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Target Atmospheric CO2
Where Should Humanity Aim?
"If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm." |
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Global warming is the result of the unnatural rise in the concentration of greenhouse gases in the Earth’s atmosphere. Carbon dioxide the greenhouse gas most responsible for the global warming trends that are happening and projected into the future.
The question we need a clear answer to is this: what concentration of CO2 and other greenhouse gases is safe for us and for future generations? For an answer to the question based on paleoclimate science, there is a single report, the Hansen report. In April 2008, ten scientists published Target CO2: Where should humanity aim? The lead writer is James Hansen, head of the NASA Goddard Institute for Space Studies in New York. The report states that a safe level of atmospheric CO2 has a ceiling of about 350 parts per million (ppm) and that the functioning of the planet will be at risk of remaining at elevated, rising levels for too long. Here is an excerpt:
If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm, but likely less than that.
The Nobel-winning International Panel on Climate Change implies a need to stabilize the concentration of greenhouse gases at levels below present levels. Here is an excerpt from the AR4 2007 Synthesis Report:
In order to stabilize the concentration of GHGs in the atmosphere, emissions would need to peak and then decline thereafter. The lower the stabilization level, the more quickly this peak and decline would need to occur. [p. 66]
Media:
The Guardian | 2008 |
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350 is the wrong target: put the science first
by David Spratt | January 21, 2009
During 2008, US environment writer Bill McKibben and colleagues established the climate activist group 350.org, with the aim of spreading the message that policy targets need to reflect the scientific imperative.
The campaign has harnessed many people and organisations' collective energy and has been successful in the United States, and internationally at such forums at COP14 in Poznan, in helping to educate people that targets such as 450 ppm (per million) carbon dioxide in the atmosphere are not acceptable, that the current level of carbon dioxide (387 ppm) is too high for a safe climate, and so our action must be zero emissions and a cooling of the planet.
The important question now is whether 350 is a target based on the science, or one that is judged to be politically appropriate.
David Spratt's full blog entry can be read at Climate Code Red:
Climate Code Red | 350 is the wrong target: put the science first
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By David Spratt | March 7, 2009 | Reposted from Climate Code Red
The “25-40/2020” scenario was published in the IPCC’s 2007 Fourth Assessment Report Working Group III report, in Box 13.7 on page 776, “The range of the difference between emissions in 1990 and emissions allowances in 2020/2050 for various GHG [greenhouse gas] concentrations for Annex I and non-Annex I [Kyoto] countries as a group”, where targets were given for stabilisation at 450, 550 and 650 ppm CO2e.The targets for 450 CO2e were:
Region: Annex 1 countries
2020: –25% to –40%
2050: –80% to –95%
Region: non-Annex 1 countries
2020: Substantial deviation from baseline in Latin America, Middle East, East Asia and Centrally-Planned Asia
2050: Substantial deviation from baseline in all regions
>>> Read the full article at Climate Code Red
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The following excerpts are from 
