Is the Greenland Ice Sheet Melting?
Skeptical Science is worried about recent ice loss from the Greenland ice sheet but is there really a problem?
The Greenland ice sheet has melted several times in geological timescales and melting was more rapid 50 years ago when compared with current melting. However, melting 50 years ago had no human input.
Chylek et al (2006) provide an analysis of Greenland temperature records and compare the current (1995-2005) warming period with the previous (1920-1930) Greenland warming. They analysed data from the stations shown in Figure 1.
Figure 1: Location of Greenland Temperature Stations (Chylek et al, 2006)
Chylek et al (2006) note that, for one station Ammassalik (AM), “The year 2003 was extremely warm on the southeastern coast of Greenland. The average annual temperature and the average summer temperature for 2003 at Ammassalik was a record high since 1895. The years 2004 and 2005 were closer to normal being well below temperatures reached in 1930s and 1940s.”
Their results for all the stations are shown in Figure 2.
Figure 2: Comparison of Current Greenland Temperatures with Previous Temperatures (Chylek et al, 2006)
Chylek et al (2006) conclude that,”… the current Greenland warming is not unprecedented in recent Greenland history. Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920-1930 was about 50% higher than that in 1995 – 2005.”
They summarise that they, “… find no direct evidence to support the claims that the Greenland ice sheet is melting due to increased temperature caused by increased atmospheric concentration of carbon dioxide…The temperature trend during the next ten years may be a decisive factor in a possible detection of an anthropogenic part of climate signal over area of the Greenland ice sheet.”
It appears that the current concern over melting of the Greenland ice sheet is due to using too short a data record. Greenland was warmer in the recent past with no input from AGW. Figure 2 shows that current temperatures are similar to those reached in the 1930s and 1940s but “… almost all post-1955 temperature averages at Greenland stations are lower (colder climate) than the pre-1955 temperature average.”
Greenland is colder now than it was pre-1955.
Perhaps we should wait until definitive records over a longer timescale are available before we reach unwarranted conclusions about AGW causing melting of the Greenland icecap.