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On May 1, 1967, Syukuro Manabe (真鍋淑郎) and Richard T. Wetherald published the landmark paper Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity (DOI: 10.1175/1520-0469(1967)024<0241:TEOTAW>2.0.CO;2) (URLs shortened because the odd characters in the URL seem to break the links), which was the first major attempt to model the earth's climate. Now, fifty years later, the science can be robustly evaluated, and they got almost everything exactly right. Ethan Siegel has an article (Javascript required) looking back at this first major attempt at global climate modelling and how well it has turned out:
The big advance of Manabe and Wetherald's work was to model not just the feedbacks but the interrelationships between the different components that contribute to the Earth's temperature. As the atmospheric contents change, so do both the absolute and relative humidity, which impacts cloud cover, water vapor content and cycling/convection of the atmosphere. What they found is that if you start with a stable initial state — roughly what Earth experienced for thousands of years prior to the start of the industrial revolution — you can tinker with one component (like CO2) and model how everything else evolves.
The title of their paper, Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity (full download for free here), describes their big advances: they were able to quantify the interrelationships between various contributing factors to the atmosphere, including temperature/humidity variations, and how that impacts the equilibrium temperature of Earth. Their major result, from 1967?
According to our estimate, a doubling of the CO2 content in the atmosphere has the effect of raising the temperature of the atmosphere (whose relative humidity is fixed) by about 2 °C.
What we've seen from the pre-industrial revolution until today matches that extremely well. We haven't doubled CO2, but we have increased it by about 50%. Temperatures, going back to the first measurements of accurate global temperatures in the 1880s, have increased by nearly (but not quite) 1 °C.
[Ed note: There seems to be an issue with the DOI link in that the URL itself contains both "<" and ">" characters. The actual URL is:
http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281967%29024%3C0241%3ATEOTAW%3E2.0.CO%3B2
If you are uncomfortable following the provided bitly link, just copy/paste this link into your browser. --martyb]
(Score: 0) by Anonymous Coward on Friday March 17 2017, @10:38AM (4 children)
Does anyone know where we can find some code for this model? It doesn't look that complicated, and it is apparently the most influential paper, so it should be out there somewhere. My searches are coming up empty though.
(Score: 2) by bradley13 on Friday March 17 2017, @11:07AM (3 children)
Really no need for code. If you boil their calculations down to their simplest form, it's what they have in the abstract: "A doubling of the CO2 content in the atmosphere has the effect of raising the temperature of the atmosphere (whose relative humidity is fixed) by about 2C."
As far as I can see from a quick skim of the paper, they make no year-to-year predictions. They were looking for an overall effect of CO2, and came to the conclusion that CO2 provices X warming by itself, and through its interaction with the rest of the atmosphere (for example, water vapor), the total warming is then 2X. Doubling the CO2 - through CO2 effects alone - would therefore warm the earth by 1 degree C (this is uncontroversion, even amongst skeptics. The real question is, and always has been, how much that effect is amplified or damped by the rest of the atmosphere. Plus, you have to remove all other (natural) effects, such as solar cycles. As far as I can tell, the paper does not address this - they are looking at the atmospheric effect independent of anything else.
Hence, to say "they said 50 years ago to expect warming X and that's what we have" is disingenious. A real evaluation would have to at least add in the effects of the known solar cycles. Where was the earth 50 years ago? Where is it today? Whatever that difference is need to be added to / subtracted from the atmospheric effects. Without that, the articles conclusions are pretty meaningless. Mind you, I have no idea what the result would be, and don't currently have time to look into it. However, before one declares this atmospheric model to be "correct", someone needes to do that.
Everyone is somebody else's weirdo.
(Score: 0) by Anonymous Coward on Friday March 17 2017, @04:08PM
It is just surprising that no one has bothered sharing code for the most influential paper about the most controversial scientific topic. They should use some of their public outreach funds on that if they care about convincing other scientists/engineers (rather than people who can do nothing but listen to authority on the topic).
(Score: 0) by Anonymous Coward on Friday March 17 2017, @08:02PM (1 child)
Plus, you have to remove all other (natural) effects, such as solar cycles.
Solar cycles? You know, the ones that have been shown over and over and over and over again as to play very little role in warming?
(Score: 0) by Anonymous Coward on Friday March 17 2017, @08:24PM
Solar cycles? You know, the ones that have been shown over and over and over and over again as to play very little role in warming?
I keep hearing that claim, but the people making it never seem to show any evidence to back up their claims...