The apocalyptic vision presented on cinema screens of a world devoid of food (Hunger Games) or with too much water (Waterworld) as a result of climate change, is not as far-fetched as some may think.
The results of a new study by the world’s biggest climate modelling system show that not only could global temperatures cross the two degrees Celsius barrier, but may warm by three degrees Celsius by 2050 if we emit atmosphere-warming gases at the current rate.
The study, led by Oxford University’s Dan Rowlands posits a substantial increase in global temperatures within little more than a generation. Most recent warnings, including those by the UN Environment Programme (UNEP), are more ambiguous, saying a two-degree hike is almost certain “by the turn of the century”.
The world authority on climate science, the Intergovernmental Panel on Climate Change (IPCC), says in its latest assessment that a two-degree Celsius increase in global temperatures by the turn of the century would have a catastrophic effect: water stress in arid and semi-arid countries, more floods in low-lying coastal areas, coastal erosion in small island states, and the elimination of up to 30 percent of animal and plant species.
A degree warmer
The decade 2001-2010 was the warmest since records began in 1850, with global land and sea surface temperatures estimated at 0.46 degrees Celsius above the long-term average (1961-1990) of 14 degrees Celsius, said the World Meteorological Organization (WMO) in 2011.
Linking the 0.46 degrees Celsius hike to man-made emissions of greenhouse gases, WMO noted an increase in “dramatic and continuing sea ice decline in the Arctic”, that global average precipitation was the second highest since 1901, and that flooding was reported as the most frequent extreme event. Two exceptional heatwaves hit Europe and Russia in 2003 and 2010 respectively, causing thousands of deaths and outbreaks of prolonged bush fires.
Temperature rise will not necessarily be uniform. “While the global average temperature may be warmer by three degrees Celsius – in some areas the change might even be double that,” explained Rowlands.
Deserts, for instance, warmed-up between 1976 and 2000 at an average rate of 0.2-0.8 degrees Celsius per decade – an overall increase of 0.5 to two degrees Celsius -much higher than the average global temperature increase of 0.45 degrees Celsius, which has been attributed to the increase in atmospheric concentrations of greenhouse gases, according to UNEP.
The four-degree scenario
In 2009, various papers presented at an Oxford University conference entitled “4 degrees and beyond” forecast a collapse of the agriculture system in sub-Saharan Africa in such a scenario.
Various studies have suggested that most of southern Africa would have given up on maize or even farming; every home in Asia and Africa would be trying to harvest some rain water; and most parts of many low-lying countries like Bangladesh would probably be under water.
“To me, the main message is that the main estimates of global temperature trends are broadly consistent with the IPCC Fourth Assessment, but with still the possibility of some more extreme outcomes,” said Maarten van Aalst, director of the Red Cross/Red Crescent Climate Centre and coordinating lead author of the summary of the special report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change (SREX), produced by IPCC in 2011.
“Even more important to humanitarian organizations is… what happens to heatwaves, floods and droughts?… As the IPCC SREX demonstrated, our knowledge is advancing on that front as well, although uncertainties remain high. For many hazards in many regions, the main message is that we need to plan for a more uncertain future.”
IPCC’s projections for global temperature increase show that if emissions of global greenhouse gases remain unchanged, a hike of 2.2 degrees Celsius is possible by 2050.
A thorough study
The Rowlands study found that global warming of three degrees Celsius by 2050 was just as plausible as a rise of 1.4 degrees, meaning that the world should prepare for either scenario.
The study ran 10,000 simulations of the impact of several variables (which affect the rate of absorption of heat by the oceans, impact of aerosols from air pollution on climate and the sensitivity of temperatures to increasing carbon dioxide concentrations) to come up with the most thorough study on climate change projections yet.
The 10,000 simulations were run on computers in people’s homes through climateprediction.net as part of a BBC Climate Change Experiment.
Climateprediction.net is a computing project which aims to produce predictions of the Earth’s climate up to 2100 and to test the accuracy of climate models. The more simulations you run of what the weather could be like, the greater the chances of a credible projection.
The project, which began in 1999, is based on the premise that running the model thousands of times will help to find out how the model responds to small changes in data. It also helps scientists to run a wide range of different scenarios. It called on ordinary citizens to donate time on their computers. All people had to do was download a climate model setup to run in the background on their home computer, returning the results to a central server after a week or so.
“There are about 90,000 active volunteers [at climateprediction.net],” said Daithi Stone, a scientist at Berkeley Lab Computing Sciences.
Stone worked with the climateprediction.net team to set up a project at the University of Cape Town to run a regional model over southern Africa on home PCs. This «weatherathome» project has so far produced 85,000 years of high-resolution modelling over southern Africa, with the help of 433 volunteers based in South Africa.
How to take part
You can take part in the weatherathome/SAF project, explained Stone. “Go to http://weatherathome.org, register, and then download a climate model simulation. This runs in the background on the computer when it is not in use, or when they are using it for something not very demanding like email. There is some visualization software that comes with the model, so you can watch the weather develop over southern Africa and the rest of the planet.
“Each simulation takes about a week on today’s computers, and at the end the programme will upload the results of the simulation back to a central server where researchers can access the data for analysis. Once a simulation is finished, another one can be downloaded and run, so it can very much be a continuous contribution.”