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
Aerosols
Aerosols
Aerosols
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 5and 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
Percent
Change in
global
emissions
CO2 (ppm)
CO2-eq.
(ppm)
Year of
Peak
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
Temperature Rise (°C)
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
21
50 years (10 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)
180
9
Last Ice Age Maximum
280
13
Interglacial Period (Holocene)
350
14
Upper Limit to Preserve Ice Sheets
387
14.6
450
16
Critical for Humans and Other Species
650
~20
Catastrophic for Humans and Other
Species
~1500
~25
Hot House Maximum
Event
Today
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