" The ozone caused stress to the trees, making them more vulnerable to pests and pathogens."

First, a study of snowfall on Canada's highest peak, Mount Logan, has greatly extended our understanding of temperature changes in the atmosphere. One of the longstanding complaints of climate change skeptics has been that our atmospheric data only goes back some 60 years - a very short length of time in terms of tracking climate trends. But a new report published in the science journal Nature provides data going back more than three centuries.

At the Mount Logan site, increased atmospheric temperatures correlate with higher snowfall levels. So researchers took ice core samples deep enough to provide 300 years of snowfall data. They found that between 1700 and 1850 there was little change in snowfall patterns. Then, around 1850, snowfalls began to increase - signaling elevated atmospheric temperatures. By 2000, snowfall levels were 15 times greater - providing strong evidence that atmospheric temperatures are on the rise, just like ground-level temperatures.

Another study, one with disturbing implications for Canada, was conducted by NASA and published in the Geophysical Research Letters. It reported that the "permanent" ice cap covering the Arctic Ocean in the Far North is disappearing faster than expected. In fact, an area the size of Alberta is melting every decade. Researchers say that at this rate, it will be gone by the end of the century, if not sooner. Temperatures are still increasing and, as the ice melts, the snow that reflects sunlight back into space is replaced by dark water, which absorbs yet more heat and further increases the warming trend. The loss of ice means less habitat for many animals. Some, like the polar bear, could disappear altogether.

A final study, also in Nature, looked not at how the climate is changing, but at what this change will mean to our forests. Trees absorb carbon from the atmosphere and store it as wood. For this reason, forests have been dubbed carbon "sinks." Some have argued that Canada should simply be allowed to grow more trees as a way to slow global warming and meet the Kyoto Protocol. But the new four-year study by 50 international scientists led by Natural Resources Canada shows that pollutants released by power plants and vehicles don't just cause climate change - they also stunt tree growth.

The researchers pumped two common gases created when fossil fuels are burned - carbon dioxide and ozone - over stands of aspen trees at a huge outdoor facility in Wisconsin. As expected, increased carbon dioxide led to increased tree growth. However, when ozone was added to the mixture, the opposite occurred. The ozone caused stress to the trees, making them more vulnerable to pests and pathogens. These pests included the poplar leaf rust - which increased three fold in a carbon dioxide and ozone-enriched atmosphere, tent caterpillars - which increased by up to 31 per cent, and aphids - whose infestations became more severe in enhanced atmospheres. Considering the damage that pests are already doing to areas like the interior forests of British Columbia, the thought of enhanced pestilence is especially disturbing.

It also means we can't count on trees to soak up all that carbon we're spewing out through the tailpipes of our cars, the chimneys of our homes and the smoke stacks of power plants. We can't count on any carbon sinks to behave consistently when the rest of the world is changing. The only reliable way to slow global warming is by reducing emissions and Kyoto is a good way to start.