The third section of the Copenhagen congress synthesis report considers the global targets and timetables that will be necessary to keep warming to no more than 2 degrees. The report acknowledges that 2 degrees introduces considerable risk to human society and natural ecosystems. However global average temperature has already risen by 0.7 degrees, and inertia in the climate system makes 1.4 degrees inevitable. So 2 degrees may be the best we can hope for.
Category: Climate science
Gone too soon
The June Sea Ice Outlook forecasts for the Arctic sea ice September minimum extent have been released today by SEARCH. Most groups are picking a minimum close to last year’s 4.7m km2, but the melt season is starting with an unusually small amount of multi-year ice. The report suggests that there is “a small but important probability of a major sea ice loss event this year, given that the ice is thinner and younger than previous years, combined with a possibility of atmospheric conditions that cause significant ice retreat.” The full range of forecasts is shown in this chart:
The range of individual outlook values is from 4.2 to 5.0 million square kilometers. All estimates are well below the 1979–2007 September climatological mean value of 6.7 million square kilometers. Half of the responses are in the range of 4.9–5.0 million square kilometers; the remaining estimates are in the range of 4.2–4.7 (Figure 1, above). The uncertainty / error values, from those groups that provided them, are close to 0.5 million square kilometers, thus many of the values overlap.
Interestingly, the forecasts showing the lowest minima are based on sea ice modelling driven by atmospheric forcings and initialised with current sea ice conditions. The projection by Jinlun Zhang (next to lowest in the chart) suggests that even with conditions like last year — that is, without the Transpolar Express of warm southerlies that set up in 2007 — the 2007 record could fall. On the other hand, a Russian scientist suggest thats Pacific sea surface temps could be priming a cooler pattern than last year.
The full report [PDF] is a very interesting read for all ice watchers (and gamblers). On this guide to the form, it looks as though I’ll lose my bets – but the weather over the next two months will be the deciding factor. Do I feel lucky…?
Copenhagen 2: dangers ahead
The second section of the Copenhagen synthesis report, Social and Environmental Disruption, discusses the dangers of climate change relating to society and the environment, noting that scientific research provides a wealth of relevant information which is not receiving the attention one might expect.  Â
Considerable support has developed for containing the rise in global temperature to a maximum of 2 degrees centigrade above pre-industrial levels, often referred to as the 2 degrees guardrail. The report however indicates that even at temperature rises less than 2 degrees impacts can be significant, though some societies could cope through pro-active adaptation strategies. Beyond 2 degrees the possibilities for adaptation of societies and ecosystems rapidly decline, with an increasing risk of social disruption through health impacts, water shortages and food insecurity.
Summing up Copenhagen: what we know now
The synthesis report from the Copenhagen climate congress of scientists held in March has been released. It updates the 2007 IPCC report in the light of the latest developments in the science, and means that the UN Copenhagen conference in December will have an overview of the state of our current understanding of climate change. Â
The report has six sections. The first deals with climatic trends and is blunt. Greenhouse gas emissions and many aspects of the climate are already changing near the upper boundary of the IPCC range of projections. In the case of sea level rise the rate is even greater than indicated by the IPCC projections. Continue reading “Summing up Copenhagen: what we know now”
“Widespread climate-related impacts are occurring now and are expected to increase”
I think I was around eleven years old when I last thought it would be good to be an American. But I admit to a small twinge of envy as I read the report released yesterday by the Administration:  Global Climate Change Impacts in the United States.  This is a scientific report, backed by the government, telling the general public what is now known of global warming and what it will mean for the US. The sort of thing one would have thought is a core function of democratic government. Meanwhile in New Zealand a select committee is required to solemnly consider submissions from climate science deniers, a PM wants us to be ready in case the science deteriorates and the sceptics are right, and a leading climate scientist is sacked for what sound like trivial offences against management policy.