February 2007

Snow!

Mini-snowperson resting on a riverside bench.

Swan statue by the river Severn.

Snow "thing", by the river.

Narrowboat in a rather icy Worcester to Birmingham canal.

Pitchcroft, covered in snow instead of water, for a change. And yes, all you pedants, I know that snow is water!

Photos Copyright © 2007 Phil Randal

Hung Up Over the Wrong Numbers

Our society has a love of numbers. If something can be measured, it will be, no matter how meaningless the figures are. Ever since I discovered my dad's copy of Darrell Huff's How to Lie With Statistics in my teens I've been fascinated by the misuse of meaningless measures and facile facts.

So it was interesting to read Roger Pielke Jr's commentary on The Economist's recent feature on climate change. Pielke reminds us that what has to be stabilised is not the levels of CO₂ emissions, but the levels of CO₂ in the atmosphere. And to do that at levels which will not be catastrophic is no easy task.

Socolow and Pacala's famous "wedge graphs" make this fundamental mistake, which leads them to weak conclusions.

Perhaps that's why politicians are so keen to talk of stabilising emissions at 199x levels. Choose your year, it doesn't really matter, it's still an easy but irrelevant target, despite all the government protests over the Kyoto Protocol being too difficult to attain.

The IPCC 4th Assessment Summary for Policymakers came out yesterday. On page 10 the IPCC scientists state:

"even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of 0.1ºC per decade would be expected."

And on page 13:

"Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium".

Baer and Athanasiou, in a chilling discussion about the European Union's CO₂ level stabilisation targets of 450 parts per million (current CO₂ concentrations are 380ppm), which corresponds to an estimated 2ºC temperature rise, argue that "even if greenhouse-gas concentrations stopped rising today, we might still already be committed to a temperature increase greater than 2ºC." And they add that "two degrees is already a compromised target, one with which we've already negotiated away thousands of species and, probably, millions of lives."

Little room for complacency there.

David Archer over at realclimate.org also points out another "wrong number":

"Most of the climate change community, steered by Kyoto and IPCC, limit the scope of their consideration to the year 2100. By setting up the problem in this way, the calculation of a safe CO₂ emission goes up by about 40%, because it takes about a century for the climate to fully respond to rising CO₂. If CO₂ emission continues up to the year 2100, then the warming in the year 2100 would only be about 60% of the "committed warming" from the CO₂ concentration in 2100. This calculation seems rather callous, almost sneaky, given the inevitability of warming once the CO₂ is released. I suspect that many in the community are not aware of this sneaky implication of restricting our attention to a relatively short time horizon."

junkscience.com isn't too happy about political influence on the IPCC scientists, and has leaked the drafts of the full 4th Assessment reports.

realclimate.org counters these claims and provides ongoing excellent coverage and debate.

The radiative forcing effects of atmospheric CO₂ have been known for almost 150 years thanks to the pioneering scientific work by John Tyndall.

If only we'd taken Arrhenius seriously back in 1896.

Postscript, June 30th, 2009

Lou Grinzo is asking similar questions about that 2 degrees Celsius number. He has links to a couple of interesting discussions about the EU's adoption of the 2 degree number, and is worth a read. These days I'm inclined to believe that even a 1 degree Celsius temperature increase is too high a figure.