Dropping Net-Zero Targets

Back in 2008 James Hansen et al, in their paper Target atmospheric CO2: Where should humanity aim? wrote:

"If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm."

But rather than reduce, the number has continued to rise by more than 2 per year and will this year pass 420 ppm. I was born at 310 ppm and for most of humanity's history, before the industrial revolution, the number was around 270.

None of this gets much of a mention in the targets promoted by politicians. The talk is all about target dates for 'net-zero'. How much CO2 there is in the air rarely gets a mention. But this is what counts. Global heating, and hence climate change, depends not on the rate of our emissions but on the atmospheric composition. We are aiming at the wrong target. If we do manage to stop emitting greenhouse gases the temperature will continue to rise, at least until equilibrium is reached. With climate sensitivity still somewhat uncertain, we're not sure quite when that will be.

To stop further global heating we have to not just stop further emissions but also remove much of CO2 that we have already put up there. We have to a target such as 'Back to 350'.

So why don't we?

Because it's really difficult. A 'net-zero' target, some considerable way off, when the current politicians are mostly retired and won't face the consequences of failure, and which can be managed by 'greening' industry, looks plausible. But actually reducing the CO2 in the air, actually doing what is necessary, is a whole different task. Best not mention it, pretend it isn't a necessary thing.

MN-350

What to do?

Drop the net-zero targets and replace them with greenhouse gas reduction targets. Achieving them will require zeroing emissions anyway, but also going further by sequestering carbon. A halt to making things worse is necessary but insufficient, we also need to repair the damage.

And just how to do that will have to wait until the next episode...