单选题 Science and politics make uncomfortable bedfellows. Rarely is this more true than in the case of climate change, where it is now time for emergency counseling. One point repeatedly made at last week's climate change congress in Copenhagen was that formulating an action plan to curb climate change is not a job of scientists. Politicians may be left scratching their heads over what to do, but at this stage climate scientists cannot provide more guidance than they did in the 2007 report from the Intergovernmental Panel on Climate Change, for two reasons. First, models will never provide a straightforward prediction of how the climate will change. As one Copenhagen delegate put it: "Tell me what the stock market will do in 100 years and I will tell you what the climate will do. " Second as most climate scientists will agree, their role is not to formulate policy. They can provide more or less apocalyptic(大灾预测的)scenarios of what will happen if emissions hit certain thresholds, from burning forests to disappearing islands. But when politicians ask what is the absolute maximum amount of carbon dioxide we should allow to be pumped out, the answer is, invariably, how much risk do you want to take? There are ways out of the deadlock. As the major climate negotiations in December approach, scientists need to be able to take off their labcoats sometimes and speak as concerned citizens. Some may feel uncomfortable with blurring the line between science and activism, but they should be aware that no one understands the risks better than they do and no one is better placed to give informed opinions. Politicians, for their part, should stop begging climatologists for easy answers. What they need instead is a new breed of advisers to descend from the ivory towers of academia and join the climate fray — people who are willing and able to weight up the risks, costs and benefits of various degrees of action. If all else fails, there may still be the safety net of geoengineering. As we have said on several occasions, this option can no longer be dismissed as fantasy. Reputable scientists are discussing options among themselves and with policy-makers, but the fact that we are even considering it should spur governments to cut emissions, cut them deeply and cut them fast. Geoengineering is no get-out-of-jail-free card; it has dangers of its own. The military are already taking an interest, raising the spectre of climate weapons able to divert rainfall and bring drought. That is the last thing we want.

单选题 Speaking of climate change, politicians______.

单选题 To bridge the gap between the two sides, according to the passage, scientists are supposed to______.

单选题 For their part, politicians ought to be reasonable and______.

单选题 The author reminds those who are talking about geoengineering of______.