Greenhouse Gases and the Carbon Cycle
AIM-North would improve our understanding of the carbon cycle of northern land regions (~40-80°N) including both the biospheric and anthropogenic components. The boreal forests are an important driver of the seasonal cycle in global atmospheric CO2 levels. Their growing season seems to have lengthened due to climate change, while at the same time disturbances such as fire and insect infestation are increasing. How these factors will alter the carbon balance of boreal forests in the future is not clear. Permafrost holds ~1672 PgC, about twice the mass of carbon in Earth’s atmosphere and with warming some fraction of this carbon will be released as CO2 and CH4, but it is uncertain how much (e.g. 9-114 PgC by 2100, Schneider von Deimling et al. (2012), Biogeosciences, 9, 649–665). This uncertainty is coupled with the offset of some CO2 emissions by uptake from increased vegetation density (‘greening’) in the Arctic. It remains important to reduce uncertainties and better understand these feedbacks on future climate change. Satellite observations of CO2 and CH4 in the North would help to reduce these uncertainties when used with model and data assimilation systems [Nassar et al., 2014].
Figure 1. A northern landscape in Jasper National Park, Alberta, Canada.
Solar Induced Fluorescence (SIF) can be used as an indicator of the start, end and intensity of the growing season, can provide information on vegetation stress and can correlate to gross primary production (GPP). The carbon dynamics of northern ecosystems is complex. Diurnal imaging of Boreal and Arctic SIF would enhance our ability to assess the health of forests and other vegetation types, including their net carbon balance at various space and time scales.
Anthropogenic activity north of ~40°N is increasing with a gradual rise in population, resource extraction and transportation. Fracking, smelting, diamond mining and oil sands operations release NO2, SO2 and other gases and aerosols that impact air quality. Vegetation fires in high latitude regions also impacts air quality. Geostationary (GEO) air quality satellites are planned over the US, Europe and East Asia, but coverage over Canada will be limited. Geostationary-like AQ observations over Canada could enable better quantification of emissions for regulatory purposes, as well as improve air quality forecasting, with the potential to impact the health of Canadians and reduce the number of premature deaths.
Quantification of anthropogenic CO2 emissions from space is of interest to support national emission reduction goals and the transparency framework of the United Nations Paris Agreement. Over 60 space and related member agencies of the Committee on Earth Observation Satellites (CEOS) have agreed to the New Delhi Declaration in 2016, which identified the need for better greenhouse gas observations to support emissions monitoring for climate agreements including development of new low Earth orbit (LEO) and GEO missions. Extending such a monitoring system to give equivalent coverage of high latitude regions is therefore desirable.
Modern weather forecasting relies on the synergy of observations from LEO and GEO satellites, but GEO observations are ineffective north of ~50-60°N because viewing angles become too large for effective measurements. Geostationary-like observations of nadir temperature and water vapour profiles, clouds and observations to derive atmospheric motion vectors north of the reach of GEO satellites, could significantly improve weather forecasts. These improvements would be most apparent for the highest latitude regions, but would extend to more densely populated regions of Canada or Europe.