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Impossible emissions scenarios make for impossible health outcomes

It is not true that 8 billion are at risk from climate-change-induced malaria and dengue fever. It is true that this is a claim put forward in a paper in The Lancet Planetary Health. Given that truth, it is the claim in the paper that is wrong.

This is nothing to do with what the effects of a 3.7 degree, or more, temperature rise might be. The important point to grasp is that such a temperature rise is not going to happen. We have explained this in detail in this paper.

The mistaken claim about malaria stems from this part of the paper’s methodology:

….across four RCPs (arranged from the most conservative to business-as-usual: RCP2.6, RCP4.5, RCP6.0, and RCP8.5)…

RCP 8.5 is not going to happen. It never was likely to happen. Actions taken so far – from fracking to the prices of solar and wind derived electricity – mean that it is never going to happen. RCP 8.5 is not even a possible outcome, let alone “business as usual”.

In more detail, the phrase “business as usual” in this context means the outcome of social and economic development without further policy changes specifically aimed at reducing emissions and thus temperature changes. To reach the emissions levels of RCP 8.5 it would be necessary to cease to use renewables at all. Further, to stop using – because we run out of conventional reserves – oil and natural gas and revert to coal for the majority of society’s energy needs. In fact, to gain more of society’s – vastly larger in the future – energy, as a portion of total energy used, from coal than we ever have done.

This is not going to happen. Therefore predictions, even model outcomes, based upon the assumption that it will happen are wrong. Not just outside likely results, or to test an extreme, but wrong.

The scientific method is that it is necessary to test theories, hypotheses, against reality. When there is disagreement it is reality that wins, not theory.

It is even possible to agree that if temperatures rise 3.7 degrees then malaria and dengue fever will become more of a problem than they are now. But given that we know that temperatures aren’t going to so rise it’s not a problem that we need to pay much attention to. Further, those that model such a rise in order to scare us – as with telling ghost stories to children perhaps – need to be reminded that such misleading of the political process is going to reduce our attention to problems we actually should be trying to solve.