The recent Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) leaves no doubt that human activity is the primary driver of changes in climate through emissions of greenhouse gases. The accumulation of gases such as carbon dioxide (CO2) and methane (CH4) in the atmosphere strengthen the greenhouse effect, and are now at the highest level in history. According to the report, mean global temperatures are likely to rise between 1.1 and 6.4°C (with a best estimate of 1.8 to 4°C) above 1990 levels by the end of this century, depending on the level of emissions. Rising temperatures will trigger many other changes to the earth’s system: rising sea levels of between 20 and 60cm by the end of this century, continued melting of ice caps, glaciers and sea ice, changes in rainfall patterns, intensification of tropical cyclones and species extinction.

Food and water supplies, human health, biodiversity and the economy will be affected, although the scale of impacts will vary considerably by region and vulnerability. The extent and severity of negative impacts will rise with temperatures. It is estimated that once temperatures rise more than 2°C a ‘tipping point’ will be reached, triggering a chain of major effects over which we have no of control, such as the acidification of oceans.


What needs to be done?
In the absence of an effective international effort, emissions will continue to grow rapidly over the coming decades. To have a reasonable chance of keeping global temperature increases below 2°C, global emissions must peak in the next decade and then decline to roughly 80% below 1990 levels by 2050 if we are to avoid catastrophic climate change. Such large-scale emissions reductions require a move away from fossil fuel, significant improvements in energy efficiency, preserving the world’s natural carbon sinks i.e. forests and a fundamental shift in government policies and economic practices.