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Новости и события в Закарпатье ! Ужгород окно в Европу !

Китай – навстречу голоду?

    26 февраля 2024 понедельник
    Аватар пользователя antuan.net roi
    Потери урожая, связанные c климатическими изменениями, подрывают способность Китая прокормить более чем 1,3 миллиарда своих жителей. В северном Китае, где пшеничные поля покрывали большинство посевных площадей на протяжении веков, земля становится сухой и теплой. В южном Китае засухи в последние годы пришли на смену сезонам дождей, рисовые поля высыхают повсюду. Китайское сельское хозяйство столкнулось с проблемами изменения климата. В состоянии ли 1.340 миллиарда китайцев в будущем прокормить себя? Китай производит чуть меньше зерна, чем потребляет. Потери урожая, вызванные экстремальными погодными явлениями, нарушают этот хрупкий баланс. ..... Проблема голода – не в засухах, а в первую очередь в неправильной связи внутри человеческого сообщества – уже давно подсчитано, что при равном распределении всего хватит на всех! А при эгоистическом потреблении голодные будут всегда. Природа вынудит нас прийти к равному распределению. As Climate Becomes Less Certain, So Does China's Ability to Grow Enough Food Crop losses from climate-related challenges are already affecting the nation's ability to feed more than 1.3 billion Chinese DUJIADUN, China -- Liu Changxiong has been farming in this southwestern Chinese village for more than a decade, but his years of experience aren't of much use these days. Last year, his corn seedlings withered at a time Liu expected would be rich in rain. It took twice as many days for his green onions to grow than Liu's estimates. But the 43-year-old farmer isn't the one to be blamed. Instead, experts say, his farming routine is being messed up by climate change. Similar phenomena are happening across the nation. In north China, where wheat fields have dominated the landscape for centuries, the crop is becoming increasingly difficult to grow as the land gets drier and warmer. In southern China, droughts in recent years have replaced rainy seasons, drying up rice paddies on a large scale. Experts are scrambling to understand the problems and to predict how serious they might become. Although forecasts for crop output vary, most agree that the future climate won't be as favorable to agriculture. While China's hunt for adaptation measures is on, little progress has been made so far. That raises the question of whether 1.34 billion Chinese -- accounting for almost one-fifth of the world's population -- would be able to feed themselves. Currently, China produces slightly less grains than its people consume. Crop losses caused by extreme weather events, insect attacks and other problems associated with climate change are rocking the already delicate balance. In 2011 alone, droughts claimed grains that could have been sufficient for nearly 60 million Chinese to eat for a whole year, official statistics show. There is also the issue of rising crop production costs being driven higher by climate change. For one, as temperatures rise, many insects that used to be killed off by the cool of winter now live longer, forcing farmers to spray more pesticides. That increases food prices, and adds pressure on the lives of the poor. Genetic engineering becomes less helpful Worse yet, China is losing its ability to produce more. During the past decades, farmers here have enjoyed an explosion of productivity, thanks partly to genetically manipulated crops that are higher-yielding and resistant to pests and diseases. But today, that help is starting to fade away, as it is falling victim to climate change. "In the 1970s, when we used genetic engineering technology to breed regionally adopted crops, we could enjoy its high yield for years; now that period is much shorter," said Pan Genxing, director of Agriculture and Climate Change Center at Nanjing Agriculture University. What is defeating the technology, according to Pan, is that the environment in which the crops grow keeps changing due to climate change, making regionally adopted crops no longer a fit for the region they were designed to. To be sure, not all the effects of climate change are an agricultural curse. For instance, the higher temperatures allow crops to grow in areas which were previously too cold, and lengthen the growing season and, for some crops, the number of times per year they can be harvested. But whether China can take advantage of those changes is another troubling question. Along north China's Haihe River Basin, where crops can now grow twice a year thanks to warmer climate, local farmers still plant only once, for lack of water, says Mo Xingguo. He researches climate change and agricultural water use at the Chinese Academy of Sciences. Experts say that other parts of northern China, which were to enjoy greater numbers of harvests per year as the climate gets warmer, confront the same obstacle. Irrigation there largely relies on groundwater, and to grow more crops would require pumping more water out of wells, an unlikely prospect in a land whose groundwater level in recent years has already dropped dangerously. "The region's water resources simply can't afford more crop plantings," Mo said. Less water and more damaging insects And climate change is continuing to intensify that shortage. During the past half-century, the nation experienced less rainfall and declining river flows. At the same time, global warming is largely causing higher evaporation. Even in places that are relatively rich in water resources now, fears are rising that farmers would lose the essential resource to grow their crops. That fear is acute in places like Linze County, an oasis city along the Silk Road. The rising temperature is causing glaciers, on which so much of the water supply in the oasis depends, to melt faster. The glacier water is greening more fields now, but when the glaciers disappear, they will leave the city with a severe water deficit within five years, says a leading scientist at the Chinese Academy of Agriculture Sciences, Lin Erda, who is helping the locals offset that gap with water-saving agricultural technology. Besides water deficit, other climate risks are coming into focus. Deep in the cornfields of northeast China's Jilin province, Ma Chunsen, an insect scientist at the Chinese Academy of Agriculture Sciences, in recent years spotted more holes on maize stems, left by an undesirable visitor -- Asian corn borer. Such insects are a natural part of the life in cornfields, but they had never bred more than once a year until nowadays, Ma said. Chilly springs in this major corn-growing region used to hold back the hatching of Asian corn borer. Today, that hold is loosening due to the temperature rise. In addition to lengthening the period that invasive insects can live, scientists say temperature rise has caused outbreaks of insect attacks to happen more extensively. For instance, wheat aphids -- insects that feed on the juice of wheat -- have chewed their way into a larger scope of areas in northern regions than ever recorded. While insects are taking a ride on climate change to invade fields, crops are becoming more vulnerable to such attacks. If the air's carbon dioxide content reaches twice the current level, as scientists expect to happen by the end of this century, chemicals of major crops like rice, wheat and corn would change, making those crops less able to defend against insects, says Ge Feng, an ecologist studying interaction among insects, crops and carbon dioxide. 'Later is better than never' It is possible that the vulnerability is less significant in real-world conditions than in lab experiments, since the rise of carbon dioxide is a slow process and crops might be able to adapt to that change, Ge said. The more troubling possibility, he added, is if crops won't adapt to it, and farmers need to use more pesticides in the future. But there might be a way other than pesticides to kill invasive insects. "If we understand how climate change is affecting crops, insects and the natural enemies of the insects, then we should be able to control insect attacks by adjusting crop planting timing, for instance," said Ma, the insect scientist. Some steps have already been taken in recent years, including developing models to trace and predict attacks by some major insects like wheat aphids, he continued. But studies on other insects are essentially stymied for lack of money. "To study all major invasive insect species would require about $2 million [in] research funds each year, but little investment has spent on the subject so far," said Ma. To continue his research, Ma says he has to squeeze money from other projects. The lack of financial support comes against the background that more studies are needed in order to understand the impact of climate change. Scientists acknowledge that their attempts to use computers to project future agriculture risks are still crude. Some of those computer forecasts, for example, were found to contradict what is happening in the fields. Besides that, all of the previous research efforts didn't answer a core question. "We have researches on the impact of increasing heat, declining rainfalls as well as other factors of climate change, but we still don't know how those factors altogether affect crops' production," said Pan, of Nanjing Agricultural University. "Agriculture is an ecosystem. We can't just add or deduct research results of each factor, and say that's what climate change has caused." To draw a fuller picture, Pan has built an outdoor monitoring station where his team can follow all the changes in fields under the influence of climate change and then study their mutual impacts on crops production. Launched in 2009, it was the first study of its kind in China. Today, more programare under way, with rising government support. The idea behind such support is that if scientists understand the role of climate change in crop production, they can suggest ways to solve it -- though translating scientific findings into practical tips that can be absorbed and put to use by the average farmer might take years. "It is quite late already," Pan said, referring to China's fresh efforts to search for adaptation measures. "But later is better than never." http://www.scientificamerican.com