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Global Warming. Inez Fung University of California, Berkeley April 21 2007. Climate Change: Recent News. Feb 7 2007: United Nations Env Programme - Intergovt Panel on Climate Change - observed warming since the 20 th C is very likely due to anthropogenic greenhouse gases

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Global warming

Global Warming

Inez Fung

University of California, Berkeley

April 21 2007


Climate change recent news
Climate Change: Recent News

  • Feb 7 2007: United Nations Env Programme - Intergovt Panel on Climate Change - observed warming since the 20thC is very likely due to anthropogenic greenhouse gases

  • April 2 2007: US Supreme Court: anthropogenic CO2 is a pollutant

  • April 7 2007: UNEP IPCC WG 2 - warming has had discernible influence on physical and biological systems


Changing composition of the atmosphere
Changing Composition of the Atmosphere

Analysis of ancient air bubbles trapped in ice

Direct measurements of atm composition in the past centuries

Increases since 1800 due to human activities


CO2

CH4

T

Now

400,000 yr


At equilibrium high co 2 warm low co 2 cold
At equilibrium:High CO2 --> warm; Low CO2 --> cold

J. Hansen


The last 500 000 years and the last 200 years
The Last 500,000 yearsand the last 200 years

J. Hansen


Warmest 12 years:

1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000

50 0.1280.026

100 0.0740.018

Global mean temperatures are rising faster with time

Period Rate

Years /decade

IPCC AR4


Drought is increasing most places

Mainly decrease in rain over land in tropics and subtropics, but enhanced by increased atmospheric demand with warming

The most important spatial pattern (top) of the monthly Palmer Drought Severity Index (PDSI) for 1900 to 2002.

The time series (below) accounts for most of the trend in PDSI.

IPCC AR4


Climate feedbacks

Evaporation from ocean,

Increase water vapor in atm

Enhance greenhouse effect

Increase cloud cover;

Decrease absorption of solar energy

Decrease snow cover;

Decrease reflectivity of surface

Increase absorption of solar energy

Climate Feedbacks

Warming


Attribution

Observations

Attribution

  • are observed changes consistent with

  • expected responses to forcings

  • inconsistent with alternative explanations

Climate model: All forcing

Climate model: Solar+volcanic only

IPCC AR4


Projections of climate change

9oF

7oF

3oF

Projections of Climate Change

IPCC AR4


Projections of climate change1
Projections of Climate Change

2020-2029

2090-2099

greatest over land & at most high N latitudes

and least over the

South. Ocean

& parts of the

N Atlantic

Ocean

IPCC AR4


Warming is faster than model projections recent rapid melting glaciers on greenland
Warming is faster than model projections: Recent rapid melting glaciers on Greenland

Jay Zwally


Stern Review 2006 melting glaciers on Greenland


2000 melting glaciers on Greenland

2020

Stern Review 2006


Strong action is needed urgently
Strong action is needed urgently melting glaciers on Greenland

Stern Review 2006


Processes in climate models
Processes in Climate Models melting glaciers on Greenland

  • Radiative transfer: solar & terrestrial

  • phase transition of water

  • Convective mixing

  • cloud microphysics

  • Evapotranspirat’n

  • Movement of heat and water in soils


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