Sunday, December 11, 2016

Climate Skepticism


Mexico City is far from Mumbai: 15,644 km separate the two.

Alternatively put: Mexico City lies 15,595 km to west and 50 km to the north of Mumbai. Mexico City is far from Mumbai.

Both statements show Mumbai is, in fact, far from Mexico City.  However, the west/north breakdown seems a bit unnecessary, no?

Now consider this from David Romer, the Herman Royer Professor of Political Economy at UC Berkeley:
Nordhaus (2008) concludes that a reasonable estimate is that the overall welfare effect as of 2100 is likely to be slightly negative--the equivalent of a reduction in GDP of 2 to 3 percent.  This corresponds to a reduction in average annual growth of only about 0.003 percentage points.  Not surprisingly, Nordhaus finds that drastic measures to combat global warming, such as policies that would largely halt further warming by cutting emissions of greenhouse gasses to less than half their 1990 levels, would be much more harmful than simply doing nothing.
Of course, it is possible that this reading of the scientific evidence or this effort to estimate welfare effects is far from the mark.  It is also possible that considering horizons longer than the 50 to 100 years usually examined in such studies would change the conclusions substantially.  But the fact remains that most economists who have studied environmental issues seriously, even ones whose initial positions were sympathetic to environmental concerns, have concluded that the likely impact of environmental problems on growth is at most moderate.
Professor Romer also happens to be the husband and frequent co-author of President Obama's first Chair of the Council of Economic Advisers, Christina Romer.  He is not a person lacking intelligence or good progressive influences.  And yet.

Now consider:
Healthy debate is the lifeblood of American democracy, and global warming has inspired one of the major policy debates of our time. That debate is far from settled. Scientists continue to disagree about the degree and extent of global warming and its connection to the actions of mankind. That debate should be encouraged — in classrooms, public forums, and the halls of Congress.
That is from Scott Pruitt, President-elect Trump's nominee to head the EPA.  Because of this position, he has been called a climate change skeptic and denier by the New York Times, WaPo, and CNN.  Scientific American, to their credit, only opted to quote a Democratic opponent's hypothetical in their headline ("A candidate who doesn't believe in science would be 'a very dangerous person to pick'") and kept a pretty honest assessment a few paragraphs down ("Pruitt focuses on the legality of climate regulations, rather than questioning climate science").

Personally, I am generally for policies to combat global warming, though this stems more from risk averse instincts rather than informed opinion.  I especially like these policies when they are coupled with broader green goals of cutting unhealthy pollutants and preserving natural habitats.  However, climate science and economic forecasting are both hard.  I find it entirely reasonable (i.e., consistent with an honest interpretation of the partial information available) to think that there is uncertainty regarding the magnitude of effects when changing inputs (like CO2 emissions) in a chaotic system (like global climate).  I also find it entirely reasonable to dispute how much, if any, economic resources should be sunk into cutting emissions.  Who am I to dismiss outright someone much more informed like David Romer?

I'm not sympathetic to skepticism to the Pruitt's bit that the anthropogenic roots of climate change are still in doubt.  I don't much care that there may be the rogue scientist or three arguing something other than industrialization's role is in doubt.  However, this to me is like pointing out Mexico City sits on a latitude fifty miles north of Mumbai.  It's a trivial point in the assessment that Mexico City is very far from Mumbai.  Similarly, there is debate left to be had on the absolute magnitude and economic consequences of climate change.  Dismissing anyone who says otherwise outright as a denialist is not likely to get us far.

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