New projections indicate that the Earth’s surface is likely to warm by between 2 – 7°C by 2100, a higher level to that predicted in the IPCC 4th assessment report. Improved scientific modelling and newer economic data shows a lower chance of emissions cuts than had been projected in the earlier scenarios.
However the lower end of the temperature rise projections will only be possible if we make deep, immediate and long-lasting reductions in our greenhouse gas emissions.
A 4 – 7°C rise would be profoundly destructive to human civilization and adversely affect every ecosystem on Earth.
The most comprehensive modelling yet carried out on the likelihood of how much hotter the Earth’s climate will get in this century shows that without rapid and massive action, climate change will be twice as severe as previously estimated six years ago – and could be even worse.
Climate change is not something in the far-off future, but something that we will experience in our lifetimes. Many of the impacts of climate change are already being felt around the world.
Unless we cut emissions now, global temperatures could rise as much as 4°C by 2060, resulting in widespread ecological and social disruption.
If we think of climate change as the result of over-spending our carbon budget, we can see that we are seriously in debt. If our carbon budget is 1000 Gigatonnes from 2000-2050, we have already spent 350 Gigatonnes, or 35%.
If we continue at this rate, we will have used up all our carbon budget by 2030 and almost certainly exceed the ’safe’ level of 2°C average global warming.
What would a high level of global warming mean? At the mid-range prediction of 4°C by 2011, oceans will warm less than the 4°C average, but many land areas will warm more 5 – 7°C.
Temperatures could climb by up to 10°C in most of Africa and the Arctic. Rainfall would be likely to decrease by 20% across of Africa, Australia, the Mediterranean and Central America.
Many other social, economic and environmental disruptions would also drastically impact quality of life around the world.
Positive feedbacks will speed the rate of warming. Currently, carbon sinks absorb around 50% of greenhouse gases produced through human activities such as burning fossil fuels. But positive feedbacks weaken carbon sinks, speeding the rate of temperature rises.
Recent climate models show far worse predictions than previously thought, if no strong policy is formed to drastically curb greenhouse gas emissions. However, there is less change from previous models in the projected outcomes if strong policies are put in place now. This means that the costs of stopping emissions now have remained stable, but the costs of not reducing emissions have grown enormously, thereby increasing the urgency for action.
References
David Chandler, ‘Climate change odds much worse than thought’, MIT News Office, 19 May 2009, http://web.mit.edu/newsoffice/2009/roulette-0519.html
Ian Ammison, et. al., ‘The Copenhagen Diagnosis: Updating the world on the latest climate science’, Elsevier, 2011, p. 74.; David Chandler, ‘Climate change odds much worse than thought’, MIT News Office, 19 May 2009, http://web.mit.edu/newsoffice/2009/roulette-0519.html
Anna Barnett, ‘No Easy Way Out’, Nature, 15 October 2009, http://www.nature.com/climate/2009/0911/full/climate.2009.106.html
Ian Ammison, et. al., ‘The Copenhagen Diagnosis: Updating the world on the latest climate science’, Elsevier, 2011, p. 76.
Matthew McDermott, ‘Half of All Animal Species Will Be Extinct in Your Lifetime, Unless Emissions Peak by 2020’, Treehugger, 28 September 2009, http://www.treehugger.com/files/2009/09/half-all-species-extinct-in-your-lifetime-unless-emissions-peak-2020.php
Anna Barnett, ‘No Easy Way Out’, Nature, 15 October 2009, http://www.nature.com/climate/2009/0911/full/climate.2009.106.html
David Chandler, ‘Climate change odds much worse than thought’, MIT News Office, 19 May 2009, http://web.mit.edu/newsoffice/2009/roulette-0519.html