Global Climate ChangeOverview

Michael D. Mastrandrea, Ph.D.

Deputy Director, Science, IPCC Working Group IIand

Assistant Consulting Professor Woods Institute for the Environment

Global climate change is…

• unequivocal,

• almost certainly caused mostly by us,

• already causing significant harm

• growing rapidly, and

• requires global action and local solutions.

The Key Facts

http://data.giss.nasa.gov/gistemp/graphs/

Warming is Unequivocal…

J. Hansen et al., PNAS 103: 14288-293 ( 2006)

…And Not Uniform

Average Surface T in 2001-2005 vs 1951-80

Muir Glacier, Alaska

NSIDC/WDC for Glaciology, Boulder, compiler. 2002, updated 2006. Online glacier photograph database. Boulder, CO: National Snow and Ice Data Center.

August 1941 August 2004

Shrinking Glaciers

1992 2002 2005

Source: ACIA, 2004, CIRES, 2005, Roger Braithwaite, University of Manchester (UK)

Surface melting on Greenland is expanding

Changing Patterns of Extreme Events

Major floods per decade, 1950-2000

Source: Westerling et al. 2006

Western US area burned

Increasing Wildfire Risk

Natural Carbon Cycle

Human Impact on the Carbon Cycle

LAND

ATMOSPHERE750 Gt C

379 ppm CO2

OCEANS

emissions fromterrestrial systems 100 Gt C per year

absorption byterrestrial systems103 Gt C per year

emissions frommarine systems100 Gt C per year

absorption bymarine systems102 Gt C per year

human-caused emissions: 9 Gt C per year

Carbon Flows (2005)

Increasing CO2 Concentrations

IPCC, 2007

IPCC, 2007

Increasing CO2 Concentrations

Ice Core Records

Source: Hansen, Clim.Change, 68, 269, 2005.

Ice Core Records

IPCC, 2007Black = ObservedGold = Human and Natural ForcingsBlue = Only Natural Forcings

Fingerprint Analysis

UCS

UCS

Projected Changes in CA Summer Temperature

2004 >9,500 ft

1900 >7,800 ft

Pika

Species Shifting and…

Diminishing Sierra SnowpackPercentage Remaining, Relative to 1961-1990

UCS

Mitigation

Adaptation

Raupach et al. 2007, PNAS

Recent emissions

1990 1995 2000 2005 2010

CO

2 E

mis

sion

s (G

tC y

-1)

5

6

7

8

9

10Actual emissions: CDIACActual emissions: EIA450ppm stabilisation650ppm stabilisationA1FI A1B A1T A2 B1 B2

1850 1900 1950 2000 2050 2100C

O2 E

mis

sion

s (G

tC y

-1)

0

5

10

15

20

25

30Actual emissions: CDIAC450ppm stabilisation650ppm stabilisationA1FI A1B A1T A2 B1 B2

20062005

Rapidly Increasing Emissions

Climate Stabilization

Raupach et al., 2007

Regional CO2 Emissions

2004 2000-2004Growth