Saturday, January 02, 2010

Cogitating carbon cycle conundrums

I haven’t posted much in this blog for a while, but that’s not to say that I haven’t been pondering lots of different things: cosmology, basic physics, chemistry (my career before getting into information technology forty years ago), evolution, and more.

There has been a lot of controversy for the last decade about climate change, and I’ve written a few posts on this topic. The just-concluded massive United Nations Climate Change Conference in Copenhagen (COP15) may, or may not, lead to significant outcomes, depending on how various countries act (especially those with large populations).

Opinions differ widely about what is happening to the climate – from the doomsayers to the sceptics – and my own position is somewhat ambivalent.

Down here in Australia, with its relatively small population (not too much over 20 million), whatever we do won’t have much effect on the world’s climate. We produce  heavy carbon dioxide outputs per capita, but this amounts only to a tiny fraction of the overall global CO2 output.

Some of us fear that federal climate change legislation in the offing will lead to savage increases in the cost of electrical power and an uncompetitive economy. What’s a balanced position for us to adopt: go easy on the legislation and suffer the climate consequences (causing only a small part of the global effect), or aim for high CO2 reductions that will cost us the proverbial arm and leg?

In this blog about “basic questions” one of the key discussion points should be about the science of climate change, rather than the politics and the economics.

So I’m still reading as much as I can find time for about anything and everything related to climate change. One very pertinent article that I’ve stumbled upon just recently is Carbon cycle conundrums in which David Schimel asks “What will control future rates of climate change?”

The carbon cycle is the largest contributor to anthropogenic climate change, yet despite decades of research significant mysteries about its behavior remain. Global analyses show that the Earth system absorbs approximately half of anthropogenic fossil fuel emissions. This uptake is partitioned between absorption by the oceans and storage in terrestrial ecosystems. Uptake by the Earth system reduces the climate effects of emitted CO2 to approximately half of what would occur without sinks. …

The reduction over time of the efficiency of the sinks is of great concern because it implies a weakening in the ability of the Earth system to mitigate the effects of fossil fuel emissions and a potential positive feedback that may strengthen in the future.

And later, under Key Questions:

Although we have learned a great deal about the carbon cycle, the scientific community is still limited in its ability to make confident predictions about the likely response of the carbon cycle to global environmental change. … Getting global phenomena right, like the observed change in the airborne fraction, is critical for testing models. Purely local or process-level validation is not enough because of the great variety of local responses.

And there’s more, please read it yourself. But as one with some science training, I appreciate the honesty and transparency – far from universally acknowledged in the climate debate -- that there are unknowns and that further research is needed!

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