Sunday, November 24, 2019

Chaos Theory And Global Climate Change

I am currently attending the Southern Economic Association meetings in Fort Lauderdale, where the street facing the hotel was underwater during the most recent hurricane to pass through.

Anyway, I saw a talk today that took me back to when I first learned about chaos theory, actuallly in the early 1970s before the word "chaos" was used for it. I learned about it and the butterfly effect, aka sensitive dependence on initial conditions, while working on a combined model of global climate change and food production.  It was called "irregular dynamics" back then, and the model showing it was climatologist Edward Lorenz, published in 1963.  Blew my mind then.  Anyway, it is widely accepted that the global climate system is chaotic, which is why one can only make weather forecasts for fairly short periods of time into the future, although one can forecast longer run average changes of averages such as average global temperature.

Anyway, I saw a talk by Emmanuele Masssetti of Georgia Tech that reminded me of all that, a talk thet explicitly drew on this chaotic effect.  So he has been simulating future climate using different assumptions for the various climate models the UN has been using for its IPCC reports.  What he found was that indeed the overall average temperature change projected did not vary as he varied initial conditions by small amounts. But what the projection for particular regions of the world did vary, indeed very much so as in the butterfly effect. So, for exmple, the Great Plains of the US would warm a lot under one simulation, but then actually cool for a simulation following a slightly changed initial conditions.  This is atunning, but not really surprising given the underlying chaotic nature  of th global climate system.

Another talk was a keynote  by Richard Zeckhauser of Harvard, who was pushing for us to study geoengineering.  He made a strong case for it.

Barkley Rosser

7 comments:

Anonymous said...

. So, for exmple, the Great Plains of the US would warm a lot under one simulation, but then actually cool for a simulation following a slightly changed initial conditions.

[ Fascinating, but I wonder what actual climatologists would say to this since this strikes me as a way to dismiss the urgency of the matter. ]

Anonymous said...

. So, for exmple, the Great Plains of the US would warm a lot under one simulation, but then actually cool for a simulation following a slightly changed initial conditions. This is stunning, but not really surprising given the underlying chaotic nature of th global climate system.

[ This definitely seems to me to undermine the broad research and findings of climatologists, and if so that is disturbing in playing at denial of the problem. I find this hard to take at all seriously. ]

Anonymous said...

Spelling:

Emanuele Massetti

Anonymous said...

Aside:

A columnist for the Washington Post by the name a Rogin, who was fortunately unknown to me, was recommended a while ago. I had no interest in the columnist, who I was told was an extremist, and never read a column since the suggested on this blog. Today, I noticed inadvertently that Rogin had attacked Michael Bloomberg in the most McCarthy-like shameful manner.

Just so we know what this columnist is all about.

Anonymous said...

https://globalchange.gatech.edu/posts/emanuele-massetti-integrating-climate-change-into-long-run-macroeconomic-analysis/

February 5, 2019

Emanuele Massetti: "Integrating Climate Change into Long-Run Macroeconomic Analysis"

On Tuesday, November 27, 2018, the Global Change Program hosted a lecture by Dr. Emanuele Massetti, Assistant Professor of Public Policy at Georgia Tech. In this lecture, entitled "Integrating Climate Change into Long-Run Macroeconomic Analysis," Dr. Massetti discussed the work of William Nordhaus, winner of the 2018 Nobel Prize in Economics. Nordhaus' main contribution to economics is the integration of climate change into long-run macroeconomic analysis; his pioneering work on climate change began in the 1970s and is at the foundations of now popular concepts in climate policy, such as the carbon tax and the social cost of carbon.

Following Dr. Massetti's talk, the Global Change Program spoke with him at length. Below, he expands on the topics he discussed in his lecture...

[ Fine interview and lecture. ]

rosserjb@jmu.edu said...

A.,

Do keep in nind that as I pointed out, there is not variation regarding the overall forecast of average global temperature increase. What is uncertain is what is happening to specific localities. Many people are unaware that right now we have large variability across the glob in terms of what is happening. The Arctic zone is warming the most rapidly, which is why we hear about polar bears so much. But there are some parts of the planet that are cooling, including portions of Antarctica. ?But the global average is rising.

Sandwichman said...

glob