Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections

Biogeosciences, Journal Year: 2020, Volume and Issue: 17(13), P. 3439 - 3470

Published: July 6, 2020

Abstract. Anthropogenic climate change is projected to lead ocean warming, acidification, deoxygenation, reductions in near-surface nutrients, and changes primary production, all of which are expected affect marine ecosystems. Here we assess projections these drivers environmental over the twenty-first century from Earth system models (ESMs) participating Coupled Model Intercomparison Project Phase 6 (CMIP6) that were forced under CMIP6 Shared Socioeconomic Pathways (SSPs). Projections compared those previous generation (CMIP5) Representative Concentration (RCPs). A total 10 CMIP5 13 used two multi-model ensembles. Under high-emission scenario SSP5-8.5, global mean (2080–2099 values relative 1870–1899) ± inter-model SD sea surface temperature, pH, subsurface (100–600 m) oxygen concentration, euphotic (0–100 nitrate depth-integrated production +3.47±0.78 ∘C, -0.44±0.005, -13.27±5.28, -1.06±0.45 mmol m−3 -2.99±9.11 %, respectively. low-emission, high-mitigation SSP1-2.6, corresponding +1.42±0.32 -0.16±0.002, -6.36±2.92, -0.52±0.23 m−3, -0.56±4.12 %. Projected exposure ecosystem depends largely on extent future emissions, consistent with studies. The ESMs generally project greater but lesser declines than comparable radiative forcing. increased warming results a general increase sensitivity CMIP5. This enhanced increases upper-ocean stratification projections, contributes ventilation. acidification primarily consequence SSPs having higher associated atmospheric CO2 concentrations their RCP analogues for same We find no reduction uncertainties, even an net uncertainties CMIP6, as

Language: Английский

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Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models

Science Advances, Journal Year: 2020, Volume and Issue: 6(26)

Published: June 24, 2020

A historical context is provided for interpreting the equilibrium climate sensitivity (ECS) and transient response (TCR).

Language: Английский

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Global predictions of primary soil salinization under changing climate in the 21st century

Nature Communications, Journal Year: 2021, Volume and Issue: 12(1)

Published: Nov. 18, 2021

Soil salinization has become one of the major environmental and socioeconomic issues globally this is expected to be exacerbated further with projected climatic change. Determining how climate change influences dynamics naturally-occurring soil scarcely been addressed due highly complex processes influencing salinization. This paper sets out address long-standing challenge by developing data-driven models capable predicting primary (naturally-occurring) salinity its variations in world's drylands up year 2100 under changing climate. Analysis future predictions made here identifies dryland areas South America, southern western Australia, Mexico, southwest United States, Africa as hotspots. Conversely, we project a decrease northwest Horn Africa, Eastern Europe, Turkmenistan, west Kazakhstan response over same period. Excess salt accumulation root zone causes health, biodiversity food security. Authors used machine learning algorithms predict global scale 21st century.

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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Projections of Precipitation and Temperature over the South Asian Countries in CMIP6

Earth Systems and Environment, Journal Year: 2020, Volume and Issue: 4(2), P. 297 - 320

Published: May 26, 2020

Abstract The latest Coupled Model Intercomparison Project phase 6 (CMIP6) dataset was analyzed to examine the projected changes in temperature and precipitation over six South Asian countries during twenty-first century. CMIP6 model simulations reveal biases annual mean Asia present climate. In historical period, median of ensemble systematically underestimates for all countries, while a mixed behavior is shown case precipitation. future climate, models display higher sensitivity greenhouse gas emissions compared with CMIP5 models. multimodel from 27 projects continuous increase century under three scenarios. shows large (over °C SSP5-8.5 scenario) northwestern parts Asia, comprising complex Karakorum Himalayan mountain ranges. Any this region will most likely result faster rate glacier melting. By end century, (uncertainty range) by 1.2 (0.7–2.1) °C, 2.1 (1.5–3.3) 4.3 (3.2–6.6) SSP1-2.6, SSP2-4.5, scenarios, respectively, relative (1995–2014) warming also on seasonal time scale. winter season than summer which if verified have repercussions snow/ice accumulations as well cropping patterns. change varies considerably between countries. country-averaged 17.1 (2.2–49.1)% Bangladesh, 18.9 (−4.9 72)% Bhutan, 27.3 (5.3–160.5)% India, 19.5 (−5.9 95.6)% Nepal, 26.4 (6.4–159.7)% Pakistan, 25.1 (−8.5 61.0)% Sri Lanka scenario. projections variability. reveals robust western Himalayas, corresponding decrease eastern Himalayas. On other hand, region, largest arid southern Pakistan adjacent areas high-emission results presented study give detailed insights into performance could be extended further develop adaptation strategies, may act guideline document climate related policymaking region.

Language: Английский

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Projected Change in Temperature and Precipitation Over Africa from CMIP6

Earth Systems and Environment, Journal Year: 2020, Volume and Issue: 4(3), P. 455 - 475

Published: July 2, 2020

Abstract We analyze data of 27 global climate models from the sixth phase Coupled Model Intercomparison Project (CMIP6), and examine projected changes in temperature precipitation over African continent during twenty-first century. The are computed for two future time slices, 2030–2059 (near term) 2070–2099 (long term), relative to present (1981–2010), entire its eight subregions. CMIP6 multi-model ensemble a continuous significant increase mean annual all Africa subregions near (long)-term period is by 1.2 °C (1.4 °C), 1.5 (2.3 1.8 (4.4 °C) under Shared Socioeconomic Pathways (SSPs) weak, moderate, strong forcing, referenced as SSP1-2.6, SSP2-4.5, SSP5-8.5, respectively. warming not uniform varies regionally. By end century, largest rise (5.6 Sahara, while smallest (3.5 Central East Africa, forcing SSP5-8.5 scenario. boreal winter summer patterns century show spatial distributions similar patterns. Uncertainty associated with increases reaches maximum On other hand, projections large variability seasonal dependency. northern southern parts reduction precipitation, central an increase, climates three reference scenarios. For periods, area-averaged 6.2 (4.8)%, 6.8 (8.5)%, 9.5 (15.2)% median simulated model remains higher than CMIP5 most reaching high 2.5 some regions, shows mixed pattern.

Language: Английский

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CMIP6 Models Predict Significant 21st Century Decline of the Atlantic Meridional Overturning Circulation

Geophysical Research Letters, Journal Year: 2020, Volume and Issue: 47(12)

Published: May 25, 2020

Abstract We explore the representation of Atlantic Meridional Overturning Circulation (AMOC) in 27 models from CMIP6 multimodel ensemble. Comparison with RAPID and SAMBA observations suggests that ensemble mean represents AMOC strength vertical profile reasonably well. Linear trends over entire historical period (1850–2014) are generally neutral, but many exhibit an peak around 1980s. Ensemble decline future (SSP) scenarios is stronger than CMIP5 models. In fact, surprisingly insensitive to scenario at least up 2060. find emergent relationship among a majority between 21st century decline. Constraining this might 6 8 Sv (34–45%) by 2100. A smaller group projects much less weakening only 30%.

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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Reduced global warming from CMIP6 projections when weighting models by performance and independence

Earth System Dynamics, Journal Year: 2020, Volume and Issue: 11(4), P. 995 - 1012

Published: Nov. 13, 2020

Abstract. The sixth Coupled Model Intercomparison Project (CMIP6) constitutes the latest update on expected future climate change based a new generation of models. To extract reliable estimates warming and related uncertainties from these models, spread in their projections is often translated into probabilistic such as mean likely range. Here, we use model weighting approach, which accounts for models' historical performance several diagnostics well interdependence within CMIP6 ensemble, to calculate constrained distributions global temperature change. We investigate skill our approach perfect test, where previous-generation CMIP5 models pseudo-observations period. distribution weighted abovementioned manner with respect matching then evaluated, find increase about 17 % compared unweighted distribution. In addition, show that independence metric correctly clusters known be similar “family tree”, enables application degree inter-model dependence. apply two observational (the fifth European Centre Medium-Range Weather Forecasts Retrospective Analysis – ERA5, Modern-Era analysis Research Applications, version 2 MERRA-2), constrain under weak (SSP1-2.6) strong (SSP5-8.5) scenarios (SSP refers Shared Socioeconomic Pathways). Our results reduction projected both because some high receive systematically lower weights. end-of-century (2081–2100 relative 1995–2014) SSP5-8.5 3.7 ∘C, 4.1 ∘C without weighting; (66%) uncertainty range 3.1 4.6 equates 13 decrease spread. For SSP1-2.6, 1 (0.7 1.4 ∘C), −0.1 −24 case.

Language: Английский

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Framing, Context, and Methods

Cambridge University Press eBooks, Journal Year: 2023, Volume and Issue: unknown, P. 147 - 286

Published: June 29, 2023

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Language: Английский

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