By Ambassador Sir William Ehrman

The impacts of climate change are already evident, both in China and across the globe. Glaciers are melting, floods and landslides becoming more frequent, and drought, desertification and water scarcity are on the increase. Climate change is already changing landscapes and harming global prosperity and security.  And yet so far the world’s average temperature has increased as a result of global warming by less than 1 degree relative to temperatures before the industrial age. We can expect average warming to increase to 4 degrees (7 degrees F) by the end of the century unless we succeed in slowing the rate at which we emit greenhouse gases into the atmosphere. If global warming of less than 1 degree can cause the serious problems we see today, what would a “4-degree world” be like to live in?

                        The impact of a global temperature rise of 4ºC (7 ºF)

To gain a better understanding of how climate change might affect our lives, the UK’s Met Office Hadley Centre has produced a map showing some of the impacts we could expect from a 4-degree rise in global temperature. The map incorporates the findings from the latest scientific research on climate impacts from 27 leading scientists, and is likely to be one of the last sets of major scientific research results on the impacts of climate change to be reported before the December Copenhagen Climate Change Summit.

The map shows that although 4 degrees is the average increase expected if emissions continue as they are, this increase will not be spread evenly across the globe.  The land will heat up more quickly than the sea, and high latitudes, particularly the Arctic, will have greater temperature increases.  The average land temperature increase will be 5.5 degrees C above pre-industrial levels. In highly populated areas of Eastern China the hottest days of the year could be as much as 6 degrees C warmer.  The Arctic is likely to experience between 6-15 degrees C of warming – enough to make it ice-free for much of the year.

The impacts on human activity shown on the map are only a selection of those that may occur, and highlight the severe effects on water availability, agricultural productivity, extreme temperatures and drought, the risk of forest fire and sea level rise.

China is especially vulnerable to climate change. For China, the map shows that water availability will become an even more serious issue than it is today.  Much of the water in rivers in China comes from meltwater, and as glacial melt increases, there will be major impacts on river flows.  Studies have shown that by 2050, half of all Himalayan glaciers will be significantly reduced, leading to 23% of the population of China being deprived of the vital dry season glacial melt water source.  Studies also show that, once the global average temperature increases beyond 3 degrees, agricultural yields are likely to decrease for all major cereal crops, including a decrease in rice yield of up to 30% in China.

Globally, population increases, together with changes in river run off as a result of changes in rainfall patterns and increased temperatures, could mean that by 2080 significantly less water is available to approximately 1 billion out of 3 billion people already living under water stress.  For many areas of the world including China, sea level rise together with the effect of storms will threaten low-lying coastal communities.  Towns and cities along the coast of China, in particular the Shanghai region, have dense populations as well as important infrastructure and high value agricultural land. This will make the human and economic impact of increased coastal flooding even more severe.

The impacts shown on the map are frightening, and these are just a small selection of potential impacts.  What is not shown are second and third order impacts such as migration of people and potential conflict over limited resources resulting from food, land and water scarcity.  By taking strong and effective action to curb greenhouse gas emissions, it may still be possible to limit global temperature rise to 2 degrees C (4 degrees F).  If we fail to achieve this, then 4 degrees of warming during the course of this century is the most likely outcome from a Business As Usual global emissions trajectory.  This demonstrates why there is such an urgent need for consensus to be reached in Copenhagen, for global leaders to come together and agree the path that needs to be taken in order to limit dangerous climate change.

For more information, please see The impact of a global temperature rise of 4ºC (7 ºF)

 

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