This article appeared in the Perspectives section of The Press yesterday, as part of the paper’s build up up to Earth Hour this weekend. I haven’t seen the letters page today, but I expect the usual suspects will be out in forceâ€¦ 😉
The news isnâ€™t good. Since the Intergovernmental Panel on Climate Change (IPCC) advised two years ago that the evidence for global warming was unequivocal, the pace of change has speeded up. Summer sea ice in the Arctic Ocean has seen a dramatic decline, and in a worrying foretaste of what may be to come, methane — a much more powerful greenhouse gas than carbon dioxide — has been found bubbling out of the ocean floor off Siberia. Down south, analysis of a core drilled into the seabed under the Ross Ice Shelf by a team including scientists from New Zealand (using Kiwi drilling expertise), demonstrates that the West Antarctic Ice Sheet is unstable and likely to collapse if warming continues as we expect over the coming century. Experts are revising their projections of sea level rise upwards with each piece of bad news. A metre or more by the 2090s is now a real possibility.
For those who follow developments in the study of climate change, this is genuinely alarming news. In this field, familiarity with the facts does not breed any sort of complacency. But by drawing attention to the uncomfortable truth, I fully expect to be labelled an â€œalarmistâ€ by those who argue for inaction.
It seems that there is a disconnect between the severity of the problem as itâ€™s perceived by experts, and how itâ€™s seen in the wider world. Climate change happens slowly in human terms — a big issue described by small numbers. Itâ€™s difficult to work up a sweat about a two degree increase in New Zealandâ€™s annual average temperature (projected for the 2090s on one scenario) when a southerly change blowing up the east coast can drop the temperature by ten degrees in ten minutes. The reality is that two degrees means that even a cool year in the 2090s will be hotter than the hottest year New Zealandâ€™s experienced in hundreds, probably thousands of years. A hot year will be scorching. Damaging droughts will be twice as frequent, the glaciers will be disappearing fast, severe floods will be more common and low-lying land will be lost to rising seas. With climate, little numbers bring big changes.
There are more uncomfortable facts we have to face. Significant changes in global climate are now inevitable. Nothing we can do, no amount of emissions reductions will prevent the planet warming up by around another 0.6ÂºC over the next 30 years, as the oceans â€œcatch upâ€ with the heat being trapped by the atmosphere. This will take the world to the brink of a two degree increase over the temperatures of 150 years ago. The dramatic changes we are already seeing are going to continue and get worse. The Arctic Ocean may be free of ice in summer, more ice shelves will collapse around Antarctica, and thereâ€™s nothing we can do stop it.
But we still have to reduce our carbon emissions — and soon. Every year we delay cutting emissions is a year of extra warming added on at the end of the catching up period. If we donâ€™t cut emissions, we condemn those of us who will live in the second half of this century to rises of 3, 4, or 5 degrees (or more) — warming that will radically transform the face of the planet and cause the deaths of hundreds of millions of people.
Thereâ€™s also a wild card in play — that the warming we canâ€™t avoid will be enough to cause large positive feedbacks to kick in. If too much methane is released from the East Siberian Shelf or the permafrost that rings the Arctic it could swamp any emissions reductions we make, and push the planet into rapid warming beyond any hope of human influence. At the moment we donâ€™t know enough to even guess at the extent of the danger, but the methane is already bubblingâ€¦
We donâ€™t have perfect knowledge of the climate system and how it will respond to increasing levels of greenhouse gases, but we already know enough to act. The direction of change is clear: itâ€™s going to get hotter. We canâ€™t be certain how hot itâ€™s going to get, or exactly what that means for New Zealand. But the risks are not that the warming will be smaller than we expect, but that it will be larger. Will climate change be a challenge or a catastrophe? The evidence still suggests that itâ€™s a challenge to which we can rise, but the possibility of catastrophic change canâ€™t be ruled out.
Sadly, there are still people who remain to be convinced that we face any problem, or who argue we need more evidence before we take any action. In reality, â€œscepticsâ€ who deny the need for action have their argument exactly the wrong way round. We have a mountain of evidence that suggests we need to act now to address a huge problem. To persuade the world that we need to do nothing, the sceptics require extraordinary proof. They need their own mountain, but all they have is a molehill. The balance of evidence is clear. The sceptics are on the wrong end of a seesaw, heading skywards.
If weâ€™re lucky climate change will continue to be a relatively gradual process, slow enough for humans to adapt to, without too many big surprises in store. The world still has time to make emissions cuts deep enough to prevent the worst effects later this century. As a scientific conference in Copenhagen earlier this month concluded, inaction is now inexcusable.