Thread by @RogerPielkeJr

Climate cost-benefit analyses are going to look very different when the question is not from below: “what bad things happens when we exceed 1.5C?” But instead, from above: “what benefits will we see if we return to 1.5C?”

https://twitter.com/Oliver_Geden/status/1454088895507881987

What happens if the world warms another 0.4C (from 1.1C today to 1.5C within a decade or so) and the world looks a lot like it does today?

Future temperature targets offer the political asset of uncertain impacts

Once those targets are exceeded that uncertainty goes away

Consider:

The 1970s global average surface temperatures were about 1C less than today … no one I am aware of is making the case that the climate of the 1970s is one we should try to return to (for obvious reasons, 1970s were a decade of many global extremes)

1.5C deadline-ism = a big gamble for climate policy

1.5C will be exceeded

Detecting & attributing differences in climate impacts bt 1.1C & 1.5C on short time scales (~decade) is largely impossible

Big dif between avoiding future impacts vs returning to a more optimal climate

The life cycle of “over-population” as a policy issue may be instructive

Public/political/advocacy attention peaked well before population growth peaked & population is expected to continue to grow for many decades

Yet, perception of the issue went from apocalypse to manageable

“Overpopulation” hasn’t gone away of course as an issue, but it is far removed from where it was in the frenzied 1970s when it was a central focus of science and politics, as well as a central focus of public attention

Context:

“Even allowing for spectacular advances in agriculture and industry, the earth simply could not support 4.4 billion people in the year 2048. There would be the constant threat of famine, pandemic disease and unthinkably vicious wars for survival”

Brandt and Payne 1948

The IPCC doesn’t foresee people overall being worse off under climate change in 2100 under all scenarios (even implausible ones)⤵️

Also for 2030, 2040 etc
That will complicate climate policy

I’ve yet to see any discussion of what post-1.5C climate policy/advocacy looks like

https://twitter.com/rogerpielkejr/status/1456239649475620868

Just as it’s now not credible to claim a world of 4.4B people is apocalyptic, climate advocates should be thinking about preparing for a world >1.5C that may not actually be apocalyptic (and in fact much like the world at 1.1C, but with most people around the world better off)

Make no mistake, apocalypse deadline-ism works well to both gather & focus attention & thus can be useful in short-term political advocacy, think WMD & Iraq

But if the deadline comes & goes with no actual apocalypse, long-term attention & credibility is at risk, think WMD & Iraq

Standard disclaimers apply:

Climate change is real & important
Net-zero emissions ASAP makes good sense
Vigorous attention to mitigation & adaptation is necessary

Taking a critical view of climate policy doesn’t make one a climate denier (LOL), it makes for better policy
🙏