Passage Five 
  This leaves us with the challenge of finding some politically practicable way to reduce greenhouse gas emissions. But it is an awkward truth that when most U.S senators were asked informally in 2000 if they would support the Kyoto Protocol should President George W. Bush send it to the Scant for ratification, the overwhelming majority, Democrats as well as Republicans, said they could not. The reason for the liberals' surprising reply is clear. Many studies, not all by conservatives, suggest that full compliance with the terms of the Kyoto Protocol would likely lead to a deep American recession. For those willing to run this risk, sober reflection on the consequences of the economic collapse of 1929 and the subsequent worldwide depression with all its political and ultimately military consequences is certainly in order.
  That said, what can be done, in particular by our own country Independent of the issues raised by the Kyoto Protocol, and given the weight of evidence that the problem of global warming is serious fraught with dire consequences, failure to do anything at all and instead to promote "business as usual" downright criminal.
  Yet the Bush administration has given no more than lip service to the problem, though that could he changing. It is one thing weigh alternatives and implements compromises that reflect the complexity of the problem; it is quite another thing to do nothing, especially if doing nothing is just a way of securing support from certain industries that worsen the problem.
  There are, after all, things that can he done. Reopening a serious international dialogue, and not just saying a few good words, would be a useful if inadequate start. Not every problem must be solving before -the weight of evidence becomes so compelling that certain initial steps become almost mandatory. We already know how to make more fuel-efficient yet no national policy has surfaced to accomplish this. The scientific and engineering communities are the ones best suited to identify the scientific research that is still needed and the technical projects that show the greatest promise. These issues should be decided by them and not the politicians. Once solutions look promising, as a few already do, industry will be all too ready to romp in, for at that stage there is money to be made. And only a fool would underestimate human ingenuity when given a proper incentive, or the strength of American industry once the boiler is lit under it.

We can learn from Paragraph 2 that （）。