The latest word on climate change...

This Friday, the UN's Intergovernmental Panel on Climate Change (known by the handy acronym of IPCC) will release its Fourth Assessment Report (the last one was in 2001) on the science of climate change. In two months time it will release a section focusing on impacts and vulnerability from climate change, and in May a third section will be published on what can be done to mitigate the impacts on climate change.

The UN IPCC is the scientific voice on climate change, bringing together the world's top climate scientists to arrive at a consensus on the future that we face together. The panel reviews all the scientific work on climate change that has been conducted in the last five years to achieve a big-picture overview on what kind of climate change we might see in the decades to come. Because it involves so many scientists, who aren't going to agree with each other all the time, the IPCC is also seen as a fairly conservative body of thought, where only the bits that everyone can agree on are included. This time around, there are already criticisms that it is too conservative in its assessment, in particular, its suggestion that climate change will have a minimal major impact on Antarctica.

The report, in any case, will make for some fairly grim reading:
- globally, the world will be warming by 0.2C per decade for the next two decades.
- current concentrations of carbon dioxide and methane far exceed pre-industrial values determined from ice core records going back for 650,000 years.
- continued greenhouse gas emissions are likely to cause changes to the global climate far greater than those experienced in the 20th century.
- changes in sea surface temperatures, snow cover and atmospheric circulation patterns are linked to longer and more intense droughts.
- the number of cyclones, hurricanes and typhoons per year is likely to decrease, but their intensity and effects will be greater.
- the timescale of climate processes, systems and feedback mean that even if greenhouse gas concentrations were to be stabilised, warming effects and sea-level rises would continue for centuries thereafter.

This picture, provided through the BBC, shows a retreating Austrian glacier over nearly 100 years. Mountain glaciers such as these are retreating nearly three times as fast as they were in the 1980s. The Alps are expected to lose 75% of their glacial cover by 2100. It's not pretty stuff and the scale and speed of change illustrated here can be found for the majority of mountain glaciers throughout the world - with effects for users of the water that melts from them - what will happen when the glaciers are gone and the streams stop flowing?