阅读理解：
A Sunshade for the Planet
Even with the best will1 in the world，reducing our carbon emissions is not going to prevent global warming.It has become clear that even if we take the most strong measures to control emissions，the uncertainties in our climate models still leaye open the possibility of extreme warming and rises in sea level.At the same time，resistance by governments and special interest groups makes it quite possible that the actions suggested by climate scientists might not be implemented soon enough.
Basically the idea is to apply sunscreen to the whole planet.One astronomer has come up with a radical plan to cool Earth;launch trillions of feather-light discs into space，where they would form a vast cloud that would block the suns rays.Its controversial，but recent studies suggest there are ways to deflect just enough of the sunlight reaching the Earths surface to counteract the warming produced by the greenhouse effect.Global climate models show that blocking just 1.8 per cent of the incident energy in the suns rays would cancel out the warming effects produced by a doubling of greenhouse gases in the atmosphere. That could be crucial，because even the most severe emissions-control measures being proposed would leave us with a doubling of carbon dioxide by the end of this century，and that would last for at least a century more.
emissionn.发射，发射物 heroinn.海洛因
n.住院治疗
geoengineering n.地质工程 astronomern.天文学家
百万兆; 万亿，兆
adj.有争议的
注释：
2. if the worst comes to theworst：如果最最糟糕的事情发生了。这是英式英语的用法，在美式英语中它说成if worst comes to worst。在不同的语境中，有不同的泽法，如：If the worst comes to the worst，Becky thought，my retreatsecure;and l have the right- hand seat inthe barouche.蓓墓想道：逼到最后一条路，逃难是不怕的了，在他的大马车里，我稳稳地有一个位子了。又如：Ifthe worst comes to the worst，well sell the car.大不了我们把车卖了。
4. methadone：美沙酮，一种有效的合成麻醉药，它不像口马啡或海洛因那样容易汁人上瘾，在戒毒治疗中被用作这些毒品的替代品。