Dit is een vervolg op mijn eerdere ‘posting’ over het lange en magistrale artikel van Oren Cass, ‘The Problem With Climate Catastrophizing – The Case for Calm’, dat onlangs is verschenen in ‘Foreign Affairs’. Daaruit blijkt dat het klimaatcatastrofisme geen steun vindt in de analyses van de klimatologische mainstream.

Ik pik er nog een aantal krenten uit.

A strong scientific consensus holds that human activity is producing climate change. But from that starting point, scientists have produced a range of estimates in response to a variety of complicated questions: How quickly will greenhouse gases accumulate in the atmosphere? What amount of warming will any given accumulation cause? What effect will any given level of warming have on ecosystems and sea levels and storms? What effect will those changes in the environment have on human society? The answers to all of these questions are much debated, but broad-based efforts to synthesize the best research in the physical and social sciences do at least offer useful parameters within which to assess the nature of the climate threat.

On scientific questions, the gold-standard summary is the Assessment Report created every few years by thousands of scientists under the auspices of the United Nations’ Intergovernmental Panel on Climate Change (IPCC). By averaging widely varying projections and assuming no aggressive efforts to reduce greenhouse-gas emissions, they estimate an increase of three to four degrees Celsius (five to seven degrees Fahrenheit) by the year 2100. The associated rise in sea levels over the course of the twenty-first century, according to the IPCC, is 0.6 meters (two feet). …

What about ecology? Predicting or quantifying damage to vulnerable ecosystems and specific species is notoriously difficult, but the IPCC offers a helpful heuristic for the likely magnitude of damage from climate change: “With 4°C warming, climate change is projected to become an increasingly important driver of impacts on ecosystems, becoming comparable with land-use change.” In other words, the impact should be similar to that which human civilization has imposed on the natural world already. Substantial and tragic, to be sure; but not something that modern society deems intolerable or a threat to human progress.

Economic tools called “integrated assessment models” attempt to convert the potential effects of climate change—on sea level and ecosystems, storms and droughts, agricultural productivity, and human health—into tangible cost estimates. This exercise is as much art as science, but it represents the best available exploration of how the impacts of climate change will likely stack up against society’s capacity to cope with them.

Three of these models form the basis of the Obama administration’s analysis of the “Social Cost of Carbon”—the U.S. government’s official estimate of how much climate change will cost and thus what benefits come from combatting it. Economists and policymakers who want to place a price (that is, a tax) on carbon-dioxide emissions to force emitters to pay for potential damage resulting from climate change typically embrace the analysis as well.

According to the assessment models, a warming of three to four degrees Celsius by 2100 will cost the world between one and four percent of global GDP in that year. To put the high end of that range concretely, the Dynamic Integrated Climate-Economy (DICE) model developed by economics professor William Nordhaus at Yale University estimates that in a world without climate change, the global economy’s GDP would grow from $76 trillion in 2015 to $510 trillion in 2100 (an annual growth rate of 2.3 percent). A rise in temperatures of 3.8 degrees Celsius would cost 3.9 percent of GDP ($20 trillion) that year, effectively reducing GDP to $490 trillion.

Twenty trillion dollars is a very large number—representing a cost greater than the entire annual economic output of the United States in 2016. But from the perspective of 2100, such costs represent the difference between the world being 6.5 times wealthier than in 2015 or 6.7 times wealthier. …

To be sure, economic estimates are incomplete. They cannot incorporate the inherent value to a community of remaining in its ancestral lands or any obligation humanity might have to protect other species and habitats. Even within the economic sphere, the assessment models depend on subjectively chosen inputs and averages across disparate forecasts; they rest atop numerous other models, each with their own subjectively chosen inputs and averages. …. But nowhere is catastrophe to be found.

… [T]he societal collapse that catastrophists envision—one that poses an “existential” threat beyond the scope of other human problems, one that makes procreation an ethically dubious proposition—is simply irreconcilable with the outlook the science and economics offers.

Deze analyse is gebaseerd op de veronderstelling van een relatief hoge klimaatgevoeligheid, die tot een aanzienlijke stijging van de temperatuur zou kunnen leiden. Maar in vorige ‘postings’ is gewezen op recente literatuur, waarin een véél lagere klimaatgevoeligheid is berekend. Zie hier en hier.

Als deze berekeningen juist zijn, dan is er nog steeds een klimaat (dat wordt niet ontkend), en nog steeds klimaatverandering (dat wordt evenmin ontkend) en wellicht zelfs nog opwarming (dat wordt ook niet ontkend), maar geen klimaatprobleem meer. Dan kan klimaatverandering worden bijgezet in het mausoleum van gesneuvelde hypes, zoals zure regen en het ‘Grosse Waldsterben’, het ozongat, ‘Peak Oil’ en meer in het algemeen de uitputting van grondstoffenvoorraden, wereldwijde voedselschaarste, en de ‘Millennium Bug’. En dan kan de mensheid weer opgelucht adem halen en zich gaan richten op de oplossing van werkelijk ernstige en urgente maatschappelijke problemen, waarvoor in dat geval jaarlijks honderden miljarden vrijkomen.

De aanvaarding van deze opvatting zal overigens op heel wat weerstand stuiten. Immers, het is niet waarschijnlijk dat de (C)AGW-adepten ((C)AGW = ‘(Catastrophic) Anthropogenic Global Warming’) hun succesvolle verdienmodel zonder slag of stoot zullen opgeven. Verwacht dus nog veel discussie, desinformatie en manipulatie.

In een uiterst leerzaam en boeiend betoog gaat de auteur, Oren Cass, vervolgens uitvoerig in op de ‘cognitive fault lines separating catastrophists from others’. Daarvoor verwijs ik naar het oorspronkelijke artikel.

Zie hier.

Verplichte lectuur voor klimatofielen van alle gezindten.

Voor mijn eerdere bijdragen over klimaat en aanverwante zaken zie hierhier, hier, hier en hier.