Poor Polar Bears
Black Carbon, Arctic Sea Ice and Himalayan Glaciers
The Problem: Scientist have long found evidence that heat-trapping gases are causing an increase in the amount of
sea ice that melts each year in the arctic. This increase in melting is causing many problems for local ecosystems (poor
polar bears) and may have long term effects on other earth systems such as air temperature, weather patterns, ocean
circulation and the water cycle. These changes directly impact us even though we are far from the arctic. Recently
scientists have found evidence that black carbon is playing a major role in increasing the rate at which glacial and
possibly sea ice melts. It is your job as a team to evaluate the effects of black carbon and to make recommendations as
to how we can reduce the effects of black carbon on melting glacial and sea ice.
Your Task:
Part 1 (DAY 1) – Become a black carbon expert. In order to solve this problem you will need to understand what
black carbon (BC) is where it comes from and what it does. You will also need to understand something called
albedo. Use the links provided as well as the materials in your folder to help you find answers to the questions
below as well as any other questions you can think of. How you organize your team is up to you. Consider dividing
the readings into sections, each of you read one section and summarize important details for the group. Remember,
even though you are working as a team, it is your responsibility to make sure you understand everything. You may
need to search for additional sources of information.



Resources:
http://www.economist.com/node/21530079 Arctic sea ice is melting far faster than climate models predict.
Why? (HC = hard copy provided)
https://www.windows2universe.org/earth/changing_planet/black_carbon_intro.html BC video
http://www.nytimes.com/2009/04/16/science/earth/16degrees.html?_r=1 Third-World Stove Soot Is Target in
Climate Fight(HC)
http://www.giss.nasa.gov/research/news/20050323 simple explanation of the effects of BC
http://www.nytimes.com/slideshow/2009/04/16/world/20090416INDIA_index.html photo’s of BC issues in poor
countries
http://msdavisapes.wikispaces.com/In+class+resources power point introduction to BC and albedo
http://www.arb.ca.gov/board/books/2012/052412/12-3-2-2pres.pdf presentation on black carbon
http://csc.noaa.gov/psc/dataviewer/#view=aerosols animation showing black carbon and dust
1.
2.
3.
4.
5.
6.
Questions:
How is black carbon (BC) emitted into the atmosphere?
What are the different sources of BC in the southern and northern hemisphere?
How does BC get to the arctic?
In which pole does BC precipitate out in snow and Ice? From which hemisphere does this BC come from?
What is albedo? How does black carbon change the albedo of ice?
What earth spheres are affected by this issue? Give examples of how changes in one sphere affect other spheres.





Part 2 (DAY 2)
1. Become an expert on albedo and heat transfer. Use the links below and the materials in your packet to build
your understanding of albedo.
 http://eo.ucar.edu/educators/ClimateDiscovery/ESS_lesson4_10.19.05.pdf Earth’s Energy Cycle: Albedo
(hard copy and materials provided)
 http://www.eoearth.org/article/Albedo?topic=54300 background on albedo with maps
 http://blogs.nasa.gov/cm/blog/whatonearth/posts/post_1292991500275.html video and article showing sea
ice change 1980-2010
 A Dusty Situation – black carbon activity (materials included)





2. Understand how black carbon is studied in the atmosphere.
http://hippo.ucar.edu/HIPPO/about-hippo background on the HIPPO project
http://www.youtube.com/watch?v=NoHnY6a2dbs&feature=youtu.be hippo route animation
http://hippo.ucar.edu/field-notes/hippo-ii-flights/hippo-flight-8-honiara-solomon-islands-to-konahi#ii_rf08_flight_video video showing change in altitude of plane
http://hippo.ucar.edu/HIPPO/videos/sampling-black-carbon-over-arctic-sea-ice-and-open-leads scientist explaining
why he studies black carbon over arctic sea ice
http://hippo.ucar.edu/instruments/aerosols-cloud-physics#sp2 info about HIPPO instruments collecting BC data
3. Understand how ice cores provide data on the atmosphere
 http://www.pbs.org/wgbh/nova/warnings/stories/ explanation and visual of ice cores Stories in the Ice (HC)
 Complete the enclosed activity: Create Your Own Ice Core or A Dusty Situation (divide and conquer).
Part 3 (DAY 3) – Data Analysis
1. Read these articles to build your background in how ice cores give us data on historical BC in the Himalayas:
 http://www.giss.nasa.gov/research/briefs/hansen_14 best article on ice cores and BC in Himalayas
 http://newscenter.lbl.gov/feature-stories/2010/02/03/black-carbon-himalayan-glaciers/ (HC)
2. Go to: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/trop/everest/rongbuk2008bc.txt to view BC data
from a Himalayan ice core taken from the East Rongbuk Glacier on Mt Everest. Make sure you scroll down to
locate the black carbon data.
3. Work as a group to graph the black carbon found in the ice core over the 50 year time period.
4. View the data in this power point: http://msdavisapes.wikispaces.com/In+class+resources
5. Work as a group to determine what the data tells you. You could start by considering the following questions:
o Is there a link between the amount of black carbon in the ice and rate or scale of glacial retreat in the
Himalayas?
o When is black carbon most prevalent in the atmosphere of the northern hemisphere?
o What is the source of this black carbon?
o What has caused the increase in black carbon in the Himalayas?
Be sure you are asking yourselves more questions. These are just a start.
Part 4 (DAY 4) – Recommendations
Now that you have some evidence that black carbon increases the rate at which ice melts, what are you going to
do about it? Time to save the polar bears. Make a list of recommendations for reducing the amount of black
carbon that reaches the arctic. Use the information and data you have collected to create convincing options
that the rest of us (and the world) can buy into.
You will share your results in a brief presentation to the class. Create a Prezi or PowerPoint using the following
guide:
 Presentation length (8-10 minutes)
o 2 minutes – background
o 2 minutes – what you learned from your data analysis
o 4 minutes – your recommendations and why they would work
o 2 minutes for questions
 Each member of your group must participate in the presentation
 Be clear so others can get a good overview of your case study
 Write 2-3 clicker questions to be used both before and after your presentation to gauge the feelings and
opinions of your audience. This should provide you a measure of how your presentation informed you
audience and changed their perceptions. These could be multiple choice, short answer, or likert scale.
Extracting ice cores in Greenland
Photo taken from: http://earthobservatory.nasa.gov/Features/Paleoclimatology_IceCores/
Photographs of East Rongbuk Glacier, 1921 (left) versus
2008. Images courtesy of Major E.O. Wheeler, Royal Geographic Society; David Breshears
Beating a retreat
Arctic sea ice is melting far faster than climate
models predict. Why?
Sep 24th 2011 | from the print edition
ON SEPTEMBER 9th, at the height of its summertime shrinkage, ice covered 4.33m square km, or 1.67m
square miles, of the Arctic Ocean, according to America's National Snow and Ice Data Centre (NSIDC). That is
not a record low—not quite. But the actual record, 4.17m square km in 2007, was the product of an unusual
combination of sunny days, cloudless skies and warm currents flowing up from mid-latitudes. This year has
seen no such opposite of a perfect storm, yet the summer sea-ice minimum is a mere 4% bigger than that record.
Add in the fact that the thickness of the ice, which is much harder to measure, is estimated to have fallen by half
since 1979, when satellite records began, and there is probably less ice floating on the Arctic Ocean now than at
any time since a particularly warm period 8,000 years ago, soon after the last ice age.
That Arctic sea ice is disappearing has been known for decades. The underlying cause is believed by all but a
handful of climatologists to be global warming brought about by greenhouse-gas emissions. Yet the rate the ice
is vanishing confounds these climatologists' models. These predict that if the level of carbon dioxide, methane
and so on in the atmosphere continues to rise, then the Arctic Ocean will be free of floating summer ice by the
end of the century. At current rates of shrinkage, by contrast, this looks likely to happen some time between
2020 and 2050.
The reason is that Arctic air is warming twice as fast as the atmosphere as a whole. Some of the causes of this
are understood, but some are not. The darkness of land and water compared with the reflectiveness of snow and
ice means that when the latter melt to reveal the former, the area exposed absorbs more heat from the sun and
reflects less of it back into space. The result is a feedback loop that accelerates local warming. Such feedback,
though, does not completely explain what is happening. Hence the search for other things that might assist the
ice's rapid disappearance.
Forcing the issue
One is physical change in the ice itself. Formerly a solid mass that melted and refroze at its edges, it is now
thinner, more fractured, and so more liable to melt. But that is (literally and figuratively) a marginal effect.
Filling the gap between model and reality may need something besides this.
The latest candidates are “short-term climate forcings”. These are pollutants, particularly ozone and soot, that
do not hang around in the atmosphere as carbon dioxide does, but have to be renewed continually if they are to
have a lasting effect. If they are so renewed, though, their impact may be as big as CO2's.
At the moment, most eyes are on soot (or “black carbon”, as jargon-loving researchers refer to it). In the Arctic,
soot is a double whammy. First, when released into the air as a result of incomplete combustion (from sources
as varied as badly serviced diesel engines and forest fires), soot particles absorb sunlight, and so warm up the
atmosphere. Then, when snow or rain wash them onto an ice floe, they darken its surface and thus cause it to
melt faster.
Reducing soot (and also ozone, an industrial pollutant that acts as a greenhouse gas) would not stop the summer
sea ice disappearing, but it might delay the process by a decade or two. According to a recent report by the
United Nations Environment Programme, reducing black carbon and ozone in the lower part of the atmosphere,
especially in the Arctic countries of America, Canada, Russia and Scandinavia, could cut warming in the Arctic
by two-thirds over the next three decades. Indeed, the report suggests, if such measures—preventing crop
burning and forest fires, cleaning up diesel engines and wood stoves, and so on—were adopted everywhere they
could halve the wider rate of warming by 2050.
Without corresponding measures to cut CO2 emissions, this would be but a temporary fix. Nonetheless, it is an
attractive idea because it would have other benefits (soot is bad for people's lungs) and would not require the
wholesale rejigging of energy production which reducing CO2 emissions implies. Not everyone agrees it would
work, though. Gunnar Myhre of the Centre for International Climate and Environmental Research in Oslo, for
example, notes that the amount of black carbon in the Arctic is small and has been falling in recent decades. He
does not believe it is the missing factor in the models. Carbon dioxide, in his view, is the main culprit. Black
carbon deposited on the Arctic snow and ice, he says, will have only a minimal effect on its reflectivity.
The rapid melting of the Arctic sea ice, then, illuminates the difficulty of modelling the climate—but not in a
way that brings much comfort to those who hope that fears about the future climate might prove exaggerated.
When reality is changing faster than theory suggests it should, a certain amount of nervousness is a reasonable
response.
It's an ill wind…
The direct consequences of changes in the Arctic are mixed. They should not bring much rise in the sea level,
since floating ice obeys Archimedes's principle and displaces its own mass of water. A darker—and so more
heat-absorbent—Arctic, though, will surely accelerate global warming and may thus encourage melting of the
land-bound Greenland ice sheet. That certainly would raise sea levels (though not as quickly as News
Corporation's cartographers suggest in the latest edition of the best-selling “Times Atlas”, which claims that
15% of the Greenland sheet has melted in the past 12 years; the true figure is more like 0.05%). Wildlife will
also suffer. Polar bears, which hunt for seals along the ice's edge, and walruses, which fish there, will both be
hard-hit.
The effects on the wider climate are tricky to assess. Some meteorologists suspect unseasonal snow storms off
the east coast of America in 2010 were partly caused by Arctic warming shifting wind patterns. One feedback
loop that does seems certain, though, is that the melting Arctic will enable the extraction of more fossil fuel,
with all that that implies for greenhouse-gas emissions.
The Arctic is reckoned to hold around 15% of the world's undiscovered oil reserves and 30% of those of natural
gas. Hence a growing polar enthusiasm among energy companies—as witnessed last month in an Arctic tie-up
between Exxon Mobil, of America, and Rosneft, Russia's state-controlled oil giant. Recent plankton blooms
suggest a warmer Arctic will provide a boost to fisheries there, too. And the vanishing ice has begun to allow a
trickle of shipping across the Arctic's generally frozen north-west and north-east passages, thus linking the
Atlantic and Pacific oceans. In August a Russian supertanker, the Vladimir Tokohonov, aided by two nuclear
icebreakers, became the first such vessel to cross the north-east route (or, as Russians refer to it, the northern sea
route), hugging the Siberian coast.
So far, despite some posturing by Canada and Russia, there are few territorial disputes in the region and the
Arctic Council, the club of Arctic nations, has functioned reasonably well. Whether the interests of these
countries coincide with those of the wider world, though, is moot. A warming Arctic will bring local benefits to
some. The rest of the world may pay the cost.
By Degrees
Third-World Stove Soot Is Target in Climate Fight
Adam Ferguson for The New York Times
Cooking in Kohlua, India. Soot from tens of thousands of villages in developing countries is responsible for 18 percent of
the planet’s warming, studies say.
By ELISABETH ROSENTHAL
Published: April 15, 2009
KOHLUA, India — “It’s hard to believe that this is what’s melting the glaciers,” said Dr. Veerabhadran
Ramanathan, one of the world’s leading climate scientists, as he weaved through a warren of mud brick huts,
each containing a mud cookstove pouring soot into the atmosphere.
As women in ragged saris of a thousand hues bake bread and stew lentils in the early evening over fires fueled by twigs
and dung, children cough from the dense smoke that fills their homes. Black grime coats the undersides of thatched
roofs. At dawn, a brown cloud stretches over the landscape like a diaphanous dirty blanket.
In Kohlua, in central India, with no cars and little electricity, emissions of carbon dioxide, the main heattrapping gas linked to global warming, are near zero. But soot — also known as black carbon — from tens of
thousands of villages like this one in developing countries is emerging as a major and previously unappreciated
source of global climate change.
While carbon dioxide may be the No. 1 contributor to rising global temperatures, scientists say, black carbon
has emerged as an important No. 2, with recent studies estimating that it is responsible for 18 percent of the
planet’s warming, compared with 40 percent for carbon dioxide. Decreasing black carbon emissions would be a
relatively cheap way to significantly rein in global warming — especially in the short term, climate experts say.
Replacing primitive cooking stoves with modern versions that emit far less soot could provide a much-needed
stopgap, while nations struggle with the more difficult task of enacting programs and developing technologies
to curb carbon dioxide emissions from fossil fuels.
In fact, reducing black carbon is one of a number of relatively quick and simple climate fixes using existing
technologies — often called “low hanging fruit” — that scientists say should be plucked immediately to avert
the worst projected consequences of global warming. “It is clear to any person who cares about climate change
that this will have a huge impact on the global environment,” said Dr. Ramanathan, a professor of climate
science at the Scripps Institute of Oceanography, who is working with the Energy and Resources Institute in
New Delhi on a project to help poor families acquire new stoves.
“In terms of climate change we’re driving fast toward a cliff, and this could buy us time,” said Dr. Ramanathan,
who left India 40 years ago but returned to his native land for the project.
Better still, decreasing soot could have a rapid effect. Unlike carbon dioxide, which lingers in the atmosphere
for years, soot stays there for a few weeks. Converting to low-soot cookstoves would remove the warming
effects of black carbon quickly, while shutting a coal plant takes years to substantially reduce global CO2
concentrations.
But the awareness of black carbon’s role in climate change has come so recently that it was not even mentioned
as a warming agent in the 2007 summary report by the Intergovernmental Panel on Climate Change that
pronounced the evidence for global warming to be “unequivocal.” Mark Z. Jacobson, professor of
environmental engineering at Stanford, said that the fact that black carbon was not included in international
climate efforts was “bizarre,” but “partly reflects how new the idea is.” The United Nations is trying to figure
out how to include black carbon in climate change programs, as is the federal government.
In Asia and Africa, cookstoves produce the bulk of black carbon, although it also emanates from diesel engines
and coal plants there. In the United States and Europe, black carbon emissions have already been reduced
significantly by filters and scrubbers.
Like tiny heat-absorbing black sweaters, soot particles warm the air and melt the ice by absorbing the sun’s heat
when they settle on glaciers. One recent study estimated that black carbon might account for as much as half of
Arctic warming. While the particles tend to settle over time and do not have the global reach of greenhouse
gases, they do travel, scientists now realize. Soot from India has been found in the Maldive Islands and on the
Tibetan Plateau; from the United States, it travels to the Arctic. The environmental and geopolitical implications
of soot emissions are enormous. Himalayan glaciers are expected to lose 75 percent of their ice by 2020,
according to Prof. Syed Iqbal Hasnain, a glacier specialist from the Indian state of Sikkim.
These glaciers are the source of most of the major rivers in Asia. The short-term result of glacial melt is severe
flooding in mountain communities. The number of floods from glacial lakes is already rising sharply, Professor
Hasnain said. Once the glaciers shrink, Asia’s big rivers will run low or dry for part of the year, and desperate
battles over water are certain to ensue in a region already rife with conflict.
Doctors have long railed against black carbon for its devastating health effects in poor countries. The
combination of health and environmental benefits means that reducing soot provides a “very big bang for your
buck,” said Erika Rosenthal, a senior lawyer at Earth Justice, a Washington organization. “Now it’s in
everybody’s self-interest to deal with things like cookstoves — not just because hundreds of thousands of
women and children far away are dying prematurely.”
In the United States, black carbon emissions are indirectly monitored and minimized through federal and state
programs that limit small particulate emissions, a category of particles damaging to human health that includes
black carbon. But in March, a bill was introduced in Congress that would require the Environmental Protection
Agency to specifically regulate black carbon and direct aid to black carbon reduction projects abroad, including
introducing cookstoves in 20 million homes. The new stoves cost about $20 and use solar power or are more
efficient. Soot is reduced by more than 90 percent. The solar stoves do not use wood or dung. Other new stoves
simply burn fuel more cleanly, generally by pulverizing the fuel first and adding a small fan that improves
combustion.
That remote rural villages like Kohlua could play an integral role in tackling the warming crisis is hard to
imagine. There are no cars — the village chief’s ancient white Jeep sits highly polished but unused in front of
his house, a museum piece. There is no running water and only intermittent electricity, which powers a few
light bulbs.
The 1,500 residents here grow wheat, mustard and potatoes and work as day laborers in Agra, home of the Taj
Majal, about two hours away by bus.
They earn about $2 a day and, for the most part, have not heard about climate change. But they have noticed
frequent droughts in recent years that scientists say may be linked to global warming. Crops ripen earlier and rot
more frequently than they did 10 years ago. The villagers are aware, too, that black carbon can corrode. In Agra,
cookstoves and diesel engines are forbidden in the area around the Taj Majal, because soot damages the
precious facade.
Still, replacing hundreds of millions of cookstoves — the source of heat, food and sterile water — is not a
simple matter. “I’m sure they’d look nice, but I’d have to see them, to try them,” said Chetram Jatrav, as she
squatted by her cookstove making tea and a flatbread called roti. Her three children were coughing.
She would like a stove that “made less smoke and used less fuel” but cannot afford one, she said, pushing a
dung cake bought for one rupee into the fire. She had just bought her first rolling pin so her flatbread could
come out “nice and round,” as her children had seen in elementary school. Equally important, the open fires of
cookstoves give some of the traditional foods their taste. Urging these villagers to make roti in a solar cooker
meets the same mix of rational and irrational resistance as telling an Italian that risotto tastes just fine if cooked
in the microwave.
In March, the cookstove project, called Surya, began “market testing” six alternative cookers in villages, in part
to quantify their benefits. Already, the researchers fret that the new stoves look like scientific instruments and
are fragile; one broke when a villager pushed twigs in too hard.
But if black carbon is ever to be addressed on a large scale, acceptance of the new stoves is crucial. “I’m not
going to go to the villagers and say CO2 is rising, and in 50 years you might have floods,” said Dr. Ibrahim
Rehman, Dr. Ramanathan’s collaborator at the Energy and Resources Institute. “I’ll tell her about the lungs and
her kids and I know it will help with climate change as well.”
Stories in the Ice
by Peter Tyson
Online Producer, NOVA
Nature's Time Machine
How would you like to have a time machine that could take you back anywhere over the past 300,000
years? You could see what the world was like when ice sheets a thousand feet thick blanketed
Canada and northern Europe, or when the Indonesian volcano Toba blew its top in the largest
volcanic eruption of the last half million years.
Well, scientists have such a time machine. It's called an ice core. Scientists collect ice cores by
driving a hollow tube deep into the miles-thick ice sheets of Antarctica and Greenland (and in glaciers
elsewhere). The long cylinders of ancient ice that they retrieve provide a dazzlingly detailed record of
what was happening in the world over the past several ice ages. That's because each layer of ice in a
core corresponds to a single year—or sometimes even a single season—and most everything that fell
in the snow that year remains behind, including wind-blown dust, ash, atmospheric gases, even
radioactivity.
Indeed, fallout from the Chernobyl nuclear accident has turned up in ice cores, as has dust from
violent desert storms countless millennia ago. Collectively, these frozen archives give scientists
unprecedented views of global climate over the eons. More important, the records allow researchers
to predict the impact of significant events—from volcanic eruptions to global warming—that could
strike us today.
The Ice Core Timeline requires JavaScript support in your browser. If your browser doesn't support
JavaScript, please try the non-JavaScript version.
Ice Core Timeline (see website)
Special thanks to Mark Twickler, University of New Hampshire
Taken from: http://www.pbs.org/wgbh/nova/warnings/stories/
Black Carbon A Significant Factor in the Melting of Himalayan Glaciers
Berkley Labs
February 03, 2010
Julie Chao 510-486-6491 JHChao@lbl.gov
Feature
The fact that glaciers in the Himalayan mountains are thinning is not disputed. However, few researchers have
attempted to rigorously examine and quantify the causes. Lawrence Berkeley National Laboratory scientist
Surabi Menon set out to isolate the impacts of the most commonly blamed culprit—greenhouse gases, such as
carbon dioxide—from other particles in the air that may be causing the melting. Menon and her collaborators
found that airborne black carbon aerosols, or soot, from India is a major contributor to the decline in snow and
ice cover on the glaciers.
“Our simulations showed greenhouse gases alone are not nearly enough to be responsible for the snow melt,”
says Menon, a physicist and staff scientist in Berkeley Lab’s Environmental Energy Technologies Division.
“Most of the change in snow and ice cover—about 90 percent—is from aerosols. Black carbon alone
contributes at least 30 percent of this sum.”
Menon and her collaborators used two sets of aerosol inventories by Indian researchers to run their simulations;
their results were published online in the journal Atmospheric Chemistry and Physics.
The actual contribution of black carbon, emitted largely as a result of burning fossil fuels and biomass, may be
even higher than 30 percent because the inventories report less black carbon than what has been measured by
observations at several stations in India. (However, these observations are too incomplete to be used in climate
models.) “We may be underestimating the amount of black carbon by as much as a factor of four,” she says.
The findings are significant because they point to a simple way to make a swift impact on the snow melt.
“Carbon dioxide stays in the atmosphere for 100 years, but black carbon doesn’t stay in the atmosphere for
more than a few weeks, so the effects of controlling black carbon are much faster,” Menon says. “If you control
black carbon now, you’re going to see an immediate effect.”
The Himalayan glaciers are often referred to as the third polar ice cap because of the large amount of ice mass
they hold. The glacial melt feeds rivers in China and throughout the Indian subcontinent and provide fresh water
to more than one billion people.
Atmospheric aerosols are tiny particles containing nitrates, sulfates, carbon and other matter, and can influence
the climate. Unlike other aerosols, black carbon absorbs sunlight, similar to greenhouse gases. But unlike
greenhouse gases, black carbon does not heat up the surface; it warms only the atmosphere.
This warming is one of two ways in which black carbon melts snow and ice. The second effect results from the
deposition of the black carbon on a white surface, which produces an albedo effect that accelerates melting. Put
another way, dirty snow absorbs far more sunlight—and gets warmer faster—than pure white snow.
Previous studies have shown that black carbon can have a powerful effect on local atmospheric temperature.
“Black carbon can be very strong,” Menon says. “A small amount of black carbon tends to be more potent than
the same mass of sulfate or other aerosols.”
Black carbon, which is caused by incomplete combustion, is especially prevalent in India and China; satellite
images clearly show that its levels there have climbed dramatically in the last few decades. The main reason for
the increase is the accelerated economic activity in India and China over the last 20 years; top sources of black
carbon include shipping, vehicle emissions, coal burning and inefficient stoves. According to Menon’s data,
black carbon emitted in India increased by 46 percent from 1990 to 2000 and by another 51 percent from 2000
to 2010.
This map of the change in annual linear snow cover from 1990 to 2001 shows a thick band (blue) across the
Himalayas with decreases of at least 16 percent while a few smaller patches (red) saw increases. The data was
collected by the National Snow and Ice Data Center.
However, black carbon’s effect on snow is not linear. Menon’s simulations show that snow and ice cover over
the Himalayas declined an average of about one percent from 1990 to 2000 due to aerosols that originated from
India. Her study did not include particles that may have originated from China, also known to be a large source
of black carbon. (See “Black soot and the survival of the Tibetan glaciers,” by James Hansen, et al., published
last year in the Proceedings of the National Academy of Sciences.) Also the figure is an average for the entire
region, which saw increases and decreases in snow cover. As seen in the figure, while a large swath of the
Himalayas saw snow cover decrease by at least 16 percent over this period, as reported by the National Snow
and Ice Data Center, a few smaller patches saw increases.
Menon’s study also found that black carbon affects precipitation and is a major factor in triggering extreme
weather in eastern India and Bangladesh, where cyclones, hurricanes and flooding are common. It also
contributes to the decrease in rainfall over central India. Because black carbon heats the atmosphere, it changes
the local heating profile, which increases convection, one of the primary causes of precipitation. While this
results in more intense rainfall in some regions, it leads to less in other regions. The pattern is very similar to a
study Menon led in 2002, which found that black carbon led to droughts in northern China and extreme floods
in southern China.
“The black carbon from India is contributing to the melting of the glaciers, it’s contributing to extreme
precipitation, and if black carbon can be controlled more easily than greenhouse gases like CO2, then it makes
sense for India to regulate black carbon emissions,” says Menon.
Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts
unclassified scientific research for DOE’s Office of Science and is managed by the University of California.
Visit our Website at www.lbl.gov/
Additional information: Read the paper, “Black carbon aerosols and the third polar ice cap” (see online)