The arctic ice thickness anomaly of the 1990s: A consistent view from observations and models

Abstract

[1] Observations of sea-ice draft from submarine cruises in much of the Arctic Ocean show that the ice cover was unusually thin in the mid-1990s. Here we limit our examination to digitally recorded draft data from eight cruises spanning the years 1987 to 1997 and find a decrease of about 1 m over the 11-year span. Comparisons of our modeled draft with observed draft show good agreement in the temporal change. Comparing average draft over entire cruises, the RMS discrepancy between modeled and observed draft is 0.3 m and the correlation is 0.98. Agreement in the spatial patterns of draft is somewhat lower; the RMS discrepancy of 50-km averages of draft is 0.7 m and the correlation is 0.73. We review reports of interannual variations of ice thickness or volume from other model studies. All models agree that thickness decreased by between 0.6 and 0.9 m from 1987 to 1996. Our model shows a modest recovery in thickness from 1996 to 1999. For the 1950s, 1960s, and 1970s, models tend to disagree on the size and to a lesser extent the timing or phase of interannual variations.

Inherent sea ice predictability in the rapidly changing Arctic environment of the Community Climate System Model, version 3

“…Similar to observations and hindcast simulations forced with atmospheric data (e.g. Maslanik et al 2007;Rothrock et al 2003), the simulated ice volume shows a considerable decline over the late twentieth to early twenty-first century in all of the CCSM3 standard runs with a corresponding reduction in the summer sea ice area. As discussed by Stroeve et al (2007), the reduction in September ice extent in these simulations is consistent with observed sea ice loss over the satellite record.…”

Arctic climate change in 21st century CMIP5 simulations with EC-Earth

“…Sea ice thickness reaches 3-4.5 m in most of the Central Arctic. Compared to existing observations and estimates of the ice thickness (Rothrock et al 2003;Belchansky et al 2008), this is an overestimation by about 0.5-1 m. At the Siberian coast, the overestimation is even larger, which is a typical problem of many coupled climate models and at least partly due to too weak offshore winds at the Siberian coast (Bitz et al 2002;DeWeaver and Bitz 2006). The thick ice at the Siberian coast prevents the complete melting of ice during summer in this area.…”

“…Also, the modelled Arctic sea ice volume (not shown) is overestimated in the twentieth century compared to estimates of today's observed ice volume (e.g. Belchansky et al 2008;Rothrock et al 2003).…”

Current estimates of freshwater flux through Arctic and subarctic seas

“…The question of long-term thinning, redistribution and retraction of Arctic Sea-ice has been extensively discussed in the literature for example, Rothrock et al (1999), Johannesen et al (1999), Wadhams and Davis (2000), Holloway and Sou (2002), Laxon et al (2003), Rothrock et al (2003), Comiso (2002) and Sroeve et al (2005). The most recent of these (Stroeve et al) shows that the downward trend in ice extent at the annual minimum (September) has been À7.7 ± 3% per decade since 1979 with evidence of a reinforced downturn in the most recent years.…”