How to adapt to climate change when the entire environment is changing? What are the limits to...
APT : Anticipating the effects of permafrost thaw on our climate
Scientists unanimously agree that the permafrost is a ticking time-bomb. Defined as areas of soil or rock which remain frozen for at least two consecutive years, the permafrost currently has more carbon locked up in it than the world’s total reserves of fossil fuels, including petroleum, natural gas and coal, put together! Now, as a result of rising temperatures, the permafrost could lose as much as 90% of its total surface by the end of the century, thus in turn dramatically accelerating the existing global warming process.
Yet none of the current climate forecast models takes into account the potentially devastating effects of permafrost thaw for the simple reason that the thawing of the permafrost and the release of its carbon into the atmosphere are still little-understood phenomena. This is the reason for the APT (Acceleration of Permafrost Thaw) project being run by a Franco-Canadian team at the Takuvik research laboratory, a joint unit of the French National Centre for Scientific Research (CNRS) and Laval University in Quebec.
“The purpose of our study is to make a forecast of temperature changes in the permafrost and estimate the quantity of carbon likely to be released into the atmosphere due to rising temperatures,” explains Project Coordinator Florent Dominé.
The planet’s largest carbon reserves
Situated in Canada’s far north, in Alaska, the Himalayas and Siberia, the permafrost regions are a focal point for climatologists. Scientists estimate that these regions currently store some 1,700 billion tonnes of carbon, the equivalent of double the total amount of carbon currently contained in the earth’s atmosphere!
This carbon has been produced by plant and animal remains accumulated and preserved over millions of years. One thing is absolutely certain: due to the warming process, some of the soil and rock is now being de-frosted, resuscitating dormant bacteria which then attack the trapped carbon, consuming it and turning it into gas – CO2, plus also methane, which has an extremely high global warming potential. The basic questions are therefore 1) just how much of the permafrost area is likely to thaw out in the near future and 2) what volume of greenhouse gases will be emitted as a result of the decomposition processes. “Whatever the answers to these questions turn out to be, the global warming scenarios drawn up by scientists will have to be revised upwards,” underlines Florent Dominé. It remains to be seen whether this rise will be of the order of 1°C or 10°C…
Measuring and monitoring the permafrost
With a view to reducing this enormous degree of uncertainty, the Franco-Canadian team at the Takuvik laboratory has since 2012 been operating three measurement stations in Canada’s Far North and a fourth is due to be set up soon.
“We need to take a wide range of measurements, because ground temperature does not only depend on air temperature,” points out Florent Dominé. For example, the vegetation cover modifies local ground warming as the wind causes snow to pile up at the feet of trees and bushes. And the thicker the snow mantle, the higher the insulation effect, which reduces ground cooling. In addition, the dark coloured vegetation diminishes the snow’s reflective power, which means that less heat is reflected back into the atmosphere, yet another factor for ground warming.
We need to take a wide range of measurements, because ground temperature does not only depend on air temperature !
The observation stations are equipped to take both the air and ground temperature automatically and also measure wind speed, sunlight patterns and the thermal conductivity of the snow. “In addition to taking these measurements, we visit the sites in person three or four times a year in order to analyse the properties of the snow and check spatial variations. We also observe vegetable cover and snow depth,” says the Project Coordinator. He has also involved the local Inuit communities in the work, as they are in a position to take measurements of ground temperature and snow depth on a more regular basis.
Umiujaq (Canada), Novembrer 2014, Denis Sarrazin (Northern Studies Centre, Université Laval)
Extensive degradation of permafrost, 2011, Denis Sarrazin (Northern Studies Centre, Université Laval)
Bylot Island (Canada), July 2013, Florent Dominé (TAKUVIK, Université Laval/CNRS)
Modelling permafrost thaw and its effects on the climate
All this information will assist in understanding the processes involved in the thawing of the permafrost. This is an essential step in creating models to simulate changes in these areas, based on such parameters as temperature and vegetation.
By coupling these simulations with dynamic models for the carbon locked up in the ground, the research team is hoping to predict how much greenhouse gas will be released from the permafrost at a given temperature level. This will in turn eventually enable climate scientists to calculate the extra global warming due to permafrost thaw in the coming years.
“ Scientists are predicting an average global temperature rise of 4°C by the year 2100. But if we take into account the effects of permafrost thaw we might well have to double that estimate! ”
Takuvik Research Laboratory
Read moreAll news
Facing global warming and ocean acidification, what is the role of marine phytoplankton, and...