Transcript CO2 Variations, 1999 Mauna Loa, Hawaii

Global Warming
Inez Fung
University of California, Berkeley
April 2007
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
Analysis of ancient air
bubbles trapped in ice
Direct measurements of
atm composition in the
past centuries
Increases since 1800 due
to human activities
At equilibrium:
High CO2 --> warm; Low CO2 --> cold
J. Hans
The Last
500,000
years
and
the last
200
years
J. Hansen
Global mean temperatures are rising faster with time
Warmest 12 years:
1998,2005,2003,2002,2004,2006,
2001,1997,1995,1999,1990,2000
Period
Rate
50 0.1280.026
100 0.0740.018
Years /decade
IPCC AR4
Drought is increasing most places
The mostin rain
Mainly decrease
over landimportant
in tropicsspatial
and
pattern
(top) of
subtropics,
but enhanced
the atmospheric
monthly
by increased
Drought
demand Palmer
with warming
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
Warming
Increase cloud cover;
Decrease absorption of solar
energy
Decrease snow cover;
Decrease reflectivity of
surface
Increase absorption of solar
energy
Attribution
• are observed
changes
consistent with
expected
responses to
forcings
inconsistent
with alternative
explanations
IPCC AR4
Observations
Climate model:
All forcing
Climate model:
Solar+volcanic
only
Projections of
Climate Change
9oF
7oF
3oF
IPCC AR4
Projections of Climate Change
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
Jay Zwally
Stern Review 2006
Strong action is needed urgently