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May 12, 2011

The Prisoner’s Dilemma

Michael Feldman

Over the past few years, there has been a subtle shift of tone about climate change solutions, from prevention and remediation to mitigation and adaptation. That shift is not all that surprising, given the failure of the international community to deliver any substantive policy solutions toward reducing greenhouse gas emissions. As a result, people seem to be talking less about reducing carbon footprints and more about how high to build the sea walls in Manhattan.

I would put the effort to build climate models for exascale supercomputers in the latter category as well. By 2018, when the first exaflop machines are expected to debut, chances are that climate change will have advanced to the point where policy decisions will be strongly focused on mitigation and adaptation. That also seems to reflect the thinking of others in the research community. Marc Snir, who is the principal investigator of the newly-hatched G8 research project on exascale climate simulations is one such person. In an article this week in HPCwire, he talked about the utility of enhancing climate simulations for exascale machines:

I suspect that all participants in our project believe that the time to act on global warming is now, not ten years from now. The unfortunate situation is that we seem incapable of radical action, for a variety of reasons. It is hard to have international action when any individual country will be better served by shirking its duties — the prisoners’ paradox — and it is hard to act when the cost of action is immediate and the reward is far in the future. As unfortunate as this is, we might have to think of mitigation, rather than remediation. More accurate simulations will decrease the existing uncertainty about the rate of global warming and its effects; and will be needed to assess the effect of unmitigated climate change, and the effect of various mitigation actions.

Marc’s reference to the “prisoner’s paradox,” sometimes known as the Prisoner’s Dilemma, refers to a situation when cooperation is trumped by the motivation to act in one’s own self-interest. The paradox has to do with the fact that individuals, or individual countries for that matter, will often behave this way even if their long-term interests would be better served by working together.

That realization appears to be sinking in more generally. A report released on Thursday from the National Research Council discusses the necessity of preparing to adapt to climate change, while also talking up the need for “substantial” action to limit its magnitude. But even here, the authors admit that such action wouldn’t turn back the clock on climate change:

Aggressive emissions reductions would reduce the need for adaptation, but not eliminate it. Climate change is already happening, and additional changes can be expected for all plausible scenarios of future greenhouse gas emissions. Prudent risk management demands advanced planning to deal with possible adverse outcomes — known and unknown — by increasing the nation’s resilience to both gradual changes and the possibility of abrupt disaster events.

I suppose it’s a good sign that the governments of the world are investing so much in climate research. In the US, most of the top US Department of Energy and NASA supercomputers spend at least some portion of their cycles on climate simulation codes (not to mention the NCAR and NOAA machines). Same goes for most of the top tier supercomputers in Europe and Asia. It’s probably not an exaggeration to say that hundreds of millions of dollars in supercomputing infrastructure and software development has been invested globally to address climate change.

As anyone who has even casually followed this research over the last 20 years knows by now, the models are all pointing in the same direction — global warming. The latest assessment by the Intergovernmental Panel on Climate Change predicts the average surface temperature of the Earth will increase between 2.0 and 11.5 Fahrenheit by the end of the century, assuming no heroic efforts are instituted to restrict greenhouse emissions.

It’s disheartening, therefore, to see how little, policy-wise has been accomplished by world governments based on the results of all the research they took the trouble to sponsor. It’s sort of like getting your car checked out every year with the latest diagnostics, but not fixing anything when the mechanic tells you the engine is going to blow. In truth though, that analogy is not quite fair. In this case, we can’t pull the car into the repair shop to fix it; we’ve got to retool it while it’s careening down the highway.

Ironically, the biggest reduction in greenhouse gas emissions was the result of the 2008-2009 recession, which brought CO2 levels down to those of the late 1990s. The depth of the economic downturn was so severe that, according to the US Energy Information Administration (EIA), emission levels aren’t expected to return to their 2008 high point of 6 billion metric tons per year until around 2025. After that, levels are expected to grow at an average of about 0.2 percent per year. Of course we could always hope for another economic disaster to mitigate an environmental one, but that seems like a poor trade-off.

Mitigating climate change, rather than reversing it, appears to be our destiny at this point. Human nature is certainly better adapted to acting on problems that confront us in real time, rather than at some point in the undefined future. Exascale-level climate simulations would almost certainly put us in a better position to do that by the end of the decade. But we still might want to start building those sea walls now.

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