Global Climate Change

150Authors

1,000Contributing Authors

5 Years Work130 Countries

1,000 Expert Reviewers

The Famous “IPCC Report”

VostokIce Core

Looking Back in Time

Temperature From 650,000 Years Ago

N20

CH4

CO2

T

Thousands years before 1950

Temperature From 1,300 Years Ago

Year

Little Ice Age

Medieval Warm Period

Tem

pera

ture

Cha

nge

(°C

)

Temperature From 150 Years Ago

Year

~1°C

Tem

pera

ture

Cha

nge

(°C

)

Surface Above

Where is This Happening?

An Explosion of New Data

• Oceans are warming

• Glaciers are retreating

• Ice sheets are melting

• Sea level is rising

• Sea-ice is melting

Oceans are Warming

Year

Hea

t C

onte

nt C

hang

e

Photos: US Geological Service, via National Snow and Ice DataCentre

1909

Toboggan Glacier, Alaska

2000

Glaciers are Retreating

Year

Leng

th C

hang

e (m

)

Ice Sheets are Melting

Elevation Change (cm/year)

Reconstructedsea level fields

Tide gauges

Satellites

Sea Level is Rising

~20 cm

Year

Sea

Lev

el C

hang

e (m

m)

Sea-ice is Melting

Year

Mill

ions

of

squa

re k

m

Why is This Happening?

• Climate models used to understand and predict climate change

• Based on physical principles, and subject to extensive validation

ObservationsClimate Models

ObservationsClimate Models

What About the Next 20 Years?

0.5°C

What About the Next 90 Years?

1-4°C

And the Next 300 Years?

Expect Sea Level Rise ~ 0.5 m

Sea Level Change Anomalies

Expect Large Warming Over Land

Temperature Change (°C)

Expect Regional Precipitation Change

Precipitation Change

Heavier Precipitation

Longer Growing SeasonMore Heat Waves

More Drought

Winners and Losers

Key Messages

• The climate has warmed, will continue to warm, and humans are the cause

• Mitigation will not substantially affect the climate over the next few decades

• But, choices made now will have a big impact on the late 21st century climate

Global Climate Change