TOEFL---IBT閱讀材料：Can Charcoal Slow Climate Change and Improve Agriculture?

地球氣候變化給人類社會和生活帶來了很多影響和潛在的威脅，因此各國科學家都十分關注如何使全球氣候變化減緩，最近有科學家的研究發現，生物碳不僅能一定程度上減少污染，同時也可以給農業發展帶來便利。
　

The ancient inhabitants of Amazonia knew how to keep fragile soils fertile—and may have hit upon a way to combat present-day climate change. That technique? Biochar, or any plant or animal waste turned to charcoal and put back into the ground.

Studies suggest as much as 900 million metric tons of carbon a year could be locked up this way—and improve the soil's ability to grow crops as well. That's nearly 20 percent of current CO2 emissions as a result of burning fossil fuels.

And a new study shows that biochar could have an impact on agriculture's other greenhouse gas emission: nitrous oxide, or laughing gas, which is no laughing matter when it comes to climate change. Biochar applied to Australian fields and left for a number of months cut such emissions by more than 70 percent as well as preventing nitrogen and ammonia from leaching out of the soil in water. Such fertilizer leaching is responsible for dead zones across the world, like the one at the mouth of the Mississippi River currently.

Of course, biochar is no panacea, despite fans like Richard Branson. Some studies suggest biochar can accelerate microbes degrading organic matter into dread CO2 in places like the boreal forests of the northern hemisphere. But perhaps charcoal is better in soil than burned as fuel for barbecues. The terra preta soils of Brazil are still being farmed, centuries after the biochar was added.