The standards for evidence in science are much higher than they are in ordinary life, which is why it has taken the scientists on the IPCC so long to announce the same conclusion any ordinary mortal who looked into the question would have reached five or 10 years ago. (The scientists really knew it, too, but they couldn't yet prove it to the required standard.)
But the World Bank, for example, has long known approximately how much food production every major country will lose when the average global temperature is 2 degrees C higher. At least seven years ago it gave contracts to think tanks to answer that question.
The think tanks told the World Bank India will lose 25 per cent of its food production. China, I have been told, will lose a catastrophic 38 per cent. These results have never been published because their governments did not want such alarming numbers out in public and restrained the World Bank from releasing them.
So, too, for example, the armed forces of many countries have been incorporating predictions of this sort into their scenarios of the future for at least five years. The Pentagon and the Central Intelligence Agency in the United States and the British armed forces have been doing it openly, and I have seen strong indications that the Russian, Indian, Pakistani, Chinese and Japanese armed forces are also doing so.
When you look closely, the scenarios do not just predict serious food shortages in most tropical and sub-tropical countries (which account for about 70 per cent of the world's population). They predict waves of refugees fleeing these countries, a proliferation of failed states in the sub-tropics, and even wars between countries that must share the same river system when there's not enough water to go around.
That's still farther than the IPCC is prepared to go, but to the military it's obvious. As for what will happen to crop yields by 2050, assuming an average global temperature 3 degrees C higher by then, you have to go elsewhere for information. The military don't plan that far ahead.
But the World Resources Institute published a map recently that estimated the losses country by country by 2050, and according to the WRI's calculations they are really bad by then. Crop yields are down everywhere in the Middle East and the Mediterranean countries. In Morocco, Egypt and Saudi Arabia, they are down by 50 per cent.
All of Africa is down except Lesotho, Rwanda and Kenya, which are all or mostly above 1000 metres in altitude. Food production is down in almost all of South America except Chile, also very high, where it is up. Crop yields in North America are down too, except in Canada and a few US states right along the Canadian border. High latitude is even better than high altitude.
In Europe and Asia, latitude is decisive. Countries far away from the equator will still be doing well; countries even a bit closer to the equator get hammered.
Russia, Scandinavia, Germany and Poland will be producing more food than ever, but southern Europe including the Balkans and even France and Ukraine will have lost production. India, China, and all of South-East Asia will be sharply down, as will Australia - but Japan will be only a bit down and New Zealand will be sharply up. It pays to be an island, too.
But this is not a "mixed" result, in the sense that it all works out about even. The total population of all the countries where food production will be stable or higher in 2050 will be less than half a billion. At least eight-and-a-half or nine billion will live in countries where food production has fallen, sometimes very steeply. It will be a very hungry world.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries.
