Canadian atmospheric greenhouse gas monitoring

 

The Canadian Greenhouse Gas Measurement Program operates stations that precisely monitor atmospheric levels of greenhouse gases (GHGs) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in all regions of the country. The most remote site, at Alert, Nunavut, contributes measurements to the Global Atmosphere Watch Programme of the World Meteorological Organization, which tracks changes in global GHG concentrations. Northern Hemisphere GHG concentrations, such as those observed at Canadian sites, are slightly higher than the global average because of larger sources of emissions in the Northern Hemisphere. The long-term trends from all Canadian sites closely track the increasing global CO2 concentration trend, while also showing clear seasonal cycles of CO2 concentration due to photosynthesis (plants remove CO2 from the atmosphere) and biogenic respiration (plants and animals breathe out CO2).

Canadian monitoring sites are also used to track changes in regional GHG emissions and removals due to the impact of the changing climate on vulnerable ecosystems, such as the tundra and boreal forest. The vast Canadian boreal forest (2.7 million km2) typically takes up a net 28 megatonnes of carbon from the atmosphere per year (Kurz et al., 2013). Fraserdale, situated close to the boreal forest, is influenced quite strongly by forest processes that affect atmospheric CO2 levels. Lower concentrations of CO2 are evident in summer (dominated by photosynthesis) and higher concentrations are evident in winter (dominated by respiration) compared with the more distant site at Alert that is not surrounded by significant vegetation. Research has found that the net amount of carbon taken up in the Canadian boreal forest has increased in warmer years (Chen et al., 2006). In contrast, studies in Scandinavian boreal forests have found that the net uptake of carbon has decreased in recent years (i.e., 1999–2013) (Hadden and Grelle, 2016). This highlights the value of performing specific atmospheric observations in the Canadian boreal forest. Furthermore, atmospheric observations of CH4 in the Arctic could detect any rapid changes in emissions due to thawing of permafrost.

In summary, atmospheric observations play a key role in tracking global trends in GHG concentrations, in monitoring changes resulting from global GHG mitigation efforts, and in understanding the climate feedback of Canadian ecosystems.