The warnings from the scientists are now grave indeed.

We, and even more our unfortunate children, the scientists are saying, face a terrifying future in a devastated world if we don’t take urgent action to get rid of fossil fuels a.s.a.p.The scientists are not divided. Many climate sceptics imagine that the climate issue is still an open one because the scientists are in disagreement. This is completely false. If it were ever true it certainly isn’t now. In 2003 Naomi Oreskes did a survey of every paper on climate science that she could find. Of the 928 she examined not a single one took the position that the current global warming is not man-made. In 2013 Cook et al surveyed as many individual climate scientists as they could in The Skeptical Scientist.   They found 97% supported the I.P.C.C. scientific consensus that climate change is being caused by human activity. Most countries have a national scientific society like The Royal Society in Britain. 197, that’s pretty much all of them, support the I.P.C.C. Every single scientific association in America, even the Association of Petroleum Scientists does the same. Nevertheless, by its nature because it is dealing with a future that by definition cannot be verified, climate science can never claim the same degree of certainty as physics, a shadow of doubt that the sceptics have been able to exploit.   But given the virtual unanimity of the scientists and the terrifying predictions about the future our children will inherit that they are giving us, is it reasonable to doubt them? Imagine a householder who is told by nine out of ten fire experts that he and his children will burn to death one night if he does not fireproof his house. What kind of irresponsible parent would take no notice beyond lip service? Are we that irresponsible parent?

Why is 2 degrees of global warming above pre-industrial levels so serious?

Many people think that the greenhouse effect means that we are pumping so much carbon into the atmosphere it is preventing heat escaping from the earth, as in a greenhouse. This is quite untrue. Compared with nature our emissions of CO2 are minuscule. But nature balances carbon emissions almost exactly with natural cooling mechanisms. These are mainly three: trees and ocean algae that absorb carbon and the polar icecaps that reflect sunlight back into space. What we are doing is disabling the cooling mechanisms. But it isn’t just that once disabled they stop working. Instead, they turn turtle and actually start adding to global warming. Every tree that catches fire not only ceases to store carbon but also releases that it has already stored. Ocean algae that die from carbon poisoning poison the seas even more.   Ice that melts turns into water that absorbs and then releases heat. Scientists think that at what they call the tipping point of 2 degrees – some think it could actually be nearer 1.5 – this feedback process will escape our ability to control it and, once started, will start to feed itself and escalate at an ever-greater rate.   There is general agreement that at present rates of carbon emissions we are on track for not just 2 but 4 to 6 degrees of warming later this century.   It would mean an uninhabitable earth.

Isn’t it the case that global temperatures have not risen since 1998 but carbon emissions have?

This shows there is no connection between the two. Anyway, variations in temperature are largely caused by the sun. We can’t do anything about that. These frequently heard arguments are completely false. Air temperatures have not risen since 1998. But ocean temperatures have. The two are intimately interconnected. If you take both together global temperatures have risen in line with carbon emissions. The sun does indeed have a major influence on our climate. But this is largely to do with flares on the sun’s surface known as sunspots that can last for centuries. When there are sunspots the earth’s temperature rises, when there are none it drops. This is why you could grow grapes in Britain in the Middle Ages but they were roasting oxen on the Thames in the seventeenth century. The essential point is that there is no evidence of sunspot activity today. It should be as cold now as it was in the seventeenth century. Why isn’t it? There is only one credible explanation. Far from being evidence for the climate skeptics’ case, activity in the sun absolutely disproves it.