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The Problem: 1,000 Years of Carbon Emissions
NASA: Six Decades of a Warming Earth
Climate Communication - Effect of Delay
TED: Bill Gates, Innovating to Zero
Climate Communication - Stabilizing Climate Affordably
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Sources:
Some numbers above are rounded for simplicity.
1) Third National Climate Assessment (2014 Draft Report) and Second National Climate Assessment (Global Change Impacts in the United States, 2009)
2) IPCC, Climate Change 2013: The Physical Science Basis
3) Atmospheric CO2 data: Scripps CO2 Program
4) Levels of atmospheric CO2 considered safe: Rockstrom, Johan, et al. "A safe operating space for humanity." Nature. Vol 461, September 24, 2009.
5) In the Copenhagen Accord, countries agreed the planet should not warm more than 2C to avoid “dangerous” changes. However, in the subsequent Cancun Agreement countries agreed to review this & look at lowering the limit to 1.5C.
6) IPCC, Climate Change 2013: The Physical Science Basis, Annex II: Climate System Scenario Tables. Table AII7.5 shows range of global mean surface temperatures
(10 year means) for modeled scenarios. After adjusting results to show change relative to pre-industrial, the RCP8.5 scenario shows: 1) a small chance of reaching +2C in 2030 2) likely to exceed +2C in 2040 and 3) very small chance of not exceeding 2C by 2050. US government uses RCP 8.5 “business as usual” scenario (US Department of Interior & US Department of Commerce).
7) Odds of staying below 2C 80% if we stop all emissions today: Hassol, Susan Joy. “Questions and Answers: Emission Reductions Needed to Stabilize Climate.” Presidential Climate Action Project
8) Odds of staying below 2C if still on current path by 2020: Meinshausen, Malte, et al. “Greenhouse-gas emission targets for limiting global warming to 2C.” Nature. Vol. 458, April 30, 2009. & United Nations Emission Gap Report 2012
9) Carbon budget of 140 billion tons is the low end of the given IPCC budget range for 2012-2100 considered "compatible with" the only scenario studied that is unlikely to exceed +2C.
10) Required emission reduction rates calculated based on cumulative carbon budget of 1 trillion tons and using IPPC adjustment to 790 to account for impact of other greenhouse gases . IPCC states this gives a 67% chance of staying below 2C. Allen, Myles, et al. "Warming caused by cumulative carbon emissions towards the trillionth tonne" Nature. Vol 458, April 30 2009 states a range of +1.3 to 3.9C for this budget with 2C as midpoint. Required reduction rates can vary with different assumptions (9% starting in 2014 for something more than a 67% chance of staying below 2C, 8% starting in 2020 for 52% chance of staying below 2C). General agreement exists that: 1) high single digit/low double digit reductions are needed, and 2) for the same outcome, larger reductions are needed with later start dates and smaller reductions needed if we begin sooner. Allowing lower reduction rates typically assumes large amounts of carbon can be removed from atmosphere (by planting forests or using currently unavailable technologies) or gives lower odds of staying below 2C. Hansen, et al. "Assessing ‘Dangerous Climate Change’: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature," (PLOS ONE, Vol 8:12, December 03, 2013) calls for 6% reduction of fossil fuel emissions if we start cuts in 2013, or 15% starting in 2020, but combines these cuts in a scenario with afforestation for a lower level of global warming.
Some numbers above are rounded for simplicity.
1) Third National Climate Assessment (2014 Draft Report) and Second National Climate Assessment (Global Change Impacts in the United States, 2009)
2) IPCC, Climate Change 2013: The Physical Science Basis
3) Atmospheric CO2 data: Scripps CO2 Program
4) Levels of atmospheric CO2 considered safe: Rockstrom, Johan, et al. "A safe operating space for humanity." Nature. Vol 461, September 24, 2009.
5) In the Copenhagen Accord, countries agreed the planet should not warm more than 2C to avoid “dangerous” changes. However, in the subsequent Cancun Agreement countries agreed to review this & look at lowering the limit to 1.5C.
6) IPCC, Climate Change 2013: The Physical Science Basis, Annex II: Climate System Scenario Tables. Table AII7.5 shows range of global mean surface temperatures
(10 year means) for modeled scenarios. After adjusting results to show change relative to pre-industrial, the RCP8.5 scenario shows: 1) a small chance of reaching +2C in 2030 2) likely to exceed +2C in 2040 and 3) very small chance of not exceeding 2C by 2050. US government uses RCP 8.5 “business as usual” scenario (US Department of Interior & US Department of Commerce).
7) Odds of staying below 2C 80% if we stop all emissions today: Hassol, Susan Joy. “Questions and Answers: Emission Reductions Needed to Stabilize Climate.” Presidential Climate Action Project
8) Odds of staying below 2C if still on current path by 2020: Meinshausen, Malte, et al. “Greenhouse-gas emission targets for limiting global warming to 2C.” Nature. Vol. 458, April 30, 2009. & United Nations Emission Gap Report 2012
9) Carbon budget of 140 billion tons is the low end of the given IPCC budget range for 2012-2100 considered "compatible with" the only scenario studied that is unlikely to exceed +2C.
10) Required emission reduction rates calculated based on cumulative carbon budget of 1 trillion tons and using IPPC adjustment to 790 to account for impact of other greenhouse gases . IPCC states this gives a 67% chance of staying below 2C. Allen, Myles, et al. "Warming caused by cumulative carbon emissions towards the trillionth tonne" Nature. Vol 458, April 30 2009 states a range of +1.3 to 3.9C for this budget with 2C as midpoint. Required reduction rates can vary with different assumptions (9% starting in 2014 for something more than a 67% chance of staying below 2C, 8% starting in 2020 for 52% chance of staying below 2C). General agreement exists that: 1) high single digit/low double digit reductions are needed, and 2) for the same outcome, larger reductions are needed with later start dates and smaller reductions needed if we begin sooner. Allowing lower reduction rates typically assumes large amounts of carbon can be removed from atmosphere (by planting forests or using currently unavailable technologies) or gives lower odds of staying below 2C. Hansen, et al. "Assessing ‘Dangerous Climate Change’: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature," (PLOS ONE, Vol 8:12, December 03, 2013) calls for 6% reduction of fossil fuel emissions if we start cuts in 2013, or 15% starting in 2020, but combines these cuts in a scenario with afforestation for a lower level of global warming.
