Tuesday, 28 March 2017

Expect fewer cyclones, but the ones that form will pack a wallop

There was a point earlier this summer when Aussies in the Top End started to wonder: Where the hell are the cyclones?

The Australian region is usually hit with 11 cyclones each season - which runs from November 1 to April 30 - but only five tropical cyclones have been named in 2016-17. The 2015-16 season was the least active on record, with only three tropical cyclones declared.
In other words, it has been eerily still.

That was until today, when a Category 4 monster will hurtle towards the Whitsundays.
The region is expected to endure destructive winds, gales and a dangerous storm surge when the cyclone hits this morning.

The latest research into cyclones suggests that this will become the norm: fewer cyclones, but the ones that do form will be destructive.

That means stronger winds, more ferocious storms and heavier rain.

Cyclones need a very specific set of conditions in the atmosphere and ocean to form. Climate change has made those conditions harder to find, which is likely to lead to fewer tropical cyclones around the world, according to University of Melbourne cyclone expert Associate Professor Kevin Walsh.

One of the key conditions is sea-surface temperature above 26.5C and cool conditions in the upper part of the troposphere, which is found 15km above sea level.

"Climate change is causing the upper troposphere to heat up even more, and so the atmosphere becomes more stable," Dr Walsh told the university's Pursuit website.


Sunday, 26 March 2017

Great Barrier Reef: 'See it while you still can'

A leading Kiwi climate scientist has a message for people wanting to visit Australia's Great Barrier Reef: see it now before it's too late.

Dr Jim Salinger said the "burning, drying and flooding" continent was now experiencing dramatic impacts from climate change.

"The iconic Great Barrier Reef, already badly damaged by global warming during three extreme heatwaves, in 1998, 2002 and 2016, is being yet damaged by a new bleaching event is under way now," said Salinger, currently an honorary research fellow at Otago University's Department of Geography.

"The extreme marine heatwave in 2016 killed two-thirds of the corals along a 700km stretch of the northern Great Barrier Reef, from Port Douglas to Papua New Guinea.

"It caused dramatic change for the reef and that climate change is here now.

"The message is simple - visit it now otherwise if we see more diebacks of corals in the next few years, little if any action on emissions and inadequate progress on water quality, then an 'in danger' listing in 2020 as a World Heritage area."

Salinger said the past summer had brought prolonged and at times extreme heat over New South Wales, southern Queensland, South Australia and parts of northern Victoria.

The three heatwaves across January and early February saw unusually high daily maximum and minimum temperatures for at least three consecutive days over large parts of the country.

During these heatwaves, daily maximum temperatures across southeast Australia exceeded 40C over very large areas and were typically 8C to 12C above the January and February averages.

Tuesday, 21 March 2017

NZ's future: Zero emissions by 2100?

Slashing pastoral stock numbers by up to 35 per cent has been suggested among ways to push New Zealand's greenhouse gas emissions down to zero by 2100.

A cross-party group of MPs have commissioned UK consultants Vivid Economics to look at the options, which have been presented as four bold scenarios for the country in a new report launched today.

Under the first scenario, the country would further slash the emissions intensity of its economic activity through technological advances, such as cost reductions in electric vehicles for freight, electric heating technologies for high temperature applications and a vaccine to reduce methane emissions from pastoral agriculture.

This would be accompanied by a structural shift away from pastoral agriculture - with animal numbers around 20 to 35 per cent lower than today - to less emissions-intensive activity.

The country would instead support a diverse range of land uses, including horticulture and crops, alongside extensive planting of forests, covering an extra million hectares of land by 2050.

This scenario could result in a 70 to 80 per cent reduction in net emissions compared with current levels, however the authors said this option still relied upon breakthroughs like high-grade heat and non-passenger transport, along with extra tech in the agriculture sector.

Under a second scenario, an extra 1.6 million hectares of forest planted by 2050 would "substantially reduce emissions" - a 65 to 75 per cent reduction - and provide opportunities in a significantly enhanced forest products industry.

"However, changed land uses may require a difficult transition for rural economies, as well as represent a lost opportunity to reintroduce native habitat."

Saturday, 18 March 2017

Tackling global warming key to saving Great Barrier Reef

The survival of the Great Barrier Reef rests on cutting global warming, with efforts to improve water quality and fishing doing little to prevent major bleaching, according to a new study.

The study, released in the scientific journal Nature, shows protecting it from fishing and poor water quality is doing little to prevent bleaching.
"Global warming is the number one threat to the reef. The bleaching in 2016 strongly reinforces the urgent need to limit climate change," said co-author David Wachenfeld from the Great Barrier Reef Marine Park Authority.

The reef experienced the worst coral bleaching on record last summer with protective efforts making no difference to the amount of bleaching during the extreme weather.

"With rising temperatures due to global warming, it's only a matter of time before we see more of these events," Wachenfeld said.


Thursday, 16 March 2017

Half of Arctic sea ice decline due to natural causes, says new study

A new study has found that as much as half of the decline in Arctic sea ice over the last several decades was due to natural causes, rather than human interaction.

And a New Zealand climate expert says the findings show how variability in the Arctic and Antarctica might not be so different after all.

Although human interaction is still a major factor in the decline, the study shows the sea ice is less sensitive to our interactions than initially thought.

"It is well recognised that recent Arctic sea-ice decline has both natural and anthropogenic drivers, but their relative importance is poorly known," said the research, published online in Nature Climate Change.

The study was conducted by Qinghua Ding from the University of California, and his colleagues.
It focused on atmospheric circulation in the summer months and how it influenced the extent of Arctic summer sea ice in September.

"We have provided a plausible mechanism for how circulation changes can impact Arctic sea ice, but it is difficult to determine causality with observational evidence alone, because of the feedbacks between sea ice and the atmosphere," the study said.

Researchers were able to conduct several model experiments to show how high-latitude circulation impacted sea ice.
The researchers found 30 to 50 per cent of the overall decline in September Arctic sea ice since 1979 could be accounted for by natural variability.


Tuesday, 14 March 2017

Villagers at mercy of rising sea levels

When the waves surrounded her first house Vasney Aitoaea was frightened. She could hear them crashing around her, and she prayed to God she would survive.

"That first house fell down," she says. "So my husband built a second near the same place. And then the waves came again. And so we built a third, and a fourth, each time further up the beach."
She looks out to the ocean, flat and oily in the grey light.

"The first house was over there, where the sun is on the sea."

She is pointing about 40m behind her, to a rock that will be covered by water at high tide, but which used to be the edge of the island Kwai, a tiny atoll in the Solomon Islands suffering the effects of a warming ocean.
Vasney Aitoaea, 71, from the island of Kwai, has had to move and rebuild her home five times due to the rise in sea level. Photo / Mike Scott
Rates of sea-level rise in the Solomons over the past two decades were among the highest in the world, averaging around 8mm a year between 1993 and 2012 - compared to below 2mm per year in New Zealand.

Some of the rise in that time has been attributed to natural climate variability, such as El Nino, and the increase has now flattened to 3.6mm a year. But already five islands in the Solomons, a country of 600,000 in remote Melanesia, have disappeared into the Pacific. A further six are so severely eroded that families have had to be relocated, including a whole village. Others have seen salt-water intrusion to the point crops will no longer grow, according to an Australian study published last year.

Kwai, a tiny, white-sand atoll off the east coast of the island Malaita, is one of those at risk.
Community leader Francis Robeni says the island has been eroded to the point it is now small and crowded.

"This island before was a fairly beautiful island," he says. "It stretched out further, 20 or 30m out that way. But during the cyclones, the big seas, the currents it started to erode.

Sunday, 12 March 2017

Exposure to pollution 'kills millions of children'

Exposure to polluted environments is associated with more than one in four deaths among children younger than 5, according to two World Health Organisation reports published today.

Worldwide, 1.7 million children's deaths are attributable to environmental hazards, such as exposure to contaminated water, indoor and outdoor pollution, and other unsanitary conditions, the reports found.

Weaker immune systems make children's health more vulnerable to harmful effects of polluted environments, the report says.

Some of the most common causes of death among children, such as malaria, diarrhea and pneumonia, can be prevented by implementing ways known to reduce environmental risks and exposure to these risks, the first report shows. About one quarter of all children's deaths and diseases in 2012 could have been prevented by reducing environmental risks.

Exposure to polluted environments is also dangerous during pregnancy because it increases the chances of premature birth. Infants and preschool children exposed to indoor and outdoor pollution are at a higher risk of contracting pneumonia and chronic respiratory diseases. The likelihood of cardiovascular diseases, cancer and stroke also significantly increases with exposure to polluted environments.

The second report quantifies the problem by providing the number of children who died because of exposure to polluted environments.

According to the report, every year:

- 570,000 children under 5 years die from respiratory infections, such as pneumonia, attributable to indoor and outdoor air pollution and second-hand smoke - smoke that is released by burning tobacco products, such as cigarettes.