It’s now day 3 of the UNFCCC climate change conference, and we’re all still on our feet despite a lack of sleep and an overload of information. One thing that has been particularly interesting of late is the discussion around which targets we need to aim for to really address climate change. There are phrases floating around such as “as far below 2 degrees as possible” and “in order to avoid dangerous climate change” but is this enough? What do we need to actually save the planet?
We must draw a line in the sand, a threshold of global temperature increase that we should not cross. We must set a target in global emission reductions that gives us the best chance of averting climate disaster. While there is no global consensus on what this should be, it would be prudent to err on the side of caution and choose a stringent target that minimizes the risk of the worst climate impacts.
The Intergovernmental Panel on Climate Change puts this threshold at two degrees global warming. It is anticipated that this temperature increase would have catastrophic impacts on natural systems that support human life. To have a reasonable chance of preventing warming of 2 degrees requires global emissions to peak in 2015 and then be reduced globally by 50-80% by 2050.
Given Australia’s emissions are four times the global average, Australia will have to reduce its emissions more significantly, by a minimum of 30% 2020 and 80% 2050. However, recent evidence suggests that this is too conservative. James Hanson, a NASA Scientist, has demonstrated that warming above 1.5 -1.7 degrees is likely to cause the melting of both the West Antarctic and Greenland Ice Sheets. If these enormous blocks of ice melt, global sea level would rise by 25metres, flooding major cities and river deltas – the world would be a very different place. To prevent this warming will require reductions of at least 100% by 2030.
If we are to prevent catastrophic changes to the earth’s climate systems we need targets based on what the science says is necessary for a safe future.
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I haven’t read it yet, but I read a good review on RealClimate (http://www.realclimate.org/index.php/archives/2007/11/six-degrees/) about the book “Six Degrees”. Apparently, it offers a strictly scientific account of the effects of global temperature rise, with each chapter representing what would happen with a 1 degree increase, a 2 degree increase, etc. up to six. It purportedly offers a rather grave image of what might happen, made even scarier by the fact that it meticulously backs up its claims with scientific study. I intend to read it soon, and I think it would probably provide a good background for determining what temperature reductions are necessary.