At this point the debate given from dwindling but increasingly aggressive climate change skeptics goes something like this:
1. We concede that the climate is warming
2. We concede that CO2 levels are rising
3. But there is still not enough evidence that the changing climate is linked to anthropogenic (man-made) CO2 emissions.
4. Therefore, we should not hasten to reduce our CO2 emissions because the consequences of doing so are extreme and may not do anything to help climate change.
Many skeptics maintain this view despite the mountains of evidence that CO2 and climate are indeed linked and that humans are more than likely a major contributor to these effects. They say this despite their counter-arguments being disproved time after time. They say this despite the fact that the risks involved with climate change far exceed the sacrifices needed to change our behavior. They say this despite the fact that the planet is not something we ought to gamble with, regardless how right or wrong the science is.
Given that this debate is often as fruitful as debating a creationist on evolution, I propose a different tact in winning support for timely action on this issue: explain the looming problem of ocean acidification.
CO2 emitted into the atmosphere is absorbed by the oceans. In fact, about a third of the CO2 we have emitted is now contained in the world's vast oceans. Once absorbed, CO2 then undergoes a chemical reaction to create carbonic acid. It's now been proven that the ocean's acidity level has slowly but surely been increasing from the CO2 humans have emitted. This has enormous consequences for the marine food web. Aquatic ecosystems are sustained by small organisms like coral, diatoms and pteropods:
The survival of these organisms depends on their ability to create a protective carbonate shells. When the water's acidity increases, their shells simply dissolve and these organisms cannot survive.
Let me make one thing clear about this phenomenon: this acidification is occurring due to a very basic chemical reaction that is well understood and has been proven countless times in the laboratory. There is no uncertainty about the effects of CO2 on water's acidity. It is also well known that the affected organisms make up the base of the food chain in many ocean ecosystems. Thus if uncertainty in climate science creates a stumbling block when arguing skeptics, perhaps we can turn to an argument unrelated to climate -- an argument for which there is virtually no uncertainty that an unchecked rise in CO2 will have global consequences. If skeptics are unwilling to be convinced on the climate argument alone, perhaps they would be willing to recognize the economic, social, and political consequences of the collapse of global fisheries.
1). This confirms that the alarmists are feeling the heat badly. First, the woeful rebutall by Environmental Defense and Michael Oppenheimer to the Senate Report and now this. They know they are losing the scientific debate badly nowadays, so they are openly admitting that a change in tactics is required. Nothing like changing the rules of the debate when you find yourself being clobbered.
2). It remains that since 1850, the total of human emissions (even including those from land use changes) consists of about 500 billion metric tons of carbon. According to the models, about 45% of that has remained in the air, the rest going 50/50 to the oceans and land. So this means that approximately 138 billion metric tons of carbon have gone into the ocean. According to the models.
Now, the ocean's reservoir of carbon stands at around 40,000 billion metric tons, the vast majority of which is dissolved in the lower depths, where pressure and coldness promotes absorption of far more CO2. Warmer surface waters tend more easily to release it.
So here are two things to consider.
A). Assume that the preindustrial surface ocean contained 1030 minus 138, or 892 billion metric tons. Following that proportion, the present surface ocean would seemingly be 15% more rich in CO2. Given that the ocean is a complex buffer solution, resisting pH changes, can a 15% increase of CO2 actually bring about the 0.1 pH change that is claimed? This question goes to the heart of the issue. (By the way, a 0.1 pH change represents a 26% increase of hydrogen ions.)
B). If it turns out that a 15% increase cannot bring about such a change, yet the 0.1 pH change is true, then consider thermohaline currents. To me it seems very reasonable to suppose that a warming ocean would circulate heat to the lower depths and thus release some of the CO2 dissolved there. This would rise up into the surface waters and necessarily influence the pH. It is entirely possible, then, that to the extent pH changes ARE real, they originate not from the sky but from the ocean below.
Just as Gore and others have the CO2/Temperature relationship backwards, prevailing assumptions about ocean acidification may be backwards too.
3). The most recent posting at CO2Science.org on this suggests that the extra CO2 stimulates biological growth in the upper ocean, which in turn is known to increase pH. So, maybe there is a biological negative feedback that helps stabilize ocean pH values?
4). According to Anthoni, whom I've cited before:
The most important limiting factor in aquatic ecosystem is the dearth of hydrogen ions (H+), which has also been overlooked. The more acidic the water, the higher biological productivity becomes, and the denser the amount of life. In the sea this is borne out by the observed fact that highly productive upwelling areas are more acidic. In other words, acidic seas are a good thing.
Bottom line, this is a confusing topic. But it does seem safe to say that how organisms use the pH that's available to them is not to be found or predicted in chemical calculations alone. I think Marc is right on target, then, that the ocean acidification issue should not be given a free pass. My own observations lead me to suspect that the present model of CO2 distribution is flat wrong. For instance, if the preindustrial ocean had nearly the same carbon content as the present one, fine, let's grant it around 40,000 GtC. But then the preindustrial atmosphere weighed 590 GtC compared to our 815. The partial pressure exerted by that preindustrial atmosphere being much less, the ability of the ocean to hold onto CO2 would have to have been correspondingly less too - in which case its carbon content could NOT have been 40,000 GtC. In short, the preindustrial ocean should have been degassing CO2 in response to the relative vacuum above it.
But if on the other hand we say, no, the preindustrial ocean was colder, so it held onto CO2 better - then we admit that the present ocean, being warmer, should be discharging CO2. And this point ties into Lance Endersbee's analysis, which shows atmospheric CO2 rising as a function of ocean temperature. But where, anywhere within the IPCC model, does it attribute rising atmospheric CO2 levels to a warming ocean? Nowhere. In fact it makes the ocean a passive sink rather than an active source. As a sink, yes, it should be getting more acidic. But as a source - CO2 upwelling from warming reservoirs below - surface waters would ALSO become more acidic. That's my point.
Posted by John Ray