The “faint young Sun paradox”: further exploration of the role of dynamical heat-flux feed backs in maintaining global climate stability

AbstractThe climate-modeling problems associated with global change underline the importance of understanding paleoclimates. The available evidence, which suggests that the Earth has never been fully glaciated, poses an especially serious problem for the early Earth when the Sun was about 20–30% fainter than today. In conventional explanations of this “faint young Sun paradox”, presumed very high levels of atmospheric greenhouse gases are required to prevent runaway glaciation of the Earth. Here we explore other possible explanations of this paradox. As an extension of our previous work on this subject, we illustrate how-dynamical beat-flux feed backs may have prevented the early Earth from freezing. Our simulations are carried out using a two-dimensional, seasonal-climate model with physically based parameterizations for atmospheric meridional-heat transport and sea ice. It ís found that dynamical heat-flux feed backs alone may have protected the Archean Earth against a runaway glaciation to a considerable degree.

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Dynamical Heat-Flux Feedbacks and Global Climate Stability

Annals of Glaciology ◽

10.3189/1984aog5-1-106-110 ◽

1984 ◽

Vol 5 ◽

pp. 106-110 ◽

Cited By ~ 1

Author(s):

Gyula Molnar ◽

Wei-Chyung Wang

Keyword(s):

Heat Flux ◽

Global Stability ◽

Heat Transport ◽

Global Climate ◽

Dynamical Model ◽

Meridional Heat Transport ◽

Low Latitude ◽

Climate Stability ◽

Vertical Heat ◽

The Face

In the face of the faint young sun-climate paradox, the plausible effects of dynamical heat-flux feedbacks on global stability were examined using a coupled high- and low-latitude radiative-dynamical model. The global stability is found to depend very strongly on the vertical heat transport, which is also closely coupled to the meridional heat transport. This coupling and the associated dynamical heat-flux feedbacks, treated within the framework of the radiative-dynamical model, was found to produce a fairly strong negative feedback. Our results indicate that the dynamical heat-flux feedbacks inherent in the climate system may potentially enhance the global stability.

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Dynamical Heat-Flux Feedbacks and Global Climate Stability

Annals of Glaciology ◽

10.1017/s026030550000358x ◽

1984 ◽

Vol 5 ◽

pp. 106-110 ◽

Cited By ~ 4

Author(s):

Gyula Molnar ◽

Wei-Chyung Wang

Keyword(s):

Heat Flux ◽

Global Stability ◽

Heat Transport ◽

Global Climate ◽

Dynamical Model ◽

Meridional Heat Transport ◽

Low Latitude ◽

Climate Stability ◽

Vertical Heat ◽

The Face

In the face of the faint young sun-climate paradox, the plausible effects of dynamical heat-flux feedbacks on global stability were examined using a coupled high- and low-latitude radiative-dynamical model. The global stability is found to depend very strongly on the vertical heat transport, which is also closely coupled to the meridional heat transport. This coupling and the associated dynamical heat-flux feedbacks, treated within the framework of the radiative-dynamical model, was found to produce a fairly strong negative feedback. Our results indicate that the dynamical heat-flux feedbacks inherent in the climate system may potentially enhance the global stability.

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Oceanic Overturning and Heat Transport: The Role of Background Diffusivity

Journal of Climate ◽

10.1175/jcli-d-18-0438.1 ◽

2019 ◽

Vol 32 (3) ◽

pp. 701-716 ◽

Cited By ~ 4

Author(s):

Magnus Hieronymus ◽

Jonas Nycander ◽

Johan Nilsson ◽

Kristofer Döös ◽

Robert Hallberg

Keyword(s):

Heat Transport ◽

Large Scale ◽

Energy Transport ◽

Climate Model ◽

Potential Temperature ◽

Meridional Heat Transport ◽

Sea Ice Extent ◽

Antarctic Sea Ice ◽

Meridional Overturning

The role of oceanic background diapycnal diffusion for the equilibrium climate state is investigated in the global coupled climate model CM2G. Special emphasis is put on the oceanic meridional overturning and heat transport. Six runs with the model, differing only by their value of the background diffusivity, are run to steady state and the statistically steady integrations are compared. The diffusivity changes have large-scale impacts on many aspects of the climate system. Two examples are the volume-mean potential temperature, which increases by 3.6°C between the least and most diffusive runs, and the Antarctic sea ice extent, which decreases rapidly as the diffusivity increases. The overturning scaling with diffusivity is found to agree rather well with classical theoretical results for the upper but not for the lower cell. An alternative empirical scaling with the mixing energy is found to give good results for both cells. The oceanic meridional heat transport increases strongly with the diffusivity, an increase that can only partly be explained by increases in the meridional overturning. The increasing poleward oceanic heat transport is accompanied by a decrease in its atmospheric counterpart, which keeps the increase in the planetary energy transport small compared to that in the ocean.

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The role of serial European windstorm clustering for extreme seasonal losses as determined from multi-centennial simulations of high-resolution global climate model data

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-2991-2018 ◽

2018 ◽

Vol 18 (11) ◽

pp. 2991-3006 ◽

Cited By ~ 4

Author(s):

Matthew D. K. Priestley ◽

Helen F. Dacre ◽

Len C. Shaffrey ◽

Kevin I. Hodges ◽

Joaquim G. Pinto

Keyword(s):

High Resolution ◽

Return Period ◽

Large Scale ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Geographic Region ◽

Near Surface ◽

Short Period

Abstract. Extratropical cyclones are the most damaging natural hazard to affect western Europe. Serial clustering occurs when many intense cyclones affect one specific geographic region in a short period of time which can potentially lead to very large seasonal losses. Previous studies have shown that intense cyclones may be more likely to cluster than less intense cyclones. We revisit this topic using a high-resolution climate model with the aim to determine how important clustering is for windstorm-related losses. The role of windstorm clustering is investigated using a quantifiable metric (storm severity index, SSI) that is based on near-surface meteorological variables (10 m wind speed) and is a good proxy for losses. The SSI is used to convert a wind footprint into losses for individual windstorms or seasons. 918 years of a present-day ensemble of coupled climate model simulations from the High-Resolution Global Environment Model (HiGEM) are compared to ERA-Interim reanalysis. HiGEM is able to successfully reproduce the wintertime North Atlantic/European circulation, and represent the large-scale circulation associated with the serial clustering of European windstorms. We use two measures to identify any changes in the contribution of clustering to the seasonal windstorm loss as a function of return period. Above a return period of 3 years, the accumulated seasonal loss from HiGEM is up to 20 % larger than the accumulated seasonal loss from a set of random resamples of the HiGEM data. Seasonal losses are increased by 10 %–20 % relative to randomized seasonal losses at a return period of 200 years. The contribution of the single largest event in a season to the accumulated seasonal loss does not change with return period, generally ranging between 25 % and 50 %. Given the realistic dynamical representation of cyclone clustering in HiGEM, and comparable statistics to ERA-Interim, we conclude that our estimation of clustering and its dependence on the return period will be useful for informing the development of risk models for European windstorms, particularly for longer return periods.

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Role of Maritime Continent Land Convection on the Mean State and MJO Propagation

Journal of Climate ◽

10.1175/jcli-d-19-0342.1 ◽

2020 ◽

Vol 33 (5) ◽

pp. 1659-1675 ◽

Cited By ~ 2

Author(s):

Min-Seop Ahn ◽

Daehyun Kim ◽

Yoo-Geun Ham ◽

Sungsu Park

Keyword(s):

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Critical Role ◽

Moisture Gradient ◽

Moisture Distribution ◽

Boreal Winter ◽

Maritime Continent ◽

The Mean

AbstractThe Maritime Continent (MC) region is known as a “barrier” in the life cycle of the Madden–Julian oscillation (MJO). During boreal winter, the MJO detours the equatorial MC land region southward and propagates through the oceanic region. Also, about half of the MJO events that initiate over the Indian Ocean cease around the MC. The mechanism through which the MC affects MJO propagation, however, has remained unanswered. The current study investigates the MJO–MC interaction with a particular focus on the role of MC land convection. Using a global climate model that simulates both mean climate and MJO realistically, we performed two sensitivity experiments in which updraft plume radius is set to its maximum and minimum value only in the MC land grid points, making convective top deeper and shallower, respectively. Our results show that MC land convection plays a key role in shaping the 3D climatological moisture distribution around the MC through its local and nonlocal effects. Shallower and weaker MC land convection results in a steepening of the vertical and meridional mean moisture gradient over the MC region. The opposite is the case when MC land convection becomes deeper and stronger. The MJO’s eastward propagation is enhanced (suppressed) with the steeper (lower) mean moisture gradient. The moist static energy (MSE) budget of the MJO reveals the vertical and meridional advection of the mean MSE by MJO wind anomalies as the key processes that are responsible for the changes in MJO propagation characteristics. Our results pinpoint the critical role of the background moisture gradient on MJO propagation.

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Shutdown and recovery of the AMOC in a coupled global climate model: The role of the advective feedback

Geophysical Research Letters ◽

10.1002/grl.50289 ◽

2013 ◽

Vol 40 (6) ◽

pp. 1182-1188 ◽

Cited By ~ 25

Author(s):

L. C. Jackson

Keyword(s):

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Coupled Global Climate Model

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Coordinated Global and Regional Climate Modeling*

Journal of Climate ◽

10.1175/jcli-d-15-0161.1 ◽

2015 ◽

Vol 29 (1) ◽

pp. 17-35 ◽

Cited By ~ 102

Author(s):

J. F. Scinocca ◽

V. V. Kharin ◽

Y. Jiao ◽

M. W. Qian ◽

M. Lazare ◽

...

Keyword(s):

Regional Climate Model ◽

Climate Model ◽

Climate Modeling ◽

Global Climate ◽

Global Climate Model ◽

Regional Climate ◽

Value Added ◽

Regional Climate Modeling ◽

Climate Projections ◽

Climate Modelling

Abstract A new approach of coordinated global and regional climate modeling is presented. It is applied to the Canadian Centre for Climate Modelling and Analysis Regional Climate Model (CanRCM4) and its parent global climate model CanESM2. CanRCM4 was developed specifically to downscale climate predictions and climate projections made by its parent global model. The close association of a regional climate model (RCM) with a parent global climate model (GCM) offers novel avenues of model development and application that are not typically available to independent regional climate modeling centers. For example, when CanRCM4 is driven by its parent model, driving information for all of its prognostic variables is available (including aerosols and chemical species), significantly improving the quality of their simulation. Additionally, CanRCM4 can be driven by its parent model for all downscaling applications by employing a spectral nudging procedure in CanESM2 designed to constrain its evolution to follow any large-scale driving data. Coordination offers benefit to the development of physical parameterizations and provides an objective means to evaluate the scalability of such parameterizations across a range of spatial resolutions. Finally, coordinating regional and global modeling efforts helps to highlight the importance of assessing RCMs’ value added relative to their driving global models. As a first step in this direction, a framework for identifying appreciable differences in RCM versus GCM climate change results is proposed and applied to CanRCM4 and CanESM2.

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The Role of Large-Scale Feedbacks in Cumulus Convection Parameter Estimation

Journal of Climate ◽

10.1175/jcli-d-15-0117.1 ◽

2016 ◽

Vol 29 (11) ◽

pp. 4099-4119 ◽

Cited By ~ 3

Author(s):

Shan Li ◽

Shaoqing Zhang ◽

Zhengyu Liu ◽

Xiaosong Yang ◽

Anthony Rosati ◽

...

Keyword(s):

Parameter Estimation ◽

Large Scale ◽

Climate Model ◽

Global Climate ◽

Cumulus Convection ◽

State Variables ◽

Climate Drift ◽

Convection Parameterization ◽

Convection Parameter

Abstract Uncertainty in cumulus convection parameterization is one of the most important causes of model climate drift through interactions between large-scale background and local convection that use empirically set parameters. Without addressing the large-scale feedback, the calibrated parameter values within a convection scheme are usually not optimal for a climate model. This study first designs a multiple-column atmospheric model that includes large-scale feedbacks for cumulus convection and then explores the role of large-scale feedbacks in cumulus convection parameter estimation using an ensemble filter. The performance of convection parameter estimation with or without the presence of large-scale feedback is examined. It is found that including large-scale feedbacks in cumulus convection parameter estimation can significantly improve the estimation quality. This is because large-scale feedbacks help transform local convection uncertainties into global climate sensitivities, and including these feedbacks enhances the statistical representation of the relationship between parameters and state variables. The results of this study provide insights for further understanding of climate drift induced from imperfect cumulus convection parameterization, which may help improve climate modeling.

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Downscaling CESM2 in CLM5 to Hindcast Pre-Industrial Equilibrium Line Altitude for Tropical Mountains

10.5194/egusphere-egu21-584 ◽

2021 ◽

Author(s):

Nicholas Heavens

Keyword(s):

Climate Model ◽

Climate Modeling ◽

Global Climate ◽

Equilibrium Line ◽

Lapse Rate ◽

Surface Mass Balance ◽

Low Resolution ◽

Equilibrium Line Altitude ◽

Surface Mass ◽

Mountain Glaciation

Highland environments are rarely preserved in the geological record, particularly from as early as the Paleozoic Era. However, several stratigraphic locations are now known which definitely or potentially preserve such environments near the paleoequator during the Late Carboniferous and Early Permian Periods, during which the Earth was in the depths of an icehouse climate like that of the Pliocene and Pleistocene Epochs, the Late Paleozoic Ice Age (LPIA). Several of these locations contain evidence of mountain glaciation at altitudes below 2000 m, leading to questions about the significance of tropical mountain glaciation for global climate during this interval of geologic time. However, climate model simulations for the LPIA have not been able to simulate mountain glaciation like that inferred from the geological record, possibly because of low resolution, incorrect boundary conditions, or climate model bias resulting from incomplete representation of moist convective processes impacting tropical lapse rates.&#160;The overarching purpose of this study is to develop a climate modeling framework that enables the significance of mountain glaciation for global paleoclimate to be evaluated. Ideally, such a framework would allow low-resolution global model output to be downscaled to the scale of a mountain range to calculate the equilibrium line altitude and similar parameters, enabling evidence of mountain glaciation in the deep past to be used to constrain/tune the low-resolution global models. While this study was designed to inform a specific problem in deep time paleoclimate, its results are likely broadly applicable to assessing how well mountain glaciation is captured by global climate modeling of the past, present, and future. &#160;&#160;Here, I present a framework in which the CMIP6 pre-industrial control simulation for the Community Earth System Model version 2 (CESM2) at 0.9&#176;x1.25&#176; resolution is used to generate a data atmosphere for the Community Land Model version 5 (CLM5) run at 0.01&#176; resolution in 10 tropical and 1 mid-latitude domain to study the surface mass balance over the domain. For computational reasons, glaciation is assumed to cover a small portion of each grid cell, but surface mass balance still can be evaluated. Topographic boundary conditions come from GMTED2010, but most other information is directly interpolated from the CESM2 simulation. CLM5 simulations require a fixed lapse rate to be assumed, which is varied in each CLM5 simulation across six different values. The CLM5 simulation output along with the mean tropical lapse rate in the CESM2 simulation is then used to evaluate the various biases of this framework in comparison with estimated pre-industrial equilibrium line altitudes for the studied domains.This work is supported by the National Science Foundation (USA) under grant EAR-1849754.&#160;

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