Science Source

Twenty-first century Arctic climate change

Summarizes the twenty-first-century Arctic climate simulated by NCAR’s Community Climate System Model, version 4 (CCSM4)
Finds the model simulates a much warmer, wetter, cloudier, and stormier Arctic climate with considerably less sea ice and a fresher Arctic Ocean under a strong radiative forcing scenario
Holds the high correlation among the variables composing these changes—temperature, precipitation, cloudiness, sea level pressure (SLP), and ice concentration—suggests that their close coupling collectively represents a fingerprint of Arctic climate change
Finds that despite more global warming in CCSM4, Arctic changes are generally less than under comparable greenhouse forcing in CCSM3, as represented by Arctic amplification (16% weaker) and the date of a seasonally ice-free Arctic Ocean (20 years later)
Finds that autumn is the season of the most pronounced Arctic climate change among all the primary variables
Finds the SLP response exhibits a significant trend toward stronger extreme Arctic cyclones, implying greater wave activity that would promote coastal erosion
Finds the region shrinks by about 40% during the twenty-first century, in conjunction with a nearly 10-K warming trend poleward of 70°N—based on a commonly used definition of the Arctic (the area encompassing the 10°C July air temperature isotherm)
Finds that despite this pronounced long-term warming, CCSM4 simulates a hiatus in the secular Arctic climate trends during a decade-long stretch in the 2040s and to a lesser extent in the 2090s