1756
From Permafrost Degradation Projection to Prediction
Ronald Daanen ([email protected]), Vladimir E. Romanovsky, Martin Stendel, Sergei S. Marchenko, Jens Hesselberg- Christensen, Thomas Ingeman-Nielsen, Keld Svenson and Niels Foged, Keld Honbeck Svendsen
On the topic of climate warming, permafrost degradation is the main focus of attention for media, government and
many researchers, from ecologists to geophysicists. The discussion is aimed at increasing ground temperatures and
permafrost thaw, with the potential released of a large amount of carbon stored in permafrost. However there are great
discrepancies between projected permafrost changes in the literature. Many of the differences can be attributed to a
lack of physical permafrost understanding, but even among permafrost scientists there are differences of opinion on
how to estimate permafrost changes as a result of a warming climate.
The projection of climate change into the future may be correct on average, but the problem with permafrost generation or degradation is that it depends strongly on the occurrence of a single extreme weather event, e.g. the accumulation of a large amount of snow during a particular winter may lead to permafrost degradation. To estimate the chance
of these weather events occurring we analyzed climate data from a 25 km resolution climate projection over Greenland
for one node point. Monthly temperatures and snow depths are analyzed statistically to understand their monthly exceedance percentages. To compare months individually we de-trend the data and calculate the distribution of temperatures for each month individually between 1950 and 2050 for the region of Ilulissat, Greenland.
These weather patterns are input for a permafrost model that describes the physical processes of heat flux, freezing
and thawing as non-linear heat conduction. We define permafrost degradation as a mean annual temperature greater
than 0 degrees Celsius at 1 meter depth. Based on this analysis we can say that permafrost in a natural setting near Ilulissat is not likely degrading within the next 40 years.
Combined 30% warmer air temperature and 30% increased
snow fall resulting in permafrost degradation in approximately
50 years from today.
Chance of temperature 30% warmer than average
Chance of snow depth greater than 30% above average
Ground temperature [1m]
25
25
10
5
20
20
Percent %
0
15
15
Current Month
Month 2
Month 2
-5
Month 3
10
current month
Month 3
10
Month 4
Month 4
-10
Month 5
5
month 5
5
-15
0
0
-20
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
10000
20000
30000
Sep
40000
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Based on deptrended snow fall distribution for
each month
The horizontal axis shows the number of days into the simulation with GIPL starting with 1950 ending in 2080.
Based on deptrended air temperature
Ground temperature [1m]
20
5
10
0
1.2
1
-5
0
-10
-10
-15
-20
-20
-30
0.6
0.4
-30
0
10000
20000
30000
40000
0
0
10000
30% more snow
20000
30000
40000
0
0.2
1
Snow depth [m]
0.15
-10
0.1
-15
0
3
4
5
6
7
8
9
10
11
0.8
0.6
0.4
-20
0.2
-25
0
12
0
10000
20000
30000
0
40000
10000
20000
30000
40000
50000
30% higher temperature
Ground temperature [1m]
Air temperature
6
5
20
40000
1.2
-5
0.05
30000
1.4
0
2
20000
SNOW
5
1
10000
Ground temperature [1m]
0.25
Snow depth [m]
0.8
0.2
-25
-40
30% more snow
Snow depth
Snow depth [m]
Normal condition
Air temperature
15
0
Added temperature [°C]
30% warmer
10
5
5
0
-5
-5
-10
-10
-15
-20
3
2
1
-15
-25
4
-30
0
1
-20
-35
0
10000
20000
30000
40000
0
10000
20000
30000
40000
2
3
4
5
6
7
Month
8
9
10
11
12