MIT Part 2: Tackling the biggest source of climate confusion

Avoiding catastrophic global warming requires stabilizing carbon dioxide concentrations, not emissions. Studies find that many, if not most, people are confused about this, including highly educated graduate students. I have personally found even well informed people are confused on this point and its crucial implications:

We need to cut emissions 50% to 80% below current levels just to stop concentrations from rising. And global temperatures will not be stabilized for decades after concentrations are stabilized. And of course the ice sheets may not stop disintegrating for decades — and if we dawdle too long, centuries — after temperatures stabilize. That is why we must act now if we want to have any reasonable hope of averting catastrophe.

One 2007 M.I.T. study, “Understanding Public Complacency About Climate Change: Adults’ mental models of climate change violate conservation of matter,” concluded “Low public support for mitigation policies may be based more on misconceptions of climate dynamics than high discount rates or uncertainty about the risks of harmful climate change.”

Here is a great video clarifying the issue, which you can send to folks. It is narrated by my friend Andrew Jones. If you want to play the simulation itself, go here. They make use of the bathtub analogy: While atmospheric concentrations (the total stock of CO2 already in the air) might be thought of as the water level in the bathtub, emissions (the yearly new flow into the air) are the rate of water flowing into a bathtub.

As John Sterman, Director of the MIT System Dynamics Group at the Sloan School of Management, noted in Part I, Bush cleverly plays into the public’s confusion with his SOTU line

… let us complete an international agreement that has the potential to slow, stop, and eventually reverse the growth of greenhouse gases.

As Sterman writes, “So the SOTU still reflects deliberate and careful use of language to make delay sound like action.”

I recommend reading the entire MIT study, whose lead author is John Sterman. Here is the abstract:

Public attitudes about climate change reveal a contradiction. Surveys show most Americans believe climate change poses serious risks but also that reductions in greenhouse gas (GHG) emissions sufficient to stabilize atmospheric GHG concentrations or net radiative forcing can be deferred until there is greater evidence that climate change is harmful. US policymakers likewise argue it is prudent to wait and see whether climate change will cause substantial economic harm before undertaking policies to reduce emissions. Such wait-and-see policies erroneously presume climate change can be reversed quickly should harm become evident, underestimating substantial delays in the climate’s response to anthropogenic forcing. We report experiments with highly educated adults–graduate students at MIT–showing widespread misunderstanding of the fundamental stock and flow relationships, including mass balance principles, that lead to long response delays. GHG emissions are now about twice the rate of GHG removal from the atmosphere. GHG concentrations will therefore continue to rise even if emissions fall, stabilizing only when emissions equal removal. In contrast, results show most subjects believe atmospheric GHG concentrations can be stabilized while emissions into the atmosphere continuously exceed the removal of GHGs from it. These beliefs-analogous to arguing a bathtub filled faster than it drains will never overflow-support wait-and-see policies but violate conservation of matter. Low public support for mitigation policies may be based more on misconceptions of climate dynamics than high discount rates or uncertainty about the risks of harmful climate change.


4 Responses to MIT Part 2: Tackling the biggest source of climate confusion

  1. Ronald says:

    That SOTU speech. (state of the union)

    Were those lines about greenhouse gases intentionally wrong or just incompetence? That is the words that Pres. Bush said about greenhouse gases, that somehow we can ‘slow, stop and eventually reverse the growth of greenhouse gases’ as some kind of victory, was that;

    1) From the President? Who doesn’t know any better.

    2) From the speechwriters? Who don’t know any better.

    3) From policy makers? Who don’t know better.

    4) From policy makers? Who knew better and that this is intentional. That they think that people don’t know any better and want to keep people misinformed by stating a lie?

    I don’t know which is worse.

    History will call out the 14 words in the 2003 state of the union speech about whether Iraq was looking for material to make a nuclear bomb. Will history also make note of a president in a 2008 SOTU speech making such a mistake about global warming and how to reduce its effects?

    Stopping, slowing and reversing the growth of greenhouse gases is not much of a goal and is very short of what needs to be done. Does this president know that? I wonder.

  2. Paul K says:

    Right now we are approaching 400 ppm. The desire is to reduce to and hold steady at 280 ppm in the second half of the century. Joe’s best case scenario sees CO2 going to 420 to 450 before going down. The president’s words, then, are an exact description of what must be done. As the preacher says, you’ve got to crawl before you walk and walk before you run. The first step in reducing CO2 concentrations is to slow the growth in emissions. U.S. emissions have increased a bit over 1.5%/year since 1990. Emissions actually decreased in 1991, 2001 and 2006 (all years with a Republican in the White House). In fact, the average increase during the Bush administration is well below the average of the Clinton years. So, here in the U.S., we may already have taken the slowing step. The next step is to stop the increase in emissions. We could be very close to doing that. The last step is precisely reversing the growth of greenhouse gases. If emissions go down rather than up, concentrations will go down too.

  3. John Sterman says:

    Paul K says: “If emissions go down rather than up, concentrations will go down too.” That is wrong, and illustrates exactly the problem our study found. Today, greenhouse gas (GHG) emissions are at least double the rate at which GHGs are removed from the atmosphere. Because the flow of emissions into the air is greater than the flow out, the concentration of GHGs in the atmosphere is rising. If emissions go down, the flow into the air will still be greater than the flow out, so the concentration of GHGs in the atmosphere will continue to rise, just not quite as fast. Concentrations will go down only when emissions fall below removal, which requires at least a 50% drop in emissions. For another example, suppose the federal budget deficit starts to drop. What happens to the national debt? It keeps rising, because any deficit at all continues to add to the debt. The debt will fall only when the government runs a surplus, meaning revenue exceeds expenditure. As long as you put water into your bathtub faster than you drain it out the amount of water in the tub will rise. That is not a political matter but conservation of matter.

  4. Paul K says:

    I read the phrase “reverse the growth of greenhouse gases” to mean emissions going in reverse. For example, in 2006 U.S. emissions went down 1.3%. For that year growth was not just slowed, it was reversed. Now if we could manage to maintain or better that rate of reversal over 20 – 30 years, we’d have the 50% reduction you say is needed to affect concentrations.