WC Archive

What I would draw attention to right now is this. We are now about 100ppm over the pre-industrial value. We will hit 200ppm above the pre-industrial value in the late 2040s in in the linear model. We could view this value as some kind of approximate indicator of the driving force behind "weather problems" - mountain glaciers all melting, increased storm activity, record heatwaves, etc. So during the expected lifetime of anyone here under about 35-40, that driving force is going to double. Whether the system is likely to respond linearly to that is another day's subject.

Next I will talk about how much we should worry about these levels of CO2. After that we'll have a look at the Kyoto protocol and its likely impact, and then we'll begin looking at how much of the 60 Gt/year of net primary productivity for carbon in biomass makes it into the economy, and where it goes. I have some interesting graphs of the total weight of matter the world economy processes each year as context for that.

The Carbon Economy article describes the carbon cycle, and looks at how we measure and understand the effects of increased atmospheric carbon concentrations. Stuart makes a point of creating his own charts and graphs from the raw data, so he's able to combine differing approaches to greenhouse gas projections. His goal is to introduce some core concepts, and he's able to do so in a manner that will appeal to the more quantitative readers.

The second item in the series, How Fast Should You Boil A Frog?, was posted today, laying out the projections for temperature increases arising from carbon concentration; again, this is something of an introduction piece, preparing the reader for future argument by making sure everyone is on the same page. These two pieces are clearly just the beginning, and more articles in the series are yet to appear; but because The Oil Drum encourages thoughtful discussion, I thought it better to point to this work now, rather than wait until he was done, so that WorldChanging readers can take part in the give-and-take, too.

Today's RealClimate gives us a hint as to why these kinds of analysis are important.

There's general consensus among climatologists that we'll start to see the more serious impacts of global warming when the global average temperature reaches 2°C higher than baseline (we've increased by 0.8° so far), and disastrous results by 4°C. In Can 2°C Warming Be Avoided?, the RealClimate team lays out what it would take to stabilize atmospheric carbon at a level that lets us remain below that 2°C threshold. Interestingly, thermal inertia -- the ocean's slow response to changes in temperature -- plays a heroic role in this discussion.

Most of the time, we're mindful of thermal inertia due to its role in keeping the planet warming for a couple of decades beyond any cut-off of greenhouse gas emissions. But that slow reaction to changes in climate forcing can be in our favor in a situation in which we let things get out of hand before reining them back in. The RealClimate authors morbidly describe our situation in terms of a cat in an oven:

Now, what is going to happen to our cat, if we turn up the heat control of our oven to about 475 ppm and then reduce it again? If we react quickly enough, we might be able to save the cat from some irreversible consequences. In other words, if concentrations are lowered fast enough after peaking at 475 ppm, the temperature might not exceed 2°C. Basically, the thermal inertia of the climate system will shave off the temperature peak that the cat would otherwise have felt if the oven temperature reacted immediately to our control button.

(For the record, as a cat owner, I'm more than a little disturbed by this choice of metaphor.) What RealClimate is saying is that, even if we can't reduce our carbon output fast enough to avoid CO2 concentrations peaking at a far-too-high level, a rapid decrease in emissions after the peak could still be enough to avoid hitting the 2°C danger level. For me, this is one more argument against simply giving up in despair or looking only to scenarios of "adaptation." It's not yet too late to make a difference.

The future is still in our hands.