Global warming pattern formation: the role of ocean heat uptake

2021 ◽  
pp. 1-46
Keyword(s):  
Pattern Formation ◽  
Coupled Model ◽  
Cooling Effect ◽  
Ocean Heat Uptake ◽  
Surface Warming ◽  
Warming Pattern ◽  
Ocean Atmosphere ◽  
Heat Uptake ◽  
Global Mean

Abstract This study investigates the formation mechanism of ocean surface warming pattern in response to a doubling CO2 with a focus on the role of ocean heat uptake (or ocean surface heat flux change, ΔQnet). We demonstrate that the transient patterns of surface warming and rainfall change simulated by the dynamic ocean-atmosphere coupled model (DOM) can be reproduced by the equilibrium solutions of the slab ocean-atmosphere coupled model (SOM) simulations when forced with the DOM ΔQnet distribution. The SOM is then used as a diagnostic, inverse modeling tool to decompose the CO2-induced thermodynamic warming effect and the ΔQnet (ocean heat uptake)-induced cooling effect. As ΔQnet is largely positive (i.e., downward into the ocean) in the subpolar oceans and weakly negative at the equator, its cooling effect is strongly polar amplified and opposes the CO2 warming, reducing the net warming response especially over Antarctica. For the same reason, the ΔQnet-induced cooling effect contributes significantly to the equatorially enhanced warming in all three ocean basins, while the CO2 warming effect plays a role in the equatorial warming of the eastern Pacific. The spatially varying component of ΔQnet, although globally averaged to zero, can effectively rectify and lead to decreased global mean surface temperature of a comparable magnitude as the global mean ΔQnet effect under transient climate change. Our study highlights the importance of air-sea interaction in the surface warming pattern formation and the key role of ocean heat uptake pattern.

scholarly journals Sensitivity of Global Warming to Carbon Emissions: Effects of Heat and Carbon Uptake in a Suite of Earth System Models

2017 ◽  
Vol 30 (23) ◽  
pp. 9343-9363 ◽  
Author(s):  
Richard G. Williams ◽  
Vassil Roussenov ◽  
Philip Goodwin ◽  
Laure Resplandy ◽  
Laurent Bopp
Keyword(s):  
Climate Sensitivity ◽  
Carbon Emissions ◽  
Radiative Forcing ◽  
Carbon Uptake ◽  
Earth System ◽  
Ocean Heat Uptake ◽  
Surface Warming ◽  
System Models ◽  
Heat Uptake ◽  
Earth System Models

Climate projections reveal global-mean surface warming increasing nearly linearly with cumulative carbon emissions. The sensitivity of surface warming to carbon emissions is interpreted in terms of a product of three terms: the dependence of surface warming on radiative forcing, the fractional radiative forcing from CO2, and the dependence of radiative forcing from CO2 on carbon emissions. Mechanistically each term varies, respectively, with climate sensitivity and ocean heat uptake, radiative forcing contributions, and ocean and terrestrial carbon uptake. The sensitivity of surface warming to fossil-fuel carbon emissions is examined using an ensemble of Earth system models, forced either by an annual increase in atmospheric CO2 or by RCPs until year 2100. The sensitivity of surface warming to carbon emissions is controlled by a temporal decrease in the dependence of radiative forcing from CO2 on carbon emissions, which is partly offset by a temporal increase in the dependence of surface warming on radiative forcing. The decrease in the dependence of radiative forcing from CO2 is due to a decline in the ratio of the global ocean carbon undersaturation to carbon emissions, while the increase in the dependence of surface warming is due to a decline in the ratio of ocean heat uptake to radiative forcing. At the present time, there are large intermodel differences in the sensitivity in surface warming to carbon emissions, which are mainly due to uncertainties in the climate sensitivity and ocean heat uptake. These uncertainties undermine the ability to predict how much carbon may be emitted before reaching a warming target.

scholarly journals Enhanced Mid-Latitude Meridional Heat Imbalance Induced by the Ocean

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 746 ◽  
Author(s):  
Hu Yang ◽  
Gerrit Lohmann ◽  
Xiaoxu Shi ◽  
Chao Li
Keyword(s):  
Global Warming ◽  
Atmospheric Circulation ◽  
Water Cycle ◽  
Strong Mixing ◽  
Jet Stream ◽  
Overturning Circulation ◽  
Ocean Heat Uptake ◽  
Climate Simulations ◽  
Heat Uptake

The heat imbalance is the fundamental driver for the atmospheric circulation. Therefore, it is crucially important to understand how it responds to global warming. In this study, the role of the ocean in reshaping the atmospheric meridional heat imbalance is explored based on observations and climate simulations. We found that ocean tends to strengthen the meridional heat imbalance over the mid-latitudes. This is primarily because of the uneven ocean heat uptake between the subtropical and subpolar oceans. Under global warming, the subtropical ocean absorbs relatively less heat as the water there is well stratified. In contrast, the subpolar ocean is the primary region where the ocean heat uptake takes place, because the subpolar ocean is dominated by upwelling, strong mixing, and overturning circulation. We propose that the enhanced meridional heat imbalance may potentially contribute to strengthening the water cycle, westerlies, jet stream, and mid-latitude storms.

Climate change in the tropical Atlantic

2020 ◽  
Author(s):  
Noel Keenlyside ◽  
Lander Crespo ◽  
Shunya Koseki ◽  
Lea Svendsen ◽  
Ingo Richter
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Coupled Model ◽  
Historical Period ◽  
Tropical Atlantic ◽  
Gulf Of Guinea ◽  
Coupled Models ◽  
Model Biases ◽  
Warming Pattern

<p>The tropical Atlantic SST have warmed by about 1 degree over the historical period, with greatest warming in the east, along the African coast and in the Gulf of Guinea. Experiments performed from the Coupled Model Intercomparison Projects (CMIP) indicate that models fail to reproduce this warming pattern, instead showing a rather uniform warming. Future projections with these models also tend to show rather uniform warming. In constrast. results from anomaly coupled models indicate that model biases impact the ability of climate models to simulate warming patterns in the tropical Atlantic. Here we investigate the role of model biases on climate change in the tropical Atlantic in the CMIP experiments. In addition, we have analyzed impacts of global warming on tropical Atlantic climate variability, and we assess the sensitive of the results are to model biases.</p>

scholarly journals The Deep-Ocean Heat Uptake in Transient Climate Change

2003 ◽  
Vol 16 (9) ◽  
pp. 1352-1363 ◽  
Author(s):  
Boyin Huang ◽  
Peter H. Stone ◽  
Andrei P. Sokolov ◽  
Igor V. Kamenkovich
Keyword(s):  
Heat Flux ◽  
Global Warming ◽  
Surface Heat Flux ◽  
Coupled Model ◽  
Deep Ocean ◽  
Surface Heat ◽  
Ocean Heat Uptake ◽  
Warming Scenario ◽  
Heat Uptake ◽  
Global Warming Scenario

Abstract The deep-ocean heat uptake (DOHU) in transient climate changes is studied using an ocean general circulation model (OGCM) and its adjoint. The model configuration consists of idealized Pacific and Atlantic basins. The model is forced with the anomalies of surface heat and freshwater fluxes from a global warming scenario with a coupled model using the same ocean configuration. In the global warming scenario, CO2 concentration increases 1% yr−1. The heat uptake calculated from the coupled model and from the adjoint are virtually identical, showing that the heat uptake by the OGCM is a linear process. After 70 yr the ocean heat uptake is almost evenly distributed within the layers above 200 m, between 200 and 700 m, and below 700 m (about 20 × 1022 J in each). The effect of anomalous surface freshwater flux on the DOHU is negligible. Analysis of the Coupled Model Intercomparison Project (CMIP-2) data for the same global warming scenario shows that qualitatively similar results apply to coupled atmosphere–ocean GCMs. The penetration of surface heat flux to the deep ocean in the OGCM occurs mainly in the North Atlantic and the Southern Ocean, since both the sensitivity of DOHU to the surface heat flux and the magnitude of anomalous surface heat flux are large in these two regions. The DOHU relies on the reduction of convection and Gent–McWilliams–Redi mixing in the North Atlantic, and the reduction of Gent–McWilliams–Redi mixing in the Southern Ocean.

Quantifying uncertainty in decadal ocean heat uptake due to intrinsic ocean variability

2020 ◽  
Author(s):  
Bablu Sinha ◽  
Alex Megann ◽  
Thierry Penduff ◽  
Jean-Marc Molines ◽  
Sybren Drijfhout
Keyword(s):  
North Pacific ◽  
Western Boundary ◽  
High Latitudes ◽  
Intrinsic Variability ◽  
Ocean Heat Uptake ◽  
Decadal Timescale ◽  
Surface Warming ◽  
Ocean Variability ◽  
Heat Uptake ◽  
Global Surface

<p>Remarkably, global surface warming since 1850 has not proceeded monotonically, but has consisted of a series of decadal timescale slowdowns (hiatus periods) followed by surges. Knowledge of a mechanism to explain these fluctuations would greatly aid development and testing of near term climate forecasts. Here we evaluate the influence of ocean intrinsic variability on global ocean heat uptake and hence the rate of global surface warming, using a 50-member ensemble of eddy-permitting ocean general circulation model simulations (OCCIPUT ensemble) forced with identical surface atmospheric condition for the period 1960-2015. Air-sea heat flux, integrated zonally and accumulated with latitude provides a useful measure of ocean heat uptake. We plot the ensemble mean difference of this quantity between 2000-2009 (hiatus) and 1990-1999 (surge). OCCIPUT suggests that the 2000s saw increased ocean heat uptake of ~0.32 W m<sup>-2</sup>compared to the 1990s and that the increased uptake was shared between the tropics and the high latitudes. OCCIPUT shows that intrinsic ocean variability modifies the mean ocean heat uptake change by up to 0.05 W m<sup>-2</sup>or ±15%. Moreover composite analysis of the ensemble members with the most extreme individual decadal heat uptake changes pinpoints the southern and northern high latitudes as the regions where intrinsic variability plays a large role: tropical heat uptake change is largely fixed by the surface forcing. The western boundary currents and the Antarctic Circumpolar Current (i.e. eddy rich regions) are responsible for the range of simulated ocean heat uptake, with the North Pacific exhibiting a particularly strong signal. The origin of this North Pacific signal is traced to decadal timescale latitudinal excursions of the Kuroshio western boundary current.</p>

scholarly journals Robust Seasonality of Arctic Warming Processes in Two Different Versions of the MIROC GCM

2014 ◽  
Vol 27 (16) ◽  
pp. 6358-6375 ◽  
Author(s):  
Masakazu Yoshimori ◽  
Ayako Abe-Ouchi ◽  
Masahiro Watanabe ◽  
Akira Oka ◽  
Tomoo Ogura
Keyword(s):  
Climate Models ◽  
Co2 Concentration ◽  
The Arctic ◽  
Ocean Heat Uptake ◽  
Arctic Warming ◽  
Surface Warming ◽  
Relative Contribution ◽  
Heat Uptake ◽  
Balance Analysis ◽  
The Difference

Abstract It is one of the most robust projected responses of climate models to the increase of atmospheric CO2 concentration that the Arctic experiences a rapid warming with a magnitude larger than the rest of the world. While many processes are proposed as important, the relative contribution of individual processes to the Arctic warming is not often investigated systematically. Feedbacks are quantified in two different versions of an atmosphere–ocean GCM under idealized transient experiments based on an energy balance analysis that extends from the surface to the top of the atmosphere. The emphasis is placed on the largest warming from late autumn to early winter (October–December) and the difference from other seasons. It is confirmed that dominating processes vary with season. In autumn, the largest contribution to the Arctic surface warming is made by a reduction of ocean heat storage and cloud radiative feedback. In the annual mean, on the other hand, it is the albedo feedback that contributes the most, with increasing ocean heat uptake to the deeper layers working as a negative feedback. While the qualitative results are robust between the two models, they differ quantitatively, indicating the need for further constraint on each process. Ocean heat uptake, lower tropospheric stability, and low-level cloud response probably require special attention.

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