The Sydney Morning Herald

By Peter Hannam

When Dan Arvizu joined the New York commission formed in the wake of hurricane Sandy, the energy expert studied recommendations made after a destructive storm a decade earlier — all of which had been ignored. The 2012 storm caused $US65 billion ($70 billion) in damage, much of it from a surge of seawater that inundated large parts of Manhattan.

Just as in the prior disaster, building owners located back-up power units in basements, their least valuable space but also the most vulnerable to flooding.

For lessons to sink in, "you don't need one disaster, you need two", Arvizu, director of the US government's National Renewable Energy Laboratory, said this week in Sydney.

Such lessons are likely to be useful in the future. New York can expect the intensity of future storms to increase, as greenhouse gases trap ever more heat in the atmosphere.

That is also been the message from the Intergovernmental Panel on Climate Change (IPCC), which this week released its report on the impacts of a warming planet. For Australia, changes under way include a decline in autumn and winter rainfall in south-west WA since 1970 and the south-east since the 1990s. Projections include worsening fire weather in southern Australia and rising sea levels putting at risk $226 billion in assets.

The US government last year put the "social cost" of emitting carbon dioxide, the principal greenhouse gas, at $US33 per tonne — more than the $24.15 carbon price the Abbott government vows to scrap.

But the IPCC report only narrowed the carbon cost to "between a few dollars and several hundreds" per tonne. It also qualified its gross domestic product impact range of 0.2-2 per cent of GDP at 2.5 degrees warming as "incomplete".

Victoria University's Roger Jones, a co-ordinating lead author of the IPCC report, is frustrated more work has not been done to estimate the cost of climate change. "It's almost as if the world doesn't believe it's going to happen and doesn't want to know the answer," he said. "It's a question worth getting better information on."

On April 13, the IPCC will release its report on the other side of the ledger — the cost of mitigation, or doing something to limit the warming. Leaked drafts suggest the bill is manageable.

Scientists say we need to keep atmospheric levels of carbon dioxide to within a range of the 430–480 parts per million (up from about 400 now) to limit the global temperature rise to 2 degrees by 2100. That effort, largely requiring less burning of fossil fuels, will cost the global economy 1–4 per cent of GDP by 2030 and 2–6 per cent by 2050, the IPCC report is likely to say. With annual growth of 2.5 per cent, for instance, the world would attain the same level of output in 2031 rather than 2030.

A Reuters report says Australia and other rich nations will be asked to halve emissions by 2030 from 2010 levels to limit warming to 2 degrees.

While sounding a steep goal, a conference on doubling Australia’s energy productivity by 2030 at the University of Technology Sydney this week heard more than half the energy used in the US is wasted. Similarly large savings are possible here from lifting energy efficiency standards for cars, homes and other uses.

Arvizu’s own headquarters in Colorado is a zero net user of energy, which he says cost ‘‘less than a building built to code’’.

Unlike previous IPCC reports, though, this one will call on developing nations “to pull their weight” alongside rich nations to curb emissions, said Frank Jotzo, an associate professor at the Australian National University, and one of its authors.

It remains “highly contested” who should bear the costs, not least because nations such as China are being asked to act at a lower average income than wealthy countries responsible for much of the problem, said Jotzo.

That also means that any move by the Abbott government to follow Canada and weaken its carbon ambitions — now set at cutting 2000 levels by 5 per cent by 2020 — would have ‘‘a strong negative signalling effect on developing countries’’, he said. Leaders of poorer nations would be much less willing to act ‘‘when parts of the rich world aren’t taking action’.

This article was originally published in the The Sydney Morning Herald