2015考研英语阅读气候变化与农作物

　　Climate change and crops

　　气候变化与农作物

　　Hindering harvests

　　妨害产量

　　Changes in the climate are already having an effecton crop yieldsbut not yet a very big one

　　气候变化已经对农作物产量造成影响但是迄今影响不大

　　May 5th 2011 | from the print edition

　　THE problems climate change looks likely to bring inthe future may increasingly be visible in the recordsof the past. Not just in the far-off ages of surging sea levels following ice-age thaws, spikes inprehistoric temperatures correlated with natural releases of greenhouse gas and ancientcivilisations brought low by drought, but in records from living memorywhich are based onreliable measurements made at the time. Using such data researchers have now compiled anestimate of global changes in crop yields which can be put down to recent increases intemperature and decreases in rainfall . The bad news is that they find that climate changehas lowered the amount of maize and wheat produced in a given area.The good news is that the effect is so far reasonably small.

　　冰河融化后的远古时代，海平面急剧上升，由于温室气体的自然释放，气温处于史前时代最高峰，古代文明由于干旱而衰落。在记忆可及的近代，人们根据可靠的测量对气候变化做了记录。根据过去的这些记录，气候变化可能造成的影响，在未来也许会越来越明显。研究人员利用这些数据，现在已经对全球农作物产量的变化做出了估计。农作物产量变化的原因可能是近来气温的升高和降水的减少。消息有好有坏。坏消息是，他们发现，在上述地区气候变化使玉米和小麦减产。好消息是，迄今为止气候变化的影响相当小。

　　David Lobell and Justin Costa-Roberts, of StanfordUniversity, and Wolfram Schlenker, of ColumbiaUniversity, first put together temperature andprecipitation figures for the parts of the worldwhere four staple cropswheat, maize, rice andsoyaare grown. Those four crops, between them,account for about 75% of the calories people end upeating, although a lot of the soya is fed to animalsfirst.

　　斯坦福大学的戴维德?罗拜耳、扎斯汀?考斯特-罗伯特和加利福尼亚大学的沃尔夫然姆?史灵克，首次将世界上以小麦、玉米、稻子和大豆作为主要农作物的部分地区的气温和降水量结合在一起。他们共同研究发现，尽管很多大豆首先被用来喂牲畜，但人们最终所吃的热量有75%是这四种作物提供的。

　　It turns out that during the seasons in which crops grow, these arable areas had on averagebecome significantly warmer in the 29 years after 1979. Some bits of Europe that grow wheat,for example, have heated up by a couple of degrees since 1980. The researchers thenassembled models of how the yields changed from year to year, and against the longer trend,to find changes linked to temperature and rainfall that are independent of improvementsthrough better farming. Finally they compared todays yields with what their models say yieldswould have been with todays farming but in the 1980s climate.

　　研究发现，从1979年以后的29年里，在农作物的生长季节，这些可耕作面积的气温普遍越来越暖。例如，自1980 年起，一些种植小麦的欧洲地区气温上升了两度。为了发现与气温和降水有关的产量变化，并且是不依赖于农耕方法的改进引起的变化，研究人员接着建立了产量逐年同比变化的模型，并与更长的趋势相对照。模型显示，产量变化除了1980年与气候变化有关外，可能与现在的耕作方法有关。最后，他们将现在的产量与模型显示的产量相对照。

　　Popping corn

　　夸大得象爆玉米花

　　For both wheat and maize, the results, published this week by Science, were negative.Globally, wheat yields are down 5.5% compared with what they would have been with noclimate change, and maize yields are down 3.8%. For soya, some places saw improvements,some saw damage, with no real net effect on the global scale. For rice, warming brought aclear benefit for crops at higher latitudes and some losses in warmer places. Temperatureplayed a bigger role than precipitation. The results seem to fit with previous studies into sucheffects in individual countries.

　　研究发表在本周的《科学》杂志上，对小麦和玉米来说，结果是否定的。在全球范围内，与没有气候变化的条件下相比较，小麦产量下降5.5%，玉米产量下降 3.8%。大豆则某些地方增产，某些地方减产，没有真正相同的全球范围的影响。对稻子来说，气温变化对较高维度地区明显有益，而对较温和的某些地区则有损害。气温比降水造成的影响更大。这一结果似乎符合以前做过的关于在单个国家里这种影响的研究。

　　But there are caveats. For example, the analysisdoes not track changes over time in the areas beingfarmed, using instead a crop map from around 2000.And many agronomists hold that relying on year-to-year yield changes for modelling exaggerates thedamage due to longer climate shifts. Farmers willtend to adapt. That said, subtler effects of climatechange such as more sudden rains and particularlyhot days with disproportionate effects on yield areleft out, which might mean the study underestimatesthe effects.

　　但是需要做一些说明。例如，这一分析没有追踪现已被耕种地区的产量随时间的变化，反而使用的是2000年前后的作物分布图。很多农学家认为，依靠逐年同比的产量变化建模，夸大了较长时间气候变化引起的损害。那样农民将会适应。这说明，诸如较为突然地降雨等气候变化的较微弱的影响，和特别热的天气对产量的很大的影响被忽视，这可能意味着研究低估了影响。

　　Some people will be surprised, even dismayed, that comparatively modest climate changes arealready doing measurable damage. But in context, it is quite small. Yields have been going uparound the world despite the warming climateand over 29 years those increases swamp theestimated global reductions due to climate. The sort of loss that climate change inflicts in adecade is often the sort of gain that better farming brings in a year. What is more, for wheatthe increasing level of carbon dioxide that is changing the climate also makes photosynthesiseasier, which should have increased yields enough to wipe out perhaps half of the climate-related loss .

　　有些人将感到吃惊甚至惊愕，因为不太大的气候变化已经造成了重大的损害。但是在上文中，这种损害相当小。尽管气候变暖，但世界各地的农作物产量一直在增加而且29年来的这种增产超过了估计的由于气候变化造成的全球减产。十年里气候变化造成的减产，经常与一年里由于耕种技术改进带来的增产相等。而且，对小麦来讲，一直影响气候的CO2的含量增加也使光合作用更为容易，这将使产量增加到足以抵消大约一半的与气候有关的损失。

　　Then there is a point made by Richard Tol of VU University Amsterdam: farm yields show theworst of the situation. Easily achievable improvements in roads, markets and other things canincrease the availability of food a lot even if farm yields stop rising. And people can adapt, atleast to lowish levels of change; indeed the study provides evidence to help them do so as itshows which crops in a given country are the most affected by global warming. So Malthuslooks beatable even when he sits astride the apocalyptic horse of climate change.

　　接着阿姆斯特丹自由大学的理查德?套耳指出一个要点：农作产量指示着最坏的情形。即使农作物产量停止增长，在公路、市场和其它方面容易取得改进能够使食物的有效利用大大增加。而且人们至少能够适应相当小的变化;的确，当研究表明在一个被考察的国家里哪一种农作物受全球升温影响最大时，研究提供的证据有助于人们去适应。因此即使马尔萨斯骑在预示气候变化大灾难的高头大马上时，看起来他也被击败了。