Heat is on to cool climate

BY NAOMI ARNOLD

The world has a window of about six years to reduce its carbon dioxide emissions to avoid severe global consequences, a climate expert told a 400-strong audience at the Nelson School of Music last night.

Niwa chief climate scientist Dr David Wratt was speaking on "Climate Change: Choice and Consequences" at the 66th annual Thomas Cawthron Memorial Lecture.

He said an increase of two degrees in global temperatures was not only almost certain to happen, but was going to require "a lot of hard work" to avoid. Limiting long-term global warming to about two degrees would mean keeping CO2-equivalent concentrations to 445-490 parts per million, and "we're getting pretty close to that now".

"There's not a lot of leeway and we're going to have to work pretty hard."

To keep under the two-degree mark, global CO2 emissions would need to peak by 2015, and by 2050 be reduced by between 50 and 80 per cent relative to 2000 emissions. Developed countries such as New Zealand would have to aim for reductions at the higher end of that, he said.

He hoped the upcoming United Nations climate change conference in Copenhagen would see a global agreement signed to reduce emissions worldwide.

"We don't want to spend six years arguing about an agreement," he said. "If we don't we're going to see very major problems in the future."

A former Motueka farm boy, Dr Wratt is vice chairman of the Intergovernmental Panel on Climate Change Working Group 1, which assesses the scientific basis of climate change. The first part of his lecture summed up climate science to date, drawing on the "robust and factually-based" findings of the 2007 IPCC report, which found "unequivocal" evidence of a long-term rise in temperatures.

"There's no doubt the world is warming up and various impacts are occurring now."

However, it wasn't just temperature that had gone up. Global sea levels had risen on average by about 17cm last century. Ice and glaciers had been disappearing at a faster rate than scientists had predicted. Oceans had become more acidic and were warming. There were also changes in rainfall and drought patterns.

Dr Wratt also discussed natural causes for changes in temperature, but they could not explain the "substantial warming" over the last century. That was due to humans, he said.

The second part of his lecture outlined the global consequences of an increase of two degrees worldwide, including water shortages, coral bleaching, disruption to ecosystems, extreme heat waves, sea level rises and flooding.

"There are things we're going to have to adapt to, but if we continue down the same sort of track we're on at present then we may finish up with four or five degrees warming by the end of the century," he said. That would mean much greater impact on many more people and ecosystems, including coral deaths, a 30 per cent loss of wetlands, decrease of food crops and a heavy burden on health services.

"Without going into these huge doomsday scenarios, these cautious [IPCC] scientists are saying that if we went to four degrees of warming we would see some really major negative effects. If we manage to stay below two degrees by reducing our emissions there will still be some impacts, but they won't be as serious."

Many countries had taken two degrees up as a target, and he recommended New Zealand do the same, though it was a "big policy challenge".

"New Zealand needs to be arguing really strongly for a two-degree target and play its fair share," he said. "We're only responsible for a small part of emissions [0.2 per cent] but the world is made up of groups of four million people."

However, he said it wasn't all "doom and gloom" and the IPCC's assessment had shown that there were many technologies available to make more efficient use of energy, carbon storage and renewable energies.

"It's feasible to meet this target if we work hard ... I would expect to see we won't be driving around in fossil-fuel guzzling cars in 20 years' time."

He said it was important not to frighten people. "That won't lead to changes of behaviour. It's really important to show people that there are answers there, and there are things we can do. I think not trying to scare people too much but to give them a realistic picture of what the risks are is the way to go. "

Brittany Packer, 18, and Abby Ward, 17, will attend the Copenhagen conference as youth delegates. Both said the lecture was "fantastic".

"He gave the facts straight, he didn't try to hype it up to make climate change seem more than it is, he just said it as it was," said Abby.

Brittany believed that because New Zealand traded on its "clean green" image, it had a lot more to lose than other countries.

"It also affects us a lot more than others because we're surrounded by Pacific islands and I think we're going to get a big influx of migration because of sea level rises, so we should be prepared for that," she said.

Nelson Environment Centre's Trevor Houghton said there were many things Nelsonians could do at a local level, such as joining Transition Towns, a free grassroots movement that brought communities together to become more sustainable.

- © Fairfax NZ News