This Is Not Your Grandfather's Pollution

Well, in a sense it is.  CO2 increases from early in the 1900s still are floating around the atmosphere.  But the problem we have isn't anything like what people are used to thinking about . . .

David Roberts gave a talk last year about how climate change is simple.  His body language and tone of voice show that he gets it.  We are in really serious trouble.

He wrote a new piece about two reasons climate change is not like other environmental problems.

They boil down to this: it's permanent.

First he talks about the permanence of CO2 emissions.

To make this clear, let’s use the old bathtub analogy. The faucet is the source of the pollutant. The tub is the environment. And the drain represents the means by which the pollutant exits the environment. The key fact to remember: The damage to public health is determined by the total amount of pollutant in the tub.
Take a familiar air pollutant like particulate matter. We are spewing it into the air from tailpipes and smokestacks (the faucet). It leaves the air through simple gravity (the drain). Most of it falls to earth in days or weeks.
So when it comes to the particulate-matter bathtub, the drain is very large. We can reduce the total level of particulate matter in the tub any time we want; all we have to do is turn the faucet down, or off, and the tub will drain rapidly.
Carbon dioxide is not like that. Once it’s in the tub, it stays there for up to 100 years before it drains out. And the drain in the bathtub (so-called “sinks” that absorb carbon out of the air, like oceans and forests) is comparatively small relative to the enormous amounts coming out of the faucet. And by the way, we’re actively making the drain smaller by cutting down forests and carbon-loading the oceans.

This makes for a very different situation. Even if we cut our emissions by a third tomorrow, we would still be increasing the total amount in the bathtub:

The other issue  is that once things get heated up, they stay heated up for a long, long time.

But as this 2009 paper in Nature (among many others) makes clear, it doesn’t work that way:

This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. [my emphasis]

This is not the time cycle of particulate pollution — days or weeks — it is the time cycle of the Earth’s basic biophysical systems, which move much more slowly. A thousand years is not “forever,” but in terms of human agency it might as well be.

 These are two things most people haven't really internalized.  Things like acid rain can be cleaned up.  Even the ozone hole can be cleaned up.  We're doing something completely different.