The concentration of carbon dioxide in the atmosphere is measured in parts per million. Before the Industrial Revolution, before men began greater coal burning, destruction of forests and use of oil, the concentration was 280 parts per million by volume. We are now at 387. The Kyoto Protocol provided not to exceed 450 parts per million. But it is only a maximum level to avoid the catastrophe, not a disaster.
At 450 parts per million, which at this rate the Earth's atmosphere will reach in less than twenty years, we will have an increase in the average temperature of 2 Celsius degrees and a raising of sea levels by half a meter. But it's only a best estimate. Other scientists argue that the increase may reach 6 degrees and sea levels will rise seven meters. Similar levels of carbon dioxide and temperature happened on Earth in the past. They occurred after devastating volcanic eruptions or meteor impacts. The result? mass extinctions of plants and animals, abrupt climate changes, destructive floods.
For this reason, many scientists now consider the goal of stopping at 450 parts per million too risky. The temperature increase and ocean acidification may cause the release of methane from the ocean floor with a chain reaction that could create a global warming much more faster than the worst predictions. To avert such a scenario today thousands of people demonstrated around the world exposing the number 350. It's the level of parts per million of carbon dioxide that we should go back to minimize the risks of climate change. Not just slow the expected increase in carbon dioxide in the atmosphere then, but get it down to the level of two decades ago. The number 350 could be the minimum level for survival of human civilization as we know it. From the eighties to now in fact, the worldwide incidence of "natural" disasters, hurricanes, typhoons, floods and droughts, has already quadrupled, and continues to increase.
In December, at the Copenhagen summit on climate change, world leaders should take drastic steps to prevent the catastrophe. It's what today's demonstrations are asking, at a time when the preliminary talks before the summit have not progressed and still yield no solid results, and too many countries, like Italy, think only to the economic advantage of the moment and not to future of humanity.
Francesco Defferrari
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