The specific patterns of change are not known precisely, but the risks of continuing on our current global course are widely appreciated. Yet the United States has refused to sign the Kyoto Protocol, which does little to change the long-term course of events on the planet, since it calls for only small steps up to the year 2012.
气候变化的详尽模式还不得而知，全球继续朝着这个方向发展的风险正引起广泛的重视。然而美国却拒绝签署《京都议定书》。由于该协议只呼吁在2012年之前采取有限的举措，所以它对改变地球长期的状况几乎产生不了什么作用。