A database for depicting Arctic sea ice variations back to 1850

Abstract

Arctic sea ice data from a variety of historical sources have been synthesized into a database extending back to 1850 with monthly time‐resolution. The synthesis procedure includes interpolation to a uniform grid and an analog‐based estimation of ice concentrations in areas of no data. The consolidated database shows that there is no precedent as far back as 1850 for the 21st century's minimum ice extent of sea ice on the pan‐Arctic scale. A regional‐scale exception to this statement is the Bering Sea. The rate of retreat since the 1990s is also unprecedented and especially large in the Beaufort and Chukchi Seas. Decadal and multidecadal variations have occurred in some regions, but their magnitudes are smaller than that of the recent ice loss. Interannual variability is prominent in all regions and will pose a challenge to sea ice prediction efforts.

Spatio-temporal variability of Arctic summer temperatures over the past two millennia: an overview of the last major climate anomalies

“…most likely experienced a pan-Arctic expansion as evidenced proxy studies (e.g. Belt et al, 2010;Kinnard et al, 2011;Berben et al, 2014;Miettinen et al, 2015) and also supported by documentary evidence for the last phase of the LIA (Divine and Dick, 2006;Walsh et al, 2017). Such sea ice expansion would lead to an increased continentality of the climate in most of the study domain, implying larger summer to winter SAT contrasts (see e.g.…”

Practice and philosophy of climate model tuning across six US modeling centers

“…Some observational targets have important (and sometimes unrecognized) structural uncertainties and therefore any tuning to those targets risks overfitting the model to imperfect data, potentially reducing skill in "out-of-sample" predictions (those for which the evaluation data either did not exist at the time of the prediction or were not used in model development or tuning). This is a particular problem for transient observations such as estimates of early 20th-century temperature changes (Thompson et al, 2008;Richardson et al, 2016), pre-1979 sea-ice extent (Meier et al, 2012;Walsh et al, 2017), pre-1990 ocean heat content change (Levitus et al, 2000;Church et al, 2011), or water vapor trends (Dessler and Davis, 2010), which have all been corrected in recent years, as nonclimate artifacts in the raw observations have been found and adjusted for. In contrast, many climatologies over the satellite era are robust metrics whose estimates over any fixed period have not changed appreciably as understanding of the observations evolved.…”

Fram Strait sea ice export variability and September Arctic sea ice extent over the last 80 years

“…This data set is an improvement upon an earlier historical record from Chapman and Walsh (1991) vides mid-month sea ice concentrations on a 0.25 × 0.25 • grid (Walsh et al, 2017). A total of 16 different sources of information were used to construct ice cover information back to 1850.…”

“…Prior to the modern satellite data record, which began in October 1978 from a series of successive passive microwave sensors (e.g., the Scanning Multichannel Microwave Radiometer (SMMR) and several Special Sensor Microwave/Imager (SSM/I) and SSMIS sensors), observations come from earlier satellite missions, aircraft and ship observations, compilations by naval oceanographers, ice charts from national ice services, and whaling log records, among others. For many regions and time periods several sources of sea ice data and weighting was applied (Walsh et al, 2017). The monthly files are intended to represent ice on the 15 or 16 of each month using the NASA Team sea ice algorithm.…”