As we saw in the last lecture, a major cause of climate change is the rapid rise in the level of carbon dioxide in the atmosphere over the last century.

上节课我们讲到，气候变化的一个主要原因是上个世纪大气层中急剧增加的二氧化碳。

If we could reduce the amount of CO2, perhaps the rate of climate change could also be slowed down.

如果我们能减少二氧化碳的排放量，那么或许我们可以减缓气候变化。

One potential method involves enhancing the role of the soil that plants grow in, with regard to absorbing CO2.

其中一个方式是增强种植土壤吸收二氧化碳的能力。

Rattan Lai, a soil scientist from Ohio State University, in the USA, claims that the world's agricultural soils could potentially absorb 13 per cent of the carbon dioxide in the atmosphere - the equivalent of the amount released in the last 30 years.

来自美国俄亥俄州立大学的土壤学家芮坦莱说，现在全球的农业土壤可以吸收大气层中13%的二氧化碳，相当于过去30年的释放量。

And research is going on into how this might be achieved.

现在他正在研究如何可以实现这一目标。

Lai first came to the idea that soil might be valuable in this way not through an interest in climate change, but rather out of concern for the land itself and the people dependent on it.

莱刚开始认为土壤很重要不是从气候变化方面想到的，而是从土壤本身以及人们对它的使用方面。

Carbon-rich soil is dark, crumbly and fertile, and retains some water.

富含碳的土壤是黑色松软且肥沃的，并且还保留了一些水分。

But erosion can occur if soil is dry, which is a likely effect if it contains inadequate amounts of carbon.

但是如果土壤中所含碳质不足，可能就会很干燥，而这可能会导致侵蚀。

Erosion is of course bad for people trying to grow crops or breed animals on that terrain.

腐蚀的土壤当然不利于耕种作物或是喂养牲畜。

In the 1970s and '80s, Lai was studying soils in Africa so devoid of organic matter that the ground had become extremely hard, like cement.

在二十世纪70至80年代，莱研究了非洲的土壤，他发现那里的土壤有机成分非常贫乏，已经接近水泥形态。

There he met a pioneer in the study of global warming, who suggested that carbon from the soil had moved into the atmosphere.

后来他从一位全球变暖的研究先驱那里得知，这边土壤里的碳元素已经挥发到了大气层中。

This is now looking increasingly likely.

而且现在这种状态正在持续加剧。

Let me explain.

让我为大家解释一下。

For millions of years, carbon dioxide levels in the atmosphere have been regulated, in part, by a natural partnership between plants and microbes - tiny organisms in the soil.

几百万年前，由于植物和土壤中微生物的良好作用，二氧化碳在大气层中的含量是固定的。

Plants absorb CO2 from the air and transform it into sugars and other carbon-based substances.

植物吸收空气中的二氧化碳，然后转化成糖分和其他含碳物质。

While a proportion of these carbon products remain in the plant, some transfer from the roots to fungi and soil microbes, which store the carbon in the soil.

这些含碳物质一部分保留在植物中，一部分从根部输出到真菌和土壤微生物中，从而帮助保持土壤中的碳元素。

The invention of agriculture some 10,000 years ago disrupted these ancient soil-building processes and led to the loss of carbon from the soil.

一万年前农业的发展破坏了原始土壤自建程序，使土壤逐渐失去碳元素。

When humans started draining the natural topsoil, and ploughing it up for planting, they exposed the buried carbon to oxygen.

当人类榨干表层土壤，并翻土种植时，埋在土壤里的碳和氧暴露了出来。

This created carbon dioxide and released it into the air.

它们结合成了二氧化碳并释放到空气中。

And in some places, grazing by domesticated animals has removed all vegetation, releasing carbon into the air.

有些地方，放牧破坏了大量植被，并使得碳元素释放到空气中。

Tons of carbon have been stripped from the world's soils - where it's needed - and pumped into the atmosphere.

大量的碳元素从全球各地的土壤中剥离出来，扩散到大气中。

So what can be done?

那么我们能做些什么呢？

Researchers are now coming up with evidence that even modest changes to farming can significantly help to reduce the amount of carbon in the atmosphere.

研究人员现在研究寻找适度的农业调整方案，帮助减少大气中碳的总量。

Some growers have already started using an approach known as regenerative agriculture.

有些种植者已经开始使用再生农业。

This aims to boost the fertility of soil and keep it moist through established practices.

这种农业旨在提高土壤的肥力，通过建立某些作业来保持土地湿润性。

These include keeping fields planted all year round, and increasing the variety of plants being grown.

比如保持全年种植和增加种植植物的多样性。

Strategies like these can significantly increase the amount of carbon stored in the soil, so agricultural researchers are now building a case for their use in combating climate change.

这样的策略可以显著增加土壤中储存的碳的数量，因此农业研究者构建关于防御气候变化的案例。

One American investigation into the potential for storing CO2 on agricultural lands is taking place in California.

美国加利福尼亚州开展了一项在农业土壤中储存二氧化碳的研究。

Soil scientist Whendee Silver of the University of California, Berkeley, is conducting a first-of-its-kind study on a large cattle farm in the state.

来自伯克利市加利福尼亚大学的土壤学家文帝·希尔福在一家大型养牛场上开展了一次前所未有的研究。

She and her students are testing the effects on carbon storage of the compost that is created from waste - both agricultural, including manure and cornstalks, and waste produced in gardens, such as leaves, branches, and lawn trimmings.

她和她的学生测试了混合肥料中碳储量的效果。这些肥料既来自包括粪便和秸秆在内的农业废料，还包括花园产生的像树叶、树枝，草坪修剪的废料。

In Australia, soil ecologist Christine Jones is testing another promising soil-enrichment strategy.

在澳大利亚，土壤生态学家克里斯汀·琼斯正在进行另一项有前景的肥沃土壤的战略测试。

Jones and 12 farmers are working to build up soil carbon by cultivating grasses that stay green all year round.

琼斯和12位农民正在通过培育全年保持翠绿的草坪测试来土壤碳。

Like composting, the approach has already been proved experimentally; Jones now hopes to show that it can be applied on working farms and that the resulting carbon capture can be accurately measured.

和混合肥料一样，这项方法也经过了实验的检验。琼斯希望这一研究能运用在农作上，这样由此产生的碳元素获取量就可以更精确地测试出来。

It's hoped in the future that projects such as these will demonstrate the role that farmers and other land managers can play in reducing the harmful effects of greenhouse gases.

未来，这些项目将有望提高农民以及土地管理者在减少温室效应中做出的巨大贡献。

For example, in countries like the United States, where most farming operations use large applications of fertiliser, changing such long-standing habits will require a change of system.

比如，像美国这样，农业作业都是由大型施肥设备完成的国家，如果要改变这一长期习惯，则需要更换另一套系统。

Rattan Lai argues that farmers should receive payment not just for the corn or beef they produce, but also for the carbon they can store in their soil.

芮坦莱认为，农民得到的薪酬不应仅仅等同于那些他们产出的玉米或是牛肉，还应该包括他们在土壤中可存储的碳含量。

Another study being carried out ...

另一研究是……