Sea levels are rising, arctic sea ice is thinning, and rainfall is becoming heavier in some parts of the world whilst others are experiencing severe drought. Climate change is fast becoming one of the most urgent global concerns - global temperatures have risen by 0.5°C in the last decade of the 20th century, and eleven of the last twelve years rank among the warmest years since global surface temperatures records began in the 1850s.
At the centre of the debate on climate change is the accumulation of human-emitted carbon dioxide (CO2) and other so-called greenhouse gases in the atmosphere. These trap the heat energy transmitted to us by the Sun, thus having a warming effect on the planet, the so-called greenhouse effect. For more information, go to the BBC Climate Change section of their website. The release of global greenhouse gases is primarily by burning fossil fuels such as coal, oil and gas, and by cutting down trees.
A continuous rise in temperatures is predicted to bring about changes in weather patterns, increasing the frequency and intensity of extreme weather events such as heat waves and hurricanes and typhoons. This is on top of an intensification in the dramatic natural disasters we have begun to see in the past few years, examples of which are the severe floods in Mexico and South Asia in 2007 and the wildfires around the globe.
Global warming is also having negative effects on plant and animal species. In addition to the direct disruptions of their habitats caused by floods and droughts, there is a growing fear that, because climate change is occurring so fast, some species won't be able to adapt quickly enough to their changing environment and will go extinct.
Ice sheet melting in polar marine regions is affecting ice-dependent species such as polar bears, which are seeing their hunting ranges decline rapidly. In the marine realm, coastal ecosystems such as mangroves and small islands are threatened by rising sea levels. Among the most threatened by climate change are coral reefs, as they are very sensitive to temperature increases and when the temperature becomes too high, they lose their colour - known as ‘bleaching' - and die.
The negative effects of climate change are disproportionately affecting poor people in developing countries. Not only do these events cause immediate deaths and displace millions of people, but they also affect crops and the natural resources on which some communities depend, and, ultimately, the economy of entire countries.