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Earth’s Climate:
Old Problems, New Thoughts
Elizabeth K. Thomas, Brown University
Sujit Datta, Harvard University
Atreyee Bhattacharya, Harvard University
Roadmap for the evening
1. Background & long-term perspective
2. Potential solution
3. Other factors
The bottom
Lower Emissions Scenario, 2080line…
2099
Higher Emissions Scenario, 20802099
Recent Past, 19611979
Number of days over
Number of Days
100°F
<10 20 30 45 60 75 90 105 >120
climatecommunication.org
Global Climate Change
A geologist’s perspective
• Earth’s energy budget
•Heat-trapping
Greenhouse gases influence
Earth’s energy budget
• Paleoclimate
• Climate change today
Global Climate Change
A geologist’s perspective
• Earth’s energy budget
• Heat-trapping gases influence
Earth’s energy budget
• Paleoclimate
• Climate change today
INCOMING ENERGY
data from
nasa.gov
INCOMING ENERGY
OUTGOING ENERGY
HEATTRAPPING
GASES
data from
nasa.gov
CARBON DIOXIDE (CO2)
CONCENTRATION IN ATMOSPHERE:
0.04%
50% OF TRAPPED HEAT
METHANE (CH4)
CONCENTRATION IN ATMOSPHERE: 0.00018%
20% OF TRAPPED HEAT
wikipedia.org
Questions about
Earth’s energy budget?
Global Climate Change
A geologist’s perspective
• Earth’s energy budget
• Heat-trapping gases influence
Earth’s energy budget
• Paleoclimate
• Climate change today
Paleoclimatologists
Study Past Climate
ICE CORES: MEASUREMENTS OF FOSSIL AIR
ppmv CO2
280
260
240
220
200
ppbv CH4
700
600
500
400
400
350
Age
research.gov; Petit et al. 1999
300
250
200
150
100
(thousands of years before present)
50
0
ICE CORES: MEASUREMENTS OF FOSSIL AIR
ppmv CO2
260
240
7.2
220
WHICH CAME FIRST,
INCREASES OF HEATTRAPPING GASES OR
WARMING?
200
ppbv CH4
700
3.6
0
-3.6
-7.2
-10.8
-14.4
600
500
400
400
350
Age
research.gov; Petit et al. 1999
300
250
200
150
100
(thousands of years before present)
50
0
Temperature relative to today (°F)
280
0
HEAT-TRAPPING
GASES!
-7.2
Global temperature
(°F)
-5.4
-3.6
-1.8
Global Temp.
Age (thousands of years before present)
Shakun et al. 2012, reprinted with permission from Nature Publishing Group
Antarctic temperature
(relative change)
Antarctic Temp.
Questions about
past climate?
Global Climate Change
A geologist’s perspective
• Earth’s energy budget
• Heat-trapping gases influence
Earth’s energy budget
• Paleoclimate
• Climate change today
1.5x
TODAY: 2.5x
HEAT-TRAPPING GASES
A GEOLOGIST’S PERSPECTIVE
ppmv CO2
260
240
4
7.2
220
3.6
2
200
0
Where do these heat-trapping
gases come from?
Temperature relative to today (°F)
Inferred temperature (°C)
280
-3.6
-2
-7.2
-4
-10.8
-6
-14.4
-8
ppbv CH4
700
600
500
400
400
Petit et al. 1999
350
300
250
200
150
100
Age (thousands of years before present)
50
0
Brayton Point coal-fired power plant, Fall River, MA
Jack Foley, epa.gov, wikipedia.org
1.5x
TODAY: 2.5x
HEAT-TRAPPING GASES
A GEOLOGIST’S PERSPECTIVE
ppmv CO2
260
240
220
200
When was the last time that
heat-trapping gas
concentrations were so high?
4
7.2
3.6
2
0
Temperature relative to today (°F)
Inferred temperature (°C)
280
-3.6
-2
-7.2
-4
-10.8
-6
-14.4
-8
ppbv CH4
700
600
500
400
400
Petit et al. 1999
350
300
250
200
150
100
Age (thousands of years before present)
50
0
Ellesmere Island today…
wikipedia.org
Ellesmere Island during the Eocene
(50 million years ago)…
reprinted with permission from the American Museum of Natural
History
HOW DOES THIS IMPACT CLIMATE HERE?
Spring 2010 floods in Rhode Island
October 2011 snowstorm
Massachusetts climate ‘migration’
wikipedia.org; northeastclimateimpacts.org
SO WHAT CAN WE DO?
Temperature relative to today (°F)
Multi-model projections of surface warming
10.8
9.0
7.2
5.4
3.6
1.8
0.0
-1.8
IPCC, 2007; climatecommunication.org
We have a choice!!
[email protected]
References cited
Christensen JH, et al. (2007) Regional Climate Projections. Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to the
Fourth Assessment Report of the IPCC, Solomon S, et al., Eds.
Cambridge University Press, Cambridge UK.
IPCC (2007) Summary for Policymakers. In: Climate Change 2007: The
Physical Science Basis. Contribution of Working Group I to the Fourth
Assessment Report of the Intergovernmental Panel on Climate Change,
Solomon, S. et al., Eds. Cambridge University Press, Cambridge, UK.
Petit JR, et al. (1999) Climate and atmospheric history of the past 420,000
years from the Vostok ice core, Antarctica. Nature 399: 429-236.
Shakun JD, et al. (2012) Global warming preceded by increasing carbon
dioxide concentrations during the last deglaciation. Nature 484: 49-55.
Most data are publicly available at http://www.ncdc.noaa.gov/paleo