Global warming in the pipeline

Oxford Open Climate Change, Journal Year: 2023, Volume and Issue: 3(1)

Published: Jan. 1, 2023

Abstract Improved knowledge of glacial-to-interglacial global temperature change yields Charney (fast-feedback) equilibrium climate sensitivity 1.2 ± 0.3°C (2σ) per W/m2, which is 4.8°C 1.2°C for doubled CO2. Consistent analysis over the full Cenozoic era—including ‘slow’ feedbacks by ice sheets and trace gases—supports this implies that CO2 was 300–350 ppm in Pliocene about 450 at transition to a nearly ice-free planet, exposing unrealistic lethargy sheet models. Equilibrium warming today’s GHG amount 10°C, reduced 8°C human-made aerosols. not ‘committed’ warming; rapid phaseout emissions would prevent most from occurring. However, decline aerosol since 2010 should increase 1970–2010 rate 0.18°C decade post-2010 least 0.27°C decade. Thus, under present geopolitical approach emissions, will exceed 1.5°C 2020s 2°C before 2050. Impacts on people nature accelerate as increases hydrologic (weather) extremes. The enormity consequences demands return Holocene-level temperature. Required actions include: (1) increasing price accompanied development abundant, affordable, dispatchable clean energy, (2) East-West cooperation way accommodates developing world needs, (3) intervention with Earth’s radiation imbalance phase down massive ‘geo-transformation’ climate. Current political crises an opportunity reset, especially if young can grasp their situation.

Language: Английский

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Assessing effective radiative forcing from aerosol–cloud interactions over the global ocean

Proceedings of the National Academy of Sciences, Journal Year: 2022, Volume and Issue: 119(46)

Published: Nov. 7, 2022

How clouds respond to anthropogenic sulfate aerosols is one of the largest sources uncertainty in radiative forcing climate over industrial era. This limits our ability predict equilibrium sensitivity (ECS)-the global warming following a doubling atmospheric CO2. Here, we use satellite observations quantify relationships between and low-level while carefully controlling for meteorology. We then combine with estimates change concentration since about 1850 constrain associated forcing. estimate that cloud-mediated from [Formula: see text] W m-2 ocean (95% confidence). constraint implies ECS likely 2.9 4.5 K (66% Our results indicate aerosol less uncertain probably larger than ranges proposed by recent assessments.

Language: Английский

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Observational Assessment of Changes in Earth’s Energy Imbalance Since 2000

Surveys in Geophysics, Journal Year: 2024, Volume and Issue: 45(6), P. 1757 - 1783

Published: May 7, 2024

Abstract Satellite observations from the Clouds and Earth’s Radiant Energy System show that energy imbalance has doubled 0.5 ± 0.2 Wm −2 during first 10 years of this century to 1.0 − 2 past decade. The increase is result a 0.9 0.3 absorbed solar radiation (ASR) partially offset by 0.4 0.25 in outgoing longwave (OLR). Despite marked differences ASR OLR trends hiatus (2000–2010), transition-to-El Niño (2010–2016) post-El (2016–2022) periods, net top-of-atmosphere flux (NET) remain within 0.1 per decade one another, implying steady acceleration climate warming. Northern southern hemisphere NET are consistent 0.06 0.31 due compensation between weak hemispheric trend opposite sign. We find large decreases stratocumulus middle clouds over sub-tropics low at mid-latitudes primary reasons for increasing northern (NH). These changes especially eastern Pacific Ocean, coincide with increases sea-surface temperature (SST). decrease cloud fraction higher SSTs NH lead significant cloud-free regions, which compensate increase. Decreases reflection weaker reduction low-cloud account hemisphere, while weak. Changes cover response SST imply feedback change yet contribution radiative forcing or internal variability cannot be ruled out.

Language: Английский

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The Role of Mesoscale Cloud Morphology in the Shortwave Cloud Feedback

Geophysical Research Letters, Journal Year: 2023, Volume and Issue: 50(2)

Published: Jan. 18, 2023

Abstract A supervised neural network algorithm is used to categorize near‐global satellite retrievals into three mesoscale cellular convective (MCC) cloud morphology patterns. At constant amount, patterns differ in brightness associated with the amount of optically thin features. Environmentally driven transitions from closed MCC other patterns, typically accompanied by more features, are as a framework quantify contribution optical depth component shortwave feedback. marine heat wave an out‐of‐sample test occurrence predictions. Morphology shifts between 65°S and 65°N under projected environmental changes (i.e., abrupt quadrupling CO 2 ) assuming cover contributes 0.04 0.07 W m −2 K −1 (aggregate 0.06) global mean

Language: Английский

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Distinct regional meteorological influences on low-cloud albedo susceptibility over global marine stratocumulus regions

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(2), P. 1073 - 1090

Published: Jan. 20, 2023

Abstract. Marine stratocumuli cool the Earth effectively due to their high reflectance of incoming solar radiation and persistent occurrence. The susceptibility cloud albedo droplet number concentration perturbations depends strongly on large-scale meteorological conditions. Studies focused dependence adjustments often overlook covariability among factors geographical temporal variability. We use 8 years satellite observations sorted by day location show global distribution marine low-cloud susceptibility. find an overall brightening potential for most warm clouds, which is more pronounced over subtropical coastal regions. A weak darkening in annual mean evident remote SE Pacific Atlantic. that fields from ERA5 reanalysis data, including lower-tropospheric stability, free-tropospheric relative humidity, sea surface temperature, boundary layer depth, have distinct covariabilities each eastern ocean basins where prevail. This leads a markedly different cycle basin. Moreover, we basin-specific regional relationships between key susceptibilities are absent analysis. Our results stress importance considering distinctiveness when scaling up local-to-global response aerosol perturbations.

Language: Английский

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Radiative forcing from aerosol–cloud interactions enhanced by large-scale circulation adjustments

Nature Geoscience, Journal Year: 2023, Volume and Issue: 16(12), P. 1092 - 1098

Published: Nov. 20, 2023

Abstract The impact of anthropogenic aerosols on clouds is a leading source uncertainty in estimating the effect human activity climate system. challenge lies scale difference between (~1–10 km) and general circulation (>1,000 km). To address this, we use convection-permitting simulations conducted long narrow domain, to resolve convection while also including representation large-scale processes. We examine set that include sea surface temperature gradient—which drives circulation—and compare these with no gradient. show effective radiative forcing due aerosol–cloud interactions strongly enhanced by adjustments aerosol. find an increase aerosol concentration suppresses precipitation shallow-convective regions, which enhances water vapour transport portion domain dominated deep convection. subsequent latent heat release deep-convective regions strengthens overturning evaporation. These changes can explain cloudiness under higher concentrations and, consequently, large effect. This work highlights fundamental importance understanding from interactions.

Language: Английский

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Global observations of aerosol indirect effects from marine liquid clouds

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(20), P. 13125 - 13141

Published: Oct. 18, 2023

Abstract. Interactions between aerosols and liquid clouds are one of the largest sources uncertainty in historical radiative forcing climate. One widely shared goal to reduce this is decompose anomalies arising from aerosol–cloud interactions into components associated with changes cloud-droplet number concentration (Twomey effect), liquid-water-path adjustments, cloud-fraction adjustments. However, there has not been a quantitative foundation for simultaneously estimating these global satellite observations. Here we present method assessing shortwave flux Twomey effect cloud adjustments over ocean 55∘ S N. We find that larger aerosol concentrations widespread brightening effect, positive adjustment decreasing water path subtropical stratocumulus regions, negative increasing fraction subtropics midlatitudes. The total have contributed −0.77 ± 0.25 −1.02 0.43 W m−2, respectively, effective since 1850 domain (95 % confidence). Our findings suggest make contribution than commonly believed.

Language: Английский

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Wet deposition in shallow convection over the Southern Ocean

npj Climate and Atmospheric Science, Journal Year: 2024, Volume and Issue: 7(1)

Published: March 22, 2024

Abstract Southern Ocean (SO) air is amongst the most pristine on Earth, particularly during winter. Historically, there has been a focus biogenic sources as an explanation for seasonal cycle in cloud condensation nuclei concentrations ( N CCN ). also sensitive to strength of sink terms, although magnitude this term varies considerably. Wet deposition, process encompassing coalescence scavenging (drizzle formation), one such that may be especially relevant over SO. Using boundary layer climatology, and precipitation observations from Kennaook/Cape Grim Observatory (CGO), we find statistically significant difference between when upwind meteorology dominated by open mesoscale cellular convection (MCC) closed MCC. When MCC dominant, lower median (69 cm −3 ) found compared (89 dominant. Open precipitate more heavily (1.72 mm day −1 frequently (16.7% time) than (0.29 , 4.5%). These relationships are observed hold across with maximum minimum Austral summer (DJF). Furthermore, morphology strongly depends meteorological conditions. The relationship can further examined diurnal season. Although was again negative out phase cycle, leading it ~3 hours, suggesting other factors, specifically play primary role influencing precipitation.

Language: Английский

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A new method for diagnosing effective radiative forcing from aerosol–cloud interactions in climate models

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(4), P. 2123 - 2146

Published: Feb. 19, 2025

Abstract. Aerosol–cloud interactions (ACIs) are a leading source of uncertainty in estimates the historical effective radiative forcing (ERF). One reason for this is difficulty estimating ERF from aerosol–cloud (ERFaci) climate models, which typically requires multiple calls to radiation code. Most commonly used methods also cannot disentangle contributions different processes ERFaci. Here, we develop new, computationally efficient method shortwave (SW) ERFaci liquid clouds using histograms monthly averaged cloud fraction partitioned by droplet radius (re) and water path (LWP). Multiplying with SW kernels gives total clouds, can be decomposed into Twomey effect, LWP adjustments, (CF) adjustments. We test data five CMIP6-era Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument simulator generate histograms. Our similar other established regions prevalent indicates that CF adjustments have contributed −0.34 ± 0.23, −0.22 0.13, −0.09 0.11 W m−2, respectively, since 1850 ensemble mean (95 % confidence). These results demonstrate widespread adoption MODIS re–LWP joint histogram diagnostic would allow its components quickly accurately diagnosed model outputs, crucial step reducing ERF.

Language: Английский

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Surface temperature effects of recent reductions in shipping SO₂ emissions are within internal variability

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(8), P. 4443 - 4454

Published: April 23, 2025

Abstract. In 2020, the International Maritime Organization (IMO) implemented strict new regulations on emissions of sulfate aerosol from world's shipping fleet. This can be expected to lead a reduction in aerosol-driven cooling, unmasking portion greenhouse gas warming. The magnitude effect is uncertain, however, due large remaining uncertainties climate response aerosols. Here, we investigate this question using an 18-member ensemble fully coupled simulations evenly sampling key modes variability with NCAR model, Community Earth System Model version 2 (CESM2). We show that, while there clear physical system IMO regulations, including surface temperature increase, do not find global mean influence that significantly different zero. 20-year average warming for 2020–2040 +0.03 °C, 5 %–95 % confidence range [-0.09,0.19], reflecting weakness perturbation relative internal variability. do, robust, non-zero regional part North Atlantic. also maximum annual and occurs around 1 decade after 2029, which means have likely had very limited observed date. further discuss our results light other, recent publications reached conclusions. Overall, may contribute up 0.16 °C [-0.17,0.52] individual years during decade, consistent some early studies, such unlikely been discernible above by end 2023 fact zero throughout period.

Language: Английский

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