Friday, January 13, 2006

Green Is Not All Good

Via Financial Times, Robert Mathews draws our attention to a startling new discovery which is a must-read in the debate about the environment. He writes:

Everyone knows trees are "A Good Thing". They take in the carbon dioxide that threatens our planet with global warming and turn it into fresh, clean oxygen for us all to breathe.

But now it seems we need to think again. In a discovery that has left climate scientists gasping, researchers have found that the earth's vegetation is churning out vast quantities of methane, a greenhouse gas far more potent even than CO2. This is not a product of trees and plants rotting, which everyone already knew was a source of methane; it is an entirely natural side-effect of plant growth that scientists had somehow missed. Yet it is by no means trivial: preliminary estimates suggest that living trees and plants account for about 10 to 30 per cent of the methane entering the atmosphere.

While no one is suggesting chopping down the world's trees to save the planet, the new research highlights the astonishing complexity of environmental science. Measures to combat climate change that once seemed simple common sense are turning out to be anything but.

Everyone knows fossil fuel power stations are hefty producers of CO2 and need urgently to be replaced. Yet they are now also recognised as hefty producers of aerosols - tiny particles in the atmosphere that play a key role in reflecting the sun's heat back into space. The scientific consensus was that this is a minor benefit of fossil fuel burning. But last month Nature published new research showing aerosols may be twice as effective at keeping the earth cool as was thought. Suddenly, wholesale closure of power stations no longer seems such a good idea.

Climate scientists would have us believe there is no doubt about the basics of global warming and the time for action is now. The recent spate of large revisions of the facts tells a different story. Yet politicians are still being pressed to do the impossible: modify the huge, chaotic system that is the earth's climate in ways guaranteed to be beneficial for all.


pennathur said...

Scientists baffled!
Filed under: Climate Science Greenhouse gases— gavin @ 5:56 pm
Every so often a scientific paper comes out that truly surprises. The results of Keppler et al in Nature this week is clearly one of those. They showed that a heretofore unrecognised process causes living plant material to emit methane (CH4, the second most important trace greenhouse gas), in quantities that appear to be very significant globally. This is surprising in two ways - firstly, CH4 emission is normally associated with anaerobic (oxygen-limited) environments (like swamps or landfills) but chemistry in plants is generally thought of as 'aerobic' i.e. not oxygen-limited, and secondly, because although the total budget for methane has some significant uncertainty associated with it (see the IPCC assessment here), the initial estimates of this effect (between 62–236 Tg/yr out of a total source of 500+ Tg/yr!) give numbers that might be difficult to incorporate without some significant re-evaluations elsewhere.

Reactions so far have been guarded, and there will undoubtedly be a scramble to check and refine the estimates of this process's importance. Once the dust settles though, the situation may not be so different to before - some emissions may turn out to have been mis-identified, this source may not be as large as these initial estimates (10-30% of total sources) suggest, or it might radically challenge our current understanding of methane's sources and sinks. However, the process by which this is decided will demonstrate clearly that the scientific method is alive and well in the climate sciences. That is, as long as a work is careful and the conclusions sound, papers that upset the apple cart can appear in the major journals and have a good chance of ending up being accepted by the rest of the field (providing the conclusions hold up of course!).

pennathur said...

Sorry to post in a hurry. There is a science to the study of Earth Systems and then there is the popular understanding where many of us begin. I had pointed you out to a few days back. Here's the site discussing the paper from Nature. Contrast the approaches of the FT on one side and Nature and Realcimate on the other.

praveen said...

It doesnt matter what discoveries climate or enivornmental studies make.
A person standing near a busy traffic road either in Mumbai or Chennai would immediately tell you that pollution is harmful. This is what matters.It is such plain commonsense!
Mindlessly bringing in polluting industries in the name of liberalization is not good for India.


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