If you are interested in, alarmed by, or politically engaged with the question of climate change then you really should watch this video. It’s not very long, just over 30 minutes, but it deals extremely clearly with two crucial aspects of the work of the IPCC (the central and most important UN body which coordinates the global analysis of climate change).
The Powerpoint slides used in the video are here:
The video presenter is Dr Roger Pielke from the University of Colorado who has, amongst other thngs, spent the last 30 years studying extreme weather events.
The first issue addressed in this video is what does the recently released 6th IPCC Climate Assessment Report actually really have to say about the connection of climate change and extreme weather events. Spoiler: almost everything you read about extreme weather events being the result of climate change is not based on what the science actually says. If for example you see headlines making connections between storms and floods and climate change then you are reading science fiction not science.
The second, and much more important, issue the video covers is how to understand the various scenarios that the IPCC promotes about future climate change. It explains how and why these scenarios were created, and how have they have been used by, and in fact steered, the much wider arena of climate related scientific research. Second spoiler: the IPPC has allowed itself, and the wider scientific community, to get into a deep muddle about which climate scenarios should be used to determine what the most likely future climate will be. The result has been a lot of bad science not based on plausible scenarios.
The question of what the likely climate future could look like is of course central to the political questions that arise from climate change such as how much danger are we really in and what would be a prudent and proportionate policy response.
As the video explains the various climate scenarios currently being used very widely were actually originally only intended as a series of thought experiments where climate modellers would create various imaginary scenarios and then feed them into their models to see what happened, the scenarios were a way to test their models and were not intended necessarily as a way to model the real world itself or likely future climate change. In order to stretch the climate models, and thus test them, a small series of scenarios were selected and one of these – which goes by the catchy name of RCP 8.5 – was deliberately written to be implausibly extreme. For example this scenario modelled that all other sources of energy would be abandoned between now and 2100 except for coal, that 33,000 new coal fired power stations will be built between now and 2100 (there are 6600 in use at the moment), and that six times as much coal will be used by by the end of the century. It was a scenario that was intended to see what the climate models came up with if we fed into the model that we were really, really cooking the planet. None of the assumptions in RCPO 8.5 bear even the slightest relationship to actual energy use, or future planned energy use. As I said it is a super extreme scenario only intended to test the limits of climate models.
Unfortunately somehow this super extreme utterly implausible scenario has become the one that is used most widely in climate related research. It’s the scenario used by all those alarming reports you see all the time about hundreds of millions of climate refugees, about cities drowned by sea level rises, about endless droughts and super heat waves. Unfortunately this scenario is about a fictional planet not our planet.
In the most recent AR6 report the IPCC formally and explicitly admits that RCP 8.5 is not plausible and should not be used to predict future climate impacts but then the report itself actually contains many references to studies using RCP 8.5. The problem is the IPCC’s job is to compile and collate the mass of climate research research and then describe what the consensus position is, and there are now literally thousands and thousands of research papers that have used the implausible RCP 8.5 as a starting point, so deeply implausible projections about the future are now deeply embedded in what is described as the scientific consensus .
Unfortunately the IPCC has managed to muck things up and is moving too slowly too sort out the scenario confusion, in the mean time a lot of bad science is being done because the wrong scenarios are being used. There are more and more scientists actively campaigning to eliminate the use of the RCP 8.5 scenario but there is also huge inertia in the system and in the meantime millions of people are being scared witless by imaginary emergencies and some very bad policy decisions are being made.
And of course the people who will pay the biggest price for bad climate decisions are, as always, the world’s poorest people.
