Global Warming 101
The Earth With No Atmosphere
(infrared)
Earth’s surface would be 60F cooler than today…no life.
But the Earth has an
atmosphere!
• Includes gases
such as nitrogen
and oxygen
• Also includes
greenhouse
gases.
What is a Greenhouse Gas?
• Greenhouse gas is a gas that that is
relatively transparent to solar radiation, but
absorbers and emits in the infrared…the
type of radiation the earth emits.
• Some examples:
– Water vapor
– Carbon dioxide
– Nitrous oxide
– Methane
Earth With An Atmosphere That
Includes Greenhouse Gases
Partly
(infrared)
Greenhouse Gases Make the Earth Warmer by Slowing the Loss of Infrared Radiation
Greenhouse Gases Warm the
Earth in a Similar Way That
Blankets Warm Us at Night
The Problem:
Rapidly Rising Greenhouse
Gases Due to Mankind
Gases Trapped in Ice Gives Us a History of the
Gases in the Atmosphere
But it is worse than that…
• There are a number of natural “amplifiers”
of mankind’s emission of greenhouse
gases.
• The warming due to increased carbon
dioxide, methane, and other greenhouse
gases will cause more water to be
evaporated from the earth’s oceans.
Why?
• The amount of evaporation increases with
temperature.
• Water vapor is the most potent greenhouse
gas and thus causes even MORE warming.
• This is caused a positive feedback.
But it gets
even worse…
• Warming temperatures melt snow and ice.
• Snow and ice help cool the planet because they
reflect much of the sun’s radiation….that is why
you need sun glasses while skiing.
• As the snow, melts less radiation is reflected to
space and more is absorbed.
• Thus, the earth gets warmer, which melts more
snow.
• Another positive feedback!
Is Global Warming Already
Happening?
• Finding the global warming signal is made more
difficult because the earth’s climate has a certain
amount of natural variability.
• Also the warming due to man was relatively
small before the middle of last century before the
large increase in fossil fuel usage.
• The consensus of most atmospheric scientists is
that some global warming signal due to man is
now evident.
Eleven of the twelve warmest years
in the past 150 years have
occurred in the past twelve years
(1995-2006)
These photographs, taken in 1928 and 2000, show how South
Cascade Glacier in the Washington Cascade Mountains has
retreated over time.
But what about the future?
The Technology of Prediction
• Atmospheric scientists use complex climate
prediction models…called General Circulation
Models…to predict the future climate.
• These models are similar to weather forecast
models, but allow the gases in the atmosphere
to change.
• They also simulate the evolution of the oceans.
• Have to assume the future emission of
greenhouse gases by mankind…a major
uncertainty.
• These models are not perfect and cannot exactly
replicate the current climate….but they are close
and getting better each year.
Details on Current Study: GCM
• Which Scenario Will Mankind Follow?
IPCC Report, 2001
IPCC Report, 2001
IPCC.AR4.2007
Sample Climate Model Output for 2100
Projections of Future Changes in Climate
Projected warming
in 21st century
expected to be
greatest over land
and at most high
northern latitudes
and least over the
Southern Ocean
and parts of the
North Atlantic
Ocean
What about the Northwest
• Several of us are applying very high
resolution simulations forced by the global
climate model predictions
• Gives a view of the local implications of
global warming.
• Could our mountains and other local
features make it worse or better?
Large Drop in Snowpack in the Mountains
Key Facts
• The overwhelming majority of atmospheric
scientists believe global warming has occurred
and will became MUCH larger during the next
decade.
• This is based on the best technology and
observations available.
• There are substantial uncertainties, so we can’t
give a specific number, but a range.
• Even if increases in the emission of greenhouse
gases stop today, a certain amount of global
warming is inevitable.
Range of Global Warming
Global Warming Goes Political
and Reaches the Public Arena
Inconvenient
Truth: Basically
Accurate But
Contains a Few
Errors
Downplays
Global
Warming:
Full of Major
Errors
The Day After Tomorrow: Global
Warming Causes Ice Age:
Complete Nonsense
Mayor Nickels and Global
Warming
• Claims of a 50% reduction in Cascade
snowpack due to global warming are
simply not true.
• Perhaps 10-15%
With a lack of Federal response,
States are beginning to push
significant responses to global
warming.
Bottom Line
• Global warming and its local implications are
extraordinarily serious.
• There are significant uncertainties, but they are
NOT in whether global warming will occur, but
rather the magnitude and its local effects.
• With the large current population of the planet,
we lack a margin of safety.
• There is much the world can do to lessen
greenhouse gas emissions (e.g., better fuel
mileage on cars, new transportation
technologies, new energy technologies, etc)
The Torah Example
• Joseph foresaw a major shift in climate…not
unlike modern scientists.
• He was able to get the attention of the powers
that be…the Pharoah… convincing him of the
threat and providing a plan of action.
• Joseph managed the plan and saved Egypt,
Israel, and other nations.
• Can we show similar foresight
and active response today?
The End