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Diamond MS, Gristey JJ, Kay JE, Feingold G. Anthropogenic aerosol and cryosphere changes drive Earth's strong but transient clear-sky hemispheric albedo asymmetry. COMMUNICATIONS EARTH & ENVIRONMENT 2022; 3:206. [PMID: 36118252 PMCID: PMC9466336 DOI: 10.1038/s43247-022-00546-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
A striking feature of the Earth system is that the Northern and Southern Hemispheres reflect identical amounts of sunlight. This hemispheric albedo symmetry comprises two asymmetries: The Northern Hemisphere is more reflective in clear skies, whereas the Southern Hemisphere is cloudier. Here we show that the hemispheric reflection contrast from differences in continental coverage is offset by greater reflection from the Antarctic than the Arctic, allowing the net clear-sky asymmetry to be dominated by aerosol. Climate model simulations suggest that historical anthropogenic aerosol emissions drove a large increase in the clear-sky asymmetry that would reverse in future low-emission scenarios. High-emission scenarios also show decreasing asymmetry, instead driven by declines in Northern Hemisphere ice and snow cover. Strong clear-sky hemispheric albedo asymmetry is therefore a transient feature of Earth's climate. If all-sky symmetry is maintained, compensating cloud changes would have uncertain but important implications for Earth's energy balance and hydrological cycle.
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Affiliation(s)
- Michael S. Diamond
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305 USA
| | - Jake J. Gristey
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305 USA
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 USA
| | - Jennifer E. Kay
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 USA
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Raghuraman SP, Paynter D, Ramaswamy V. Anthropogenic forcing and response yield observed positive trend in Earth's energy imbalance. Nat Commun 2021; 12:4577. [PMID: 34321469 PMCID: PMC8319337 DOI: 10.1038/s41467-021-24544-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 06/16/2021] [Indexed: 11/09/2022] Open
Abstract
The observed trend in Earth's energy imbalance (TEEI), a measure of the acceleration of heat uptake by the planet, is a fundamental indicator of perturbations to climate. Satellite observations (2001-2020) reveal a significant positive globally-averaged TEEI of 0.38 ± 0.24 Wm-2decade-1, but the contributing drivers have yet to be understood. Using climate model simulations, we show that it is exceptionally unlikely (<1% probability) that this trend can be explained by internal variability. Instead, TEEI is achieved only upon accounting for the increase in anthropogenic radiative forcing and the associated climate response. TEEI is driven by a large decrease in reflected solar radiation and a small increase in emitted infrared radiation. This is because recent changes in forcing and feedbacks are additive in the solar spectrum, while being nearly offset by each other in the infrared. We conclude that the satellite record provides clear evidence of a human-influenced climate system.
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Affiliation(s)
| | - David Paynter
- NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA
| | - V Ramaswamy
- Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA
- NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA
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3
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Gebbie G. Combining Modern and Paleoceanographic Perspectives on Ocean Heat Uptake. ANNUAL REVIEW OF MARINE SCIENCE 2021; 13:255-281. [PMID: 32928022 DOI: 10.1146/annurev-marine-010419-010844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Monitoring Earth's energy imbalance requires monitoring changes in the heat content of the ocean. Recent observational estimates indicate that ocean heat uptake is accelerating in the twenty-first century. Examination of estimates of ocean heat uptake over the industrial era, the Common Era of the last 2,000 years, and the period since the Last Glacial Maximum, 20,000 years ago, permits a wide perspective on modern-day warming rates. In addition, this longer-term focus illustrates how the dynamics of the deep ocean and the cryosphere were active in the past and are still active today. The large climatic shifts that started with the melting of the great ice sheets have involved significant ocean heat uptake that was sustained over centuries and millennia, and modern-ocean heat content changes are small by comparison.
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Affiliation(s)
- Geoffrey Gebbie
- Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA;
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Sherwood SC, Webb MJ, Annan JD, Armour KC, Forster PM, Hargreaves JC, Hegerl G, Klein SA, Marvel KD, Rohling EJ, Watanabe M, Andrews T, Braconnot P, Bretherton CS, Foster GL, Hausfather Z, von der Heydt AS, Knutti R, Mauritsen T, Norris JR, Proistosescu C, Rugenstein M, Schmidt GA, Tokarska KB, Zelinka MD. An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence. REVIEWS OF GEOPHYSICS (WASHINGTON, D.C. : 1985) 2020; 58:e2019RG000678. [PMID: 33015673 PMCID: PMC7524012 DOI: 10.1029/2019rg000678] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 04/22/2020] [Accepted: 06/24/2020] [Indexed: 05/10/2023]
Abstract
We assess evidence relevant to Earth's equilibrium climate sensitivity per doubling of atmospheric CO2, characterized by an effective sensitivity S. This evidence includes feedback process understanding, the historical climate record, and the paleoclimate record. An S value lower than 2 K is difficult to reconcile with any of the three lines of evidence. The amount of cooling during the Last Glacial Maximum provides strong evidence against values of S greater than 4.5 K. Other lines of evidence in combination also show that this is relatively unlikely. We use a Bayesian approach to produce a probability density function (PDF) for S given all the evidence, including tests of robustness to difficult-to-quantify uncertainties and different priors. The 66% range is 2.6-3.9 K for our Baseline calculation and remains within 2.3-4.5 K under the robustness tests; corresponding 5-95% ranges are 2.3-4.7 K, bounded by 2.0-5.7 K (although such high-confidence ranges should be regarded more cautiously). This indicates a stronger constraint on S than reported in past assessments, by lifting the low end of the range. This narrowing occurs because the three lines of evidence agree and are judged to be largely independent and because of greater confidence in understanding feedback processes and in combining evidence. We identify promising avenues for further narrowing the range in S, in particular using comprehensive models and process understanding to address limitations in the traditional forcing-feedback paradigm for interpreting past changes.
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Affiliation(s)
- S C Sherwood
- Climate Change Research Centre and ARC Centre of Excellence for Climate Extremes University of New South Wales Sydney Sydney New South Wales Australia
| | - M J Webb
- Met Office Hadley Centre Exeter UK
| | | | | | - P M Forster
- Priestley International Centre for Climate University of Leeds Leeds UK
| | | | - G Hegerl
- School of Geosciences University of Edinburgh Edinburgh UK
| | | | - K D Marvel
- Department of Applied Physics and Applied Math Columbia University New York NY USA
- NASA Goddard Institute for Space Studies New York NY USA
| | - E J Rohling
- Research School of Earth Sciences Australian National University Canberra ACT Australia
- Ocean and Earth Science, National Oceanography Centre University of Southampton Southampton UK
| | - M Watanabe
- Atmosphere and Ocean Research Institute The University of Tokyo Tokyo Japan
| | | | - P Braconnot
- Laboratoire des Sciences du Climat et de l'Environnement, unité mixte CEA-CNRS-UVSQ Université Paris-Saclay Gif sur Yvette France
| | | | - G L Foster
- Ocean and Earth Science, National Oceanography Centre University of Southampton Southampton UK
| | | | - A S von der Heydt
- Institute for Marine and Atmospheric Research, and Centre for Complex Systems Science Utrecht University Utrecht The Netherlands
| | - R Knutti
- Institute for Atmospheric and Climate Science Zurich Switzerland
| | - T Mauritsen
- Department of Meteorology Stockholm University Stockholm Sweden
| | - J R Norris
- Scripps Institution of Oceanography La Jolla CA USA
| | - C Proistosescu
- Department of Atmospheric Sciences and Department of Geology University of Illinois at Urbana-Champaign Urbana IL USA
| | - M Rugenstein
- Max Planck Institute for Meteorology Hamburg Germany
| | - G A Schmidt
- NASA Goddard Institute for Space Studies New York NY USA
| | - K B Tokarska
- School of Geosciences University of Edinburgh Edinburgh UK
- Institute for Atmospheric and Climate Science Zurich Switzerland
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Thorsen TJ, Kato S, Loeb NG, Rose FG. Observation-Based Decomposition of Radiative Perturbations and Radiative Kernels. JOURNAL OF CLIMATE 2018; 31:10039-10058. [PMID: 35095187 PMCID: PMC8793621 DOI: 10.1175/jcli-d-18-0045.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The Clouds and the Earth's Radiant Energy System (CERES)-partial radiative perturbation [PRP (CERES-PRP)] methodology applies partial-radiative-perturbation-like calculations to observational datasets to directly isolate the individual cloud, atmospheric, and surface property contributions to the variability of the radiation budget. The results of these calculations can further be used to construct radiative kernels. A suite of monthly mean observation-based inputs are used for the radiative transfer, including cloud properties from either the diurnally resolved passive-sensor-based CERES synoptic (SYN) data or the combination of the CloudSat cloud radar and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar. The CloudSat/CALIPSO cloud profiles are incorporated via a clustering method that obtains monthly mean cloud properties suitable for accurate radiative transfer calculations. The computed fluxes are validated using the TOA fluxes observed by CERES. Applications of the CERES-PRP methodology are demonstrated by computing the individual contributions to the variability of the radiation budget over multiple years and by deriving water vapor radiative kernels. The calculations for the former are used to show that an approximately linear decomposition of the total flux anomalies is achieved. The observation-based water vapor kernels were used to investigate the accuracy of the GCM-based NCAR CAM3.0 water vapor kernel. Differences between our observation-based kernel and the NCAR one are marginally larger than those inferred by previous comparisons among different GCM kernels.
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Affiliation(s)
| | - Seiji Kato
- NASA Langley Research Center, Hampton, Virginia
| | | | - Fred G Rose
- Science System and Applications, Inc., Hampton, Virginia
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Decadal Ocean Heat Redistribution Since the Late 1990s and Its Association with Key Climate Modes. CLIMATE 2018. [DOI: 10.3390/cli6040091] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ocean heat content (OHC) is the major component of the earth’s energy imbalance. Its decadal scale variability has been heavily debated in the research interest of the so-called “surface warming slowdown” (SWS) that occurred during the 1998–2013 period. Here, we first clarify that OHC has accelerated since the late 1990s. This finding refutes the concept of a slowdown of the human-induced global warming. This study also addresses the question of how heat is redistributed within the global ocean and provides some explanation of the underlying physical phenomena. Previous efforts to answer this question end with contradictory conclusions; we show that the systematic errors in some OHC datasets are partly responsible for these contradictions. Using an improved OHC product, the three-dimensional OHC changes during the SWS period are depicted, related to a reference period of 1982–1997. Several “hot spots” and “cold spots” are identified, showing a significant decadal-scale redistribution of ocean heat, which is distinct from the long-term ocean-warming pattern. To provide clues for the potential drivers of the OHC changes during the SWS period, we examine the OHC changes related to the key climate modes by regressing the Pacific Decadal Oscillation (PDO), El Niño-Southern Oscillation (ENSO), and Atlantic Multi-decadal Oscillation (AMO) indices onto the de-trended gridded OHC anomalies. We find that no single mode can fully explain the OHC change patterns during the SWS period, suggesting that there is not a single “pacemaker” for the recent SWS. Our observation-based analyses provide a basis for further understanding the mechanisms of the decadal ocean heat uptake and evaluating the climate models.
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The Hiatus in Global Warming and Interactions between the El Niño and the Pacific Decadal Oscillation: Comparing Observations and Modeling Results. CLIMATE 2018. [DOI: 10.3390/cli6030072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ocean oscillations interact across large regions and these interactions may explain cycles in global temperature anomaly, including hiatus periods. Here, we examine ocean interaction measures and compare results from model simulations to observations for El Niño and the Pacific decadal oscillation (PDO). We use the global climate model of the Met Office Hadley Centre. A relatively novel method for identifying running leading-agging LL-relations show that the observed El Niño generally leads the observed PDO and this pattern is strengthened in the simulations. However, LL-pattern in both observations and models shows that there are three periods, around 1910–1920, around 1960 and around 2000 where El Niño lags PDO, or the leading signature is weak. These periods correspond to hiatus periods in global warming. The power spectral density analysis, (PSD), identifies various ocean cycle lengths in El Niño and PDO, but the LL-algorithm picks out common cycles of 7–8 and 24 years that shows leading-lagging relations between them.
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