The weather forecast tells us roughly speaking whether tomorrow will be wet or fine. For example, if we see a forecast saying "tomorrow there will be rain from the afternoon", we can remember to take an umbrella when we go to school or work in the morning. Similarly, if we could forecast what was going to happen to the Earth's climate, could we formulate some kind of response?
Scientists around the world have been wondering the same thing, and using the latest, most advanced supercomputers to conduct research on forecasting the Earth's future climate. In 2005, Japanese researchers employed the high-performance Earth Simulator supercomputer to make the world's most precise (as of April 2006) global warming predictions.
Earth Simulator © ESC/JAMSTEC
The Earth Simulator is a supercomputer capable of performing an incredible 40 trillion calculations per second. Six hundred and forty large computers sit in a room the size of a gymnasium, linked to function as one giant supercomputer. Even this supercomputer takes a month to calculate a 100-year forecast, an indication of the mammoth calculations involved.
When trying to predict global warming, it is important to consider not just natural variations, but also the effects of human industrial activity. To do this, scientists come up with several scenarios for the society of the future, and input these as part of the calculations. The global warming simulation you can view on Earthrium assumes that the current high level of economic growth will continue and predicts that as a result, the average global temperature compared to that in the pre-industrial era will rise 2｡C by 2028, 3｡C by 2052, and 4｡C by 2069.
The figure of 2｡C is currently attracting global attention. This is because many believe that a temperature rise of more than 2｡C would have an enormous impact on human society, pose a huge risk, and most European nations have now made keeping any temperature rise below 2｡C as an important policy objective. Don't imagine global warming is something that will happen after you've gone: in reality, it is not far away at all.
Of course, this is just one computer-generated outcome, and there is still much we don't know about climate mechanisms, so things will not necessarily turn out as predicted. But just as we can hear on the weather forecast that it is going to rain and think to carry an umbrella, surely if we are told that in 20 years time climate change will intensify, we can start making preparations now.
Forecasting changes in average temperatureunder the high-growth scenario
It is thought that if the average global temperature rises by 2｡C compared to before industrialization the climate risk will increase significantly. The question for us now is what action we should take to ensure this 2｡C limit is not breached.