When I wrote The Weather Makers, I laid out the state of climate science as it was understood in 2005. The book received much acclaim, but it was also criticised by climate-change sceptics as extremist and alarmist.
Since the book was published, the Intergovernmental Panel on Climate Change (IPCC) has completed two major summaries, in the form of its fourth and fifth assessment reports, and thousands of scientific publications have added to our understanding of how Earth’s climate system responds to carbon pollution.
As a result, many details of climate science have been clarified. Not only are the scientific projections of major trends more certain than ever, but today many of us also have firsthand experience of living in a strongly shifted climate. With climate change an experienced reality, and the science verified, the room for climate change denialism keeps shrinking.
Despite their vast increase in computational power, the models remain consistent in telling us that our Earth is warming, and will continue to warm in proportion to the volume of fossil fuel we burn. What has changed is the detail they reveal about the things that will unfold.
While no climate model can predict the future – simply because the future is impossible to predict – the increasing computational power of the models means that they are becoming ever more useful at explaining how climatic changes are being influenced by humanity. Studies of past climates are also becoming ever more informative. One that examines over 1,000 years of temperature records has shown that climate trends have sometimes differed markedly in the northern and southern hemispheres.
One example of hemispheric difference, which the sceptics used to cast doubt on the fact that CO2 causes warming, concerns the medieval warm period. The new study demonstrates unequivocally that this warm period was restricted to the northern hemisphere.
But such is the unprecedented volume of greenhouse gases that humans have released into the atmosphere that the climate system is being overwhelmed, and today warming is occurring in both hemispheres. The contemporary world is changing fast; few changes have been as profound or disturbing as the increases in extreme weather experienced right across the planet. For that dwindling band who continue to deny anthropogenic climate change, this is the new battleground – albeit one which is becoming ever more difficult for them to defend.
When, in late 2013, Australian prime minister Tony Abbott and his environment minister Greg Hunt argued that there is no link between the warming trend and extreme bushfires, they were arguing not only against science, but also contrary to common sense.
The link between extreme weather and climate change is a critical area for public understanding, because it’s the devastating extremes, rather than a shift in averages, that have the greatest impact. To deny the link also permits people to believe that climate change is something only for future generations to worry about. It is not.
Our climate has already changed, and over the last decade we have begun to witness more frequently the consequences of our profligate burning of coal, oil and gas. Very recent advances have allowed scientists to quantify the human impact on individual extreme weather events. Extremes in the weather are therefore a good place to begin looking at what has changed in climate science over the past decade.
Press link for more: Tim Flannery | theguardian.com