• Every scientific academy in the world - without exception - agrees that the planet has been getting hotter, and that emissions from human activity are almost certainly the main cause. Of course the earth's temperature has altered before, but during the period that humans have evolved and prospered the climate has been relatively stable - that is until recently. What is worrying the experts is that they don't know how much warming there will be or how it will affect us.
  • The temperature of the planet has gone up by about 0.80Celsius over the last 100-200 years. Most of us hardly notice the change because during one day temperatures normally vary by much more than that 0.80C. A huge effects of climate change has been in the Arctic where summer ice cover has halved over the last two decades.There have been increased extremes of weather - hurricanes, heat waves, droughts, torrential downpours - throughout the world. As the global temperature rises we can expect: sea levels to rise, more extreme downpours, heat waves, droughts, floods, more water scarcity and more intense hurricanes and typhoons.
  • A big worry is the risk that the climate could change rapidly to a climate very different from the climate that has supported human life until now. This is called "runaway climate change" or the "tipping point". As the sea ice melts, less heat will be reflected by it and the sea will get hotter. The melting of snow and ice on normally covered earth and rock will have a similar effect, also increasing the amount of heat absorbed from the sun. As the frozen soil of northeren countries warms, it will release normally trapped methane (a powerful greenhouse gas) and accelerate climate change.
  • The risks can't be measured accurately. At the last UN climate talks (in Copenhagen) the nations agreed that a rise in global temperature of 20C above the level before temperatures began to rise was the maximum that might be safe. They believed that this would be manageable but still serious. It was felt that this would keep the risk of runaway global warming low enough for safety. There is no doubt that there are very real risks. There is a lot of work being done to find out how great the risks are but there is still no certainty. Nobody knows for sure how great the risks are. The next question is "how to reduce the risks?"

Clyde Mitchell, Chairman, SusKes.

Source: "The Burning Question" by Mike Bernars-Lee and Duncan Clark.

September 2013