The consequences are upon us

The era of procrastination, of half-measures, of soothing and baffling expedients, of delays, is coming to its close. In its place we are entering a period of consequences.

That was Churchill in a speech to the House of Commons in 12 November 1936 as the clouds darkened over Europe, a speech Al Gore quotes as he illustrates with example after example that climate change is not an abstract or theoretical notion but an experiential reality. With superb graphics and spectacular photography the film pounds away with fact piled upon fact. Only the most recalcitrant could leave the theatre without a realisation that the planet is on the move, that dramatic changes are in train, changes that are not sympathetic to many existing life forms, including us.

This is accepted by many climate change denialists. They are not arguing against the facts on display but rather the cause of and responsibility for the changes. Any geologist, for example, knows that over 500 million years ago in the Proterozoic era the temperature fluctuated between 12 and 26 degrees Celsius (compare this with the pre-1900 average of 13.7C.) During the ‘Snowball earth’ episodes there were glaciers at sea level near the equator. Every geologist knows that we are in a long-term cooling trend going back at least 65 million years, albeit with markedly accentuated shorter term fluctuations. So inconvenient though it may be for homo sapiens, to whom the earth does not owe a living, for some geologists these things just happen from time to time in geological time.

At issue here is whether climate change is due to "anthropogenically generated global warming" (AGW for short) and more particularly whether we are guilty of "dangerous anthropogenic interference". In other words can we dig up all those billions and billions of tons of carbon sequestered deep in the earth over tens of millions of years, join each atom of carbon with two of oxygen so that each ton of carbon becomes 3.67 tons of CO2, then dump it all in the atmosphere within the geological blink of an eye and expect life to go on as before?

Also at issue is whether our only response can be adaptation to the climate change occurring naturally or whether there is anything meaningful we can do about mitigation.

As a non-scientist, my response is that on the face of it the notion is heroic, preposterous and absurd. We have been in a very sweet spot climate-wise for the last 8,000 years and, released by the invention of agriculture, we have colonised every corner of the earth. The earth has been good to us. But in the 100 years from when Gore was born in 1948, as he says the life-time of a baby boomer, the human population will explode from 2 billion to 9 billion. We have multiplied to plague proportions to place extreme pressure on the whole earth system quite apart from any changes flowing from global warming and climate change.

Gore’s answer is also an emphatic “no”. We are guilty as charged and there will be consequences. Old habits plus new technology lead to dramatically changed consequences, he tells us in the film. We have put our civilisation in collision with the earth. The decent thing, the moral thing to do for the sake of our children and grandchildren and disruption to other life, is to desist forthwith and to limit the damage as much as possible. This is possible, he tells us, all that is lacking is the political will. It is our (meaning America’s) time “to rise again and secure our future.”

The relationship between carbon emissions and temperature change is crucial to this question of human responsibility and whether there is any point in trying to reduce carbon emissions in the future. Gore shows us the graphs of temperature and carbon dioxide from 650,000 years of ice core measurements. That there is a relationship is a no-brainer. He shows us how the CO2 has fluctuated over the last seven ice ages between 180ppm and 280-300ppm on the large screen that occupies the whole wall behind him. He then mounts a “contraption” a hydraulic lift to take him up the wall to point upwards to where it is now at 380ppm. Given the axes the graph is essentially vertical. Then the graph soars even further above his head to where it is projected to go in the future on a ‘business-as-usual’ scenario.

It is of course conceivable that the relationship is mere correlation and that both are caused by other factors. We non-scientists have to decide which expertise we are going to trust. This is what two of the climate scientists at RealClimate say in their post on Al Gore’s film: ”But this is a case where there is a great deal of causality, and not just correlation. The Vostok T and CO2 data alone cannot be used to conclude that CO2 affects temperature, but together with other things we know about climate it is a real showstopper. You simply cannot get anything like this without a very significant effect of Co2 on climate.” - Ray Pierre

”Yes, I agree with Ray on this. The simple CO2 -T correlation = causation argument is overly simplistic, but it is not wrong. What is clearly going on in the glaciological record of climate change on long timescales is a positive feedback system -- temperature goes up, leading to more CO2, leading to increased T…” - Eric

Eric is Eric Steig, author of the post. This is an extract from his bio: ”Eric Steig is an isotope geochemist at the University of Washington in Seattle. His primary research interest is use of ice core records to document climate variability in the past. He also works on the geological history of ice sheets, on ice sheet dynamics, on statistical climate analysis, and on atmospheric chemistry.”

He’s published over 60 peer-reviewed articles in international journals and is an editor of Quaternary Research. This is what he said of the film in general: ”How well does the film handle the science? Admirably, I thought. It is remarkably up to date, with reference to some of the very latest research.”