From the TUC

Carbon Diary: Observastories

08 Feb 2010, by in Environment

Pledges from developed nations signing the Copenhagen Accord add up to a mere 19% cut in CO2 below 1990 levels. This is well short of the range of CO2 emission reductions – 25 to 40% – that the UN says is necessary to stabilise global temperature increases. Still, apparently there’s no need to be “irrationally alarmist”, as Benny Peisner puts it. The blogmeister at Lord Lawson’s Global Warming Policy Foundation keeps sending me bulletins on how bad the science is.

As Peisner said in his heated exchange with Observer science editor Robin McKie yesterday: “In all likelihood, we will not know for the next 20 or 30 years who is right or wrong on the scale and impact of global warming…the debate has become irrationally alarmist.” To me, the phrase “in all likelihood” means “I am virtually 100% certain”. What, we’d like to know, is this based on, actually? 

This we do know. Global warming is linked to rising concentrations of CO2 in the atmosphere.  CO2 concentrations are measured monthly at Mauna Loa Observatory, Hawaii. They send balloons way up into the air. The measure scientists record is the number of molecules of carbon dioxide divided by the number of all molecules in air, including CO2 itself, expressed as parts per million. We are now at 390 parts per million (ppm). In 2005 it was 378ppm. The curve is steadily upwards.

As CO2 concentrations have increased since pre-industrial times (1790), so have global average temperatures.  So what’s the risk here? Scientists express the risk of overshooting the 2 degrees temperature threshold in percentages. Clearly, the higher the CO2 reading, the more likely it is temperature rises will follow. A leading expert is Malte Meinshaisen of the Swiss Federal Institute of Technology. He wrote:

The probabilistic assessment is derived from a compilation of recent estimates of the uncertainties in climate sensitivity, which summarizes the key uncertainties in climate science for long-term temperature projections. The risk of overshooting 2°C equilibrium warming is found to lie between 26% and 78% for stabilisation at 450ppm CO2. Only at levels around 400ppm CO2 are the risks of overshooting low enough so that the achievement of a 2°C target can be termed “likely”.

Can the Global Warming Foundation match that analysis? One of the biggest UN backsliders is the Canadian government, now resiling on earlier CO2 commitments, to the deep frustration of the Canadian Labour Congress. See the CLC’s Copenhagen blog.