วันอังคารที่ 16 ตุลาคม พ.ศ. 2555

If extreme weather becomes the norm, starvation awaits | George Monbiot

With forecasts are currently based only on average, food production can Splutter on even earlier than expected

think I could have made a mistake a mistake whose consequences, if I'm not mistaken, it would be difficult to exaggerate. I believe that global food production forecasts could be totally wrong. Food prices are rising again, partly because of damage to crops in the northern hemisphere by the fierce weather. United States, Russia and Ukraine, cereal crops were affected by the extraordinary drought. In some parts of northern Europe, including the UK, have been hit by the endless rain.

However, this is not, as a report in The Guardian last week, "one of the worst global harvests over the years." It is one of the best. World cereal production last year was the highest ever recorded, the harvest this year is only 2.6% lower. The problem is that, thanks to the combination of increased population and immoral diversion of grain for animal feed and biofuels, a new record must be established each year. Although 2012 is the third largest of the world harvest in history (after 2011 and 2008), it is also a year of food shortages, we consume more than 28m tonnes grain farmers produce. If the harvest of 2013 does not set a new world record, the poor are in serious trouble.

Thus, the question of how climate change could affect food production could not be more important. It is also very difficult to solve, and rely on instruments as impressive as "switching endogenous multinomial regression models." The problem is there are so many factors involved. More rain is canceled by additional evaporation ? Does the fertilizing effect of carbon dioxide is more powerful than the heat damage is due to what extent farmers can adapt? Does new varieties to meet changing Climate

But speaking in general terms, the consensus is that climate change will affect farmers in the tropics and help farmers in temperate countries. A famous article published in 2005 concluded that if we follow the path most extreme for the production of greenhouse gas emissions (which we at the time), global warming could increase yields in rich countries 3% during the ten 2080, and reduce them in poor countries than 7%. This gives an overall reduction of food supply in the world (compared to what would have happened without climate change caused by humans) by 5%.

published since then support this conclusion: Provides tough times for farmers in Africa and South Asia, but a boon for farmers in the coldest regions of the world, whose yields increase as that the developing countries are becoming less able to feed themselves. Climate change can have devastating effects for many poor people in the world. If farmers in developing countries can not participate in both income and food security will decrease, and the number of undernourished people could rise permanently. Countries in which they live, in large part, where growth is expected to come from food production will have to import most of its food from abroad. But in terms of flow models predict gross product not an insurmountable problem.

So this is where the problem arises. The models used by most of these documents predict the effects of changes in average conditions. They do not take into account the extreme weather events. All right: are complicated enough. But what if the changes in the size of the global harvest relies less on average conditions ending?

This is what happened in 2012. This is what seems likely to occur in the following years. Here is why. A document of this year by the scientist in the world in climatology, James Hansen, shows that the frequency of extreme heat events (such as drought that hammered the United States and Russia) has increased by a factor of about 50, compared to decades prior to 1980. Forty years ago, the extreme summer heat usually affects between 0.1 and 0.2% of the globe. Today it is burned by 10%. "We can not project a high degree of confidence," says the document, "the area covered by extreme heat anomalies continue to increase in the coming decades and until the above will happen." But these points are not included in the standard models that predict changes in agricultural production. If the proposed mechanism is correct for another article, not just the extreme heat that can be removed. I explained this before, but I think it bears repeating. The jet stream is a current of air to the east, traveling through the north of the upper hemisphere. It separates the wet and cold weather in the northern climate warmer and drier in the south. Wobbling along this belt are huge maze called Rossby waves. As the warming of the Arctic,. Meandering slowly and become more pronounced time stuck.

Time Stuck Perhaps nothing more normal. Perhaps the gentle warming trends mean that climate models predict - simultaneously terrifying and strangely reassuring - extreme wild mask so that no farmer can plan and no farmer can answer. Where does this leave a world that is keep increasing production or starve?

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