This is a guest post of sorts from my mate Mark Cochrane, a qualified Climate Scientist I have been privileged to meet on Chris Martenson’s website.
A link to a story explaining some new scientific research findings (link) about the relative timing of changes in solar forcing (strength of the sunlight reaching Earth) and responses of atmospheric CO2 levels was recently posted on the Definitive Climate Change Thread over at Peak Prosperity. If you are not registered with PP, you won’t be able to read this. This is Mark’s explanation of how it all works, in his usual clear and incisive way.
It was far too good to allow it to be lost in cyberspace among the squillion posts on that website…..
The paper “Synchronous change of atmospheric CO2 and Antarctic temperature during the last deglacial warming” by Parrenin et al. (2013 Science) may not sound like a best selling page turner but it addresses an important feedback in the Earth’s climate system.
Now, talk of partial pressures of trace gases and their equilibria in ocean waters may sound esoteric and totally outside of most people’s daily experience but really it is not since anyone who has ever had a soda/beer (any flavor/brand will do!) has direct experience with the process. Soda is just fizzy carbonated water which gets that way by dissolving carbon dioxide into the water at high pressure. If you notice, plastic bottles of soda are always stiff until you open them because they are pressurized. Once you open them they start to equalize with the air around you and the extra bubbles of CO2 start coming out of solution and your soft drink starts going ‘flat’. The warmer the water the less CO2 it can hold and therefore the faster it goes flat, which may help explain why we often like to keep it cold!
What has this got to do with climate? Well, the oceans are just like your open soda drink. If things are stable then they will be ‘flat’ with water that is colder holding more CO2 per unit volume than warm waters. During long climate cycles that are triggered by changes in Earth’s orbital relation to the sun (i.e. getting closer or further) this process is a primary feedback (amplifier) of the solar signal. For example, coming out of the last ice age, our orbital changes resulted in just a little bit more sunlight reaching the Earth each year as we got a smidge closer during parts of the year. A little more sunlight, means a little more heat. Some of it melted ice but most of it just poured into the giant heat sink known as the oceans. However, as the oceans warm bit by bit this forces CO2 out of the water and into the atmosphere. As we’ve discussed here, CO2 is a greenhouse gas that acts to retain heat on the Earth a little longer, thereby raising the temperature a bit more than expected (like a thin blanket). As the air temperature rises, it starts to hold more water vapour which is an even more efficient greenhouse gas further accelerating the warming process.
In climate science we’ve known for quite a while that temperature and atmospheric CO2 levels rise and fall in close synchrony (together) but the devil has been in figuring out the timing. Did the CO2 rise first and cause the warming? Did it rise in concert with the warming and amplify it like we theorize it should? Or, did it rise well after the warming, thereby signifying CO2 was either unimportant or at best of much delayed importance? Science progresses from greater to lesser uncertainty. It took a long time to tease out the sequence of timing but it became increasingly clear that CO2 didn’t precede the warming (except for unusual time periods such as the PETM). Until the recent Parrenin et al. (2013) paper, the best timing relationship between the warming and CO2 rise indicated as much as 800 years of lag time (meaning CO2 might not be as important as theorized). However, the recent peer reviewed findings using more samples and more rigorous methods support the theory – specifically “we find no significant asynchrony between them” – which translated means that the temperature rise and the CO2 rise happened at the same time (within the certainty of the measurements).
Bottom line – atmospheric CO2 is an important feedback that amplifies warming. The ‘theory’ of global warming is continually being tested by scientists and it has been vindicated time and again.
But if CO2 is a feedback, what do our actions to augment CO2 levels mean for the present and future? Well, for the present it means that we have caused a greater amount of the gas to be in the atmosphere which is akin to turning up the volume on global warming. More heat stays trapped longer meaning that we keep warming more than we would have if we had left fossil fuels in the ground.
However, as we raise the pressure of CO2 in our atmosphere the oceans have to equalize. At present that means that CO2 is being forced into the waters, making them more acidic (CO2 becomes carbonic acid in solution) which causes a host of problems for life in the water, but it also has implications for our future climate. Roughly 25% of all the CO2 that we emit ends up being soaked up by the oceans each year. The oceans soak up excess heat and CO2 – good right? Yes, in the short term this helps smooth out rapid changes in either quantity but what it means in the long term is that we will have to live with our actions (collectively) for long after we get serious about stopping our carefree fossil fuel burning ways.
There will be no rapid cooling for the same reasons there has not been rapid warming. Even if we find some way to start sopping up CO2 from the atmosphere it will just be like taking the cap off your soda. All of that stored CO2 will start bubbling out of the oceans to keep the atmospheric CO2 levels high. Until we pump the excess, indirectly, from the oceans we will not do anything to reduce atmospheric CO2 even if we can come up with some way of attempting such a thing (which is doubtful). Then, once the CO2 levels do start coming down and we finally stop accumulating heat on a global level (yeah!), all of that excess energy (>93% of everything so far!) will have to bleed out into the atmosphere, as well, before we truly start to cool the planet. There is no rapid fix to our climate predicament. The best estimates that I have seen so far indicate that after we stop or at least stabilize our level of emissions we will have perhaps 200 years of continued warming as all of the other feedbacks in the climate system play out. It will then take another thousand years or more for the system to meaningfully start the cooling process. Whether you realize it or not, we are currently undertaking our first planetary-scale terraforming experiment, with ourselves as lab rats.
Give that a thought next time you open a soda (or a beer!).