Professor Lennart Bengtsson – the leading scientist who three weeks ago signalled his defection to the climate sceptic camp by joining the board of the Global Warming Policy Foundation – has now dramatically been forced to resign from his position.

His views on the weakness of the “consensus” haven’t changed. But as he admits in his resignation letter, he has been so badly bullied by his alarmist former colleagues that he is worried his health and career will suffer.

Bengtsson’s recruitment by the GWPF (the London-based think tank set up by former Chancellor Lord Lawson) represented a huge coup for the climate realist cause. The Swedish climatologist, meteorologist, former director of the Max Planck Institute for Meteorology in Hamburg and winner, in 2006, of the 51st IMO Prize of the World Meteorological Organization for his pioneering work in numerical weather prediction – was by some margin the most distinguished scientist to change sides.

But this, of course, is why he has been singled out for especial vitriol by the climate alarmist establishment – as he describes in his resignation letter.

I have been put under such an enormous group pressure in recent days from all over the world that has become virtually unbearable to me. If this is going to continue I will be unable to conduct my normal work and will even start to worry about my health and safety. I see therefore no other way out therefore than resigning from GWPF. I had not expecting such an enormous world-wide pressure put at me from a community that I have been close to all my active life. Colleagues are withdrawing their support, other colleagues are withdrawing from joint authorship etc. I see no limit and end to what will happen. It is a situation that reminds me about the time of McCarthy. I would never have expecting anything similar in such an original peaceful community as meteorology. Apparently it has been transformed in recent years. Under these situation I will be unable to contribute positively to the work of GWPF and consequently therefore I believe it is the best for me to reverse my decision to join its Board at the earliest possible time.

Responding to the letter, the chairman of the GWPF’s academic advisory council, Professor David Henderson, wrote:

Your letter came as a surprise and a shock. I greatly regret your decision, and I know that my regret will be shared by all my colleagues on the Council. Your resignation is not only a sad event for us in the Foundation: it is also a matter of profound and much wider concern. The reactions that you speak of, and which have forced you to reconsider the decision to join us, reveal a degree of intolerance, and a rejection of the principle of open scientific inquiry, which are truly shocking. They are evidence of a situation which the Global Warming Policy Foundation was created to remedy. In your recent published interview with Marcel Crok, you said that ‘if I cannot stand my own opinions, life will become completely unbearable’. All of us on the Council will feel deep sympathy with you in an ordeal which you should never have had to endure.

At his blog Climate Audit, in a piece headlined ‘The Cleansing of Lennart Bengtsson’, Steve McIntyre commented: