Guest essay by Dr. Matt Ridley
Phil Plait, who goes by the name of the “bad astronomer”, has now written three articles in Slate attacking two of my columns in the Wall Street Journal on the topic of climate change. My columns, and responses to critics are here and here. I have no problem with Mr Plait disagreeing with me, but I am a little taken aback by his name calling and sheer nastiness.
I asked for a right to reply in Slate, encouraged by the editor. But when the editor read my polite reply, he refused, on the grounds that “we publish such responses when critics have new or compelling arguments or evidence that call into question what we have published. You have differences with Phil, but we don’t believe your response offers such evidence.” I disagree. You be the judge.
The latest attack is strangely self-contradictory. Without citing a single study to back up his claims, Mr Plait accuses me, wrongly, of not citing a single study to back my claims. He writes:
“He just states it like it’s true. However, we know that’s not the case.”
Was there ever a better shooting of one’s own foot? (Something he accused me of.)
Let’s leave the invective on one side and examine the argument without ad-hominems.
The argument I made was that climate change has benefits as well as costs and that the benefits are likely to be greater than the costs until almost the end of the current century. I maintain that the balance of evidence supports the conclusion that up to a certain level of warming — about 2 degrees Celsius — the benefits of climate change will probably outweigh the costs. Plait admits that there will be benefits, but he assumes that they are smaller than the harm however small the warming and that I am somehow foolish for not sharing his assumption. He gives no source for this claim, which flies in the face of peer-reviewed sources.
I’d like to direct him to this 2004 survey of many studies, and this 2013 study, which confirm that climate change of 1 or 2 degrees Celsius will probably, in aggregate, do net economic and humanitarian good to mankind. It will do so by lengthening northern growing seasons, reducing winter deaths (which greatly exceed summer deaths even in countries with hot summers) and increasing precipitation, but without raising sea levels sufficiently to do serious harm.
It’s worth noting that the IPCC used to claim in its early reports that a great increase in malaria as a result of global warming would bring early and large net harm to humankind. Professor Paul Reiter of the Pasteur Institute, one the world’s experts on malaria, disagreed and spent many years trying to change the IPCC’s view. His point was that malaria was not now limited by climate, but by human intervention: it had been banished from Europe, North America, much of Asia and much of Latin America by the draining of swamps, the use of insecticides, the use of glass windows and screens, and many other measures. Warming up the world would not reverse these trends and would create only tiny expansions in malarial range at high altitudes in Africa. Malaria mortality has dropped by 25% since 2000. Reiter was ignored for years, but now the IPCC agrees with him and has largely dropped the claim. This is just one example of where the climate establishment eventually had to admit that the likely harm was being exaggerated.
It is not just human benefit that mild warming will probably bring. Please note that the papers cited in the 2004 paper I mention also discuss how such mild warming will raise biodiversity, ecosystem productivity and net primary production, so the net benefits are ecological as well as economic. Again, this is not a minority view. Most ecologists accept that if you warm up the world slowly, and consequently increase precipitation, you will increase the energy flow through ecosystems, which will support more creatures and species of creatures – all other things being equal.
As well as the warming, there’s the effect of carbon dioxide itself. Plants need CO2 and they struggle to get enough without losing water from their leaves. More CO2 in the air means faster growth rates and more drought tolerance. That’s why commercial growers pump CO2 into their greenhouses. I would ask Mr Plait to consult this study by Randal Donohue, which confirms that there has been net greening of arid areas of the planet as a result of rising carbon dioxide levels. This is something that has been confirmed by both ground and satellite data. Here’s what the American Geophysical Union had to say about the Donohue paper:
“Scientists have long suspected that a flourishing of green foliage around the globe, observed since the early 1980s in satellite data, springs at least in part from the increasing concentration of carbon dioxide in Earth’s atmosphere. Now, a study of arid regions around the globe finds that a carbon dioxide “fertilization effect” has, indeed, caused a gradual greening from 1982 to 2010.”
Nor is Donohue alone in this. A fascinating talk by Dr Ranga Myneni of Boston University confirms that between 1982 and 2011,
“31% of the global vegetated area greened…This greening translates to a 14% increase in gross productivity [and] The greening is seen in all vegetation types”
He finds that most of this was down to relaxation of climate constraints (ie, warming and wetting) or other anthropogenic factors — ie, chiefly rising carbon dioxide levels.
Mr Plait is welcome to disagree with me that the crossover from net benefits to net harm from climate change will occur at about 2 degrees Celsius of warming (it might well be higher, or lower, and it will depend on how fast it happens – I don’t claim to know the answer). But he is simply wrong to assert that the harm certainly outweighs the benefits whatever the warming, let alone that this is the current consensus view.
Mr Plait then claims to know that weather is getting more extreme with horrible consequences, and that the deaths of trees from pine beetles is caused by climate change. In the first instance he is simply wrong. The IPCC itself has issued a report on extremes, which refutes the suggestion that we are seeing extreme weather as a result of climate change. As Professor Roger Pielke Jr of the University of Colorado put it in recent testimony to Congress: “It is misleading, and just plain incorrect, to claim that disasters associated with hurricanes, tornadoes, floods or droughts have increased on climate timescales either in the United States or globally. It is further incorrect to associate the increasing costs of disasters with the emission of greenhouse gases.”
In any case, there has been no net change in global temperature for 15 years to drive an increase in extreme weather. Meanwhile, the global death rate from droughts, floods or storms has fallen by 98% since the 1920s. Not because weather got less dangerous but because people got richer and better equipped to cope. See here.
Mr Plait then claims that beetles are killing pine forests because of climate change. I don’t doubt it has played a role, although I note that the main reason most sources give for the increase in beetle infestation is the growth of even-age lodgepole pine stands. None the less, suppose that he’s right. This is one relatively minor (in global terms) ecological change, which is unlikely to result in much change to the productivity of an ecosystem in the long run (indeed it may accelerate plant growth by clearing the shade of trees) or biodiversity (again, these pine stands tend to be monocultures so diversity may rise). Yet he asks us to take this one small change in one small corner of the world as evidence that climate change is harmful even at low levels.
Why does all this matter? Because we now know that action against climate change has severe costs. Cutting carbon dioxide emissions means rolling out land-hungry, expensive renewable technologies that raise food prices or energy costs driving poor people to death in measurable numbers. See Indur Goklany’s careful and cautious calculation about biofuels here. And see any number of sources on the health costs of indoor air pollution caused by cooking over wood fires where cheap electricity has not ben made available because of political objections to the use of coal. Is that a price worth paying? Maybe if it prevents a catastrophe; but not if it averts a beneficial change in the climate. I may be wrong in thinking the latter is more likely than the former, but I am not wrong – factually or morally – for raising the possibility.
And I think it is very relevant indeed that if you consult the probability density functions of most recent studies of climate sensitivity, conducted by senior IPCC-affiliated scientists, you will find that there is a significantly higher than 50-50 probability of warming of less than 2 degrees Celsius during the next 70 years.