↑ comment by Pawntoe4 ·
2019-08-07T13:17:20.701Z · EA(p) · GW(p)
I do not disagree that the Vice piece and the think tank research are likely alarmist and unrepresentative, but unfortunately in my opinion John Halstead's analysis and the underlying IPCC reports are entirely too optimistic on the flipside. I think this leaves a lot of room for further serious evaluation of the potential existential risks on climate change.
Firstly, John Halstead's review of existing literature. I was privileged enough to go to his talk EA Global London 2018 which was a summary of this work. It is a very large and understudied field and partially as a result of this his work has focused on direct and existential risks.
Indirect risks seem to include a huge host of pressures on society, infrastructure, and other trappings of civilisation where the impulse of these pressures could be very significant in causing widespread collapse. I don't think he specifically states here but he goes with the more clear, academic definition of existential risk of the extinction of the human species.
These two put the frame for the whole analysis as entirely too narrow for what most people are asking, and why the Vox piece is misrepresenting his work by saying it likely isn't an existential threat. In my opinion the responses of multiple competing nations to a world with increasingly shrinking and variable resources is a critical factor and while it is nearly impossible to forecast likely interactions, I don't think they're going to be pretty. Nuclear war is a separate X-risk and its probability is likely to be vastly increased with severe climate effects to start with, but there are several other indirect and interdependent mechanisms that could exacerbate the rate of collapse.
The definition of existential risk as more widely accepted in the EA community is a lot more general than that seemingly assumed by John Halstead or stated in the Vox piece - the permanent or sufficiently long-term curbing of the progress rate of the human species is included, generally to sustained existence at pre-industrial levels. While he does state when talking for the Vox article that he doesn't see even +10C being a threat to this broader definition, I at least don't see any substantiation of that in his research document, and throughout the Vox piece (and in his analysis) this seems to be a throw-away comment rather than the overriding definition that is being used is either strict extinction or is confused and assumed.
Interestingly as an aside, in Halstead's reasoning he seems to have updated from his previous dismissal of ecological collapse where he now sees it as a more complex and uncertain issue. There were some pre-Eocene extinctions related to carbon release events (the counterfactual being a large part of his justification for the theory's dismissal), as well as the paleontological record not accounting for unique Anthropocene pressures on populations including "speed, magnitude, and spatial scale" (from the IPCC). I see these as critical factors for the determination of adequate adaptation response in ecosystems / specific species at the high-impulse end where we seem to be operating. At longer timescales of thousands of years (still very high impulse climate change for paleontology) this does allow for some Darwinian selection and migration, whereas we are operating on a scale of approx. 200 years (and we are already living through a mass extinction - whether this leads to ecological collapse is another matter).
Aside from the framing of the research with narrow definitions (and leaving out a significant chunk of relevant mechanisms that could contribute to climate change being an X-risk by confining it to direct effects only), for me there is a real problem with Halstead's analysis in that he bases it largely on the IPCC reports, which are (in my opinion) egregiously optimistic. The simplest reason for this is the case of incentive. IPCC stands for "Intergovernmental Panel on Climate Change" and while it does take into account the consensus of climate scientists it is also an intergovernmental report that has specifically political objectives and the language of which is curbed and adjusted in various ways to further various agendas. This includes a Summary for Policymakers (SPM) which includes a "final round of written comments on the SPM, before governments meet in plenary session to approve the SPM line by line and accept the underlying report." This is the final stage but also governments have individual and serious involvement in the assessments made and to assess how palatable the conclusions are in order to try to foster (or impede) positive progress on these issues in their home countries. [It has been speculated that one of the reasons why the IPCC reports are so illegible for laypeople - excessive stating of confidence intervals and complex justifications - is to allow policymakers to more easily ignore it as they are, largely, laypeople themselves, and this is by design and for plausible deniability]. There is also widespread consensus that (for reasons above and others) the IPCC reports also aim to be conservative and non-alarmist in order to prompt change by making it appear more feasible.
Additional glaring problems with a lot of climate models is that many don't account for feedback loops, and there are plenty of reports about gross underestimations of releases and warming effects, and we don't have very good data on runaway effects and how much they could accelerate warming, in addition to how fragile the Earth's global ecosystem is. It is only relatively recently that it was calculated by NASA that 27.7 million tons of phosphorous-rich sand is being carried by cross-Atlantic winds from the Sahara to the Amazon (where soils are notoriously poor, and as such this transfer is important for the flourishing of the Amazon). Since the Amazon is about the size of the Indian sub-continent, a change in wind patterns that stopped this nutrient transfer could prove highly damaging to this rainforest. As far as I know transfer mechanisms such as this are also not considered in many climate change models.
As a brief summary: I don't think that alarmism such as "high confidence of extinction" is helpful or accurate, but there is a significant chance that climate change could be an X-risk which isn't being studied in anywhere enough detail, especially since climate change is an immediate threat where we could be "locking in" permanent changes (and possibly runaway destabilisation effects, such as clathrate melting / Arctic sea ice melting / permafrost thaw) for hundreds of years inside the next 30 or 40 years, even by conservative and heavily adulterated IPCC estimates. It would be good to know if those changes we're locking in will soon lead to the extinction of the species or (in my opinion far more likely) the regression of humanity to pre-industrial levels, potentially for millennia.