GISS‐E2.1: Configurations and Climatology

Journal of Advances in Modeling Earth Systems, Journal Year: 2020, Volume and Issue: 12(8)

Published: July 10, 2020

This paper describes the GISS-E2.1 contribution to Coupled Model Intercomparison Project, Phase 6 (CMIP6). model version differs from predecessor (GISS-E2) chiefly due parameterization improvements atmospheric and ocean components, while keeping resolution same. skill when compared modern era climatologies is significantly higher than in previous versions. Additionally, updates forcings have a material impact on results. In particular, there been specific representations of modes variability (such as Madden-Julian Oscillation other Pacific) significant simulation climate Southern Oceans, including sea ice. The effective sensitivity 2 × CO2 slightly previously at 2.7-3.1°C (depending version) result lower radiative forcing stronger positive feedbacks.

Language: Английский

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Climate model projections from the Scenario Model Intercomparison Project (ScenarioMIP) of CMIP6

Earth System Dynamics, Journal Year: 2021, Volume and Issue: 12(1), P. 253 - 293

Published: March 1, 2021

Abstract. The Scenario Model Intercomparison Project (ScenarioMIP) defines and coordinates the main set of future climate projections, based on concentration-driven simulations, within Coupled phase 6 (CMIP6). This paper presents a range its outcomes by synthesizing results from participating global coupled Earth system models. We limit our scope to analysis strictly geophysical outcomes: mainly averages spatial patterns change for surface air temperature precipitation. also compare CMIP6 projections CMIP5 results, especially those scenarios that were designed provide continuity across CMIP phases, at same time highlighting important differences in forcing composition, as well results. precipitation changes end century (2081–2100) encompassing Tier 1 experiments Shared Socioeconomic Pathway (SSP) (SSP1-2.6, SSP2-4.5, SSP3-7.0 SSP5-8.5) SSP1-1.9 spans larger compared CMIP5, due higher warming (by close 1.5 ∘C) reached upper 5 %–95 % envelope highest scenario (SSP5-8.5). is both wider radiative new cover sensitivities some models their predecessors. Spatial averaged over have familiar features, an variations confirms model structural be dominant source uncertainty. Models differ with respect size evolution internal variability measured individual models' initial condition ensemble spreads, according simulations available under SSP3-7.0. These suggest tendency decrease along course this scenario, result will benefit further Benefits mitigation, all else being equal terms societal drivers, appear clearly when comparing developed SSP but which different degrees mitigation been applied. It found mild overshoot few decades around mid-century, represented SSP5-3.4OS, does not affect outcome 2100, return levels gradually increasing SSP4-3.4 (not erasing possibility, however, other aspects may easily reversible). Central estimates means reach given level might biased inclusion shown faster historical period than observed. Those show reaching ∘C 1850–1900 baseline second half current decade, span between slow fast covering 20 27 years present. 2 early 2039 mean SSP5-8.5 late mid-2060s SSP1-2.6. considered (5 only until mid-2090s.

Language: Английский

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Effective radiative forcing and adjustments in CMIP6 models

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(16), P. 9591 - 9618

Published: Aug. 17, 2020

Abstract. The effective radiative forcing, which includes the instantaneous forcing plus adjustments from atmosphere and surface, has emerged as key metric of evaluating human natural influence on climate. We evaluate in 17 contemporary climate models that are participating Coupled Model Intercomparison Project (CMIP6) have contributed to Radiative Forcing (RFMIP). Present-day (2014) global-mean anthropogenic relative pre-industrial (1850) levels stands at 2.00 (±0.23) W m−2, comprised 1.81 (±0.09) m−2 CO2, 1.08 (± 0.21) other well-mixed greenhouse gases, −1.01 0.23) aerosols −0.09 (±0.13) land use change. Quoted uncertainties 1 standard deviation across model best estimates, 90 % confidence reported forcings, due internal variability, is typically within 0.1 m−2. majority remaining 0.21 likely be ozone. In most cases, largest contributors spread (ERF) (IRF) cloud responses, particularly aerosol–cloud interactions aerosol forcing. As determined previous studies, cancellation tropospheric surface means stratospherically adjusted approximately equal ERF for gas but not aerosols, consequentially, total. ranges −0.63 −1.37 exhibiting a less negative mean narrower range compared 10 CMIP5 models. 4×CO2 also narrowed CMIP6 13 Aerosol uncorrelated with sensitivity. Therefore, there no evidence suggest increasing sensitivity models, related high-sensitivity consequence stronger present-day little modelling groups systematically tuning or recreate observed historical warming.

Language: Английский

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Contribution of the world's main dust source regions to the global cycle of desert dust

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(10), P. 8169 - 8193

Published: May 27, 2021

Abstract. Even though desert dust is the most abundant aerosol by mass in Earth's atmosphere, relative contributions of world's major source regions to global cycle remain poorly constrained. This problem hinders accounting for potentially large impact regional differences properties on clouds, energy balance, and terrestrial marine biogeochemical cycles. Here, we constrain contribution each main cycle. We use an analytical framework that integrates ensemble model simulations with observationally informed constraints size distribution, extinction efficiency, optical depth (DAOD). obtain a dataset constrains nine size-resolved emission, atmospheric loading, DAOD, concentration, deposition flux. find 22–29 Tg (1 standard error range) loading geometric diameter up 20 µm partitioned as follows: North African contribute ∼ 50 % (11–15 Tg), Asian 40 (8–13 American Southern Hemisphere 10 (1.8–3.2 Tg). These results suggest current models average overestimate sources at 65 %, while underestimating 30 %. Our further show region's peaks local spring summer, which partially driven increased lifetime those seasons. also quantify flux Amazon rainforest be yr−1, factor 2–3 less than inferred from satellite data previous work likely overestimated efficiency. The obtained this paper can used improved impacts climate, cycles, other parts Earth system.

Language: Английский

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Tropospheric ozone in CMIP6 simulations

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(5), P. 4187 - 4218

Published: March 18, 2021

Abstract. The evolution of tropospheric ozone from 1850 to 2100 has been studied using data Phase 6 the Coupled Model Intercomparison Project (CMIP6). We evaluate long-term changes coupled atmosphere–ocean chemistry–climate models, focusing on CMIP Historical and ScenarioMIP ssp370 experiments, for which detailed tropospheric-ozone diagnostics were archived. model ensemble evaluated against a suite surface, sonde satellite observations past several decades found reproduce well salient spatial, seasonal decadal variability trends. multi-model mean burden increases 247 ± 36 Tg in value 356 31 period 2005–2014, an increase 44 %. Modelled present-day values agree with previous determinations (ACCENT: 336 27 Tg; Atmospheric Chemistry Climate Project, ACCMIP: 337 23 Tropospheric Ozone Assessment Report, TOAR: 340 34 Tg). In 416 35 by 2100. budget examined over same lumped production (PO3) loss (LO3) diagnostics. Both chemical terms steadily 2100, net (PO3-LO3) reaching maximum around year 2000. residual term, contains contributions stratosphere–troposphere transport reaches minimum time before recovering 21st century, while dry deposition 1850–2100. Differences between are explained variation tropopause height stratospheric burden.

Language: Английский

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The Pliocene Model Intercomparison Project Phase 2: large-scale climate features and climate sensitivity

Climate of the past, Journal Year: 2020, Volume and Issue: 16(6), P. 2095 - 2123

Published: Nov. 4, 2020

Abstract. The Pliocene epoch has great potential to improve our understanding of the long-term climatic and environmental consequences an atmospheric CO2 concentration near ∼400 parts per million by volume. Here we present large-scale features climate as simulated a new ensemble models varying complexity spatial resolution based on reconstructions boundary conditions (the Model Intercomparison Project Phase 2; PlioMIP2). As global annual average, modelled surface air temperatures increase between 1.7 5.2 ∘C relative pre-industrial era with multi-model mean value 3.2 ∘C. Annual total precipitation rates 7 % (range: 2 %–13 %). On temperature (SAT) increases 4.3 over land 2.8 oceans. There is clear pattern polar amplification warming polewards 60∘ N S exceeding factor 2.3. In Atlantic Pacific oceans, meridional gradients are reduced, while tropical zonal remain largely unchanged. statistically significant relationship model's response associated doubling in (equilibrium sensitivity; ECS) its response. Earth system (including ice sheet feedbacks) 67 greater than ECS; this larger 47 obtained from PlioMIP1 ensemble. Proxy-derived estimates sea used assess model ECS give range 2.6–4.8 This result general accord presented previous Intergovernmental Panel Climate Change (IPCC) Assessment Reports.

Language: Английский

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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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Large-scale features and evaluation of the PMIP4-CMIP6 <i>midHolocene</i> simulations

Climate of the past, Journal Year: 2020, Volume and Issue: 16(5), P. 1847 - 1872

Published: Oct. 1, 2020

Abstract. The mid-Holocene (6000 years ago) is a standard time period for the evaluation of simulated response global climate models using palaeoclimate reconstructions. latest simulations are entry card Palaeoclimate Model Intercomparison Project (PMIP4) component current phase Coupled (CMIP6) – hereafter referred to as PMIP4-CMIP6. Here we provide an initial analysis and results experiment mid-Holocene. We show that state-of-the-art produce changes broadly consistent with theory observations, including increased summer warming Northern Hemisphere associated shifts in tropical rainfall. Many features PMIP4-CMIP6 were present previous generation (PMIP3-CMIP5) simulations. ensemble has mean temperature change −0.3 K, which −0.2 K cooler than PMIP3-CMIP5 predominantly result prescription realistic greenhouse gas concentrations Biases magnitude sign regional responses identified PMIP3-CMIP5, such amplification northern African monsoon, precipitation over Europe, aridity mid-Eurasia, still Despite these issues, opportunity both quantitative derivation emergent constraints on hydrological cycle, feedback strength, potentially sensitivity.

Language: Английский

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Constraining human contributions to observed warming since the pre-industrial period

Nature Climate Change, Journal Year: 2021, Volume and Issue: 11(3), P. 207 - 212

Published: Jan. 18, 2021

Language: Английский

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Systematic Climate Model Biases in the Large‐Scale Patterns of Recent Sea‐Surface Temperature and Sea‐Level Pressure Change

Geophysical Research Letters, Journal Year: 2022, Volume and Issue: 49(17)

Published: Sept. 1, 2022

Abstract Observed surface temperature trends over recent decades are characterized by (a) intensified warming in the Indo‐Pacific Warm Pool and slight cooling eastern equatorial Pacific, consistent with Walker circulation strengthening, (b) Southern Ocean cooling. In contrast, state‐of‐the‐art coupled climate models generally project enhanced weakening, warming. Here we investigate ability of 16 model large ensembles to reproduce observed sea‐surface sea‐level pressure 1979–2020 through a combination externally forced change internal variability. We find large‐scale differences between modeled that very unlikely (<5% probability) occur due variability as represented models. Disparate ratio tropical‐mean warming, which shows little multi‐decadal models, hint biases response historical forcing constitute part discrepancy.

Language: Английский

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