In their estimation, the most savage heat waves that we experience today will likely become routine in a matter of decades. The coastal inundation that has already begun will grow worse and worse, forcing millions of people to flee. The immense wave of refugees that we already see moving across continents may be just the beginning.
Scientists urged decades ago that we buy ourselves some insurance by cutting emissions. We yawned. Even today, when millions of people have awakened to the danger, tens of millions have not. So the political demand for change is still too weak to overcome the entrenched interests that want to block it.
In Washington, progress on climate change has stalled. The administration has announced its intent to withdraw from the global Paris climate accord. And top Trump appointees insist that the causes of climate change are too uncertain and the scientific forecasts too unreliable to be a basis for action.
This argument might have been halfway plausible 20 years ago – or, if you want to be generous, even 10 years ago. But today?
Today, salt water is inundating the coastal towns of the United States, to the point that they are starting to put giant rulers in the intersections so people can tell if it is safe to drive through. The city leaders are also posting “no wake” signs — not on canals but on the streets, to stop trucks from plowing through the water so fast as to send waves crashing into nearby homes.
We all see the giant storms, more threatening than any in our lifetimes — and while scientists are not entirely comfortable yet drawing links between the power of these hurricanes and climate change, many people are coming to their own common-sense conclusions.
As the challenges in the real world worsen, some senior Republicans continue to question the link between human-caused emissions and rising temperatures. Scott Pruitt, the head of the Environmental Protection Agency, said this on CNBC in March:
“I think that measuring with precision human activity on the climate is something very challenging to do and there’s tremendous disagreement about the degree of impact, so no, I would not agree that it’s a primary contributor to the global warming that we see.”
Note that he acknowledges the planet is warming. Note that he offers no alternative hypothesis about the cause of that warming — nor will he ever, for the simple reason that there is no plausible alternative. But still, he clings to uncertainty as a reason to do nothing.
To be sure, fair-minded people can and should ask: What are the real uncertainties?
They exist in climate science, and despite claims to the contrary made by climate denialists, nobody hides them. You can spend long days at conferences, as I have, hearing from the scientists themselves about all the error bars of their studies and all the weak points of their computer models.
We are not entirely sure, for instance, how much the planet will warm in response to a given level of emissions. That is a pretty basic question, and the inability of climate science to narrow it down has been one of the great frustrations of the field these past few decades.
In the 1970s, the experts made a best guess about how sensitive the Earth would be to greenhouse gases, and as evidence accumulates, that early estimate is holding up pretty well. Forecasts from the 1980s and 1990s about the rate of warming have proven fairly accurate, too, give or take 20 percent.
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