Oceans are ‘soaking up less CO2’ is the headline of a recent BBC News article. (Well, it is recent in most senses of the word though not in blogger-land…Rabbet Run discusses it here, Stoat did it here, and Michael Tobis blogged about it here).
So the news is that a some new research indicates that the rate at which atmospheric CO2 is being absorbed into the ocean is falling. The findings are new, the authors are not sure if natural varibility is involved or not, but regardless it is a troubling sign. If it does turn out to be the case it signals the cessation of a free ride nature has allowed the human race since we began polluting the air with excess CO2.
Roughly half of all the anthropogenic emissions of CO2 have not been accumulating in the atmosphere. Roughly half of what nature has been cleaning up for us has been going into the ocean. If this process stops we will see faster rates of CO2 accumulation and correspondingly faster rates of climate change. Well, I say “if”, but really it is a question of “when”.
There is a long anticipated feedback effect related to warming oceans. As water warms, its ability to hold dissolved CO2 diminishes. When that happens, the CO2 it is holding is released into the air. It is therefore a reasonable anticipation that not only will oceans stop taking up our new CO2 emissions, they will begin releasing their own. This positive feedback is the leading hypothesis for why CO2 rose over and over as the earth came out of its many ice ages observed to have occurred over the last million years.
Though it is expected, there is simply no solid way to predict with confidence when exactly it will start. In fact, this effect is not incorporated into any of the latest IPCC report projections. So if this latest study is the breaking news that that process has begun we will find yet again that far from being alarmist, the IPCC projections are too conservative.