Like Dr. House, I have no means of personally measuring increase of carbon dioxide in the atmosphere, or sea level rise, or (with one exception, the Grossglockner Glacier in Austria, which I saw in about 1990, and my stepdaughter saw again just a couple of years ago, much depleted) the rate of melting of glacial ice. It behoves both of us, therefore, to be careful which experts we turn to in order to understand what is going on.

I am currently reading, for the second time, 'Farewell to Ice', by Peter Wadhams, and would like to draw this book to the attention of Dr. House and to anyone else interested. It is a very thorough explanation of the nature of ice, a history of the ice ages and the greenhouse effect. It considers the future of Arctic sea ice, the so called 'death spiral', the accelerating effects of Arctic feedbacks, the potential for massive methane release as the permafrost melts, the rise in sea levels. It considers events in the Antarctic and the acceleration of glacers there. He does not draw attention to the Thwaites Glacier, which has become a matter of concern since the 2016 publication of this book. He discusses and gives a clear explanation of the Milankovitch cycles (the natural variation of climate caused by regular oscillations in the Earth's revolution)

He discusses how we know with certainty how temperatures, carbon dioxide and methane have varied over the last 400,000 years. There is a clear demonstration of the alarming increase in all these in the last couple of centuries, and the consequent accelerating rise of sea level and loss of reflective ice. He discusses the way the speed of glaciers has accelerated, many Greenland glaciers flowing twice as fast as a few years ago. Concerning CO2 levels, he says 'given that levels are already too high for non-disruptive climate change, the fact that they are continuing to accelerate upwards with no let up at all is profoundly distressing.'

What are Peter Wadhams' qualifications for telling us this? To quote the blurb on his book, he is the UK's most experienced sea ice scientist. He has been Director of the Scott Polar Institute, and Professor of Ocean Physics at Cambridge. He has made more than fifty epiditions to both polar regions, working from ice camps, icebreakers, aircraft and, uniquely, Royal Navy submarines (making six submerged voyages to the North Pole). He has held visiting professorships in universities in Tokyo and the US, including the Scripps Institute of Oceanography.

Dr. House appears to have had an academic education. He must know that he cannot, should not, dismiss such study by Wadhams and many other scientists as 'the simple posivistic "science" underpinning the flaky notion of "climate change"', without providing real reason to do so, which would involve study of climate change at at least the same standard as Wadhams' work. My definition of an expert is someone who knows what they are talking about, and I think that Wadhams meets that definition. I doubt if Dr. House has been under the sea ice any more often than I have. And this lack of understanding throws all other things he advocates into doubt: particularly, of course, vaccination.

So why should I believe Dr. House over Peter Wadhams?

Roger Plenty, Stroud