By Roger Pielke Jr.
Excerpt: From the IPCC’s fourth to fifth assessment report our collective future, as envisioned by the IPCC, changed dramatically. The world was no longer heading for a wide range of possible futures, conditioned on enormous uncertainties, but instead was heading with some certainty toward a future characterized by an extreme level of carbon dioxide emissions. Quantitatively, futures with less than 50 billion tons of carbon dioxide emissions in 2100 simply disappeared from the IPCC scenarios and the focus was placed on a “business as usual” scenario of more than 80 billion tons of carbon dioxide emissions in 2100.
The apocalypse had been scheduled.
The decision by the IPCC to center its fifth assessment report on its most extreme scenario has been incredibly consequential. Thousands of academic studies of the future impacts of climate change followed the lead of the IPCC, and have emphasized the most extreme scenario as “business as usual” which is often interpreted and promoted as where the world is heading. For instance, so far in 2019 two new academic studies have been published every day that present this most extreme scenario as “business as usual” and predict extreme future impacts. Journalist promote these sensationalist findings, which are amplified by activists and politicians and as a consequence climate change becomes viewed as being more and more apocalyptic.
The problem with the extreme “business as usual” scenario of the IPCC’s fifth assessment report is that it is already out of date. For 2020 the scenario wildly overstates emissions, and has been critiqued in the academic literature as a highly unlikely if not impossible future. The International Energy Agency has proposed scenarios for the next several decades that diverge greatly from the favored scenario of the IPCC. It is of course possible that the world will collectively choose to emit massive quantities of carbon dioxide, which would require a massive increase in coal burning. But that scenario is certainly not preordained, and other futures are certainly possible.
Remarkably, the IPCC is set to repeat its reliance on extreme scenarios as “business as usual” in its forthcoming sixth assessment report, even though these scenarios are already out of date.
I will have much more to say on this subject in coming columns, as this topic is an active focus of my research. The bottom line for today is to understand that a fateful decision by the IPCC to selectively anoint an extreme scenario from among a huge range of possible futures has helped to create the climate apocalypse, a scary but imaginary future.
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