Bjorn Lomborg on Climate Costs in the Australian

Australian Climate Madness blog points to an article, “Wrong way, go back“, in the Australian Newspaper by Skeptical Environmentalist Bjorn Lomberg on Australia’s climate policies. This is my comment.

This statement in the article is significant

When economists estimate the net damage from global warming as a percentage of gross domestic product, they find it will indeed have an overall negative impact in the long run but the impact of moderate warming (1C-2C) will be beneficial. It is only towards the end of the century, when temperatures have risen much more, that global warming will turn negative.

Now consider the Apocalypse Delayed? posting of March 28th. Referring to an Economist article, it says that a number of empirical studies show that climate sensitivity is much lower than the climate models assume. Therefore, moving into the net cost range seems much less likely.
But why are there net costs? Lomberg’s calculations are based on William Nordhaus’s DICE model that

calculates the total costs (from heat waves, hurricanes, crop failure and so on) as well as the total benefits (from cold waves and CO2 fertilisation).

I would claim that the destablisation of the planet’s climate by rapid warming has very little evidence. Claims in AR4 that hurricanes were getting worse; that some African countries would see up to a 50% reduction in crop yields by 2020; that the Himalayan Glaciers would largely disappear by 2035; that the Amazon rainforest could catastrophically collapse – all have been over-turned.
Thus the policy justification for avoiding climate catastrophe as a result rising greenhouse gases is a combination of three components. First, a large rise in temperatures. Second, the resulting destablisation of the climate system having net adverse consequences. Third, is that the cost of constraining the rise in greenhouse gases is less than the cost of doing nothing.
It is only this third aspect that Bjorn Lomberg deals with. Yet despite that he shows that the Australian Government is not “saving the planet for future generations”, but causing huge net harm. Policy-making should consider all three components.

That is, there are three components to the policy justification to combatting “climate change” by constraining the growth in greenhouse gas emissions

  1. That there will be a significant amount of global warming.
  2. That this is net harmful to the planet and the people on it.
  3. That the net harm of policies is less than the net harm of warming. To use a medical analogy, the pain and risks of treatment are less than the disease.

Lomberg, using the best cost model available, comes up with far less costs of global warming than, say, the Stern Review of 2006. He also uses actual policy costs to assess the net harm of global warming. Lomberg does not, however, challenge the amount of warming from a given quantity of CO2 rise, nor the adverse consequences of that warming. The Economist article
and editorial of March 30th conversely challenges the quantity of warming from arising from a given rise in CO2, but just sees it as “apocalypse delayed” and not “apocalypse debunked“.

Kevin Marshall

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