Climate Change & Governance: Tuesday Morning

The first day of the Climate Change and Governance Conference focussed on the science. Here's a rundown of what was covered in the first session:

Professor Peter Barrett (VUW) spoke about the long-term climate record, as seen in the geological record. 65 million years ago, the Earth was 6-10 degrees warmer, and CO₂ levels were significantly higher than pre-industrial levels. Since then, there has been a long-term cooling trend, mirroring and mirrored by a long-term decline in CO₂. We now seem to be reversing that trend. Particular attention was paid to the record of the growth and shrinking of the Antarctic ice-cap, which fluctuates in the long-term according to the Milankovitch cycles, with CO₂ tracking the change within a certain natural band. We are now well outside that natural band of fluctuations, with a CO₂ level unprecedented for at least a million years. This is expected to produce climate change not seen since the age of dinosaurs.

Dr Dave Lowe (NIWA) spoke on the changing composition of the atmosphere and the atmospheric greenhouse gas record. He first talked about the Keeling curve - that lovely set of measurements of atmospheric CO₂ from Mauna Loa - and then his own data collected over the last 30 years from Baring Head near Wellington. The upward trend in atmospheric CO₂ concentration is consistent across multiple data sets and increasing; the long-term growth rate was a mere 0.5 ppm/year when measurements first started, and is now 2 ppm/year (with Baring Head showing 2.5). It tracks the increase in fossil fuel use, and isotope studies show that that is very definitely where the carbon is coming from. what's frightening is that fossil fuel use continues to increase at 2% a year.

Professor David Vaughan (British Antarctic Survey) talked on Antarctic de-glaciation and the global climate system, and particularly about the Antarctic Peninsula and West Antarctic ice shelf. While other parts of Antarctica are cooling and thickening, the Antarctic Peninsula has warmed significantly, and 87% of the glaciers in the area are in retreat - a change which does not seem to be part of any natural cycle according the geological record. More concerning, the West Antarctic ice sheet is thinning, and would need to thin only a little more in order to float free of the seafloor and break up, causing significant sea-level rise. Studies of the underlying geology show the areas this is likeliest to occur, and all they can do is watch. Vaughan made the point that while in the developed world sea-level rise will simply cost money (on flood defences, seawalls etc), in the developing world it will kill, as these societies simply lack the resources to cope with or protect against it.

That's all for now; maybe I'll post more later, when I've had a chance to digest it all.