Burning question

By Rebecca Priestley In Science

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14th August, 2014 Leave a Comment

A satellite image of the Earth. Photo/ Getty

What do you do if your fridge is playing up? Open the main compartment to see whether the food’s rotting? No. “You open the door to the freezer and there you see the melt and the dripping and you say, ‘Oh, the fridge is bad’, or ‘The power’s been turned off’.”

That’s oceanographer David Carlson’s analogy for seeing the effects of climate change.

“It’s the same thing with the planet. If you really want to look at where it’s getting warmer, you look at the snow and ice – at Antarctica, Greenland, Northern Hemisphere snow, Arctic sea ice and Antarctic sea ice. And the other place to look is in the cold oceans, because that’s where the climate machinery happens.”

Carlson, director of the World Climate Research Programme, is one of about 2000 international scientists attending a series of conferences in Auckland from August 23 at which climate change will be a major talking point. The SCAR (Scientific Committee on Antarctic Research) and ICSU (International Council for Science) meetings are being held under the umbrella of World Science Week New Zealand.

Antarctica, a continent covered with the planet’s biggest ice mass and surrounded by the biggest cold ocean, is a crucial place to look for climate change clues. Another significant thing about the frozen continent, says Tim Naish, director of Victoria University’s Antarctic Research Centre, is that “so little is known about it”.

Compared with the Arctic, Antarctica is poorly understood. “There are limited observations about what’s going on with the Antarctic ice sheet, yet we know it’s critical in terms of how it might respond to global warming or contribute to sea level change. The Antarctic contribution to future sea level rise is one of the big uncertainties we still face; we lack fundamental understanding of the dynamic response of the Antarctic ice sheet to warming.”

Naish’s main research focus is how Antarctic ice sheets have contributed to global sea level change in the past, particularly during warm periods. As part of the Andrill geological drilling project, Naish and others found direct evidence that the West Antarctic ice sheet (WAIS) “is capable of significant retreat and even complete collapse under an atmospheric concentration of CO2 of around 400 parts per million, which is what we have today”.

In May, Nasa scientists released a study that said the WAIS was already headed for an inevitable and unstoppable collapse. Online news site Mother Jones reported this as a “holy shit” moment for climate-change science. Collapse of the WAIS would raise the global sea level by 3-5m. “The jury is still out” on whether or not the Nasa study provides definitive evidence for irreversible collapse of the WAIS, says Naish, but it is consistent with the findings of the Andrill project. The bottom line, says Naish, “is that the warming ocean is doing the melting, and once you heat up the Southern Ocean from the top to the bottom – which we are doing – it takes a long time to cool down and a certain amount of commitment to ice sheet loss is already built in”. If the WAIS is headed for collapse, a key question for scientists is how long is it going to take to melt: 200 years or 1000 years?

Other SCAR conference attendees are concerned with sea ice, which Naish says “is critical in terms of controlling or modulating the production of deep ocean water, which helps drive global ocean circulation”. The continued presence of a significant summer sea-ice apron around Antarctica is one of the factors suppressing the type of amplified warming seen in the Arctic, he says.

Many other researchers at the SCAR meeting – zoologists, microbiologists and even conservators restoring historic huts – are also concerned with the impact and signs of climate change.

Surprisingly, though, few of New Zealand’s Antarctic scientists are involved in the Deep South Challenge – informally known as the Antarctic science challenge – the second of the Government’s National Science Challenges to have its funding confirmed. Although the challenge includes research into Antarctic sea ice and the southern ocean, excluded are Antarctic biology, glaciology, ice-sheet modelling and paleoclimate research, says Naish. He describes the exclusion of Antarctic ice-sheet research from the challenge as “inexplicable”.

Earlier this year, 80 of the world’s top Antarctic scientists met in Queenstown with the goal of identifying the highest-priority research questions for the next 20 years. The results of this exercise were published this month in Nature and will be presented at the SCAR conference. Improved understanding of how Antarctic ice sheets will respond as the climate warms over the coming centuries is at the top of the list.

Why do we still need climate science?

In a recent video clip that went viral, US TV host John Oliver staged a “mathematically representative climate change debate”, pitching three climate change deniers against 97 scientists who agreed human activity was causing climate change. It was a graphic demonstration of the scientific consensus.

We know the planet is warming, we know sea levels are rising, we know human activity – primarily increased carbon emissions raising atmospheric CO2 levels – is responsible. Despite the fact that some level of climate change is inevitable, it’s clearly time for governments and businesses to act if we want to avoid the worst-case temperature and sea level scenarios. So why do we still need so many scientists focused on climate change?

Think of it as a left foot, right foot problem, Carlson suggests. “I gave my first climate change talk in 1985, so for 30 years, the left foot – the scientists – have been saying climate is changing. Then the right foot – the public – started to catch up. But what’s going to happen is they’re going to say, ‘What next?’ And the ‘what next?’ is going to be regional.” People’s focus, says Carlson, will be on “what climate change will mean to my location, my economy, my decisions”.

“So the left foot – the scientists – are going to have to catch up again. Suppose the public does grab this issue and we get some kind of control on carbon emissions. Given what’s already in the atmosphere, what’s already in the ocean, what are going to be the consequences? In particular, what are going to be the regional consequences?”

Naish agrees. “There’s an absolute urgency that we stop debating scientific questions around climate change that are old, that are known, and we get on and deal with the consequences of that climate change and preparing for it – while also looking at how we can reduce greenhouse gas emissions.” The world is warming but “there are some areas of uncertainty we must continue to work on so we can provide better, more precise information for decision makers”.

Meetings such as SCAR’s, of scientists from all disciplines, are essential, says Carlson. In his own work, he deals with the idea of a “safe operating space”, which is about “trying to understand a planet with limits, and how we as humans are either pushing against or transgressing those limits, and then using that concept to try to get a coherent response both from the science community and from the public”.


Arctic Ocean, Arctic National Wildlife Refuge, Alaska. Photo/ Getty

Climate change from all angles

The scientists gathering in Auckland will talk about issues such as pandemics and climate change, ice melt and sea level rise, and food security in a time of climate change.

Scientists need to do two things, Carlson says. “First, we need to be much more open and engaged about doing our science.” During the 2007-08 International Polar Year, for which Carlson directed the International Programme Office, he found a public appetite for information about the research process – whether scientists went to sea or to the ice and if they used climate models.

“So we need to share not only our information but the process of how we do science. And we need to listen more to what our users need.” If scientists are only communicating through 500-page technical reports, he says, “then probably we’re missing the audience we really ought to be hitting”.

Be prepared for the plague

Professor Nils Christian Stenseth, president, International Biological Union

Plague, a disease caused by the bacterium Yersinia pestis, is endemic in many countries in the Americas, Asia and Africa. Each year, several thousand people are infected.

After an incubation period of up to a week, there is a sudden onset of fever, chills, headaches, body aches, weakness and vomiting. Many people die. Bubonic plague, the most common form of plague, results from the bite of an infected flea.

“In a world of climate change,” says Professor Nils Stenseth of the University of Oslo, “we ought to be prepared for an increasing number of human plague cases. Tourists in this globalised world need to pay particular attention. If you catch the disease in, for example, Central Asia, most doctors will know what it is – whereas this might not be so in Europe or New Zealand.

“My work focuses on the ecological effects of climate change on the dynamics of this disease system – the host (gerbils) and the vector (fleas). We have shown that for Central Asia, specifically Kazakhstan, an increase of summer temperature of 1°C will essentially double the chance of catching the disease.

“In other parts of the world, though, this might be different. In the US, for example, increased temperatures might reduce the chances.

“These ecological interactions are complicated – but we are making good progress. If we are to understand the changing likelihood of catching the plague, we need to understand the dynamics of this disease in the wilderness, where the reservoirs are.”

Pandemics and Climate Change, Friday, August 29.

Digging the dirt on carbon

Emeritus Professor Stephen Nortcliff, Reading University, UK

One of the things that happens when we cultivate soils is that we release carbon, by oxidation,” says Professor Stephen Nortcliff. As the land is cultivated, or stirred up, soil carbon is exposed to the atmosphere and reacts with oxygen – it oxidises – to form CO2.

“All the predictions say that as you increase temperature, the degree of oxidation will increase, so there will be less carbon in the soil.”

As atmospheric CO2 levels continue to increase, the loss or reduction of any carbon sinks is significant. But organic carbon also plays an essential role in keeping soil healthy, and healthy soil is essential to produce food for a growing global population.

“Many of the functions we expect a soil to perform – its ability to hold and exchange nutrients and its ability to hold water – relate to soil carbon,” says Nortcliff.

So, as the temperature warms and soil carbon reduces, “there will be a knock-on effect in terms of the soil’s ability to perform those functions”.

Nortcliff and colleagues are looking at ways of using waste carbon – in the form of compost made from food-­processing wastes, sewage sludge and anaerobic digestates – to produce materials to add to soils to increase carbon, provide nutrients and improve the structural stability of the soil.

Getting farmers – many of whom are used to using inorganic fertilisers – to use these products is the next challenge, says Nortcliff. Benefits, though, will include a reduced dependence on inorganic fertilisers, many of which are expensive and release CO2 during the manufacturing process.

Future Food for the Planet, Saturday, August 30.

Deep diving into ocean changes

Steve Rintoul, CSIRO, Australia

More than 90% of the extra heat energy that’s absorbed through the Earth has gone into warming up the oceans,” says Steve Rintoul. In addition, “about 30% of the carbon dioxide that’s been emitted by human activities has been removed from the atmosphere and stored in the oceans.

“By storing heat and carbon dioxide, the oceans have acted to slow the rate of climate change. So if we want to understand how fast the climate is changing and how the Earth is responding to extra greenhouse gases in the atmosphere, we really need to be measuring how much heat and carbon dioxide are stored in the oceans.”

There are good measurements of the upper 700m of the ocean, where most of the heat is stored. The deep ocean, though, is hard to monitor and few direct measurements have been taken.

Closer to the surface, ocean monitoring can reveal information about local rainfall more accurately than individual rain gauges can.

“Changes in ocean salinity, the pattern of saltiness in the ocean, tell us that the global water cycle is changing, and it’s changing in the way that we expect to happen in a warmer climate. Areas where there’s more precipitation than evaporation are getting even more rainfall and snowfall. And areas where the ocean tends to evaporate more water than it receives in rain are evaporating even more and becoming saltier.”

So what’s in store? “Overall we expect the oceans to continue to warm and to continue to acidify … the impact of that on ecosystems and organisms that live in the sea is still something that we know very little about.”

Melting Ice, Rising Sea, Tuesday, August 26.

Science goes public

With Auckland bursting at the seams with international scientific talent during the next fortnight, the public is getting a chance to glimpse the scientists’ work.

Under the banner World Science Week New Zealand, running from August 25 to September 3, the Royal Society and Ministry of Business, Innovation and Employment have combined to put on a number of public events (worldscienceweek.org.nz).

The talent is in town for the SCAR Open Science Conference (August 25-28) and a meeting of the International Council for Science (ICSU) (September 1-3).

The Open Science Conference brings together Antarctic researchers. The ICSU, which consists of 121 national science academies and 31 discipline-specific scientific unions, is holding its three-yearly general assembly to discuss issues related to using science “for the benefit of society”.

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