Greenhouse gases

At opposite corners of Alberta two towers stand above grassy fields, quiet sentinels keeping watch on how the Earth breathes.

At opposite corners of Alberta, two towers stand above grassy fields, quiet sentinels keeping watch on how the Earth breathes.

The towers and their associated science instrumentation, located near Athabasca in northern Alberta and Lethbridge in the province’s southern half, are part of a five-year project that has a team of scientists, including Dr. Robert Grant of the University of Alberta, working to find out just how much carbon dioxide (CO2) is building up in the atmosphere.

Working with scientists from the University of Lethbridge and other universities across Canada, Grant is part of Fluxnet-Canada, a research network that will contribute valuable scientific information to Canada’s policy development on managing harmful greenhouse gas emissions and international agreements such as the Kyoto Accord.

“We are basically monitoring the breathing of Canada’s forests and grasslands, using Fluxnet to measure the CO2 that goes in and comes out of ecosystems across the country,” said Grant, who conducts mathematical modeling to evaluate and analyze the data collected by the Fluxnet towers. “We are testing our understanding of the process that controls the uptake and emission of CO2.”

The instruments on the two towers run continuously. The Alberta towers have cousins scattered across the country in British Columbia, Saskatchewan, Ontario, Manitoba, Quebec and New Brunswick. There are also two auxiliary towers which run during the summer, located north of Edmonton. Equipment on the towers measures wind speed, direction, and concentration of water vapour and carbon dioxide. Solar radiation, air and soil temperature, and a variety of other environmental variables are also measured. The data is used to calculate the flux, or exchange, of CO2 in the air.

Over the last 150 years, human activity has altered the Earth’s global carbon cycle – the natural uptake of carbon dioxide by trees and its subsequent conversion, or cleaning, through photosynthesis. Globally, the uptake is 120 billion tonnes per year by land surfaces (tundra, grasslands, forests, oceans and deserts), and another 100 billion tonnes by the oceans.

 “Together, our terrestrial ecosystems and our marine ecosystems are fixing many times as much CO2 as we are putting into the atmosphere.”

But even so, Grant added, the fossil fuel emissions being pumped into the atmosphere appear to be more than the Earth’s natural ecosystems can clean. Annually, about four billion tonnes of carbon dioxide from human emissions are not being filtered by the forests or oceans.

Complicating matters is activity such as logging or burning, which affects the forests and puts more carbon dioxide into the air.

Fluxnet is charged with the task of discovering to what extent Canada’s forests can be used to offset the fossil-fuel emissions. “We hope to arrive at an estimate of what the national carbon balance is of Canada’s forests, and how it can contribute to offsetting fossil fuel emissions of CO2,” Grant said.

The project, which wraps up its first five-year phase in a year and a half, will also be studying watersheds and measuring CO2 concentration above the Earth’s surface.

Ultimately, the data gathered from Fluxnet’s towers and scientists will have many practical uses, including projecting future wood growth and supply for forestry companies, predicting future climate impacts on forestry productivity and establishing a scientific basis for carbon credit trading schemes.