Science and Technology for Canadians

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Summary

Ice cores can open a window to the past on a changing climate. Some parts of the Canadian Arctic are cooling (the east) while others are warming (the west). Ice core drilling in Ellsemere Island tells an interesting climate change story. Ice cores are studied at Natural Resources Canada in Ottawa and other international labs to decipher past environmental change.

Transcript of Video

Jay Ingram
Throughout this week we will be exploring some of the issues surrounding global warming There is some debate in the scientific community about the causes and effects of our changing climate, and this week politicians from around the world are discussing the cure at a UN convention on climate change in Argentina. So we'll be showing you how global warming IS being measured and how scientists are figuring out what's likely to happen as a result. Tonight, we take to Canada's North where scientists are digging up some frozen lessons from the past.

Jay Ingram
Buried in the snow of the Canadian arctic are clues to our climate... how it HAS changed in the past... how it MIGHT change in the future. Are the fossil fuels we burn in the south warming the north? Have greenhouse gases knocked nature's climate patterns off-course? The answers are found deep in the ice caps.

Roy Koerner
The arctic is considered to be the area that is going to change most in the future. If climate changes globally, it tends to change most in the polar regions. So clearly it's a good place to look for changes, to monitor what's going on now and in the past.

Jay Ingram
Every spring, Dr. Koerner travels north to study the ice. Ice caps help cool the earth's climate, but they also respond to it. Up here, only a bit of snow melts each summer, so it piles up, layer by layer, year by year... and compresses into ice at the bottom. The deeper he digs, the further back in time he goes...

Roy Koerner
The ice as a resource is a museum and it's a museum of volcanic activity, it's a museum of bomb tests... It's a museum of atmospheric constituents in terms of acid snow for all types of pollution. It gives you the temperature, the annual temperature, the summer temperature... You can see all these things in the ice and of course the more sophisticated technology gets, the more you get out.

Jay Ingram
Dr. Koerner and his colleagues have compiled a 35-year record of ice caps across the eastern arctic, using mechanical drills to pull up very old samples called ice cores.

Jay Ingram
... this one came from the very bottom of the Agassiz ice cap on Ellesmere Island... 300 meters down. It's 100-thousand years old, stored inside a freezer with thousands more samples at the Geological Survey of Canada in Ottawa.

Jay Ingram
In a sub-zero laboratory, the cores are cut into sections. This piece comes from the Devon Island ice cap. It's not nearly as old, but it can be given an approximate date. First, a small section is melted down to a thin sliver.

Jay Ingram
... SO thin you can almost see through it. Then the sample is placed between two Polaroid lenses. An experienced eye can judge the approximate age of the ice from the size of the colored crystals.

Roy Koerner
The crystals generally get bigger the older the ice, other things being equal... and from this, one can say this is about 200 years old, just from the size of the crystal.

Jay Ingram
With a simple light table and an ice core, Dr. Koerner can also see how summer temperatures have shifted over time on an individual ice cap. Summer melts show up as clear, bubble-free rings in the core.

Roy Koerner
These ice layers are formed by the water percolating down through the snow when it melts in the summer and refreezes to form clear ice. And the more of these you get, the warmer the summer. So by counting these over several years, you can say whether you have a set of warm summers or a set of cool summers.

Jay Ingram
Summer melts are just one way of gauging temperature shifts. Another is to analyze oxygen isotopes in the ice cores. They can be converted into annual average temperatures, which can be plotted over time, right back to the last ice age. This graph shows how temperature has changed at a typical ice cap on Ellesmere Island.

Roy Koerner
The temperature changes show you coming out of the ice age, very warm 8-9,000 years ago and then... Lots of wiggles up and down -- warmer, colder, warmer, colder -- but a persistent cooling trend until about 150-200 years ago and then the modern warming right at the end of it.

Jay Ingram
Zero represents the mean temperature for the last thousand years. Today's temperatures are about a degree and a half higher.

Jay Ingram
Interestingly enough, these shifting temperatures vary a lot across the arctic. To the west, there's been a lot of warming in recent decades. But to the east, climate has been much more stable... even cooling slightly in some places. That's what the white and blue areas show on this map.

Roy Koerne
These regional differences are related to the atmospheric circulation -- how one area responds to change compared to another. It's a subject of quite intensive study right now because it's the regional changes that are of importance... the global change is one thing but it really comes down to what's going to happen where I live.

Jay Ingram
Overall, though, the trend is towards warming, and not just in the CANADIAN north. Dr. David Fisher has compiled summer temperature records from ice core and tree-ring studies across the northern hemisphere... in Canada, Europe, Greenland and Russia. His "north of 40" times series looks at the last 200 years in detail.

David Fisher
The temperature's starting to increase in the late 1800s and in the early part of this century around 1930 it really did start to increase quite markedly ... 40s, 50s, 60s very warm. Hesitation... back to cold in the 70s and had the graph continued, undoubtedly, it would show continued warming.

Jay Ingram
The question is, is this warming caused by human activity, or is it part of a natural trend? The geologists' long-term view gives us a hint. The current burst of warming stands in sharp contrast to the long, slower cooling trend that preceded it.

David Fisher
Certainly our century is the warmest one we've seen in our records for the last 3,000 years... and the suspicion, the strong suspicion, is that human beings have helped it along. It may be a natural warming but I rather suspect that our activities are helping it along quite a bit.

Jay Ingram
Industrial pollution is certainly making its way north. It shows up in laboratory samples of melted ice. This "spectrophotometer" measures toxic metals by taking tiny quantities of melted ice and atomizing them with a blast of heat of more than 2,000 degrees Celsius. Changing levels of toxic pollutants are plotted and compared with natural aerosols, like dust. Other human-made pollutants, like sulphates and nitrates, can also be measured.

David Fisher
From 1950 on, the levels and the seasonal variations have been increasing. Prior to 1950, the overall levels are lower and the only major changes would be the natural ones, periodically, like due to a volcano. Katmai, for example, in 1912.

Jay Ingram
The research suggests some of these pollutants come from Europe and Asia, the particles travelling over the top of the globe, across the north pole and into the Canadian snow.

Jay Ingram
Atomic bomb activity shows up too... particles of plutonium carried to the arctic and preserved in the ice... This too can be tracked. In this graph, the first peak is from Hiroshima and Nagasaki in 1945. The levels build, as bomb testing increased, through the 1950s, to a peak in 1962.

Jay Ingram
So our human activities are changing the nature of the northern snow. But there is some GOOD news here too. So far, in Dr. Koerner's study area, the glaciers and ice caps are holding their own against climate change. Over three decades of careful measurements, they've found no major change in either snow accumulation or ice melt. And in the very long-term, he believes the earth's natural cooling trend will prevail.

Roy Koerner
On the short-term, we've got this warming trend and if it's driven by fossil fuels, it will last for a couple of hundred years, in that order. But if you look at it on a longer time scale of a few thousand years, it will look like a rather nasty hiccup in terms of climate change. And it will go on cooling, cooling, cooling into the onset of the next ice age... a few thousand years away.

Jay Ingram
In the meantime, while we're BETWEEN ice ages, the goal is to limit that short-term warming trend. To keep the ice caps from melting, and to preserve the arctic and its fragile ecosystems.

Voice Over
Tonight's edition of Earth Tones was produced along with Natural Resources Canada.