The figures speak for themselves. Earth’s veil of atmosphere has warmed by 0.8 degrees since the middle of the 18th century when smoke billowing from furnaces of the Industrial Revolution began.

The temperature rise might not sound like a great deal, but make no mistake: the carbon dioxide being churned out today will linger for centuries to come, scientists say.

The polar icesheets, in particular, are vulnerable to a positive feedback loop that tends to boost the speed at which melting occurs. This, in part, is why the Arctic sea ice has shrunk to its smallest extent yet, raising concerns that Arctic summers might be largely free of ice by the 2030s.

Melting of sea ice does not, in itself, lead to a rise in sea level – but the melting of continental ice sheets, such as the Greenland ice cap in the Arctic, does, explains Monash University plant physiologist Roslyn Gleadow.

“Ice is white and reflects sunlight, ensuring that our polar regions keep cold,” Associate Professor Gleadow explains. “Areas that are ice-free are darker in colour and thus absorb sunlight; they also warm faster than if they were covered with ice.” This positive feedback mechanism serves to increase the initial warming.

To discuss these and related matters, the Royal Society of Victoria is hosting a climate change symposium that opened last night in Melbourne with a free public lecture entitled “Addressing the myths of climate change”.

Today, the symposium begins in earnest with world experts discussing each of three key areas of research: science, impacts and adaptation.

“The symposium aims to provide a forum where experts can engage with the community about issues without the need for overly technical language or political hype,” says co-organiser Associate Professor Gleadow.

The first session this morning will review the welter of evidence for climate change, how it is measured and what is understood about these changes. It will then move to describe projections for the future.

The second session will address impacts on Victoria, along with matters such as water supply, sea-level inundation, agricultural productivity and extreme-weather expectations.

The symposium’s final session will consider options for adaptation to reduce exposure to climate-change impacts. “This is really important because there are opportunities as well as challenges ahead, and we need people from all walks of life to be engaged in this process if we are to arrive at the best possible outcomes,” Associate Professor Gleadow says.

Likely impacts

The projected effects of sea level rise are of intense interest worldwide.

NASA satellite measurements show that coastal regions of the East Antarctic ice sheet, including long stretches of the Australian Antarctic Territory, have been losing about 57 billion tonnes of ice each year for the past three years. The complete loss of the sheet, the world’s biggest expanse of frozen water, would raise sea levels by roughly 50 metres, polar scientists believe.

The West Antarctic ice sheet, in particular, is losing about 132 billion tonnes of ice a year. Global ice losses now contribute an estimated 1.8 millimetres a year to rises in sea level.

Such calculations have given rise to reports suggesting that more than 250,000 homes in Australia could be damaged or lost due to storm surge and sea level rise in coming decades.

Claims that up to 45,000 homes in Victoria alone – worth more than $10 billion – would be threatened by rising sea levels by 2100, were followed by two CSIRO reports that suggest sea levels during storms are likely to be about 15 centimetres higher in 2030 than today.

Another report will consider four sea-level scenarios by 2100, including two based on rises of 80 centimetres, one of 110 centimetres and one of 140 centimetres. Victorian planning regulations currently forecast a rise in sea level of 80centimetres by the end of the century.

Australia contributes significantly to its own potential problems. The nation’s “ecological footprint” is estimated to be something like 7.8 global hectares per person – 2.8 times the average global footprint.

Links

• Find out what’s on today at the Royal Society’s climate change symposium here

• Learn more about environmental chemistry here

• Discover the effects of chemical compounds on the atmosphere here

THE United States has advised its citizens to keep away from Martin Place and Hyde Park this weekend amid fears of another outbreak of anti-American violence.

The deputy Police Commissioner, Nick Kaldas, said yesterday he had no intelligence to suggest there would be protests this weekend, but the Herald has learnt a special operation is in place to ensure there is no repeat of last Saturday’s unrest.

Officers from 10 squads, including mounted police, the dog unit and riot squad, will be supported by the force’s helicopter as part of Operation Waterman over the weekend.

Deputy Commissioner Kaldas and Sheikh Mousselmani. Photo: Sahlan Hayes

There have been messages circulating on Facebook encouraging further retaliation against the anti-Islamic film Innocence of Muslims and the police who quelled last week’s demonstration.

And a letter, titled ”Emergency Message for US Citizens” and sent to all those registered with the US consulate, states that ”law enforcement authorities” have warned of possible demonstrations tomorrow or Sunday.

”Fast-forming anti-American protests in Australia remain possible,” the letter states.

A similar warning has been issued in 33 other countries including Afghanistan, Egypt, Indonesia and Lebanon. One US citizen living in Sydney said he had never received such a specific warning in his five years overseas.

And the publication of cartoons of a naked Prophet Mohammed in a French magazine has prompted the French consulate in Sydney and the embassy in Canberra to increase security measures.

Police said last night that Sydney remained ”one of the safest cities in the world” and the city centre would be open for tourists and locals this weekend.

However, one message posted by a Muslim woman on Facebook has attracted hundreds of comments and states: ”This Sunday 23 September 1 pm at Hyde Park we can all bring own pepper spray!”

Another says: ”This Sunday at Hyde Park 23 September we show the kufar [non-believers] what we can do again!”

Some of the country’s most senior Muslim leaders met police yesterday to affirm their support for the police actions during and after the protests.

The grand mufti of Australia, Dr Ibrahim Abu Mohamed, who has never fronted the media in such a way, said Muslims who wanted to protest again were turning themselves from ”victim to criminal”.

Their show of support for the police is likely to anger some Muslims who have insisted police baited protesters in Hyde Park and responded heavy-handedly.

Meanwhile, claims by a controversial sheikh that he had nothing to do with the protest have been slammed by a Muslim activist, Jamal Daoud, as ”cheap lies”.

After days of speculation that he or his students were linked to the protests, Sheikh Feiz Mohammad broke his silence yesterday to tell the Muslim Village website that the protests were ”against every facet and tenor of the Islamic teachings” and that none of his students was involved.

But Mr Daoud, a refugee advocate, said the majority of violent protesters came from the mosques and musallahs of ”extreme Wahabi sheikhs” like Sheik Feiz and Sheikh Abdel Salam Zoud.

Ahmed Elomar, one of the men arrested over the riot, was a former student of Sheikh Feiz and messages urging people to go to the rally were posted in forums for the Ahlus Sunnah wal Jama’ah group that Sheikh Feiz leads.

Police last night charged a ninth person over the weekend riots. A 19-year-old man was charged with affray and throwing missiles at police and was granted bail to appear in court next month.