The relevance of mid-Holocene Arctic warming to the future
<p>There remain substantial uncertainties in future projections of Arctic climate change. There is a potential to constrain these uncertainties using a combination of paleoclimate simulations and proxy data, but such a constraint must be accompanied by physical understanding on the connection...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-07-01
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| Series: | Climate of the Past |
| Online Access: | https://www.clim-past.net/15/1375/2019/cp-15-1375-2019.pdf |
| Summary: | <p>There remain substantial uncertainties in future
projections of Arctic climate change. There is a potential to constrain
these uncertainties using a combination of paleoclimate simulations and
proxy data, but such a constraint must be accompanied by physical
understanding on the connection between past and future simulations. Here,
we examine the relevance of an Arctic warming mechanism in the mid-Holocene (MH) to the
future with emphasis on process understanding. We conducted a
surface energy balance analysis on 10 atmosphere and ocean general
circulation models under the MH and future Representative Concentration Pathway (RCP) 4.5 scenario forcings. It is
found that many of the dominant processes that amplify Arctic warming over
the ocean from late autumn to early winter are common between the two
periods, despite the difference in the source of the forcing (insolation vs.
greenhouse gases). The positive albedo feedback in summer results in an
increase in oceanic heat release in the colder season when the atmospheric
stratification is strong, and an increased greenhouse effect from clouds
helps amplify the warming during the season with small insolation. The
seasonal progress was elucidated by the decomposition of the factors
associated with sea surface temperature, ice concentration, and ice surface
temperature changes. We also quantified the contribution of individual
components to the inter-model variance in the surface temperature changes.
The downward clear-sky longwave radiation is one of major contributors to
the model spread throughout the year. Other controlling terms for the model
spread vary with the season, but they are similar between the MH and the
future in each season. This result suggests that the MH Arctic change may
not be analogous to the future in some seasons when the temperature response
differs, but it is still useful to constrain the model spread in the future
Arctic projection. The cross-model correlation suggests that the feedbacks
in preceding seasons should not be overlooked when determining constraints,
particularly summer sea ice cover for the constraint of autumn–winter
surface temperature response.</p> |
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| ISSN: | 1814-9324 1814-9332 |