Global weather disasters a sign the heat is on

Global weather disasters a sign the heat is on

08 January 2011

published by www.theaustralian.com.au


Australia — You probably already had guessed something like that was going on and it may have eased your concerns about global warming. Perhaps it even made you more inclined to the view of geologist and paleontologist Bob Carter that it is “the greatest self-organised scientific and political conspiracy that the world has ever seen”?

If only. Being duped is preferable to being fried. Unfortunately, it is hard to find such comfort from the data.. But then perhaps that is because it has been collected by the alleged co-conspirators.

The Bureau of Meteorology said this week the 2010 mean temperature was above the average of the three decades to 1990, which is the standard reference period, though only by 0.19C.

The first decade of the 21st century was also the warmest since standard records began in 1910. And based on preliminary data to November 30, sea surface temperatures around Australia were the warmest on record last year, as were those for the past decade.

The news for the rest of the world is not so promising, either. The World Meteorological Organisation, on the basis of data collected from 189 countries and territories (co-conspirators all?), says the year to the end of October was the warmest since instrumental climate records started in 1850 – 0.55C above the 1961-90 average of 14C.

Perhaps the cold northern winter will bring the final figure, which will not be published until March, down a little but the WMO was confident enough last month to say that 2010 would rate in the top three warmest years.

And the decade also was the warmest on record – despite the annual peak in 1998.

That puts a bit of a dent in the argument that the world has been cooling since 1998.

While the records cover only a relatively short period, the trends happen to follow closely the predictions over the past 40 years of temperature rises resulting from increased greenhouse gas emissions.

In 1972, John Sawyer of the British Meteorological Office estimated an increase of about 0.6C by the end of the century. The actual figure was about 0.5C.

Most scientists agree that doubling the carbon dioxide in the atmosphere is likely to lead to warming of 2C-3C, an amount that risks significant economic and environmental damage.

So far the increase since the mid-18th century of all greenhouse gases has been 38 per cent, including a 27.5 per cent rise from 1990 to 2009.

As well as rising temperatures, the WMO says that Arctic sea ice shrank last year to its third lowest area in the satellite records and was offset only slightly by Antarctic sea ice at just above the long-term average. Global snow cover is falling and sea levels rising.

Despite that, much of the debate about global warming still is conducted in terms of future and uncertain consequences.

Perhaps we should start looking harder at the present. Recent extreme weather events include not only the Victorian bushfires and record floods in Queensland. According to the international insurance group Munich Re, 2010 saw the second-highest number of natural catastrophes since 1980, with 90 per cent of them weather-related.

Australia always has been a land of drought and flooding rains, and weather records are broken as regularly as cricket records. But not in the way they have been recently.

The temperature of 46.4C in Melbourne on Black Saturday was more than 3C above the previous highest for February.

July 29 last year saw the temperature reach 38.2C in Moscow, while for the whole month the mean temperature was more than 2C above the previous record.

Munich Re says the heatwave and associated fires and air pollution in central Russia killed at least 56,000 people, making it the worst natural disaster in Russia’s history.

Pakistan experienced its worst ever floods, costing 1769 lives. Munich Re says the hurricane season in the North Atlantic was one of the most severe in the last century even though most countries, including the US, had a lucky escape, with the storms mostly over the sea.

So, can we blame climate change? Probably to some degree, even cautious scientists tend to say.

CSIRO research has identified climate change as contributing to the 20 per cent decline in rainfall in southwest Western Australia over the past 40 years, as well as the reduced rainfall in southeastern Australia.

Neville Nicholls, meteorologist, Monash University professor and one of the lead authors of the 2007 Intergovernmental Panel on Climate Change report, says of the Queensland floods: “The reality is that we don’t know if there is a climate change component in it.”

On his estimate, the current La Nina that usually generates higher rainfall in eastern and northern Australia is the strongest or second strongest we have ever experienced. While there is no evidence to link La Nina to climate change, one possible connection is that water temperatures in the oceans around Australia have never been so warm and the La Nina has been unusually strong.

“But honestly we don’t know,” says Nicholls.

Nor does he attribute the Victorian bushfires per se to global warming. “The particular weather situation we had is the kind of weather situation we have had in the past: it was hot, it was dry and it was windy.”

The differences were that the 12 years of drought was twice as long as the previous longest drought in the region, the heatwave at the end of January 2009 was the worst Melbourne had ever experienced and the temperatures on Black Saturday saw a large step up from the previous record. “What you can say is that there is very strong evidence that global warming exacerbated the fire situation.”

Applying the same reasoning, Nicholls does not argue that climate change is responsible for any other single event.

But he does point to the succession of extraordinary heatwaves, with big jumps in record temperatures, starting in Europe in 2003 and continuing all around the world, culminating in Russia last year. More than 17 countries broke their maximum temperature records in 2010. “Putting them together, you really have to strain credibility to say it has nothing to do with climate change,” he says.

“With climate change you expect many more of these really hot events and that is what we are getting. At the same time there are still records being set for cold temperatures. But for the last couple of decades we have certainly been getting more hot records being set than cold records.”

Even if the world achieved what so far has proved beyond it – a mechanism to stabilise greenhouse emissions at 450 parts per million of CO2 – global temperatures still will rise by an estimated 2C; that is, four times the increase that has occurred in the past 30 years. That means further consequences already are locked in and we will have to turn our minds increasingly to adapting to them.

Nicholls says most developed countries, including Australia, already have set up heatwave alert systems.

Other changes will be harder. Reducing water allocations in the Murray-Darling Basin is still years away at best, and the recent rain will tempt politicians to postpone it further.

Building rail lines that don’t buckle and electricity systems that don’t fail, as they did at the time of the Victorian bushfires, let alone the bigger tasks of managing increasingly vulnerable coastlines and transforming agriculture, will be big challenges but ones that only will get bigger the longer we delay.


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