Modeling a modern-like <i>p</i>CO<sub>2</sub> warm period (Marine Isotope Stage KM5c) with two versions of an Institut Pierre Simon Laplace atmosphere–ocean coupled general circulation model
<p>The mid-Piacenzian warm period (3.264 to 3.025 Ma) is the most recent geological period with present-like atmospheric <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> and is thus expected to have exhibited a warm climate sim...
Main Authors: | , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2020-01-01
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Series: | Climate of the Past |
Online Access: | https://www.clim-past.net/16/1/2020/cp-16-1-2020.pdf |
Summary: | <p>The mid-Piacenzian warm period (3.264 to 3.025 Ma) is the most
recent geological period with present-like atmospheric <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> and is thus expected to have exhibited a warm climate similar to or warmer
than the present day. On the basis of understanding that has been gathered on
the climate variability of this interval, a specific interglacial (Marine
Isotope Stage KM5c, MIS KM5c; 3.205 Ma) has been selected for the Pliocene
Model Intercomparison Project phase 2 (PlioMIP 2). We carried out a series
of experiments according to the design of PlioMIP2 with two versions of the
Institut Pierre Simon Laplace (IPSL) atmosphere–ocean coupled general circulation model (AOGCM): IPSL-CM5A
and IPSL-CM5A2. Compared to the PlioMIP 1 experiment, run with IPSL-CM5A, our
results show that the simulated MIS KM5c climate presents enhanced warming
in mid- to high latitudes, especially over oceanic regions. This warming can
be largely attributed to the enhanced Atlantic Meridional Overturning
Circulation caused by the high-latitude seaway changes. The sensitivity
experiments, conducted with IPSL-CM5A2, show that besides the increased
<span class="inline-formula"><i>p</i>CO<sub>2</sub></span>, both modified orography and reduced ice sheets contribute
substantially to mid- to high latitude warming in MIS KM5c. When considering
the <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> uncertainties (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>+</mo><mo>/</mo><mo>-</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="aaf64dc90f991cd4fcb7f25788bfe4fa"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-16-1-2020-ie00001.svg" width="25pt" height="14pt" src="cp-16-1-2020-ie00001.png"/></svg:svg></span></span>50 ppmv) during the Pliocene, the
response of the modeled mean annual surface air temperature to changes to
<span class="inline-formula"><i>p</i>CO<sub>2</sub></span> (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>+</mo><mo>/</mo><mo>-</mo><mn mathvariant="normal">50</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="5afaeba59c8bc52b10020ca531f7e775"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-16-1-2020-ie00002.svg" width="39pt" height="14pt" src="cp-16-1-2020-ie00002.png"/></svg:svg></span></span> ppmv) is not symmetric, which is likely due to the
nonlinear response of the cryosphere (snow cover and sea ice extent). By
analyzing the Greenland Ice Sheet surface mass balance, we also demonstrate
its vulnerability under both MIS KM5c and modern warm climate.</p> |
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ISSN: | 1814-9324 1814-9332 |