> Climate scientists may err on the side of “least drama”, whose causes may include adherence to the scientific norms of restraint, objectivity and skepticism, and may underpredict or down-play future climate changes. In 2007, security analysts warned that, in the two previous decades, scientific predictions in the climate-change arena had consistently under-estimated the severity of what actually transpired.
> This problem persists, notably in the work of the Intergovernmental Panel on Climate Change (IPCC), whose Assessment Reports exhibit a one-sided reliance on general climate models, which incorporate important climate processes, but do not include all of the processes that can contribute to system feedbacks, compound extreme events, and abrupt and/or irreversible changes.
> Other forms of knowledge are downplayed, including paleoclimatology, expert advice, and semi-empirical models. IPCC reports present detailed, quantified, complex modelling results, but then briefly note more severe, non-linear, system-change possibilities in a descriptive, non-quantified form. Because policymakers and the media are often drawn to headline numbers, this approach results in less attention being given to the most devastating, difficult-to-quantify outcomes.
> In one example, the IPCC’s Fifth Assessment Report in 2014 projected a sea-level rise of 0.55-0.82 metre by 2100, but said “levels above the likely range cannot be reliably evaluated”. By way of comparison, the higher of two US Department of Defence scenarios is a two-metre rise by 2100, and the “extreme” scenario developed by a number of US government agencies is 2.5 metres by 2100.
> Another example is the recent IPCC 1.5°C report, which projected that warming would continue at the current rate of ~0.2°C per decade and reach the 1.5°C mark around 2040. However the 1.5°C boundary is likely to be passed in half that time, around 2030, and the 2°C boundary around 2045, due to accelerating anthropogenic emissions, decreased aerosol loading and changing ocean circulation conditions.
What I haven't seen any expert argue for is almost certainly guaranteed extinction for humanity. I don't mean to sound like I'm nitpicking on the wording, but the core problem I'm pointing to here is the game of telephone that gets played in climate science, where "this is a crazy extreme possibility that could happen if everything goes wrong" becomes "this is a realistic worst case scenario that's likely if nobody tries to stop it" becomes "this will definitely for sure happen unless we stop emissions right this second".
This is science. It's what science is made of. Abandon these and you abandon science altogether. Which is fine, I guess, but it has no connection to reality.
> "They’re conservative, because insufficient attention has been given to the importance of tipping points, feedback loops and outlier predictions; consensus, because more extreme scenarios have tended to be marginalized."
A good summary of the overall problem is found here:
https://www.washingtonpost.com/politics/2021/07/19/you-shoul...