Uncertainties in projected surface mass balance over the polar ice sheets from dynamically downscaled EC-Earth models
<p>The future rates of ice sheet melt in Greenland and Antarctica are an important factor when making estimates of the likely rate of sea level rise. Global climate models that took part in the fifth Coupled Model Intercomparison Project (CMIP5) have generally been unable to replicate observed...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-01-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/16/17/2022/tc-16-17-2022.pdf |
| Summary: | <p>The future rates of ice sheet melt in Greenland and
Antarctica are an important factor when making estimates of the likely rate
of sea level rise. Global climate models that took part in the fifth Coupled
Model Intercomparison Project (CMIP5) have generally been unable to
replicate observed rates of ice sheet melt. With the advent of the sixth
Coupled Model Intercomparison Project (CMIP6), with a general increase in
the equilibrium climate sensitivity, we here compare two versions of the
global climate model EC-Earth using the regional climate model HIRHAM5
downscaling of EC-Earth for Greenland and Antarctica. One version (v2) of
EC-Earth is taken from CMIP5 for the high-emissions Representative
Concentration Pathway 8.5 (RCP8.5) scenario and the other (v3) from CMIP6 for
the comparable high-emissions Shared Socioeconomic Pathway 5-8.5 (SSP5-8.5)
scenario. For Greenland, we downscale the two versions of EC-Earth for the
historical period 1991–2010 and for the scenario period 2081–2100. For
Antarctica, the periods are 1971–2000 and 2071–2100, respectively. For the
Greenland Ice Sheet, we find that the mean change in temperature is 5.9 <span class="inline-formula"><sup>∘</sup></span>C when downscaling EC-Earth v2 and 6.8 <span class="inline-formula"><sup>∘</sup></span>C
when downscaling EC-Earth v3. Corresponding values for Antarctica are 4.1 <span class="inline-formula"><sup>∘</sup></span>C for v2 and 4.8 <span class="inline-formula"><sup>∘</sup></span>C for v3. The
mean change in surface mass balance at the end of the century under these
high-emissions scenarios is found to be <span class="inline-formula">−290</span> Gt yr<span class="inline-formula"><sup>−1</sup></span> (v2) and <span class="inline-formula">−1640</span> Gt yr<span class="inline-formula"><sup>−1</sup></span> (v3) for Greenland and 420 Gt yr<span class="inline-formula"><sup>−1</sup></span> (v2) and 80 Gt yr<span class="inline-formula"><sup>−1</sup></span>
(v3) for Antarctica. These distinct differences in temperature change and
particularly surface mass balance change are a result of the higher
equilibrium climate sensitivity in EC-Earth v3 (4.3 K) compared with 3.3 K
in EC-Earth v2 and the differences in greenhouse gas concentrations between
the RCP8.5 and the SSP5-8.5 scenarios.</p> |
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| ISSN: | 1994-0416 1994-0424 |