Aerosol-cloud-climate cooling overestimated by ship-track data

Science, Journal Year: 2021, Volume and Issue: 371(6528), P. 485 - 489

Published: Jan. 28, 2021

Making tracks The magnitude of the effect anthropogenic aerosols on formation clouds is an important unknown about how humans are affecting climate. Studies stratocumulus cloud that formed by ship exhaust have been used to estimate radiative impact this process, but Glassmeier et al. now show approach overestimates cooling aerosol addition up 200%. These findings underscore need quantify responses understand climate system. Science , issue p. 485

Language: Английский

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Aerosol‐Forced AMOC Changes in CMIP6 Historical Simulations

Geophysical Research Letters, Journal Year: 2020, Volume and Issue: 47(14)

Published: July 9, 2020

Abstract The Atlantic Meridional Overturning Circulation (AMOC) has been, and will continue to be, a key factor in the modulation of climate change both locally globally. However, there remains considerable uncertainty recent AMOC evolution. Here, we show that multimodel mean strengthened by approximately 10% from 1850–1985 new simulations 6th Coupled Model Intercomparison Project (CMIP6), larger than was seen CMIP5. Across models, strength trend up 1985 is related proxy for aerosol forcing. Therefore, difference result stronger anthropogenic forcing on average CMIP6 CMIP5, which primarily due more models including aerosol‐cloud interactions. observational constraints—including historical sea surface temperature fingerprint shortwave radiative decades—suggest and/or response may be overestimated.

Language: Английский

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Simulated Tropical Precipitation Assessed across Three Major Phases of the Coupled Model Intercomparison Project (CMIP)

Monthly Weather Review, Journal Year: 2020, Volume and Issue: 148(9), P. 3653 - 3680

Published: Aug. 18, 2020

Abstract The representation of tropical precipitation is evaluated across three generations models participating in phases 3, 5, and 6 the Coupled Model Intercomparison Project (CMIP). Compared to state-of-the-art observations, improvements CMIP6 are identified for some metrics, but we find no general improvement on different temporal spatial scales. Our results indicate overall little changes CMIP summer monsoons, double-ITCZ bias, diurnal cycle precipitation. We a reduced amount drizzle events CMIP6, occurs still too frequently. Continuous number consecutive dry days, modes variability, namely, Madden–Julian oscillation El Niño–Southern Oscillation, trends months twentieth century. observed positive trend extreme wet is, however, not captured by any phases, which simulate negative extremely regional biases larger than climate change signal one hopes use identify. Given pace as compared model precipitation, question past strategy development present class global mainstay scientific response change. suggest exploration alternative approaches such high-resolution storm-resolving that can offer better prospects inform us about how might with anthropogenic warming.

Language: Английский

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Decadal climate variability in the tropical Pacific: Characteristics, causes, predictability, and prospects

Science, Journal Year: 2021, Volume and Issue: 374(6563)

Published: Sept. 30, 2021

Climate variability in the tropical Pacific affects global climate on a wide range of time scales. On interannual scales, is home to El Niño–Southern Oscillation (ENSO). Decadal variations and changes Pacific, referred here collectively as decadal (TPDV), also profoundly affect system. Here, we use TPDV refer any form or change that occurs atmosphere, ocean, over land within Pacific. “Decadal,” which broad sense encompass multiyear through multidecadal includes about mean state externally forced mean-state unfold behavior higher-frequency modes like ENSO.

Language: Английский

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The hemispheric contrast in cloud microphysical properties constrains aerosol forcing

Proceedings of the National Academy of Sciences, Journal Year: 2020, Volume and Issue: 117(32), P. 18998 - 19006

Published: July 27, 2020

Significance Enhancement of aerosol that can nucleate cloud droplets increases the droplet number concentration and albedo clouds. This amount sunlight reflected to space. Uncertainty in how aerosol−cloud interactions over industrial period have increased planetary by this mechanism leads significant uncertainty climate projections. Our work presents a method for observationally constraining change due anthropogenic emissions: hemispheric difference remotely sensed between pristine Southern Ocean (a preindustrial proxy) polluted Northern Hemisphere. Application constraint models reduces range estimated since industrialization suggests current underpredict era.

Language: Английский

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Isolating the Evolving Contributions of Anthropogenic Aerosols and Greenhouse Gases: A New CESM1 Large Ensemble Community Resource

Journal of Climate, Journal Year: 2020, Volume and Issue: 33(18), P. 7835 - 7858

Published: Aug. 12, 2020

Abstract The evolving roles of anthropogenic aerosols (AER) and greenhouse gases (GHG) in driving large-scale patterns precipitation SST trends during 1920–2080 are studied using a new set “all-but-one-forcing” initial-condition large ensembles (LEs) with the Community Earth System Model version 1 (CESM1), which complement original “all-forcing” CESM1 LE (ALL). number ensemble members (15–20) each LEs enables regional impacts AER GHG to be isolated from noise model’s internal variability. Our analysis approach, based on running 50-yr trends, accommodates geographical temporal changes forcing response. shown primary driver externally forced ALL before late 1970s, dominate thereafter. spatially distinct except 1970s transition phase when aerosol mainly confined lower latitudes. is also characterized by relative minimum amplitude trend ALL, due combination reduced partially offsetting effects GHG. Internal variability greatly limits detectability AER- GHG-forced individual realizations pattern correlation metrics, especially historical period, highlighting need for LEs. We estimate that <20% spatial variances observed attributable forcing, although model biases response signal-to-noise may affect this estimate.

Language: Английский

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Effective radiative forcing from emissions of reactive gases and aerosols – a multi-model comparison

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(2), P. 853 - 874

Published: Jan. 21, 2021

Abstract. This paper quantifies the pre-industrial (1850) to present-day (2014) effective radiative forcing (ERF) of anthropogenic emissions NOX, volatile organic compounds (VOCs; including CO), SO2, NH3, black carbon, and concentrations methane, N2O ozone-depleting halocarbons, using CMIP6 models. Concentration emission changes reactive species can cause multiple in composition radiatively active species: tropospheric ozone, stratospheric water vapour, secondary inorganic aerosol, methane. Where possible we break down ERFs from each emitted into contributions changes. The are calculated for models that participated AerChemMIP experiments as part project, where relevant model output was available. 1850 2014 multi-model mean (± standard deviations) −1.03 ± 0.37 W m−2 SO2 emissions, −0.25 0.09 carbon (OC), 0.15 0.17 (BC) −0.07 0.01 NH3. For combined aerosols (in piClim-aer experiment) it is −1.01 0.25 m−2. means well-mixed greenhouse gases (including any effects on ozone aerosol chemistry) 0.67 methane (CH4), 0.26 0.07 nitrous oxide (N2O) 0.12 0.2 halocarbons (HC). Emissions precursors nitrogen oxides (NOx), both together (O3) lead 0.14 0.13, 0.20 respectively. differences different reflect complexity their chemistry schemes, especially case captures increased production.

Language: Английский

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An integrated approach to quantifying uncertainties in the remaining carbon budget

Communications Earth & Environment, Journal Year: 2021, Volume and Issue: 2(1)

Published: Jan. 18, 2021

Abstract The remaining carbon budget quantifies the future CO 2 emissions to limit global warming below a desired level. Carbon budgets are subject uncertainty in Transient Climate Response Cumulative Emissions (TCRE), as well non-CO climate influences. Here we estimate TCRE using observational constraints, and integrate geophysical socioeconomic uncertainties affecting distribution of budget. We median 0.44 °C 5–95% range 0.32–0.62 per 1000 GtCO emitted. Considering only uncertainties, our 1.5 is 440 from 2020 onwards, with 230–670 , (for 67–33% chance not exceeding target). Additional related human decisions regarding scenarios can further shift by ±170 .

Language: Английский

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Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA)

Bulletin of the American Meteorological Society, Journal Year: 2021, Volume and Issue: 103(2), P. E619 - E641

Published: July 20, 2021

Abstract With their extensive coverage, marine low clouds greatly impact global climate. Presently, are poorly represented in climate models, and the response of to changes atmospheric greenhouse gases aerosols remains major source uncertainty simulations. The eastern North Atlantic (ENA) is a region persistent but diverse subtropical boundary layer clouds, whose albedo precipitation highly susceptible perturbations aerosol properties. In addition, ENA periodically impacted by continental aerosols, making it an excellent location study cloud condensation nuclei (CCN) budget remote perturbed anthropogenic emissions, investigate impacts long-range transport on clouds. Aerosol Cloud Experiments Eastern (ACE-ENA) campaign was motivated need comprehensive situ measurements for improving understanding CCN budget, drizzle microphysics, precipitation. airborne deployments took place from 21 June 20 July 2017 15 January 18 February 2018 Azores. flights were designed maximize synergy between ongoing long-term observations at ground site. Here we present measurements, observation strategy, meteorological conditions during campaign, preliminary findings. Finally, discuss future analyses modeling studies that improve representation precipitation, interactions among them.

Language: Английский

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Observational Evidence of Increasing Global Radiative Forcing

Geophysical Research Letters, Journal Year: 2021, Volume and Issue: 48(7)

Published: March 25, 2021

Abstract Changes in atmospheric composition, such as increasing greenhouse gases, cause an initial radiative imbalance to the climate system, quantified instantaneous forcing. This fundamental metric has not been directly observed globally and previous estimates have come from models. In part, this is because current space‐based instruments cannot distinguish forcing climate’s response. We apply kernels satellite observations disentangle these components find all‐sky increased 0.53 ± 0.11 W/m 2 2003 2018, accounting for positive trends total planetary imbalance. increase due a combination of rising concentrations well‐mixed gases recent reductions aerosol emissions. These results highlight distinct fingerprints anthropogenic activity Earth’s changing energy budget, which we can detect within 4 years.

Language: Английский

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