Ice cores reveal climate change

[Fabulous]

In the frosty depths of a vast commercial warehouse in Dandenong, alongside boxes of frozen fish balls, pizzas and hamburger buns, lies a collection of ancient ice.

Drilled from a barren plateau in Antarctica, these long columns of ice are up to 2000 years old and contain millions of tiny air bubbles. If you let a piece melt, the escaping air makes the ice crackle and pop like a noisy bowl of Rice Bubbles.

Over the past 15 years, CSIRO scientist Dr David Etheridge has led the Australian analysis of this frozen air, which has revolutionised the scientific understanding of climate change.

In 1982, Dr Etheridge had just finished studying earth science and meteorology at Melbourne University when his mother pointed out an ad inviting people to work in Antarctica.

By the following summer he found himself on a gut-churning two-week ride across the Southern Ocean, and still remembers his first glimpse of the icy coast.

"It's a big white wilderness. Approaching from 10 or 20 kilometres away you can see this big ice dome and then if you look really hard you can see (one of Australia's main bases) Casey station, which is just a dot in comparison."

A container of information

But for a budding climate scientist, Antarctica's stark beauty was overshadowed by its potential for discovery.

"The way I saw it, Antarctica was a container of information from our past, because it had been soaking up climatic information from the atmosphere over hundreds of thousands of years."

That information was locked up inside air bubbles in the ice, which could reveal how the earth's atmosphere had changed over time. Although there had been other studies of ice in Antarctica, Greenland and Europe by the mid-1980s, no one had uncovered any ice samples showing distinct atmospheric changes over recent centuries.

That was largely because Antarctica's fierce winds leave most of the landscape as hard and smooth as polished glass. So scientists were on the lookout for a sheltered spot, where ice had accumulated evenly over time.

In 1984, an Australian expedition literally stumbled on the perfect site.

Dr Etheridge was back in Melbourne working with the Australian Antarctic Division when a telex arrived from fellow scientist Dr Rik Thwaites - the brother of the current Victorian Environment Minister John Thwaites - saying his expedition's tractor was bogged up to its axles in snow on the east side of Law Dome, about 100 kilometres from Casey station.

"I immediately thought, 'That's where we need to go'," recalls Dr Etheridge.

The following summer, he and an international team camped out in blizzards for more than a month to drill out ice cores from Law Dome.

The cheese grater

Returning to Melbourne, the scientists used an invention by Dr Etheridge, nicknamed the "cheese grater", which separates the air bubbles from the ice.

Analysis of the air showed a clear change in the earth's atmosphere over 1000 years, with carbon dioxide emissions skyrocketing since the Industrial Revolution as people burned more fossil fuels such as coal.

It reinforced warnings that greater concentrations of "greenhouse gases" such as carbon dioxide in the atmosphere would trap more heat, warming the planet unnaturally fast.

Air pumped from the snow samples was also crucial. While ice takes longer to build up, the fresher snow falls revealed atmospheric changes up to the present day. For the first time, it was possible to compare atmospheric records from Antarctica with contemporary air monitoring from places as far away as Hawaii and Cape Grim, off Tasmania's north-west coast.

The remarkably consistent results sparked an international flurry of research and debate.

"I got heaps from the 'sceptics' about those findings, because it was clear evidence that greenhouse gases were rising because of human activities," says Dr Etheridge.

"There are still a handful of people out there denying this, but the debate has moved on since then. The challenge is now to understand how those changes interact with the earth's systems, like the oceans and the biosphere, as well as what humans are doing."

Twenty years on, the work of Dr Etheridge and his CSIRO colleagues is a fundamental part of the science behind climate change.

Some of their research will appear in the Intergovernmental Panel on Climate Change report being released in Paris on Friday.

"You don't have to go to Antarctica to see that climate change is happening, we're seeing more and more evidence that things are changing closer to home too," says Dr Etheridge.

"If we keep relying on traditional carbon-based energy - such as burning coal - the greenhouse emissions are going to go through the roof, with pretty scary consequences. So the challenge is to move to renewables or to capture and store carbon emissions or other sources of energy. We've just got to get on with it."


http://www.theage.com.au/news/nation...594482202.html

[Charlie99]

The increase in atmospheric CO2 is a very well documented phenomena.

The impact of the increase in CO2 is less certain.


Here's an interesting article from April '75 Newsweek about the impending global COOLING problem.

The pdf version of the article, http://denisdutton.com/newsweek_coolingworld.pdf , has some nice charts showing how the average global temperature plummeted from 1940 to 1970, with survey by NOAA showing average ground temperatures in the entire Northern Hemishpere falling by a full 1/2 degree between 1945 and 1968.

"The evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it."

"Meteorologists disagree about the cause and extent of the cooling trend, as well as over its specific impact on local weather conditions. But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century. . If the climatic change is as profound as some of the pessimists fear, the resulting famines could be catastrophic. 'A major climatic change would force economic and social adjustments on a worldwide scale,' warns a recent report by the National Academy of Sciences, 'because the global patterns of food production and population that have evolved are implicitly dependent on the climate of the present century.' ”


"Climatologists are pessimistic that political leaders will take any positive action to compensate for the climatic change, or even to allay its effects. They concede that some of the more spectacular solutions proposed, such as melting the Arctic ice cap by covering it with black soot or diverting arctic rivers, might create problems far greater than those they solve."

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Obviously, we should take statements made in 1975 with some scepticism. Of course, everthing is different this time around.