Agricultural experts worry that global warming will lead to food shortage in the first place. A decrease in grain harvest will mean an increase in food prices, which may lead to riots in dozens of countries around the world, which may lead to political turmoil and weaken global economic development. For the richer countries in the northern hemisphere, global warming is caused by more greenhouse gases, and global warming may be a good thing for their agriculture. People in developing countries who are not responsible for global warming are starving. Experts call for large-scale planting of crops that can cope with global warming, and these breeding efforts are likely to succeed.

Xinhua News Agency, United Nations, February 24th-The English version of Globe and Mail today published an article by Martin Mirtl Stadt entitled How Global Warming Affects Food Production. The full text is as follows: Perhaps surprisingly, most people in the world may experience the consequences of global warming for the first time through their stomachs and changes at the dinner table.

This is the opinion of a few but influential agricultural experts. They are increasingly worried that global warming will lead to food shortage in the first place, long before it leads to more well-known but distant threats such as rising sea level and flooding in coastal cities.

At the end of last year, the Consultative Group on International Agricultural Research (CGIAR), a large organization representing 15 of the world's top crop research centers, released an amazing forecast, talking about the impact of climate change on wheat crops in a major grain producing area in the world, and emphasizing the destructiveness of global warming on agriculture.

The researchers used computer models to simulate the possible weather patterns around 2050, and found that the best wheat planting area in the vast fertile farmland from Pakistan, northern India, Nepal to Bangladesh would be seriously reduced. Most areas here will be too hot and dry for wheat growth.

The food supply of 200 million people will be threatened. Dr Louis Walshaw, chief ecologist of the World Agroforestry Center in Nairobi, Kenya, said: "Agriculture in developing countries, especially those irrigated by rain, is likely to suffer a devastating blow."

Wheat is the food source of15 in the world, but it is not the only crop that may be damaged by climate change. Warshaw pointed out that Africa's grain and corn, as well as Indian and Southeast Asian rice will be threatened.

The cruel fate is that most people who will be hungry because of global warming are those who should not be responsible for it, people in developing countries. At the same time, global warming may be a good thing for richer countries in the northern hemisphere, which emit more greenhouse gases that cause climate instability.

Walshaw said: "With climate change, the arable land in Canada, Russia and Europe will expand, while the arable land in the tropics will decrease. The basic situation is that those countries that are rich now will be richer in the future, and those countries that have problems now will face even bigger problems. "

Agriculture is vulnerable to global warming, because corn, wheat and rice, the most commonly eaten food crops in the world, are very sensitive to temperature rise. In tropical and subtropical regions, many crops grow at the highest temperature they can tolerate.

In the farming history of more than 10 thousand years, the temperature has been quite stable, at the present level or slightly lower than now. Plants are also very adapted to this climate pattern.

Although the applicability to each crop is different, an empirical rule summarized by agricultural scientists is that at the important stage of the growing season, such as pollination, when the temperature is above 35 degrees Celsius, the crop yield will be reduced by about 1 degree for every increase in temperature.

Taking rice as an example, the researchers found that this crop is most sensitive to the temperature rise at night. For general crops, the optimum growth conditions are usually between 20 and 35 degrees Celsius. If the temperature is higher, the yield will drop sharply. At 40 degrees Celsius, this kind of thermal stress begins to appear in many areas, which will lead to the closure of photosynthesis. This kind of temperature is becoming more and more common, such as the catastrophic high temperature that swept through most parts of Europe in the summer of 2003, causing tens of thousands of deaths.

According to the official data of the Intergovernmental Panel on Climate Change, the global average temperature may rise by 1. 1 to 6.4 degrees Celsius in the next century. This means that it will be difficult for crops to reduce production during most of the future temperature changes. The organization also warned that global warming will change rainfall patterns, leading to more and more floods and droughts.

The threatened wheat growing area near India is called the Indus-Ganges Plain. The summer temperature here is sometimes as high as 45 degrees Celsius, although the global warming process is still in its infancy.

According to the agricultural researchers of the Consultative Group on International Agricultural Research, the problem of declining wheat planting capacity in this plain, including Punjab Province, is really worrying, so they soon made this discovery public, although the whole investigation report entitled "Can Wheat Overcome High Temperature" will not be released until later this year.

In such a legendary agricultural area, the origin of the global 1/6 wheat crop may be seriously affected by the rising temperature, which is of great symbolic significance, because the Indus-Ganges Plain represents the greatest victory in the world's struggle against food shortage.

Nathan Russell, spokesman of the Consultative Group on International Agricultural Research, pointed out that this area "was indeed the center of the green revolution in the 1970s. Wheat and rice breeders have gained the first harvest of modern breeding technology from here. " Worryingly, climate change may "offset all these achievements".

Perhaps the most famous person who worries about climate change and its impact on agriculture is Lester Brown. He is the founder of the Earth Policy Institute, an American environmental think tank, and an advocate of the view that global warming and agricultural production will conflict. Referring to the threat of global temperature rise to agriculture, Brown said: "This is obviously imminent." He pointed out that the global grain reserve is already very small, so if the temperature rise and the change of precipitation pattern caused by global warming reduce the crop yield in any major agricultural areas, people may feel the consequences of global warming at any time, even this summer.

He said that last year's grain surplus decreased year by year, to the point where there was almost no surplus grain to bear even a poor harvest.

"The unfortunate reality is that the buffering capacity to cope with climate change is currently at the lowest level in 34 years, because in six of the past seven years, world grain production has been lower than consumption."

In addition, one solution to prevent global warming is to make clean biofuels such as ethanol from crops, which will aggravate the shortage of harvest, because people are transferring so much corn, sugar and soybeans from the table to the fuel tank.

The Earth Policy Institute inspected the world grain reserves and calculated the annual consumption and output. It claims that the global grain reserve has been reduced to only 57 days of consumption. This is close to the lowest point in modern history, second only to the reserve value of 56 days after the poor harvest in the early 1970s. That supply shortage once caused the world food price to double, which means that if global warming leads to a reduction in food production, similar consequences may occur.

Even the most important agricultural area in North America, equivalent to the Indus-Ganges Plain in North America, is facing the danger of climate change.

Computer models simulating the possible effects of climate change show that the areas with the highest temperature rise are the middle and high latitudes and the inland areas far away from the ocean mitigation effect.

Brown said: "These conditions are equivalent to the corn belt in the United States and the great plains where wheat is grown in the United States and Canada to some extent. Since we are the bread basket of the world, if our wheat and corn start to reduce production, it will affect the whole world. "

This study by the Consultative Group on International Agricultural Research did find that the rising temperature will lead to the obvious northward movement of the wheat planting belt. Theoretically, this crop will grow in the top area of North America, from Cape Harrison in Canada in the east to Ketchikan in the Alaska Panhandle in the west.

However, agricultural experts pointed out that the northern region should not be expected to become a barn that can make up for the losses in the tropical region. Replacing the rich land in Punjab and the Midwest of the United States with the barren land on the northern shore of Labrador and Lake Superior is like a gambler replacing his trump card with the worst 2 points. This is probably a stupid gamble.

Dr. Hans Brown, head of global wheat project of CIMMYT, a Mexican crop research institution, said: "Moving the climatic zone northward to areas where crops are not usually grown does not necessarily mean that crops like wheat will grow well there."

Scientists have made another worrying discovery, this time about carbon dioxide itself. This major greenhouse gas is very important for plant growth. In 1980s, according to greenhouse experiments, it was inferred that the increase of carbon dioxide concentration in the atmosphere would promote the growth of plants and increase the harvest of some crops by as much as 30%.

Partly for this reason, few people are worried about the adverse effects of global warming on agriculture today. It is believed that although climate change may bring disaster to polar bears in cold regions and low-lying coastal cities, it is not a bad thing for farmers.

However, a new study published last year conducted experiments in the United States, Japan, Switzerland and New Zealand, and found that the beneficial effects of carbon dioxide are greatly overestimated if crops are planted in open-air farmland that is more realistic than greenhouses. The harvest of corn has not increased at all, and the harvest of wheat and rice is less than half of what was previously expected. Of course, not everyone thinks that crop problems are inevitable. Donald Cox, global portfolio strategist of BMO Financial Group, said that plant breeders have made remarkable progress in cultivating crops that are more resistant to extreme conditions. He said: "Their ability is amazing."

As an investment consultant in Chicago, Cox has been paying close attention to the trend of agricultural products and mineral products markets. If the food shortage intensifies, the prices of agricultural products will rise. He said last year's corn harvest was a case in point.

Illinois, located in the center of the American corn belt, suffered from high temperature and dry weather last year, but many farmers still have good harvests because the cultivated seeds have improved the drought resistance of crops.

He said: "Frankly speaking, Illinois surprised everyone last year, even people in the agricultural industry."

Researchers from the International Agricultural Research Consulting Group have called for large-scale planting of crops that can cope with global warming, and these breeding efforts are likely to succeed.

But Brown warned that if it fails, the consequences could be very serious, because food supply is crucial to global stability.

The reduction of grain harvest will mean a rapid rise in food prices. Brown said that soaring prices "may lead to food riots in cities in dozens of countries around the world. These food riots may lead to political turmoil, which may further weaken global economic development. "

Stern Review, a British government research report on climate change, points out that slight global warming may help agricultural development, but even a small temperature rise may bring disaster to farmers.

Increase 1℃: the grain harvest in temperate regions will increase moderately, such as northern Europe, the United States and most parts of Canada.

Increase by 2 degrees Celsius: The global tropical region will begin to see a decrease in harvest. The reduction in production may be equivalent to 5% to 10% of Africa's grain output.

Increase by 3 degrees Celsius: The agricultural harvest in high latitude countries such as Canada is likely to reach its peak. However, due to crop reduction, there will be1.500 million to 550 million people facing the threat of hunger.

Increase by 4 degrees Celsius: Africa's harvest may plummet by as much as 35%, and some areas such as Australia will no longer be able to grow crops.

Increase by 5 degrees Celsius: Due to the increase of seawater acidity, fish resources are likely to be in danger.

Rising above 5 degrees Celsius: The weather has become so hot that many parts of the world will no longer be suitable for developing agriculture, leading to the emergence of a large number of environmental refugees. Stern Review called this situation "catastrophic".