rising temperatures. various temperature reconstructions from 200-2008
TRANSCRIPT
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
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.
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.
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.
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.
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.
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