Is a worst-case situation (of local weather change) actually dangerous? – Watts up with that?

Reposted by Clintel

Ross McKitrick, the Canadian economics professor who publishes regularly in climate magazines, gave an online presentation for the Irish Climate Science Forum and the international CLINTEL Foundation (of which I am co-founder). I have a special relationship with McKitrick and McIntyre because in 2004, when I was the editor of a Dutch monthly science magazine, my editor-in-chief told me I had to write an article about what is called a hockey stick diagram. I had never written about climate change before, so I was completely blank. Two months later (and a lot of research), on the day McIntyre and McKitrick posted their criticism of the hockey stick in GRL, my article about this saga appeared (in both Dutch and English). It was my entry into the climate debate and, above all, thanks to the (lack of) reaction to this criticism of M&M, I was fascinated by the climate discussion, quit my job and started working full-time on climate issues. And I’m still stuck in it.

So I’ve followed McKitrick’s work pretty closely over the years. He has the wonderful gift of being able to carry out profound scientific as well as technical / mathematical work and having it published in top-class scientific journals (often after long battles with reviewers) and at the same time being able to write essays and Op-Eds (mainly for the Financial Post in Canada) that are easy for anyone to understand. He sounds a little emotionless in presentations, but everything he says is well thought out.

So let’s talk about his presentation (a 45-minute recording of the lecture can be found here), which this time was not about the debate about physical climate science, but about climate policy: “Climate policy – when emotions meet reality”. The central question in the lecture was: Why is it so difficult to do something about CO2? McKitrick gave the answers on this slide:

These six points were each discussed in greater detail during the conversation. I will just focus on a few remarks that grab my attention. The most important for me was point 3: “Emissions related to the use of fossil fuels, which are essential for economic growth and development.” McKitrick explained that in so-called worst-case scenarios, people only focus on climate effects . You forget to look at the economic side of this scenario and that makes for a spectacular view. In this scenario, people in developing countries will be 70 times (!) Richer by 2100 and have an average annual income of $ 70,000. That means they will be considerably richer than we are now. This means that by this point in time every development problem known to mankind will be solved. Mckitrick joked that the main loss of jobs at this point will be in foreign aid.

The question then, of course, is how catastrophic the climate impacts will be in this scenario. McKitrick then began showing some of his own work on the long track record of overestimating both CO2 trends and temperature projections. Since the latter are known to most readers, let’s focus on the former for this moment. McKitrick showed this graphic:

Source: Hausfather, Z., Drake, H., Abbott, T. and Schmidt, G. (2019) Assessment of the performance of previous climate model projections. Geophysical Research Letters doi: 10.1029 / 2019GL085378.

As you can see, the real concentration of CO2 in the atmosphere hugs the lower end of the forecast range (after decades of forecasting). McKitrick added that this will be the case again in the upcoming AR6 report. It also showed the overestimation of temperature trends.

He then moved on to the costs of reduction (reduction), first emphasizing that people often have the wrong impression of the potential of reduction:

People tend to believe that all of the costs associated with global warming can be avoided (left blue bar) if we just stopped emitting CO2. However, this is not the case. After decades of research and measurement, and after a steady rise in CO2, no trends can be identified, for example in the case of hurricanes and floods (two extremes that McKitrick mentioned). Damage due to such events also (or also) occurs after the reduction. The potential benefits of climate policy are therefore much smaller (the little white box in the top right corner of the blue bar).

And it just keeps getting better. McKitrick with colleagues published two very interesting articles in 2017 and 2019 on the so-called social costs of carbon, which reflect the additional costs to society of emitting an additional ton of CO2. In the 2017 paper, they used empirically constrained estimates for climate sensitivity (adapted from a paper by Nic Lewis and Judith Curry) instead of much higher model-based estimates. The impact on the social cost of carbon was as follows:

In the second paper in 2019, they also added the additional benefits of CO2 for agriculture. The social costs of carbon then fall more or less to zero or even to negative values, depending on the discount rate used. What does it all mean? McKitrick: “The CO2 benefits far outweigh the climate costs.”

With uncertain climate effects, very costly mitigation measures (applies to both Kyoto and Paris), overestimation of both CO2 and temperature trends, low to zero estimates for social carbon costs (if you use observational estimates for climate sensitivity and consider due to the benefits higher CO2 values ​​for agriculture, there is only one possible conclusion: “We are on fairly safe ground to prioritize economic growth over a very ambitious climate policy.”

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