Sorry, global warming has not been cancelled

There are many other kinds of evidence for human-caused global warming. The evidence is becoming ever clearer, as is demonstrated in a recent report by a group of prominent scientists (The Copenhagen Diagnosis). Glaciers are melting, the Arctic is melting, the Antarctic ice sheet seems now to be losing mass, sea level rise has accelerated, the oceans are warming and becoming more acid, drought and other extreme weather events are increasing, pest infestations are killing forests, and so on. Geological records show there was much less polar ice when last the Earth had this much carbon dioxide in the atmosphere. If we don’t soon slow the increase in carbon dioxide, it will within a few decades reach levels at which the Earth was completely ice free in the past.

Sceptics and denialists misunderstand or misrepresent the scientific process. Even when there is broad agreement on the main features of a topic, scientific debates still continue about details and underlying mechanisms. This is true, for example, of evolution as well as climate science. The Intergovernmental Panel on Climate Change is charged specifically with finding those things that most climate scientists can agree on, despite continuing debates. Its 2007 statement was relatively conservative, yet still quite clear: it is at least 90 per cent probable that humans are causing global warming. Many scientists consider the evidence has strengthened significantly since then.

When the collective professional judgment of climate scientists is stated so clearly, politicians can have no reason to delay action. The imperative to action is actually even stronger, because we have known all along that the full effects of greenhouse gas emissions are delayed by decades. By the time the full effects of current emissions become apparent it will be far too late for effective action.

The denial of global warming by the Liberal Party is now exposed to the bright sunlight. Denialism lurks also in the other major parties, courtesy of the coal lobby. Hopefully it will soon melt away. Perhaps Kevin Rudd will even start acting as though he believes his own rhetoric. The Greens are waiting to co-operate on sensible, cost-effective and urgent measures that can actually reduce Australia’s emissions.