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　　Scientists say many of the long-term effects of rising temperatures are still unknown. They’re discussing the problem at the U.N. climate change conference in Durban, South Africa. Researchers say climate change is a complex mix of potential benefits and consequences, especially regarding food production.
科学家们表示，温度升高造成的很多长期影响现在还不清楚。这些科学家们目前正在南非德班举行的联合国气候变化会议上讨论这个问题。研究人员表示，气候变化是一个具有带来潜在益处和结果的复杂混合体，在粮食生产方面尤为如此。
In early November, researchers from several countries met in Beijing. They represented the so-called BRICS countries – Brazil, Russia, India, China and South Africa – as well as the United States and Indonesia. They discussed climate change and food security and agreed on a number of issues and recommendations to present to the Durban conference.
11月初，来自一些国家的研究人员曾经在北京会晤。他们来自包括巴西、俄罗斯、印度、中国和南非在内的所谓金砖国家，以及美国和印尼。这些研究人员讨论了气候变化和粮食安全问题，并同意在提交给德班会议的诸多议题和建议方面达成共识。
One of those researchers – Gerald Nelson – said they came up with a work program for climate change treaty negotiators. It concentrates on the role of agriculture.
这些研究人员之一的杰拉德·尼尔森表示，他们为气候变化协定的谈判者制定出一套工作计划。这个计划重点关注的是农业方面的影响。
“The advantage of the work program is that it puts these research findings about the importance of looking at climate change effects on agriculture – and also agriculture’s role in mitigation – directly into the record for delegates to look at,” he said.
尼尔森说：“这项工作计划的优点在于，它把考虑气候变化对农业产生影响的重要性，以及农业在气候缓和这方面的研究发现，直接放入与会代表的审议记录当中。”
We know we don’t know
Nelson is a senior fellow at IFPRI, the Washington-based International Food Policy Research Institute.
尼尔森是设在华盛顿的国际粮食政策研究所的资深研究员。
The ancient Greek philosopher Socrates is quoted as saying, “I know that I don’t know.” Nelson said it’s not that researchers don’t know anything about climate change, it’s just that they need to know a lot more.
尼尔森表示，古希腊哲学家苏格拉底曾经说，“我唯一知道的事情是我什么都不知道。”并不是说研究人员对于气候变化一无所知，而是说，他们需要知道得更多。
"Our research results, our understanding of what’s going on on the surface of the planet today, is really hindered by a lack of data. We just have very little information about the actual changes that are taking place on the planet. We are still groping, perhaps not in the complete dark, but with only very limited illumination, to understand those changes. And we need to do a much better job of collecting data about where things are changing and how they’re changing,” he said.
他说：“我们的研究结果，我们对这个星球的外部今天正在发生什么的认知，确实受到缺乏数据支撑的阻碍。我们对于正在这个星球上实际发生的变化所知甚少。我们正在黑暗中探索，也许不是完全漆黑一团，但是确实只有极其有限的光线和启发，来理解懂得这些变化。我们在搜集有关哪里的气候在改变，以及如何改变的数据方面，需要做更为出色的工作。”
Good and bad
At first glance, some of the changes being seen appear to be beneficial, at least for now.
尼尔森表示，一眼看上去，观察到的一些气候变化看来是有益的，至少现在如此。
“Take for example, in Iowa, farmers there are seeing longer growing seasons. They’re planting earlier in the year. They’re seeing wetter springs, with more summer precipitation happening. If you take a look at China, you see that Heilongjiang Province, which used to have essentially¹ no rice production, now accounts for 15 percent of China’s rice production. In the northern parts of Russia, you’re finding grain growing that was not possible to grow there 20 or 30 years ago,” he said.
他说：“举例来说，在艾奥瓦州，那里的农场主看到作物的生长季更长了。他们在一年当中的播种期更早，他们看到春季更为湿润，夏季的降水更多。如果你看看中国，你会看到黑龙江省，过去本来不产稻米，现在的稻米产量则占到中国稻米总产量的百分之15。在俄罗斯的北部，你会看到在20到30年前不可能生长谷物的地方，现在也有谷物在那里出产。”
But what if global temperatures continue to rise? Would those apparent benefits continue? Maybe not.
但是如果全球温度继续升高，结果会怎样呢？这些明显的益处还会继续下去吗？也许不会。
“In the short run, they do seem to be positive,” said Nelson, “That is, rice production further north because it’s warmer potentially is a good thing for China. It’s harder to sort out the climate signals as you get towards the middle of the planet. It’s the northern extremes where you can see it earlier. But of course that’s with the climate change we have so far.”
尼尔森说：“在短期来看，这些气候变化看上去是正面的，也就是说，由于气候变暖导致稻米生长可以更为靠北，这对中国来说是一个潜在的好事。但是你越往地球的中部地带走，你就越难以梳理出气候的信号。在北极地区你可以早一些看到这种变化。但是当然这是我们目前气候变化下的情况。”
Nelson says predictions call for substantially greater temperature increases. He says there’s been about a one degree Celsius² rise over the past 100 years. But the forecast is for a two degree Celsius increase by 2050. Such an increase, he says, could have a dramatic effect on corn or maize³.
尼尔森表示，预报显示还有更为显著的温度升高。他说，在过去的100年中，气温已经升高了1摄氏度。但是预报显示，到2050年，气温还要升高2摄氏度。尼尔森说，气温如此升高，会给谷物玉米带来重大的影响。
“The corn plant, for example, can do ok as long as the temperature is in the range of 30 to 31 degrees Celsius. But as the temperature increases get above 30 or 31 to 32 or 33, recent research has shown substantial drop-off in yields,” he said.
他说：“举例说，只要气温在30到31摄氏度的范围内，玉米的生长就没有问题。但是随着气温升高，超过30度到31度的范围，达到32度或者33度，最近的研究显示，玉米的收成会急剧下降。”
Priorities
Nelson and others at the Beijing meeting came up with a list of 12 climate change priorities. One of them warns that a rise in temperature can also mean a rise in pests that attack crops.
尼尔森和其他在北京开会的与会者，提出了一份列有12项应对气候变化的首要任务清单。其中一项警告说，气温的升高可能还意味着袭击庄稼的害虫增加。
“For insects, in particular, as the temperatures rise then they reproduce more rapidly. So, instead of having three cycles of a pest per season you might end up with four or five. And that means more damage to the plants as they grow,” he said.
尼尔森说：“尤其对于昆虫来说，随着温度的升高，它们的繁殖会更加迅速。因此，现在每个农耕季节有三轮害虫繁殖周期，结果可能会增加到4到5轮。这意味着在作物生长过程中会遭到更多害虫的破坏。”
And as temperatures rise, regions may lose killing⁴ frosts, which help limit insect populations. As for weeds, many are thriving in the richer CO2 or carbon dioxide environment.
随着气温升高，不少地区可能会失去具有杀伤力的霜冻，霜冻可以限制昆虫的数量。对于杂草来说，很多杂草在富含二氧化碳的环境中会茂盛生长。
Then there are ruminants, animals that produce lots of methane⁵ gas while digesting their food. Nelson says methane is much more powerful than CO2. More nations are expected to raise livestock⁶ for food as their lifestyles improve.
还有反刍动物，它们在消化食物的时候，会产生大量甲烷气体。尼尔森表示，甲烷比二氧化碳更有破坏力。而随着生活的改善，预计会有更多的国家提高家畜的产量。
Other priority areas include soil ecosystems⁷, irrigation, land use, biotechnology, food supply storage losses and training for researchers, farmers and others to better deal with climate change.
其它重点关注的领域还包括土壤生态系统、灌溉、土地利用、生物科技、粮食供应仓储的损耗，对研究人员、农民以及其他人的培训，以更好地应对气候变化