I have copied part of the email conversation:
Letters to a heretic: An email conversation with climate change sceptic Professor Freeman Dyson
World-renowned physicist Professor Freeman Dyson has been described as a 'force-of-nature intellect'. He's also one of the world's foremost climate change sceptics. In this email exchange, our science editor, Steve Connor, asks the Princeton scholar why he's one of the few true intellectuals to be so dismissive of the global-warming consensus
From: Steve Connor
To: Freeman Dyson
You are one of the most famous living scientists, credited as a visionary who has reshaped scientific thinking. Some have called you the "heir to Einstein", yet you are also a "climate sceptic" who questions the consensus on global warming and its link with carbon dioxide emissions. Could we start by finding where we agree? I take it you accept for instance that carbon dioxide is a powerful greenhouse gas that warms the planet (1); that atmospheric concentrations of CO2 have risen since direct measurements began several decades ago (2); and that CO2 is almost certainly higher now than for at least the past 800,000 years (3), if you take longer records into account, such as ice-core data.
Would you also accept that CO2 levels have been increasing as a result of burning fossil fuels and that global temperatures have been rising for the past 50 years at least, and possibly for longer (4)? Computer models have shown that the increase in global temperatures can only be explained by the increase in atmospheric CO2 concentrations (5). Climate scientists say there is no other reasonable explanation for the warming they insist is happening (6), which is why we need to consider doing something about it (7). What part of this do you accept and what do you reject?
From: Freeman Dyson
To: Steve Connor
First of all, please cut out the mention of Einstein. To compare me to Einstein is silly and annoying.
Answers to your questions are: yes (1), yes (2), yes (3), maybe (4), no (5), no (6), no (7).
There are six good reasons for saying no to the last three assertions. First, the computer models are very good at solving the equations of fluid dynamics but very bad at describing the real world. The real world is full of things like clouds and vegetation and soil and dust which the models describe very poorly. Second, we do not know whether the recent changes in climate are on balance doing more harm than good. The strongest warming is in cold places like Greenland. More people die from cold in winter than die from heat in summer. Third, there are many other causes of climate change besides human activities, as we know from studying the past. Fourth, the carbon dioxide in the atmosphere is strongly coupled with other carbon reservoirs in the biosphere, vegetation and top-soil, which are as large or larger. It is misleading to consider only the atmosphere and ocean, as the climate models do, and ignore the other reservoirs. Fifth, the biological effects of CO2 in the atmosphere are beneficial, both to food crops and to natural vegetation. The biological effects are better known and probably more important than the climatic effects. Sixth, summing up the other five reasons, the climate of the earth is an immensely complicated system and nobody is close to understanding it.
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