Geoengineering schemes range from increasing the amount of sulfur dioxide in the atmosphere to cool things down to covering polar and glacial ice with panels to slow melting to creating artificial trees to sequester carbon. But what’s wrong with just planting more real trees?

The average American could not name the last 10 presidents if you put a gun to his head. So why do we care what they think about a complex problem like global warming. Well, because the average legislator is no smarter than the citizens he or she represents, but they are smart enough to know which way the political wind blows.

The battle over climate change is not just about climate. It is about the impact of human activities on the planet, a leading example of which is climate, to be sure. But climate is hardly the only area feeling the weight of human activity.

Right now, the climate change doubters and deniers have the momentum. That will change over time, partly because it always does and partly because there are some facts over which there can be no doubt.

A British newspaper published an article on ties between denier groups and Exxon Mobil. Not exactly news.

Faced with the inevitability of change, some argue even harder for keeping things the way they are for as long as possible, extracting every last drop of oil, every last piece of coal no matter what the cost to the environment.

Climate change is just one way in which human activity is affecting life on the planet. The enormous growth in our population has had some serious side effects other than on climate.

When President Barack Obama was elected, all things seemed possible. Now . . . not so much. The optimism was certainly overstated; it remains to see if the same will ultimately be said of the pessimism that now grips those who favor action on climate change, especially in the wake of the debacle at Copenhagen.

The world is stretched thin. We can’t take too many Haiti’s without the whole system collapsing. As bad as that ounce of prevention to forestall the worst effects of climate change may look right now, it will be a bargain at twice the price if it turns out we can’t afford the pound of cure.

Dr. Betsy Dresser in New Orleans, is taking DNA from endangered or extinct species and preserving it in liquid nitrogen. There it will stay, frozen in time, waiting to be brought back to life in a world that is better able to care for the web of life on the planet. From the looks of things, it may be a long wait.