When Will the Summer Arctic Be Nearly Sea-Ice free? James Overland NOAA Pacific Marine Environmental Laboratory Seattle
Global Warming Arctic amplification Teleconnection and circulation pattern change “Arctic Amplification”: Global Warming +Multiple Feedbacks Reduction of Arctic sea Ice Atmosphere warming Ocean absorbs more heat OND Temp Anomaly Sept Sea Ice Extent JAS SSTA Heat releases to atmosphere in the fall. Surface albedo decrease
When will the Summer Arctic be Nearly Sea Ice Free? Literature search: Trendsetters (extrapolation of sea ice volume data) Stochasters (assume several more rapid loss events such as 2007 and 2012) Modelers (use CMIP3 and CMIP5 climate model projections, includes IPCC) (Overland and Wang 2013)
50 % 75 % Loss in Sea Ice Volume
75 % Loss in Sea Ice Volume Since the 1980s Sea Ice Reanalysis recently verified by satellite thickness estimates Overland et al GRL 2013 Schweiger et al. 2011, Maslowski et al. 2012 Laxon et al. 2013 Wadhams, 2012
SEA ICE SEPTEMBER 2012 ~50 % loss from climatology
Wide Range of September Sea Ice Extent Hindcasts and Predictions 89 ensemble members from 36 CMIP5 (IPCC) models under strongest (RCP8.5) emissions scenario Muyin Wang
Observed loss is faster than expected by models80% of 56 CMIP5 ensemble members have trends slower than the 2 standard deviation bound for the observations Stroeve, et al. 2012
When will the Summer Arctic be Nearly Sea Ice Free? Trendsetters : By 2020Extrapolation of sea ice volume Stochasters : 2030 Due to timing of multiple events with large range Modelers: 2040average for fastest ensemble members of 7 “selected” models.Average of models 2060. It is not possible to choose one approach over another depending on relative weights given to data versus models. Summer sea ice loss is very likely to occur before 2050, with a possibility of within a decade or two Current rapid Arctic change is likely out of sample for most Global Climate Models results in the CMIP5 archive. (Overland and Wang 2013)
Already 250 Miles of Open Water North of Alaska Alaska Sea Surface Temperatures
Chukchi Sea Number of months of ice cover from IPCC Models (more than 15% ice concentration) Ice Free: Shift from 2-3 Months to 4-5 months by 2030 Winter wins!
Sources of uncertainty in Arctic temperature projections ARCTIC TEMPERATURE Hodson et al. 2012, Clim. Dyn.
Arctic (60-90°N) Temperatures 2080-2100 Mitigation scenario (Rcp 4.5) late fall +7 °C ; late spring +2 °C Business as usual (Rcp 8.5) late fall +13 °C ; late spring +5 °C
Cascading Climate Impacts to Ocean and Biology Arctic Amplification From E Carmack
Adaptation time scale (2025-2040) due to single emission scenario, sea ice loss data, and user interest. The fix is in. Human forcing is already in the climate system. Summer sea ice loss is very likely to occur before 2050, with a possibility of within a decade or two, based on multiple information Mitigation time scale (2080-2100) models test range of emission scenarios: Business as usual (RCP 8.5) versus mitigation scenarios (RCP 4.5) give large (2X) differences