilities to climate change.
Dismissing
an
individual
event
as
happenstance because scientists did not link
it individually to climate change fosters a
dangerously passive attitude toward rising
climate risk. The uncertainty about future
weather conditions and the illogic of
attributing single events to global warming
need not stand in the way of action to
manage the rising risks associated with
extreme weather. Indeed, such uncertainty
is why risk managers exist – insurance
companies, for example – and risk
management is the correct framework for
examining the link between global climate
change and extreme weather.
An effective risk management framework accommodates uncertainty, takes advantage
of learning opportunities to update understanding of risk, and probes today’s rare
extreme events for useful information about how we should respond to rising risk. Risk
management eschews futile attempts to forecast individual chaotic events and focuses
on establishing long-term risk certainty; that is, an understanding of what types of risks
are increasing and what can be done to minimize future damages. An understanding of
the meaning of risk and how it relates to changes in the climate system is crucial to
assessing vulnerability and planning for a future characterized by rising risk.
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Food riots predicted over US crop failure
By Robert Kennedy
Date: 21 Aug 2012
Analysts say crippling drought in the US likely to trigger unrest in impoverished nations
dependent on food imports.
Some scientists say the use of corn for biofuels is exacerbating the food crisis [Reuters]
The world is on the brink of a food "catastrophe" caused by the worst US drought in 50
years, and misguided government biofuel policy will exacerbate the perilous situation,
scientists and activists warn.
When food prices spike and people go hungry, violence soon follows, they say. Riots
caused by food shortages - similar to those of 2007-08 in countries like Bangladesh,
Haiti, the Philippines and Burkina Faso among others - may be on the horizon,
threatening social stability in impoverished nations that rely on US corn imports.
This summer's devastating drought has scorched much of the mid-western United
States - the world's bread basket.
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Crops such as corn, wheat, and soy have been decimated by high temperatures and
little rain. Grain prices have skyrocketed and concerns abound the resulting higher food
prices will hit the world's poor the hardest - sparking violent demonstrations.
Early dryness in Russia's wheat growing season, light monsoon rains in India, and
drought in Africa's Sahel region, combined with America's lost crop, mean a perfect
storm is on the horizon.
Surging food prices could kick off food riots similar to those in 2008 and 2010, Professor
Yaneer Bar-Yam, president of the New England Complex Systems Institute, told Al
Jazeera.
"Recent droughts in the mid-western United States threaten to cause global
catastrophe," said Bar-Yam, whose institute uses computer models to identify global
trends.
Hopes were high in May of a bumper corn crop this year, but sizzling temperatures in
June and July scuttled those predictions. US corn yields are now expected to be the
lowest in 17 years.
The United States accounted for 39 per cent of global trade in corn in 2011-12.
Stockpiles are now down 48 per cent, according to the US Department of Agriculture.
Corn prices have shot up 60 per cent since June 15.
Corn is a primary staple in Sub-Saharan Africa, and in much of Central and South
America. In South Africa, the cost of maize has increased about 40 per cent in the last
year, even before the US drought struck.
Bar-Yam highlighted the food riots of 2007-08 and 2010-11 that were fuelled by sudden
and dramatic spikes in food prices. He said his institute recently entered data from the
US drought into its computer model, which predicted the outbreak of food-related unrest
"in a short period of time".
"When people are unable to feed themselves and their families, widespread social
disruption occurs," Bar-Yam said. "We are on the verge of another crisis, the third in five
years, and likely to be the worst yet, capable of causing new food riots and turmoil on a
par with the Arab Spring."
Fighting for food
While Americans and other Westerners will largely escape the financial pain spawned
by the drought, impoverished people around the globe won't be so fortunate.
People in wealthy industrialised countries spend between 10 to 20 per cent of their
income on food. Those in the developing world pay up to 80 per cent. According to
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Oxfam, a one per cent jump in the price of food results in 16 million more people
crashing into poverty.
More than 60 food riots occurred worldwide between 2007 and 2009, when rapidly
rising commodity prices wreaked havoc on family budgets.
The world is not yet in a food crisis, said David Hallam, the UN Food and Agriculture
Organisation's director of trade and markets.
"We're a long way from that … Some of the elements that we saw in 2007-08 are very
much missing at the moment", Hallam told Reuters. He said wheat stocks were
currently stable, and a bumper rice crop was still expected later this year.
But he added: "We are in a very vulnerable situation in markets, and any further supplyside shocks or any disruptive policy actions that individual countries might take could
add further to the problems we have and create turmoil in markets."
Hallam said wheat production in Russia was a wildcard in the food-crisis equation.
Russian wheat crop yields look lower than expected, but just how much lower is the
major question, he explained.
Export bans and panicked-buying by governments would only compound the problem,
said Hallam.
The International Food Policy Research Institute - a Washington- based organisation
that monitors food prices - warned last week a global crisis could "hit us very soon".
Director-General Shenggen Fan said using corn for ethanol in automobiles needed to
be halted. "That actually pushed global food prices higher and many poor people,
particularly women and children, have suffered," Fan told Bloomberg.
The folly of food for fuel
The United States uses about 13 per cent of global corn production for biofuels. About
37 per cent of this year's corn crop is earmarked for ethanol production.
The biofuels industry says it has helped combat climate change and reduced American
reliance on foreign oil, lowering its dependence on imported oil from 60 per cent to 45
per cent since 2007.
Industry group Growth Energy challenged those who "tie biofuel production to alleged
increased food prices". CEO Tom Buis blamed high oil prices and "Mother Nature".
But many question whether using corn to fuel vehicles is justified with food prices rising.
"Given the possibility of price-driven famines, burning corn for cars is unconscionable,"
Professor Bar-Yam said.
Page # 19
Robert Bryce, author of Power Hungry: The Myths of "Green" Energy and the Real
Fuels of the Future, agrees, adding ethanol as a fuel is grossly inefficient.
"There should be an immediate, global, prohibition placed on the use of food crops for
fuel production," said Bryce.
Global Warming - The Effects and Impacts on the Environment
By: Willie Scott & edited by: Sarah Malburg
Date: 2/3/2011
The effects and impacts of global warming on the environment may include the
continuing rise in the Earth’s temperature, rising sea levels and rising temperatures
causing glaciers to melt. This combination of impacts will eventually cause many
tropical low lying islands to become submerged.

Introduction to the Effects of Global Warming
Global warming is a direct result of the accumulation of greenhouse gases that have
gathered in the earth’s upper atmosphere and are preventing some of the solar infrared
radiation emitted from earth from entering deep space. This causes the earth to
overheat, unbalancing our fragile climate structure, and causing detrimental effects such
as rising sea levels, windy, wetter and warmer weather paterns and melting of the ice
caps. Some species of flora and fauna, along with ecosystems already under stress, will
become extinct if we continue to sit back and do little to mitigate the situation.
This is another article in my series on climate change. In this article, we shall examine
the major effects of global warming on the environment.
We start by listing these impacts and go on to look at the repercussions of them.
The Effects of Global Warming
The major effects of global warming are numerous. Some of these effects are listed
below:


Rising world temperatures
Rising sea levels
Page # 20




Climate change
Melting glaciers, polar ice and sea ice
Bleaching of coral reefs
Species extinction
The Effects of Global Warming
Rising Sea Levels
Rising sea levels are caused by two distinct events, the melting of polar glaciers, and
the expansion of seawater.

Melting of Polar Glaciers
Due to the rise in the Earth’s temperature, the polar glaciers are being closely monitored
and have been seen to be melting and reducing in area. Glaciers are formed on top of
landm therefore, when they melt they add to the volume of the world's seawater.

Expansion of seawater
As the Earth's temperature rises, heat is transmitted to our oceans. This causes the
seawater at the top 100 meters or so of our oceans to expand, thus raising their levels.
This rise in the temperature of the sea has the adverse effect of causing coral reefs to
become bleached. This is the term given to the reefs when the algae and other marine
life which live on the coral die, causing the coral to lose its vibrant colors.
Climate change due to rising temperatures
This is one of the major issues being investigated today in relation to global warming.

Weather variations
Scientists have predicted that our climate will become more windy, wet and warmer.
Wind will increase in speed and duration. Rainfall will increase in the winter months and
decrease in the summer months. Temperatures are already rising at an estimated 0.1 οC
every year and scientists predict that a rise of 4 οC can be expected by the end of this
century.
Melting glaciers

Increase in adverse geological occurrences
As well as causing a rise in sea levels, some geologists have blamed the increase of
occurrence of earthquakes, volcanoes and tsunamis on the disappearing glaciers.
Page # 21
Species extinction
Loss of habitat is caused by flooding or turning it into a barren dessert. Reduction in
flora and fauna will result from the extinction of species due to stress and starvation.
The Impacts of Global Warming on the Environment
Rising Sea Levels
This will exacerbate coastal flooding necessitating erection of higher coastal barriers;
control by this method by the industrial nations is being acted upon. However, the
poorer third world nations, especially those with low-lying tropical islands, cannot afford
this protection, so they are likely to lose their homes to the sea.
Rising sea levels will also threaten many of the world's estuaries. Some of these
estuaries have valuable ecosystems within their mudflats, which are supported by the
freshwater from the rivers. The encroachment of saltwater into this habitat could do
irreparable damage to its habitants, causing mass extinction of some species. This will
escalate to the reduction of some already endangered species of permanent and
migrating wildfowl, which depend on the mudflats for food.
Ingress of seawater into freshwater supplies has been predicted, which is bad enough
in the western world, but is even more disastrous for the third world countries already
suffering from lack of clean drinking water supplies.
Climate Change
Wind is predicted to increase in velocity causing structural damage, bringing down trees
and power lines and causing storms at sea.
Rainfall is also forecasted to increase in winter but decrease in summer. We have
already suffered from flooding over the last decade, and some of us have seen water
rationing because of drought.
A predicted rise in the world’s temperature of 4οC will reduce our crop yields and will
eventually lead to changes in current methods of crop cultivation, necessitating their
replacement by more tropical suited varieties.
Finally, there have been recorded instances of spring being early by up to two weeks,
totally confusing the wildlife population. Reports have also been made that some rivers
are becoming too warm to support fish, especially salmon.
Melting Glaciers
Page # 22
The glaciers exert an enormous pressure on the land they have been formed on. When
they melt, this pressure is released and geologists believe this sudden release of
pressure on the Earth is the cause of the recent increase in volcanic action,
earthquakes, and tsunamis worldwide.
Species Extinction
The species which may be already endangered can be exposed to flooding or drought,
with the loss of their food chain and destruction of their habitats, eventually leading to
extinction.
Summary
Global warming is caused by the accumulation of anthropogenic greenhouse gasses
which prevent the exit of long-wave infrared radiation emitted from Earth into space.
There are many effects of global warming, all requiring immediate action, but climate
change with the associated rise in sea levels and elevated world temperatures being the
most urgent cases.
These three major effects alone are harbingers of major world disasters for humans,
flora and fauna throughout the world.
Some of these disasters, such as floods, droughts, hurricanes and earthquakes, are
escalating, and are set to continue throughout this century - unless we all do something
about it.
This can be achieved by mitigation of greenhouse gas emissions to reduce the impacts
of global warming.
Wildfires ignite debate on global warming
By S. COLE MORITZ,
Date: 18 July 2012
As temperatures soar, forests blaze and houses burn, the media and public may be
forced to face up to the reality of a changing climate, says Max A. Moritz.
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Article tools
I published an academic paper on climate change and global fire predictions last month,
and I have been in my own media storm ever since. The huge wildfires that have broken
out in the western United States had prompted dozens of enquiries from the press,
nearly all asking the same question: “Are these fires due to climate change?”.
For me, that marks a significant shift from previous years. During the conflagrations in
southern California in 2003 and 2007, and the Black Saturday fires in the state of
Victoria, Australia, in 2009, the question most reporters asked was: “Who is to blame
here?”.
This fresh curiosity about the link between fire and climate change is an important
opportunity, of sorts. The media and the public seem to be searching for the evidence
they need to take climate change more seriously. It is sad that it seems to take disasters
to shift perspective, but perhaps they will also lead to a more science-based discussion
of policy and planning. The term 'tipping point' gets thrown about too much, but I wonder
if the United States is near one in terms of public perception about climate change.
Related stories



A decade of weather extremes
Heavy weather
Climate and weather: Extreme measures
The start of this year's fire season has been unusually fierce. Much of the western
United States is extremely dry, and there are many reports of temperatures and forest
fires that have broken records. The number of buildings destroyed — nearly 1,000 in a
recent count — is staggering. Even if the fire season does not continue at the same a
terrifying pace, these events could help to make climate change more real for many
people. Is there a link with global warming? We have good reason to think so, and not
taking the link seriously could have disastrous repercussions.
Climate change is not the only explanation. As usual, the conservative end of the
political spectrum (including climate-change deniers) tends to blame environmental
groups for opposing projects to thin forests, arguing that harvesting timber could have
averted the devastating fires or mitigated their effects. Another argument focuses on the
fact that we increasingly build homes in fire-prone ecosystems, including those that
experience high-intensity fires as a natural event.
The latest fires in the interior west leave several open questions, and sometimes 'all of
the above' is the best scientific explanation. Fire hazard can increase sharply after
suppression of natural fires in dry forests of ponderosa pine, so the lack of active forest
management (including prescribed fires) is indeed a potential culprit there. The picture
is less clear for other forest types, and only further examination of fire-severity patterns
will determine the role that forest management could have.
Page # 24
However, even if objections from environmentalists have contributed to more severe
fires in some places, it does not follow that they contributed to the destruction of homes.
Typically, structures ignite in exceptionally windy conditions, and this greatly offsets the
effectiveness of forest thinning. Embers can be carried on the wind for kilometres until
they find their way into a vulnerable spot, such as an unscreened vent or dry leaves
under exterior decking. Poor planning decisions regarding building development and
land use are at the heart of the structure-loss problem.
“For some, climate change will become a fact only when its effects hit close to home.”
Most scientists avoid drawing conclusions about the contribution that climate change
has made to forest fires on the basis of individual years or events. That said, the fires of
this year and last seem to fit a documented pattern. Research shows a trend towards
warmer spring and summer temperatures in many forests of the western United States,
which leads to earlier melting of snow and a longer, more severe fire season.
The latest fires in the western United States are also consistent with models of fire
activity expected from global-climate-change projections over the next few decades,
including models that my lab helped to develop. The links to anthropogenic climate
change are thus based on established relationships, operating at different scales of
space and time, between climate and fire activity in various environments.
After reporters ask about wildfires and global warming, the next question is: “If these
fires are related to climate change, what can we do about it?”. Some people may cry
“reduce greenhouse-gas emissions”, but that is not what this question is about. Instead,
these enquiries reveal a growing anxiety over how humanity can adapt to the firerelated impacts of climate change, rather than how to mitigate climate change itself.
To co-exist with fire will require extending our approach to living with environmental
risks. Mapping other natural hazards, such as flood and earthquake zones, has taught
us to avoid building on the most dangerous parts of the landscape or to engineer
solutions into the built environment when we do. Encouraging the 'right kind of fire' —
with frequencies, sizes and intensities appropriate to the ecosystem in question — will
be necessary, where possible, so that 'record-breaking' fires are less likely to occur
during 'record-breaking' heat or drought.
For some, climate change will become a fact only when its effects hit close to home. For
this reason, perhaps we should expect an awareness of the need to adapt to climate
change to precede a wider commitment to mitigating climate change itself. If that is the
case, reporters are, finally, asking the right questions
Page # 25
Global Warming: Our Story So Far
By Michael Goodfellow
I was talking to a 20-something friend the other day, griping about the lack of good
science fiction these days. He laughed and said that we already had the Internet and
robots running around on Mars, so who needed SF? I replied that SF is one of the ways
we think about the future, our dreams about what we hope or fear will happen. He then
said "Well, it doesn't matter much does it? We don't have much of a future, do we? The
Earth is going to bite back."
He then repeated most of the doom and gloom you hear regularly, about pollution,
overpopulation, global warming. "Al Gore says we're all going to drown." Combine that
with a cynicism about politics and you come to the conclusion that there are horrible
problems and that we won't do anything about them. I argued against this, telling him
that even the EPA says the air in the U.S. is cleaner than it's been in 30 years, that
population trends are for a leveling off, not an explosion, and that there are lots of
problems with the simple view of the global warming debate given in "An Inconvenient
Truth." He just shrugged, waiting for the geezer (I'm 48) to wind down his rant. None of
it penetrated. Frankly, the idea that a whole generation thinks the world is doomed
scares me more than global warming.
Like it or not, real or not, global warming is a huge problem for the world. Serious
debate is going on about what to do, government action on this is already affecting us
all, and will continue to do so. The potential effects of legislation on the world economy,
the politics of trade and on our lifestyles are all huge. So it makes sense to follow this
debate as closely as you follow any other big issue, from the housing bubble to the Iraq
war. The problem, as usual, is getting some context and separating the facts from the
political bias.
If you want to be reassured that global warming is real and the "deniers" are all idiot oil
company employees, go to www.realclimate.org. And if you want to be reassured that
global warming scientists have all sold their integrity for research dollars, are ignoring
contrary data, refusing to release methods and results, and even faking data, go to
Page # 26
www.climateaudit.org. For a thorough and interesting summary of the anti-warming
arguments, go to a paper by Zbigniew Jaworowski and skip to page 4 ("The Truth About
Ice Cores"), after the pages of abuse heaped on the global warming community.
Fun, fun, fun!
The rest of this article is my attempt to summarize the debate as I understand it.
The History of Climate
Let's start with the big picture. This graph is a reconstruction of the Earth's temperature
for the last 500 million years. As with the rest of these graphs, read them from right to
left. The left edge, at zero, is the present.
As you can see, the temperature of the Earth has bounced around a lot. We are
currently (left side) in a cold spell, the coldest the Earth has been in 450 million years.
Zooming in on the last 65 million years, you can see more detail (from here):
Page # 27
Again, the left side is the present, and right is 65 million years ago. As you can see, the
temperature was higher 50 million years ago (the Eocene Optimum), and with a bit of
wobbling around, has been steadily cooling. The whole period from 40 million years ago
is described as an "ice age." Zoom in on the last 5 million years (from here) and you
start to see some short-term cycles.
This graph is very jagged! The temperature is swinging by several degrees each
100,000 years. Remember the left side is the present and is the coldest part of the
graph. The zero line (right-side scale) is the current temperature. The Earth has spent
almost all of the last 2.5 million years colder than it is now. Let's zoom in again to the
last 450,000 years (from here.)
This one has three datasets -- temperature in blue, CO2 in green, and dust in red.
Again, the present is on the left. The black line at zero represents current temperature
(top-left scale.) This is data from the Vostok ice cores and is the same data used by Al
Gore in "An Inconvenient Truth."
Notice several things about this graph. The Earth spends nearly all of its time colder
Page # 28
than we are now. In fact, if you were describing this to someone, you'd say that the
Earth is normally several degrees colder, and every 100,000 years or so, it spikes up to
a bit warmer than we are now for a few thousand years, then goes cold again. And in
fact, science calls the current period an "interglacial", a temporary gap in the long ice
age.
The second thing you might notice is that we've already had a long warm stretch
(around 10,000 years), and the next move for the climate would be colder. Much colder.
Lastly there's the famous CO2 line (in green), which almost matches the temperature
line. Clearly, there's a link between the two! For Al Gore, it's that CO2 causes a
temperature increase. For the deniers, it's the other way around. More research has
shown that the temperature change precedes the CO2 change by a few hundred years.
The obvious question for the pro-warming people is "what causes CO2 to increase
naturally (back before there were any humans to burn fossil fuels?)" The obvious
question for the deniers is "what causes temperature to rise naturally?"
The problem of CO2 increase after temperature increase is mentioned on RealClimate
(the pro-warming site), and basically dismissed (see here.) Their point is that it's a
feedback loop, where increased temperatures release CO2 from the oceans which then
further increase temperatures. It's not clear to me why this cycle stops, or what gets it
started in the first place. At the end of this item, RealClimate states that
CO2 may have reached levels of 1000 parts per million (ppm) -- perhaps much higher -- at times
in the distant geological past (e.g. the Eocene, about 55 million years ago).
This is worth keeping in mind -- the current CO2 levels are high (the highest on this graph of the
last 450,000 years), but not unprecedented. Nature can produce numbers this high on its own.
And although the Earth was much hotter then, it was not a runaway greenhouse effect that
flooded the world or turned it into a second Venus.
What I notice about all these graphs is how noisy they are. If these are accurate, there are huge
swings in the Earth's climate, even over short periods. It would be very hard to tell if any change
is natural or man-made. After all, in this last graph, a single pixel is still hundreds of years. A
swing upwards of 1 or 2 degrees would be lost in that noise. If you were looking at it from a
million year context, everything that has happened in the last 50 years would be an irrelevant
little blip.
Let's zoom in again, to the last 12,000 years. This graph shows eight temperature lines
representing different reconstructions, and the average (from here.)
Page # 29
You start to see where all the disagreement comes in. Each line (each different "proxy" for
measuring past temperature) gives a fairly different picture. In the average, you see a gradual
cooling from a peak 8000 years ago to the present.
Finally, let's see the last 2000 years (from here.)
This graph is read from left to right (2000 on the right is present time.) This is the first graph
Page # 30
where we can start to get independent measures from historical records. We can ask about the
Roman cultivation of grapes in England, the Viking directions to Greenland that don't mention
ice, or the Thames river freezing over (as it's shown in paintings.) We can start to compare with
long-running temperature records like the ones kept by the British Navy. Unfortunately, there is
still no agreement. This shows 11 different reconstructions of past climate. Note how much they
vary from one another, and how much temperature varies from time to time.
You do see that 1000 years ago, temperatures were also high, about the same as today (and
colder than 8000 years ago, from the previous graph.) The increase in temperature from 1600
looks dramatic, but of course, nothing but the 20th century numbers could really be blamed on
industrialization and burning fossil fuels. If you took the graph from 1900 only, it would look like
a dramatic increase, but in the context of the last 2000 years, it looks more like a continuation of
an existing trend. The "deniers" simply call this the end of the "Little Ice Age".
Background Summary
No one doubts that CO2 is a greenhouse gas, along with methane, nitrous oxide, and ozone.
But also no one doubts that water vapor (especially as clouds) is the most significant
greenhouse gas. In fact, without its atmosphere, the average temperature of the Earth would be
considerably colder.
No one doubts that climate is extremely variable, as is CO2 concentration. As the graphs above
show, the average temperature has swung several degrees in each direction, from very hot
millions of years ago, to very cold during the last ice age, just ended 10,000 years ago. The
recent history of the Earth is a series of ice ages interrupted by warm periods. Without some
effect from human activity, the climate will almost certainly return to an ice age, its normal state
for millions of years.
This variability is seen on all time scales - 100 million years, 1 million years, 100,000 years,
1000 years and even over decades. The climate warmed up to 1940 or so, cooled again to
1970, then warmed again to the present.
The long-term variations in climate are thought to be due to changes in the Earth's orbit (see
Milankovitch cycles), but there are apparently problems with this theory. The 100,000 year
climate cycle is much stronger than would be predicted. Also, it seems to have been a 41,000
year cycle back a million years ago, and there's no obvious reason that the orbital factors
should have changed abruptly.
The shorter-term variations are blamed on everything from changes in solar activity to
continental drift to volcanic activity, all amplified by CO2 and other greenhouse gases. From
what I've read, this is all a very unsettled part of climate science.
Finally, I don't think anyone doubts that it would be great to have better data. In fact, one
criticism of global warming research is that they aren't spending enough money to get this data.
Page # 31
There should be a concerted effort to put together a really solid record of past temperatures,
using many different proxies (things like fossil tree rings or pollen counts) from many different
parts of the world. Any historical records (like crop yields or river levels) that can shed light on
this should also be collected and correlated. My impression from the debate is that we are
spending a lot more on computer models than on the data that goes into them.
The three most common theories of what's going on now are:
1. Anthropogenic (Man-made) Global Warming. Industrialization using fossil fuels is
releasing more CO2 which is heating the atmosphere.
2. Solar cycles and other natural variation. The output of the sun changes, long-term cycles
shift and the earth warms. CO2 is released by the oceans in response.
3. Bad data. Nothing in particular is happening. Random variation in the climate has scared
us into producing theories backed up by incomplete computer models and really skimpy
information.
Anthropogenic Global Warming
The modern global warming theory is basically the following:
1.
2.
3.
4.
5.
6.
There is an increase in CO2
The increase is due to the burning of fossil fuels
There is an increase in temperature
The temperature increase is due to the CO2 increase
CO2 will continue to increase due to economic growth
Computer models say the temperature will get a lot higher, with disastrous effects.
All parts of this come with criticisms, ranging from quibbles to outright rejection.
1. There is an increase in CO2. According to some researchers (see the discussion in
Jaworowski) the ice core data isn't reliable. There are chemical processes that can change the
amount of CO2 held, and there is debate on the lag between when the ice is formed and when
the CO2 is finally captured. He says the ice core CO2 measurements don't agree completely with
other proxies. Also that the levels of CO2 in the atmosphere have been measured by chemists
since 1812 and don't agree with reconstructed measurements. A sample paragraph:
This is the reason that between 1880 and 1940, when the global average temperature warmed
up by about 0.5 deg C, the direct measurements in the atmosphere registered a very large
increase of CO2, from about 290 ppmv in 1885 up to 440 ppmv in 1940 about 60 ppmv higher
than now (Beck 2007).
2. The increase is due to the burning of fossil fuels. If CO2 is varying naturally, you would have
to separate this component from the output of industry to get a true measure of CO 2 increase
due to humans.
3. There is an increase in temperature. There is considerable debate about this too. Satellite
Page # 32
measurements don't go back far enough to give much history. Weather stations have measured
the temperature for over 100 years, but there's concern that as cities have grown up around
them, the "heat island" effect has biased the temperatures upwards. See
http://www.surfacestations.org/, which claims that rural stations with properly maintained
facilities show no increase in temperatures, whereas urban stations or ones with lots of nearby
development show increases.
And the farther we go back, the more problematic it becomes. Before weather records, we must
estimate temperature from proxies, and data becomes very uncertain again. The methods used
to manipulate the data and correlate various different sequences are also an issue. The
infamous IPCC "hockey stick" graph which showed temperatures skyrocketing after 1950 turned
out to be an artifact of the way the data was processed.
4. The temperature increase is due to the CO2 increase. Again, there's a range of opinion about
this. CO2 should increase temperature, but it's only one factor. Increase in temperature should
also release more CO2 from the oceans, so cause and effect is hard to figure (or it may be both
-- a feedback loop where temperature increases CO2 which increases temperature.) The
competing theory is that the sun is driving all the recent increases in temperature, and that is
driving the increase in CO2.
5. CO2 will continue to increase due to economic growth. The Peak Oil idea implies that there
isn't enough oil to keep the CO2 output increasing for 100 years. Other technologies like
gasification of coal or recovery of oil from tar sands aren't going to substitute. Economists have
said that the IPCC climate models are very naive about economic growth, simply assuming that
every country in the world will continue to grow at high rates. This leads to a model of the year
2100 where a billion Chinese own an SUV getting 12 mpg. And of course, no new technologies
are assumed. Is this reasonable?
6. Computer models say the temperature will get a lot higher, with disastrous effects. Everyone
admits that the computer models are incomplete. They don't have fine enough resolution, they
don't model clouds well, and there are all kinds of external factors that just have to be fudged in
the model, not derived from a basic understanding of the atmosphere. You can't model
everything! There are aspects of the air, oceans, soil, and ecology you have to just measure
and then plug into the model as constants ("external variables.") And as mentioned above, you
have to make a lot of assumptions about the economy too. If your economic prediction for the
next 100 years is worthless, so is your climate model.
And in my opinion, there are more fundamental problems with modeling the climate.
For one, there's no track record that can be used to validate the models. They just haven't been
around long enough. Getting one version of the model to retroactively predict the past 100 years
doesn't tell you much. It could just have the right fudge factors to make it come out right. What
you want is something that keeps making accurate predictions into the future. Unfortunately, this
is impossible. There will always be unpredictable events, from volcanoes to variations in solar
Page # 33
output, which throw off the model. Given how complex the system is and how coarse the
models are, you are never going to make an exact prediction of a single year. The model could
only be tested against a long range of years, showing that the model had the trends right, not
the specific weather. But this takes decades of comparing the model to the actual (future)
weather. If global warming is a disaster in progress, by the time you trust the model, it's too late.
Another problem is that none of these models even attempt to capture the long-term climate
cycles. Any recovery from the "Little Ice Age", let alone something driven by the larger 100,000
year cycle, is just a constant to the model. And that means it's an assumption that can't be
tested. A really good model of climate should be able to take data from many previous periods
and accurately predict the subsequent climate. Not just the last 100 years, but the weather 1000
or 2000 or 10,000 years ago, given the conditions at the start of that period. But, you can't do
that either, since we don't have good enough data on previous periods. You'd want
measurements of the atmosphere and oceans at thousands of points around the globe. Instead,
we have a handful of data points.
Solar Cycles and Other Natural Causes
We know there are larger forces outside the atmosphere that affect the Earth's climate. The
Earth and Sun are moving through the galaxy, exposed to different environments as the solar
system orbits the galactic core, over a period of 225-250 million years. The eccentricity of the
Earth's orbit (difference from a perfect circle) changes over a 100,000 year period. The tilt of the
Earth on its axis varies over 41,000 years, from 21.5 degrees to 24.5 degrees. The axis of the
Earth changes direction, undergoing precession (see here) over 26,000 years. All of these
change the amount of sunlight received, and the timing of the seasons.
The 100,000 year and 41,000 year periods in these orbital changes certainly correspond to
similar periods seen in the climate data (see the 5 million year graph above.) It's certainly not a
stretch to think that the Sun has something to do with climate!
The output of the Sun itself varies. On an 11-year "Schwabe Cycle", the number of sunspots
varies. They also vary over longer periods, a 75-90-year "Gleissberg Cycle," a 200-500-year
"Suess Cycle" and a 1,100-1,500-year "Bond Cycle." In the National Post article here, R.
Timothy Patterson says that a close correlation between the output of the Sun and climate is
seen:
Our finding of a direct correlation between variations in the brightness of the sun and earthly
climate indicators (called "proxies") is not unique. Hundreds of other studies, using proxies from
tree rings in Russia's Kola Peninsula to water levels of the Nile, show exactly the same thing:
The sun appears to drive climate change.
Sunspots have been counted continuously since around 1749, with earlier data points to 1610.
Before that, carbon-14 levels can be used as a proxy for solar activity. The last 1100 years are
shown
below.
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You can compare this data with the 2000 year temperature graph above (which unfortunately
runs the other direction.) Around 1000 AD the peak of the Medieval Warm Period, you have a
maximum in solar activity. Similarly, the modern warm spell also corresponds to a peak. The
Little Ice Age on the other hand, lines up with a minimum of activity.
The brightness of the sun doesn't vary enough to cause these effects on temperature, so until
recently, there was no mechanism that would explain this. However, it was shown in a
laboratory experiment that cosmic rays could affect cloud formation. If I understand correctly, an
increase in solar activity increases the Sun's solar wind, which shields the Earth from cosmic
rays. This in turn means fewer clouds form, allowing more sunlight to reach the ground. In times
when solar activity is low, the reverse happens, and more clouds are formed, resulting in less
sunlight.
This is the "deniers" answer to the current change in climate. The sun is more active than it has
been in 8000 years. This is heating the Earth. The CO2 increase results from the oceans
releasing the gas as they warm. Human-produced CO2 is a minor factor.
There are some reports of similar changes on Mars, which would naturally also be warmed by
changes in the Sun (though I would think that cloud formation would happen differently in the
Martian atmosphere, and that the solar wind would naturally thin farther out, making Mars less
sensitive.) See here for more information, or here for a rebuttal of the whole idea (warming site
RealClimate.)
Bad Data
We've seen that the climate is extremely variable, over both the longest timescales and the
shortest. We're told that temperature has risen one degree centigrade in the last 100 years. As
we've seen, shifts this large happen to the climate all the time. In the National Post article by R.
Timothy Patterson here, we have this paragraph:
Ours is one of the highest-quality climate records available anywhere today and in it we see
obvious confirmation that natural climate change can be dramatic. For example, in the middle of
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a 62-year slice of the record at about 4,400 years ago, there was a shift in climate in only a
couple of seasons from warm, dry and sunny conditions to one that was mostly cold and rainy
for several decades.
We're not even sure that the temperature data is correct. I've listed a few of the
criticisms - that various reconstructed temperature sequences don't agree and that
modern temperature data (from weather stations) may be biased due to the growth of
cities around the stations. What data we do have doesn't cover the whole world (far
from it), so some of the effects we've seen may be local.
The timing of the modern warming doesn't really correspond very well to CO 2 levels
(which Jaworowski thinks are also poorly reconstructed.) The 2000 year graph above
has some reconstructions that show a continuous temperature increase since the worst
of the Little Ice Age in 1600 -- long before industrialization could have played a role.
The solar cycle certainly seems to have some effect on climate. Even if we are definitely
warming, you'd have to subtract the influence of the solar cycle to gauge the human
impact.
Most of the concern about the future comes not from any measurement, or any simple
theory of what will happen. Instead, it comes from predictions produced by extremely
complicated computer models. Models which are known to be incomplete and which
can't be realistically tested against real data (not for decades yet.)
You and I can't directly evaluate these models, but it's not as if these are the only
computer models in existence. Models are used for all kinds of things we are familiar
with. Computer models give us our daily weather forecasts. Computer models predict
hurricane and tornado tracks during a storm. Computer models are used by traders on
stock exchanges. We have experience with these models and how accurate they are.
Climate models are the biggest models around, with less of a track record than any
other economic or weather model.
If someone told you they had a computer model that would predict the size of the
economy in 2100, you'd laugh. If they demanded (and got) a massive government
spending program based on this model, you'd be angry. Yet the warming model must
include an economic model. The economic model tells you how much CO 2 is being put
into the atmosphere, which then drives the climate model. If the economic model is
wrong, so is the climate model.
It's certainly possible that we are scaring ourselves over nothing. It has happened
before! In the 1970's, science was just as certain that the world was going into a new ice
age. They were sure that this was imminent because temperature was falling from the
1940's to the 1970's. If they had had access to the ice core data, they would have been
even more certain. The graphs above show that the Earth has been in an ice age for
millions of years, and our brief warm period is already as long as the typical warming
every 100,000 years.
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But the predictions of a new ice age were wrong. After 1975, the climate started to
warm again. We think of the climate as stable, but it's not. We think the current climate
is normal, but we're wrong. We have to remember that these events happen on a much
longer timescale than human lives or even human history. The period we live in is a
brief gap in an ice age lasting millions of years.
Think of it another way. If the dust bowl drought of the 1930's were to happen today,
everyone would blame it on global warming. Yet there's no way that global temperature
had increased enough in the 1930's to cause droughts. In fact, the geological record in
the Southwest says that droughts have come and gone for millennia, and that some
droughts naturally lasted over 100 years.
So when you look at the global warming idea, you could just put it down to us not having
a long enough experience to know what's "normal." We're like mayflies who have never
seen summer and think it's the end of the world.
REFERENCES:
http://thinkprogress.org/climate/2012/08/17/706311/the-shape-of-droughts-to-come2012-versus-the-1930s-dust-bowl/?mobile=nc
http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/07/17/how-droughts-willreshape-the-united-states/
http://thinkprogress.org/climate/2012/05/13/483247/james-hansen-is-correct-aboutcatastrophic-projections-for-us-drought-if-we-dont-act-now/
http://www.c2es.org/publications/extreme-weather-and-climate-change
http://www.aljazeera.com/indepth/features/2012/08/20128218556871733.html
http://www.brighthub.com/environment/science-environmental/articles/66413.aspx
http://www.nature.com/news/wildfires-ignite-debate-on-global-warming-1.11025
http://www.free-the-memes.net/writings/warming/warming.html
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