Right now, the atmospheric concentration of carbon dioxide (CO2) is around 385 parts per million (ppm), up from about 280 ppm before the Industrial Revolution. Scientists, economists, and others disagree about what figure to accept as a ‘safe’ maximum concentration, with uncertainty enduring both about what temperature increase any particular concentration level will mean and what the social, political, physical, and biological consequences would follow.
Probably the most cautious group of all, with regards to what concentration is safe, is Bill McKibben’s 350.org, with their target of a reduction to 350 ppm. One major supporter is top NASA climatologist James Hansen:
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.”
By contrast, many environmental organizations have expressed support for targets between 450 ppm and 550 ppm, usually while hoping that such an increase would not generate more than 2°C of additional warming. Whether it would do so or not depends primarily on the relative strength of feedbacks within the climate system.
With extremely aggressive cuts in human greenhouse gas emissions, it could be possible to stabilize concentrations below their current levels. One major reason for this is the oceans. When CO2 is added to the atmosphere, it is akin to adding more CO2 to the area of air at the top of a soda bottle. Left alone, some of that extra CO2 will end up dissolved in the soda. In precisely the same way, if human beings were to stop emitting CO2 today, the levels would gradually begin to decline, until the amount of CO2 dissolving into the ocean became equal to the amount bubbling out of the oceans: a stable equilibrium with constant macroscopic properties. As such, the oceanic acidification that arises from climate change does, to some extent, reduce the amount of warming that would result from any set quantity of CO2 emissions.
Recentlly, Bill McKibben appeared on The Colbert Report, where he did quite a good job of getting his message across despite Colbert’s unique style of interview. (Link for those in Canada)
I really like this photo ; although the building is run down, it is not threatening , but rather quite charming.
Three papers released earlier this year changed all that. The first one, published in the Proceedings of the National Academy of Sciences in February, set the scene. It showed that the climate change we cause today “is largely irreversible for 1,000 years after emissions stop”. Around 40% of the carbon dioxide produced by humans this century will remain in the atmosphere until at least the year 3000*. Moreover, thanks to the peculiar ways in which the oceans absorb heat from the atmosphere, global average temperatures are likely to “remain approximately constant … until the end of the millennium despite zero further emissions”.
In other words, governments’ hopes about the trajectory of temperature change are ill-founded. Most, including the UK’s, are working on the assumption that we can overshoot the desired targets for temperature and atmospheric concentrations of CO2, then watch them settle back later. What this paper shows is that wherever temperatures peak, that is more or less where they will stay. There is no going back.
350 ppm is all we’ve got
350 ppm
A new campaign by leading environmental organisations focuses on the simple message of 350, being the parts per million CO2 equivalent that recent science is telling us is the planet’s long-term budget to avoid catastrophic human-induced climate change.
They’re calling for a day of action on 24 October, prior to ‘COP 15’, the Copenhagen climate change conference from 7 to 18 December this year.
Here is some discussion of a 350ppm stabilization level, as well as the general question of how aggressively we should mitigate, given uncertainties about climate sensitivity and other factors.
Is 350 Possible?
Hansen (Figure 1) described a detailed scenario for reducing greenhouse gas emissions with the goal of reaching 350 ppm CO2 by 2100. It included phasing out coal completely (or achieving 100% carbon capture) by 2030, along with a combination of large-scale reforestation, avoided deforestation and carbon capture and storage to withdraw huge quantities of CO2 from the atmosphere. To reach the 350 target by 2100, the world would have to quickly go beyond reductions to achieve net negative emissions-removing more greenhouse gases from the atmosphere than are emitted each year.
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The bottom-line on the technical side: Decarbonizing by 2050 is possible with, roughly, the suite of technologies now available or on the near-term horizon. Very aggressive policy, however, will still be required very soon to drive down the costs of renewables, to redesign cities, reimagine transport and agricultural systems, and insure that all efficiencies are captured. Doing all this gets the world to 350 by 2200. Taking the additional steps to achieve negative emissions (and 350 by 2100) would require the development of large-scale, cost-effective sequestration technologies that go well beyond reforestation.
350 on the front page of the New York Times
Campaigns like this don’t “win,” but sometimes they have moments of real success.
We’re showing you the current front page of the New York Times, which has a picture from Copenhagen. Roughly the same kind of coverage is happening in the Associated Press, on Google News, at the BBC and CNN, and on and on.
This has nothing to do with us, and everything to do with you–with the creativity and passion and sheer energy that you bought to this day, which eventually overwhelmed even the most jaded reporters and editors. It’s an outpouring different than any the world has ever seen.
Maybe what happened to the climate since 2000, especially the
sequence of typhoons on Taiwan, Phillipine and VieThe tname and
the loss of properties and lives. I have just launched a new
product called GAIA version of 3-pole tennis which use only
recycled material thus contributing nothing to co2 on planet Earth.
The 350 movement, if it develops into a movement should
suppportsuch industries. For information, please visit my
website.
or simple use google search with “pole-tennis” keyword.
All industries that could use recycled material should back
this movement.
Corrections of typos:
Maybe what happened to the climate since 2000, especially the
sequence of typhoons on Taiwan, Phillipine and Vietnam and
the loss of properties and lives. I have just launched a new
product called GAIA version of 3-pole tennis which uses only
recycled material thus contributing nothing to co2 on planet Earth.
The 350 movement, if it develops into a movement should
suppport such industries. For information, please visit my
website.
or simple use google search with “pole-tennis” keyword.
All industries that could use recycled material should back
this movement.
Reforming tennis would have a pretty insignificant impact.
After all, to achieve the 350 target we need to cut global emissions to zero, which means ending deforestation and the use of fossil fuels.