This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
I don't think I'd compare James Hansen with James Lovelock - Lovelock is intelligent.
There might be a verbal infelicity in the statement that "up to 80% of the world's population could be dead by the end of the 21st Century", since as it stands it is an entirely unexceptionable statement. At the very least 80% of the world's current population will be dead by the end of the 21st century, among them me, James' Hansen and Lovelock and the vast majority of you. Such is the nature of average human lifetimes of less than a century. I see no cause for concern therein.
Presumably what is meant is that the world's population may be 20% of its current size by 2100. Again, is this a problem? This septic isle had a population of about 1.5 million in Roman times, rising to about 3 million by 1700. Such a density supported several major towns and a sufficient degree of social interaction to give rise to a flowering of the sciences and arts leading to the Agricultural and Industrial Revolutions. To get back to that level of population would require a 95% reduction and still not lead to social collapse - indeed, I suspect it would lead to a veritable Arcadia with bosky dells and shepherdesses all over the place. Sure, getting there from here could be a bit sticky, but all it really requires is a continued drop in fertility rates plus a major plague.
Hansen and Lovelock's statements show that at the back of much Warmism is the universal Prometheus myth, the idea that we have all been too clever by half with our SUVs, space rockets and outdoor hot tubs and that the gods will visit some dreadful revenge on us for our extreme cheek. The Aztecs sacrificed other people to ensure that their gods would keep time from ending. We, now, have to placate Mother Gaia. We must dress and act penitentially; we must deny ourselves; we must make sacrifices (except for the Priests, of course).
It's a very powerful myth and grips people who might otherwise have turned to religion. It also helps to explain why Warmists become so angry when their faith is questioned ang why they were so disappointed when Tropical Storm Irene only killed 40 or so people.
In reply to Disputin, I think both Lovelock and Hansen would have to be regarded as intelligent, if we interpret intelligence the way employers do. Lovelock is an FRS and Hansen is the US equivalent, a member of the National Academy of Sciences.
You may be swallowing the UK media hype, particularly by the BBC, that Lovelock is some sort of scientific genius. Lovelock is a scientist who environmentalists regard as a genius because of two major contributions he has made to the Green agenda - he invented some gadget called the 'electron capture detector' which provided a major boost to anti-pesticide campaigners, and he developed something called 'Gaia theory' which gives a semblance of scientific credibility to the notion that mankind should live in awe of nature. The BBC takes a chattering class-type view of science where somehow 'the environment' is conflated with science, an example being that the science news webpage is broadened into being the science and environment news webpage, and hence Lovelock is portrayed as a scientific genius.
On your point where a reduction of the Earth's population to about a billion or so wouldn't necessarily be that big a setback, I thought I'd check what Lovelock has said on that. According to this link:
"Lovelock’s “80% figure” was given in 2008. In his 2009 book (op. cit.) he states (p. 6) “we do have to take seriously the possibility that global heating may all but eliminate people from Earth.” And (p. 33): “The climate war could kill nearly all of us and leave the few survivors living a Stone Age existence.”"
So it looks like Lovelock is predicting a regression to the Stone Age rather than just pre-Industrial Revolution conditions.
For anybody interested in Hansen's not very well publicised view that the Earth is in grave danger of turning into Venus, some details are given in a lecture he gave in 2008 with presentation slides available on this link:
The relevant bit is the second half of the document, and he calls it the 'Venus Syndrome'. I remember Hansen was called in as an expert witness by Greenpeace to defend some of their activists who climbed up a chimney at Kingsnorth coal-fired power station. Hansen's view is that civil disobedience is necessary to avoid the Venus Syndrome. Greenpeace managed to win the case, but the prosecution could, if they'd known what they were doing, have discredited Hansen as an expert witness because he takes such an extreme view of the consequences of AGW.
Thanks, Dave, I'd never heard of the electron capture detector - sounds interesting. I'd agree that by the narrow standards of IQ tests Hansen probably is intelligent, but to judge by some Mensa members that's not saying much.
Hansen's Venus hypothesis is obvious junk for the simple reason that Venus' atmosphere is opaque to IR and visible light and there is no liquid water to remove the heat from the surface. On Earth, incoming radiation heats the surface, evaporating water which then convects to release its latent heat near the tropopause whence it is radiated to space. This doesn't happen on Venus, so Earth can never get like it as long as there is liquid water on the surface.
On the electron capture detector, here is a description of its importance to the Green agenda by Lovelock himself (from http://www.ecolo.org/lovelock/lovedeten.htm ):
"When devising a series of ionisation detectors for gas chromatography in the mid 1950's I had no notion that one of them, the electron capture detector, would significantly affect the development of environmental thinking. It was invented in 1957, and is still among the most sensitive of chemical analytical methods in existence; moreover it is specifically sensitive to those chemicals that are a threat to the environment. Its use led to the discovery of the ubiquitous distribution of pesticide residues in the natural environment, and to Rachel Carson's book, The Silent Spring, which can be said to have started the environmental movement. It was later used to discover and measure the abundance of PCBs, chlorofluorcarbons and nitrous oxide in the atmosphere. Most recently, the detector has made possible a system of atmospheric and oceanic tracer technology. Perfluorocarbons, which are othervise inert and harmless, are easily detected tracers by electron capture. This system has enabled meteorologists to follow the movement of air masses across continents and is now finding use in ocean research."
If you regard modern-day environmentalism as a religion, Lovelock would be one of its saints. Modern day environmentalism (as opposed to the older version of environmentalism that was concerned about things like dirty rivers, London smogs and litter) is all about detecting vanishingly small amounts of some man-made chemical and creating a scare around it. So the people who invent the sensitive detectors like Lovelock are critical to the whole malarkey.
The electron capture detector played a big role in the DDT scare, and later on it detected the CFCs which eventually led to the ozone hole scare.