Rising Temperatures

Various Temperature Reconstructions from 200-2008

Arctic Air Temperatures from Proxies (blue) and Observed Temperatures (red)

Temperatures from Proxies and Instruments for Last 1,800 Years

• The current temperature rise is unprecedented

• It coincides with the Industrial Revolution and the exponential population growth

• It also coincides with the rapid rise in greenhouse gas emissions

Radiative and Net Climate Forcing(1880-2006)

Temperature Anomaly (1880-2009)Base: 1951-1980

AerosolsAerosolsAerosols

Hemispheric Temperature Anomaly (1880-2009)Base: 1951-1980

5-year and 11-year Monthly Mean Temperatures for the Entire Earth and the

Northern (N.H.) and Southern (S.H.) Hemispheres.

(Base is 1951-1980)

Temperature Change from 1850-2009• Mean surface temperature

change for 2001-2007 relative to the 1951-1980 base (top).

• Global average temperature 1850-2009 relative to the baseline period 1880-1920 estimated from NASA/GISS data set (red) and the Hadley data (blue).

• The final bold point is estimated for 2009.

Temperature Trend 1983-2008

Global Temperature Index for 5- and 11-year Running Mean

Hottest Years Ranked by the British Meteorological Office The Current Decade Was the Hottest

Variations of the Arctic Oscillation that are responsible for cold Arctic air reaching lower latitudes (negative values). The

extreme negative oscillation for Dec. 2009 is shown.

IPCC Projected Temperature Rise

Temperature, CO2 Concentrations and Carbon Emissions

Temperature Increase 1992-2004• The yellows and reds

on these world maps are positive (warm) anomalies while blues are negative (cool) anomalies.

• The greatest amount of heating has occurred generally in the Northern Hemisphere and specifically in the Arctic regions.

Temperature Anomaly for 2007

CO2 and Temperature Stabilization

Temperature Rise (°C) CO2 (ppm) CO2-eq. (ppm)

Year of Peak

Emissions

Percent Change in

global emissions

Global average temperature increase above pre-industrial

at equilibrium, using “best estimate” climate sensitivity

CO2 concentration at stabilization

(2010 = 388 ppm)

CO2-eq. Concentration at

stabilization including GHGs

and aerosols (2008 = 395

ppm)

Peaking year of CO2

emissions

Change in CO2 emissions in 2050 (percent of 2000

emissions)

2.0-2.4 350-400 445-490 2000-2015 −85 to −50

2.4-2.8 400-440 490-535 2000-2020 −60 to −30

2.8-3.2 440-485 535-590 2010-2030 −30 to +5

3.2-4.0 485-570 590-710 2020-2060 +10 to +60

4.0-4.9 570-660 710-855 2050-2080 +25 to +85

4.9-6.1 660-790 855-1130 2060-2090 +90 to +140

Data from: IPCC, 2007:Synthesis Report.

Temperature Anomaly at CO2 Stabilization Relative to 1800

Only Human-caused Greenhouse Gas Emissions Can Account for Global Warming

• The black line is the observed temperature rise.

• The red area is computer simulations of all emissions, including human.

• The blue area is computer simulations of only natural emissions and the increase in solar activity.

Rise in the Ocean Heat Content

The Warming Oceans

Earth’s Heat Gain During the Past 50 years (1021 Joules*)

•Oceans = 145 (84%)•Continents = 10.4 (6%)•Earth’s Ice = 8.1 (5%)•Atmosphere = 6.6 (4%)*A joule is a unit of heat energy

What Global Average Temperatures Become Critical and Catastrophic for Humans?

• The current best estimate is 2° C above pre-industrial levels is potentially critical. About 4° C is potentially catastrophic. The Earth is now 0.8° C above pre-industrial levels.

• When the CO2 abundance reaches ~450 ppm the temperature anomaly will eventually exceed 2° C. At ~650 ppm it will eventually reach a minimum of 4° C.

• The current abundance (2010) is 388 ppm and rising at a rate of ~2 ppm/year, and this rate is increasing.

• We have about 30 years to stabilize the greenhouse gas abundance by cutting emissions ~70% (~80% for CO2 only). Even at today’s abundance the temperature anomaly will reach the critical level in about 40 years.

WHAT IS CRITICAL AND WHAT IS CATASTROPHIC?

• CRITICAL --- serious drop in food production, serious water shortages, significant sea level rise, political unrest, major drop in world GDP, major animal extinctions and millions of human deaths. Third-world countries, e.g. Africa, are affected most, including large human migrations.

• CATASTROPHIC --- mass extinction event (>50% species extinction), major sea level rise, mass starvation, political and economic chaos, ~50% human deaths (>3 billion people). Probably the end of civilization as we know it today.

Atmospheric Abundance of CO2 and Global Temperatures

CO2 (ppm)

Average Global

Temperature (°C)

Event180 9 Last Ice Age Maximum

280 13 Interglacial Period (Holocene)

350 14 Upper Limit to Preserve Ice Sheets

387 14.6 Today

450 16 Critical for Humans and Other Species

650 ~20 Catastrophic for Humans and Other Species

~1500 ~25 Hot House Maximum

Possible CO2 Concentrations and Temperature Increases

Possible Temperature Rise

Projected Temperature Rise for Additional Greenhouse Gases (GHGs)

Added CO2 Equivalent for Other GHGs

Warming or Cooling for CO2, Other GHGs and Aerosols

Past and Future Temperatures