According to the late Freeman Dyson, computer models do a good job of helping us understand climate but they do a very poor job of predicting it.
“As measured from space, the whole earth is growing greener as a result of carbon dioxide, so it’s increasing agricultural yields, it’s increasing the forests and it’s increasing growth in the biological world, and that’s more important and more certain than the effects on climate,” Dyson said during an interview with Conversations that Matter in 2015.
Freeman Dyson (1923-2020) was a British-born American theoretical physicist and mathematician known for his work in quantum field theory, astrophysics, random matrices, mathematical formulation of quantum mechanics, condensed matter physics, nuclear physics, and engineering. He was one of the most celebrated figures in 20th-century physics.
In 2006 Dyson published ‘The Scientist as Rebel’, in which he questioned the role of human activity in global warming. In a 2008 interview with Physics World, he said that the money being spent on addressing climate change should instead be targeted at “other problems that are more urgent and more important such as poverty, infectious diseases, public education and health.” He also said that thinking about the potential benefits of climate change “will not do us any harm.”
In 2015 he joined Stuart McNish host of Conversations that Matter. “There is man-made climate change,” he said. “It’s a question of how much and is it good or bad.”
“First of all, we don’t understand the details. It’s probably much less than it’s generally claimed and the most important thing is that there are huge non-climate effects of carbon dioxide which are overwhelmingly favourable [and] which are not taken into account,” he said. As measured by satellites, “the whole Earth is growing greener as a result of carbon dioxide in the atmosphere.”
Dyson began studying the effects of carbon dioxide (CO2) in the atmosphere on vegetation “37 years ago” i.e., in around 1978.
He explained that increased CO2 is increasing agricultural yields, forests and all kinds of growth in the biological world. “And that’s more important and more certain than the effects on climate,” he said.
When he first started studying the effects of CO2 on plants, he thought the effect may be about 10%. But 35 years later he found it was about 25%. CO2 has increased by about 40% and “about half of that has gone into raising vegetation,” he said. “It’s enormously beneficial to both food production and also to the biodiversity, preservation of species and everything else that’s good.” This is from observable evidence, he added.
Regarding the idea that the models are good predictors, he recalled what Japanese climate expert Suki Manabe, who developed the first climate model in the 1960s linking the warming of Earth’s climate with increasing carbon dioxide, always said, and still says: “These climate models are excellent tools for understanding climate but they’re very bad tools for predicting climate.”
The reason why they are bad at predicting climate is simple, Dyson explained. “They are models which only have a few factors in them that may be important … But there’s a whole lot of things that they leave out … The real world is far more complicated than the models.”
“I don’t think any of these models can ever really be predictive,” he added because climate change is too complex and there are too many factors involved. “You just cannot model everything, it’s way, way out of sight,” he said.