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The world is literally a greener place than it was 20 years ago, and the data from NASA satellites has revealed a counterintuitive source for much of this new foliage: China and India.

与20年前相比,这个世界确实是一个更加绿色的地方,来自美国宇航局卫星的数据揭示了这么一个违反直觉的源头:中国和印度。

This surprising new study shows that the two emerging countries with the world’s biggest populations are leading the improvement in greening on land. The effect stems mainly from ambitious tree planting programs in China and intensive agriculture in both countries. In 2017 alone, India broke its own world record for the most trees planted after volunteers gathered to plant 66 million saplings in just 12 hours.

这一令人惊讶的新研究表明,世界上人口最多的两个新兴国家在改善土地绿化方面处于领先地位。这种效应主要源于中国雄心勃勃的植树计划和两国的集约化农业。仅在2017年,印度就打破了自己种植树木最多的世界纪录,志愿者们聚集在一起,在短短12小时内种植了6600万棵树苗。

The greening phenomenon was first detected by researchers using satellite data in the mid-1990s, but they did not know whether human activity was one of its chief, direct causes.

上世纪90年代中期,研究人员首次利用卫星数据发现了这种绿化现象,但他们不知道人类活动是否是其主要直接原因之一。



An advantage of the MODIS satellite sensor is the intensive coverage it provides, both in space and time: MODIS has captured as many as four shots of every place on Earth, every day for the last 20 years.

MODIS卫星传感器的一个优势是它在空间和时间上提供了密集的覆盖:在过去20年里,MODIS每天拍摄了地球上每个地方多达四张的照片。

“This long-term data lets us dig deeper,” said Rama Nemani, a research scientist at NASA’s Ames Research Center and a co-author of the new work. “When the greening of the Earth was first observed, we thought it was due to a warmer, wetter climate and fertilization from the added carbon dioxide in the atmosphere, leading to more leaf growth in northern forests, for instance. Now, with the MODIS data that lets us understand the phenomenon at really small scales, we see that humans are also contributing.”

“这些长期数据让我们可以更深入地挖掘,”NASA艾姆斯研究中心(Ames research Center)的研究科学家、这项新研究的合著者拉马·内马尼说。“当我们第一次观察到地球变绿时,我们认为这是由于气候变暖、变湿,以及大气中二氧化碳的增加,例如,导致北方森林中更多的叶子生长,从而产生了肥料。现在,通过MODIS的数据,我们可以在非常小的范围内理解这种现象,我们发现人类也在做出贡献。”

China’s outsized contribution to the global greening trend comes in large part (42%) from programs to conserve and expand forests. These were developed in an effort to reduce the effects of soil erosion, air pollution and climate change. Another 32% there – and 82% of the greening seen in India – comes from intensive cultivation of food crops.

中国对全球绿化趋势的巨大贡献(42%)在很大程度上来自于保护和扩大森林的计划。这些措施是为了减少土壤侵蚀、空气污染和气候变化的影响而制定的。在印度,32%的绿化来自于粮食作物的集约种植。

The land area used to grow crops – more than 770,000 square miles – is comparable in China and India and it has not changed much since the early 2000s; yet these regions have greatly increased both their annual total green leaf area and their food production. This was achieved through multiple cropping practices, where a field is replanted to produce another harvest several times a year. Production of grains, vegetables, fruits, and more have increased by about 35-40% since 2000 to feed their large populations.

用于种植农作物的土地面积——超过77万平方英里——中国和印度相当,自本世纪初以来变化不大;然而,这些地区的年总绿叶面积和粮食产量都大大增加了。这是通过复种实现的,在复种的过程中,一块土地每年会被重新种植几次,以便再次收获。自2000年以来,谷物、蔬菜、水果等的产量增加了35-40%,以养活其庞大的人口。



“Once people realize there’s a problem, they tend to fix it,” he said. “In the 70s and 80s in India and China, the situation around vegetation loss wasn’t good; in the 90s, people realized it; and today things have improved. Humans are incredibly resilient. That’s what we see in the satellite data.”

“一旦人们意识到有问题,他们往往会去解决它,”他说。“在70年代和80年代,印度和中国的植被损失情况并不好;在90年代,人们意识到了这一点;今天情况有所改善。人类具有难以置信的适应力。这就是我们从卫星数据中看到的。”