These are not exhortations from overwrought extremists, but carefully phrased warnings from some of the world's finest scientists.

We shouldn't fuel the future with the polluting methods of the past, ... We have the technology to power our future in ways that don't threaten our health or poison our planet. Let's choose to use it.

With time environmental issues got much more complicated. It is pretty easy, if you know what you are doing, to stop a company from pouring poison into a lake where kids swim. It is much harder to address all the myriad greenhouse gases emitted by different sources - from petrochemical refineries to hundreds of millions of peasants cutting down trees for their incredibly inefficient cook stoves.

We got everyone's attention, but we didn't solve any environmental problems.

Obama wants to build such things as smart electrical grids and high-speed rail lines, which will offer big environmental improvements. Another obvious thing is that large-scale project financing is virtually frozen, so a lot of renewable energy projects are on hold. If the system doesn't get unclogged before the developers run out of cash, they will be cancelled. Money matters, and we are racing against time.

These are not exhortations from overwrought extremists, but carefully phrased warnings from some of the world's finest scientists.

Politicians had always viewed environmental issues as narrow things of no great political consequence. Sort of NIMBY issues. A big part of the reason was that the groups that cared about wilderness didn't talk with the groups that were trying to stop freeways from cutting through inner cities, and neither of them talked to the folks who wanted to stop the military from dumping Agent Orange on Vietnam.