Under the Microscope: I am very worried about our warming world. Unless we successfully tackle this situation right away, we will bequeath a nightmare world to our children. There is now no doubt that what I say is scientifically valid, so why is there no great sense of urgency about this matter? asks Prof William Reville
Jim Hansen, director of the Nasa Goddard Institute for Space Studies has just reviewed this area in an excellent article in the New York Review of Books, Vol. 53, www.nybooks.com/articles/19131.
The world has been artificially warmed by human activities since the advent of the industrial revolution, mainly by emitting carbon dioxide into the atmosphere from burning coal, oil and gas. Other gaseous emissions are also significant, principally methane. In line with these emissions of greenhouse gases, the average temperature of the world has gradually risen.
World temperature can vary due to natural causes. Is our current warming simply due to natural fluctuation? The answer is no; it is largely caused by human emissions. Scientists can only simulate current world temperature trends when greenhouse gas emissions are factored into climate models. The world is now warming quickly. The year 2005 was the hottest on record; and 19 of the hottest 20 years on record have occurred since 1980.
We are faced with two scenarios. In one we continue with annual emissions of greenhouse gases increasing at the current rate for 50 years. The alternative scenario is where we tackle emissions as best we can, causing emissions to level off this decade, then to decline for a few decades and, finally, to decline rapidly as new technology kicks in. The first scenario would warm the world by 5 degrees Fahrenheit this century; the second scenario would warm the world less than 2 degrees F.
One big risk arising from global warming is the melting of polar ice caps, particularly the ice sheets of Greenland and Antarctica, raising sea levels and causing catastrophic coastal flooding. A 5 degree F rise in global temperature would melt the ice sheets, raising sea levels by 80ft. Most US east coast cities, including the entire state of Florida, would be lost. Most of Bangladesh would be lost, 250 million people would be displaced in China and 150 million in India. The sea level rise of 80ft would happen over about 300 years, but the disruption would be massive. Global warming of less than 2 degrees F this century would also cause a significant rise in sea level, but at the much slower rate of about 2ft per century. This would allow enough time to develop coping strategies.
A 5 degree F warming over this century would also cause a huge loss of biological species as conditions in the lower latitudes became unbearable. Many species are already under pressure.
The sweltering planet resulting from a 5 degree F temperature rise would only support a fraction of the current global human population. Life would be hard and not the least burden would be the psychological trauma of knowing that we deliberately ruined the planet.
The response to this international emergency has been the Kyoto Treaty. The lower temperature scenario described previously is the probable outcome of a successful enforcement of the terms of Kyoto. But unfortunately, the US, a chief emitter of greenhouse gases, has refused to sign up to the treaty. Kyoto cannot succeed without the US. The US oil and gas industry doesn't accept the scientific evidence that global warming is man-made (no prizes for guessing why!). President Bush does not want "to harm the economy". This would be funny if it weren't so serious. The policy being pursued by the present administration won't harm the economy - it will ruin it and the global economy along with it.
The intergovernmental panel on climate control (IPCC), a body of top scientists, has been studying global warming since 1988. It has unambiguously concluded that human activities are warming the planet. Contrary voices are very few and lack credibility. Nevertheless the IPCC has not galvanised international action well. Its public pronouncements have been very cautiously worded in language more appropriate to a scientific journal. This has allowed self-interested detractors to deny the IPCC conclusions in language much more attuned to the public ear.
We are in trouble and carbon dioxide emissions must be tackled immediately. A significant fraction of current emissions come from oil and coal-burning electricity generating power stations. We will have to change over to nuclear power and renewable energy which emits no carbon dioxide and, in the meantime, sequester and bury the carbon dioxide emitted from conventional fossil fuel burning stations. Nobody but the Greens, who have a "religious"objection to nuclear energy, believe renewable sources alone can generate sufficient energy to sustain a modern economy. Nuclear energy must be in the mix at least for the time being.
There are many things we must do in addition to reducing carbon dioxide emissions. Another thing we must address is the capitalist philosophy which demands continuous economic growth. Such rampant growth is behind many of our problems. We should remember the Cree Indian saying: "Only when the last tree has died and the last river been poisoned and the last fish been caught will we realise we cannot eat money."