How to Think about Global Warming

I’ve had a back and forth with some people I respect on global warming.  I wanted to present my point of view in loose outline.  This post is not technical; it is not laden with data and statistics.  If there is interest and/or pushback, maybe we can go deeper into the weeds.  This is, step-by-step, how I came to my present position on the global climate, starting from standard liberal goodthink.  I had taken a course taught by a prominent climate scientist, I had read many of the reports issued by international bodies, my views were entirely kosher up until the point in late-2015 where the following train of thought led me to revisit the underlying science.

1. If global warming is caused by human activity and can be mitigated by human activity, it is a collective action problem, and so can only be solved if the underlying collective action problem is solved, not by Stakhanovite volunteers.

regional-co2-emissions-1965-through-20132. In order to solve the collective action problem properly, we must bargain for our own good, because we will be doing the most to solve the collective action problem (and thus the most to end anthropogenic global warming) when we exchange our own offer in exchange for the maximum possible sacrifices from all other countries. In other words, the more selfish we are, the harder the bargain we drive, the more we save the world.

3. In order to be able to drive a hard bargain, we need to know the strength of our own (US) bargaining position. That means knowing exactly how much different levels of global warming hurt and harm the US (and how much they hurt and help our negotiating partners, as well).

4. In order to calculate this basket of costs and benefits, we need a clear model of the (range of likely outcomes for) effects that different levels of carbon dioxide emissions would have on atmospheric CO2, and through this on global average temperatures, and through global average temperatures on regional climates (including temperature range, precipitation, hours of sunlight), sea level, and other variables that directly affect human life.

5. If you cannot build such a model, you cannot effectively solve the collective action problem (because you cannot effectively drive a hard bargain, so China and India will continue to produce a huge and growing volume of the “greenhouse gases”).  But also, if you cannot build such a model, you do not know that the theory connecting human energy production and agriculture to temperature changes is accurate.  Here we should be precise.  Is the greenhouse effect real?  Yes, of course: and you can go to a greenhouse and see the effect in real life.  This is different from asking whether any climate model which makes the greenhouse effect central to it’s account of climate change is able to generate robust predictions, and not just about one dependent variable of interest (like average global temperature or average global sea level) but about intermediate causes (ocean temperatures, the behavior of polar ice, and so on).

Statistics joke: three statisticians go hunting.  They spot a moose.  First one takes aim, fires, and shoots a little to far to the left.  Second one takes aim, fires, and shoots a little too far to the right.  The third jumps up and yells “We got him, we got him!”

gwfrom18kyaThere is no need for a greenhouse model of human activity to explain the warming of the Earth and the rising of sea levels during the period of industrial civilization.  The last glacial maximum took place 22kya.  Since then, there have been periods of both warming and cooling, but on average the Earth has been getting warmer.  Throughout the entire post-glacial period global sea levels have continued to rise.  Climatic forces much older than industrial civilization (much older than our species, in fact) would be sufficient to explain not only global warming/global sea level rise, but a much more rapid rate of change than what we are observing today.  The greenhouse model is only valuable if it explains relationships between the relevant variables (a) better than alternative models and (b) better than random chance (which is a stiff standard due to degrees of freedom and selection on dependent variables). gwmeltwater24kya There is nothing very ecologically friendly about retooling industrial production entirely to prevent global warming, if the effects on global temperatures are not what we think.  Dams destroy entire river valleys and have already led to the extinction of fascinating species (like the Yangzi dolphin). Nuclear power is what it is.  Windmills kill birds and their comical scale creates a monstrous disruption of our relationship with nature.  Solar does not seem to have any disastrous consequences – yet! – but every “disruptive” technology reveals its risks only after it has been unrolled on a sufficiently large scale for these to be exploited.  Even when “greenhouse-friendly” policies do not actively destroy the environment, the mere fact that we lower GDP means that we are sacrificing the same slice of the globe to industrial civilization, but for fewer toys; if people can be persuaded to give up some toys, best we produce them as efficiently as possible (including by use of fossil fuels) so that industrial civilization can be rolled back as much as possible in exchange for the sacrifice.  Climate science needs to justify any sacrifices we make to eliminate greenhouse gases with reliable predictions about these gases effects.  No predictive model, no justification, no case for “fighting global warming” even in strictly environmental terms.

delfin_blanco
The now-extinct Yangzi dolphin. Thanks, Obama!

(From the perspective of deep ecology one may find some of these considerations trivial or even backwards.  The bourgeois environmentalist is afraid of nuclear power because, in the event of a nuclear meltdown, humans may need to evacuate an entire region; the deep ecologist is excited by possible nuclear meltdowns because the risk of fallout allows the natural world to completely reclaim the affected area from industrial civilization, as it has already reclaimed the Chernobyl region.  But by the same token, is any deep ecologist afraid of global warming?  The sea levels have been higher, the sea levels have been lower.  Some sea levels may be more or less convenient from a human perspective, but that is only one perspective.  All populations eventually stress their environments in ways that check their own further expansion.  Diatoms created oxygen waste until they poisoned themselves and killed off most existing species.  This was a necessary final check on the unlimited expansion of the diatoms, and after much death, the beautiful unfolding of terrestrial biodiversity continued. Do deep ecologists see anything in global warming but a long-awaited reckoning?)

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