13 research outputs found
Effect of high dust amount on surface temperature during the Last Glacial Maximum: a modelling study using MIROC-ESM
The effect of aerosols is one of many uncertain factors in projections of
future climate. However, the behaviour of mineral dust aerosols (dust) can be
investigated within the context of past climate change. The Last Glacial
Maximum (LGM) is known to have had enhanced dust deposition in comparison
with the present, especially over polar regions. Using the Model for
Interdisciplinary Research on Climate Earth System Model (MIROC-ESM), we
conducted a standard LGM experiment following the protocol of the
Paleoclimate Modelling Intercomparison Project phase 3 and sensitivity
experiments. We imposed glaciogenic dust on the standard LGM experiment and
investigated the impacts of glaciogenic dust and non-glaciogenic dust
on the LGM climate. Global mean radiative perturbations by glaciogenic and
non-glaciogenic dust were both negative, consistent with previous studies.
However, glaciogenic dust behaved differently in specific regions; e.g. it
resulted in less cooling over the polar regions. One of the major reasons for
reduced cooling is the ageing of snow or ice, which results in albedo
reduction via high dust deposition, especially near sources of high
glaciogenic dust emission. Although the net radiative perturbations in the
lee of high glaciogenic dust provenances are negative, warming by the ageing of
snow overcomes this radiative perturbation in the Northern Hemisphere. In
contrast, the radiative perturbation due to high dust loading in the
troposphere acts to warm the surface in areas surrounding Antarctica,
primarily via the longwave aerosol–cloud interaction of dust, and it is
likely the result of the greenhouse effect attributable to the enhanced cloud
fraction in the upper troposphere. Although our analysis focused mainly on
the results of experiments using the atmospheric part of the MIROC-ESM, we
also conducted full MIROC-ESM experiments for an initial examination of the
effect of glaciogenic dust on the oceanic general circulation module. A
long-term trend of enhanced warming was observed in the Northern Hemisphere
with increased glaciogenic dust; however, the level of warming around
Antarctica remained almost unchanged, even after extended coupling with the
ocean.</p
Large-scale features of Last Interglacial climate: Results from evaluating the lig127k simulations for the Coupled Model Intercomparison Project (CMIP6)-Paleoclimate Modeling Intercomparison Project (PMIP4)
Abstract. The modeling of paleoclimate, using physically based tools, is
increasingly seen as a strong out-of-sample test of the models that are used
for the projection of future climate changes. New to the Coupled Model
Intercomparison Project (CMIP6) is the Tier 1
Last Interglacial experiment for 127 000 years ago (lig127k), designed to
address the climate responses to stronger orbital forcing than the
midHolocene experiment, using the same state-of-the-art models as for the future and
following a common experimental protocol. Here we present a first analysis
of a multi-model ensemble of 17 climate models, all of which have completed
the CMIP6 DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. The equilibrium climate sensitivity (ECS) of
these models varies from 1.8 to 5.6 ∘C. The seasonal character of
the insolation anomalies results in strong summer warming over the Northern
Hemisphere continents in the lig127k ensemble as compared to the CMIP6 piControl and
much-reduced minimum sea ice in the Arctic. The multi-model results indicate
enhanced summer monsoonal precipitation in the Northern Hemisphere and
reductions in the Southern Hemisphere. These responses are greater in the
lig127k than the CMIP6 midHolocene simulations as expected from the larger insolation anomalies
at 127 than 6 ka. New synthesis for surface temperature and precipitation, targeted for 127 ka, have been developed for comparison to the multi-model ensemble. The
lig127k model ensemble and data reconstructions are in good agreement for summer
temperature anomalies over Canada, Scandinavia, and the North Atlantic and
for precipitation over the Northern Hemisphere continents. The model–data
comparisons and mismatches point to further study of the sensitivity of the
simulations to uncertainties in the boundary conditions and of the
uncertainties and sparse coverage in current proxy reconstructions. The CMIP6–Paleoclimate Modeling Intercomparison
Project (PMIP4) lig127k simulations, in combination with the proxy record, improve
our confidence in future projections of monsoons, surface temperature, and
Arctic sea ice, thus providing a key target for model evaluation and
optimization.
</jats:p
Large-scale features of Last Interglacial climate: results from evaluating the lig127k simulations for the Coupled Model Intercomparison Project (CMIP6)–Paleoclimate Modeling Intercomparison Project (PMIP4)
The modeling of paleoclimate, using physically based tools, is increasingly seen as a strong out-of-sample test of the models that are used for the projection of future climate changes. New to the Coupled Model Intercomparison Project (CMIP6) is the Tier 1 Last Interglacial experiment for 127 000 years ago (lig127k), designed to address the climate responses to stronger orbital forcing than the midHolocene experiment, using the same state-of-the-art models as for the future and following a common experimental protocol. Here we present a first analysis of a multi-model ensemble of 17 climate models, all of which have completed the CMIP6 DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. The equilibrium climate sensitivity (ECS) of these models varies from 1.8 to 5.6 ∘C. The seasonal character of the insolation anomalies results in strong summer warming over the Northern Hemisphere continents in the lig127k ensemble as compared to the CMIP6 piControl and much-reduced minimum sea ice in the Arctic. The multi-model results indicate enhanced summer monsoonal precipitation in the Northern Hemisphere and reductions in the Southern Hemisphere. These responses are greater in the lig127k than the CMIP6 midHolocene simulations as expected from the larger insolation anomalies at 127 than 6 ka.
New synthesis for surface temperature and precipitation, targeted for 127 ka, have been developed for comparison to the multi-model ensemble. The lig127k model ensemble and data reconstructions are in good agreement for summer temperature anomalies over Canada, Scandinavia, and the North Atlantic and for precipitation over the Northern Hemisphere continents. The model–data comparisons and mismatches point to further study of the sensitivity of the simulations to uncertainties in the boundary conditions and of the uncertainties and sparse coverage in current proxy reconstructions.
The CMIP6–Paleoclimate Modeling Intercomparison Project (PMIP4) lig127k simulations, in combination with the proxy record, improve our confidence in future projections of monsoons, surface temperature, and Arctic sea ice, thus providing a key target for model evaluation and optimization
Inner Edge of Habitable Zones for Earth-sized Planets with Various Surface Water Distributions
International audienceWhen planets receive insolation above a certain critical value called the runaway threshold, liquid surface water vaporizes completely, which forms the inner edge of the habitable zone. Because land planets can emit a large amount of radiation from the dry tropics, they have a higher runaway threshold than aqua planets do. Here we systematically investigated the runaway threshold for various surface water distributions using a three-dimensional dynamic atmosphere model. The runaway threshold for the meridionally uniform surface water distribution increases from the typical value for the aqua-planet regime (~ 130% S0) to one for the land-planet regime (~ 155% S0) as the dry surface area increases, where S0 is the present Earth's insolation. Although this result is similar to the previous work considering zonally uniform surface water distributions, the runaway threshold for the land-planet regime is quite low compared to that of the previous work. This is because a part of the tropical atmosphere is always wet for the meridionally uniform case. We also considered the surface water distributions determined by the Earth's, Mars' and Venus' topographies. We found that their runaway thresholds are close to that for the meridionally uniform cases, and the amount of water at the boundary between an aqua-and land-planet regime is around 10% of the Earth's ocean. This clearly shows that the runaway threshold is not determined uniquely by the luminosity of the central star, but it has a wide range caused by the surface water distribution of the terrestrial water planet itself
The GRENE-TEA model intercomparison project (GTMIP): overview and experiment protocol for Stage 1
As part of the terrestrial branch of the Japan-funded Arctic Climate Change
Research Project (GRENE-TEA), which aims to clarify the role and function of
the terrestrial Arctic in the climate system and assess the influence of its
changes on a global scale, this model intercomparison project (GTMIP) is
designed to (1) enhance communication and understanding between the modelling
and field scientists and (2) assess the uncertainty and variations stemming
from variability in model implementation/design and in model outputs using
climatic and historical conditions in the Arctic terrestrial regions. This
paper provides an overview of all GTMIP activity, and the experiment
protocol of Stage 1, which is site simulations driven by statistically
fitted data created using the GRENE-TEA site observations for the last 3
decades. The target metrics for the model evaluation cover key processes in
both physics and biogeochemistry, including energy budgets, snow,
permafrost, phenology, and carbon budgets. Exemplary results for
distributions of four metrics (annual mean latent heat flux, annual maximum
snow depth, gross primary production, and net ecosystem production) and for
seasonal transitions are provided to give an outlook of the planned analysis
that will delineate the inter-dependence among the key processes and
provide clues for improving model performance
Large-scale features of Last Interglacial climate: results from evaluating the lig127k simulations for the Coupled Model Intercomparison Project (CMIP6)–Paleoclimate Modeling Intercomparison Project (PMIP4)
The modeling of paleoclimate, using physically based tools, is increasingly seen as a strong out-of-sample test of the models that are used for the projection of future climate changes. New to the Coupled Model Intercomparison Project (CMIP6) is the Tier 1 Last Interglacial experiment for 127 000 years ago (lig127k), designed to address the climate responses to stronger orbital forcing than the midHolocene experiment, using the same state-of-the-art models as for the future and following a common experimental protocol. Here we present a first analysis of a multi-model ensemble of 17 climate models, all of which have completed the CMIP6 DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. The equilibrium climate sensitivity (ECS) of these models varies from 1.8 to 5.6 ∘C. The seasonal character of the insolation anomalies results in strong summer warming over the Northern Hemisphere continents in the lig127k ensemble as compared to the CMIP6 piControl and much-reduced minimum sea ice in the Arctic. The multi-model results indicate enhanced summer monsoonal precipitation in the Northern Hemisphere and reductions in the Southern Hemisphere. These responses are greater in the lig127k than the CMIP6 midHolocene simulations as expected from the larger insolation anomalies at 127 than 6 ka.
New synthesis for surface temperature and precipitation, targeted for 127 ka, have been developed for comparison to the multi-model ensemble. The lig127k model ensemble and data reconstructions are in good agreement for summer temperature anomalies over Canada, Scandinavia, and the North Atlantic and for precipitation over the Northern Hemisphere continents. The model–data comparisons and mismatches point to further study of the sensitivity of the simulations to uncertainties in the boundary conditions and of the uncertainties and sparse coverage in current proxy reconstructions.
The CMIP6–Paleoclimate Modeling Intercomparison Project (PMIP4) lig127k simulations, in combination with the proxy record, improve our confidence in future projections of monsoons, surface temperature, and Arctic sea ice, thus providing a key target for model evaluation and optimization