Sensitivity of an Earth system climate model to idealized radiative forcing

Abstract Recent research indicates that the warming of the climate system resulting from increased greenhouse gas (GHG) emissions over the next century will persist for many centuries after the cessation of these emissions, principally because of the persistence of elevated atmospheric carbon dioxide (CO2) concentrations and their attendant radiative forcing. However, it is unknown whether the responses of other components of the climate system—including those related to Greenland and Antarctic ice cover, the Atlantic thermohaline circulation, the West African monsoon, and ecosystem and human welfare—would be reversed even if atmospheric CO2 concentrations were to recover to 1990 levels. Here, using a simple set of experiments employing a current-generation numerical climate model, the authors examine the response of the physical climate system to decreasing CO2 concentrations following an initial increase. Results indicate that many characteristics of the climate system, including global temperatures, precipitation, soil moisture, and sea ice, recover as CO2 concentrations decrease. However, other components of the Earth system may still exhibit nonlinear hysteresis. In these experiments, for instance, increases in stratospheric water vapor, which initially result from increased CO2 concentrations, remain present even as CO2 concentrations recover. These results suggest that identification of additional threshold behaviors in response to human-induced global climate change should focus on subcomponents of the full Earth system, including cryosphere, biosphere, and chemistry.

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If Anthropogenic CO2 Emissions Cease, Will Atmospheric CO2 Concentration Continue to Increase?

Journal of Climate ◽

10.1175/jcli-d-12-00751.1 ◽

2013 ◽

Vol 26 (23) ◽

pp. 9563-9576 ◽

Cited By ~ 12

Author(s):

Andrew H. MacDougall ◽

Michael Eby ◽

Andrew J. Weaver

Keyword(s):

Greenhouse Gases ◽

Radiative Forcing ◽

Climate Model ◽

Carbon Sources ◽

Co2 Concentration ◽

Earth System ◽

Terrestrial Source ◽

The University ◽

Aerosol Emissions ◽

Over Time

If anthropogenic CO2 emissions were to suddenly cease, the evolution of the atmospheric CO2 concentration would depend on the magnitude and sign of natural carbon sources and sinks. Experiments using Earth system models indicate that the overall carbon sinks dominate, such that upon the cessation of anthropogenic emissions, atmospheric CO2 levels decrease over time. However, these models have typically neglected the permafrost carbon pool, which has the potential to introduce an additional terrestrial source of carbon to the atmosphere. Here, the authors use the University of Victoria Earth System Climate Model (UVic ESCM), which has recently been expanded to include permafrost carbon stocks and exchanges with the atmosphere. In a scenario of zeroed CO2 and sulfate aerosol emissions, whether the warming induced by specified constant concentrations of non-CO2 greenhouse gases could slow the CO2 decline following zero emissions or even reverse this trend and cause CO2 to increase over time is assessed. It is found that a radiative forcing from non-CO2 gases of approximately 0.6 W m−2 results in a near balance of CO2 emissions from the terrestrial biosphere and uptake of CO2 by the oceans, resulting in near-constant atmospheric CO2 concentrations for at least a century after emissions are eliminated. At higher values of non-CO2 radiative forcing, CO2 concentrations increase over time, regardless of when emissions cease during the twenty-first century. Given that the present-day radiative forcing from non-CO2 greenhouse gases is about 0.95 W m−2, the results suggest that if all CO2 and aerosols emissions were eliminated without also decreasing non-CO2 greenhouse gas emissions CO2 levels would increase over time, resulting in a small increase in climate warming associated with this positive permafrost–carbon feedback.

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Carbon-nitrogen feedbacks in the UVic ESCM

Geoscientific Model Development ◽

10.5194/gmd-5-1137-2012 ◽

2012 ◽

Vol 5 (5) ◽

pp. 1137-1160 ◽

Cited By ~ 20

Author(s):

R. Wania ◽

K. J. Meissner ◽

M. Eby ◽

V. K. Arora ◽

I. Ross ◽

...

Keyword(s):

Radiative Forcing ◽

Climate Model ◽

Gross Primary Production ◽

N Deposition ◽

Strong Nonlinearity ◽

Earth System ◽

Soil System ◽

Biological N2 Fixation ◽

Plant Soil ◽

Nitrogen Pools

Abstract. A representation of the terrestrial nitrogen cycle is introduced into the UVic Earth System Climate Model (UVic ESCM). The UVic ESCM now contains five terrestrial carbon pools and seven terrestrial nitrogen pools: soil, litter, leaves, stem and roots for both elements and ammonium and nitrate in the soil for nitrogen. Nitrogen cycles through plant tissue, litter, soil and the mineral pools before being taken up again by the plant. Biological N2 fixation and nitrogen deposition represent external inputs to the plant-soil system while losses occur via leaching. Simulated carbon and nitrogen pools and fluxes are in the range of other models and observations. Gross primary production (GPP) for the 1990s in the CN-coupled version is 129.6 Pg C a−1 and net C uptake is 0.83 Pg C a−1, whereas the C-only version results in a GPP of 133.1 Pg C a−1 and a net C uptake of 1.57 Pg C a−1. At the end of a transient experiment for the years 1800–1999, where radiative forcing is held constant but CO2 fertilisation for vegetation is permitted to occur, the CN-coupled version shows an enhanced net C uptake of 1.05 Pg C a−1, whereas in the experiment where CO2 is held constant and temperature is transient the land turns into a C source of 0.60 Pg C a−1 by the 1990s. The arithmetic sum of the temperature and CO2 effects is 0.45 Pg C a−1, 0.38 Pg C a−1 lower than seen in the fully forced model, suggesting a strong nonlinearity in the CN-coupled version. Anthropogenic N deposition has a positive effect on Net Ecosystem Production of 0.35 Pg C a−1. Overall, the UVic CN-coupled version shows similar characteristics to other CN-coupled Earth System Models, as measured by net C balance and sensitivity to changes in climate, CO2 and temperature.

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Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models

npj Climate and Atmospheric Science ◽

10.1038/s41612-020-00159-2 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Zhili Wang ◽

Lei Lin ◽

Yangyang Xu ◽

Huizheng Che ◽

Xiaoye Zhang ◽

...

Keyword(s):

Climate Change ◽

Radiative Forcing ◽

Impact Analysis ◽

Climate Model ◽

Regional Climate ◽

Eastern China ◽

Coupled Model ◽

Regional Climate Change ◽

Anthropogenic Aerosol ◽

Wide Range

AbstractAnthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 historical simulation, due to an opposite trend over eastern China compared with observations. The incorrect AOD trend over China is attributed to problematic AA emissions adopted by CMIP6. There are obvious differences in simulated regional aerosol radiative forcing and temperature responses over Asia when using two different emissions inventories (one adopted by CMIP6; the other from Peking university, a more trustworthy inventory) to driving a global aerosol-climate model separately. We further show that some widely adopted CMIP6 pathways (after 2015) also significantly underestimate the more recent decline in AA emissions over China. These flaws may bring about errors to the CMIP6-based regional climate attribution over Asia for the last two decades and projection for the next few decades, previously anticipated to inform a wide range of impact analysis.

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Anthropogenic forcing and response yield observed positive trend in Earth’s energy imbalance

Nature Communications ◽

10.1038/s41467-021-24544-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Shiv Priyam Raghuraman ◽

David Paynter ◽

V. Ramaswamy

Keyword(s):

Radiative Forcing ◽

Climate Model ◽

Solar Spectrum ◽

Internal Variability ◽

Satellite Observations ◽

Positive Trend ◽

Energy Imbalance ◽

Model Simulations ◽

Heat Uptake ◽

Climate Model Simulations

AbstractThe 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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Projected Changes in Extreme Temperature and Precipitation Indices Over CORDEX-MENA Domain

Atmosphere ◽

10.3390/atmos12050622 ◽

2021 ◽

Vol 12 (5) ◽

pp. 622

Author(s):

Tugba Ozturk ◽

F. Sibel Saygili-Araci ◽

M. Levent Kurnaz

Keyword(s):

Regional Climate Model ◽

Radiative Forcing ◽

Climate Model ◽

Global Climate Model ◽

Regional Climate ◽

Climate Extreme ◽

Pronounced Increase ◽

Temperature And Precipitation ◽

Projected Changes ◽

Extreme Indices

In this study, projected changes in climate extreme indices defined by the Expert Team on Climate Change Detection and Indices were investigated over Middle East and North Africa. Changes in the daily maximum and minimum temperature- and precipitation- based extreme indices were analyzed for the end of the 21st century compared to the reference period 1971–2000 using regional climate model simulations. Regional climate model, RegCM4.4 was used to downscale two different global climate model outputs to 50 km resolution under RCP4.5 and RCP8.5 scenarios. Results generally indicate an intensification of temperature- and precipitation- based extreme indices with increasing radiative forcing. In particular, an increase in annual minimum of daily minimum temperatures is more pronounced over the northern part of Mediterranean Basin and tropics. High increase in warm nights and warm spell duration all over the region with a pronounced increase in tropics are projected for the period of 2071–2100 together with decrease or no change in cold extremes. According to the results, a decrease in total wet-day precipitation and increase in dry spells are expected for the end of the century.

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Simulations of the Mid-Pliocene Warm Period using the NASA/GISS ModelE2-R Earth System Model

Geoscientific Model Development Discussions ◽

10.5194/gmdd-5-2811-2012 ◽

2012 ◽

Vol 5 (3) ◽

pp. 2811-2842 ◽

Cited By ~ 4

Author(s):

M. A. Chandler ◽

L. E. Sohl ◽

J. A. Jonas ◽

H. J. Dowsett

Keyword(s):

North Atlantic ◽

Climate Models ◽

Climate Model ◽

Geographic Region ◽

Earth System Model ◽

Warm Period ◽

System Model ◽

Earth System ◽

Intergovernmental Panel ◽

Future Global Warming

Abstract. Climate reconstructions of the mid-Pliocene Warm Period (mPWP) bear many similarities to aspects of future global warming as projected by the Intergovernmental Panel on Climate Change. In particular, marine and terrestrial paleoclimate data point to high latitude temperature amplification, with associated decreases in sea ice and land ice and altered vegetation distributions that show expansion of warmer climate biomes into higher latitudes. NASA GISS climate models have been used to study the Pliocene climate since the USGS PRISM project first identified that the mid-Pliocene North Atlantic sea surface temperatures were anomalously warm. Here we present the most recent simulations of the Pliocene using the AR5/CMIP5 version of the GISS Earth System Model known as ModelE2-R. These simulations constitute the NASA contribution to the Pliocene Model Intercomparison Project (PlioMIP) Experiment 2. Many findings presented here corroborate results from other PlioMIP multi-model ensemble papers, but we also emphasize features in the ModelE2-R simulations that are unlike the ensemble means. We provide discussion of features that show considerable improvement compared with simulations from previous versions of the NASA GISS models, improvement defined here as simulation results that more closely resemble the ocean core data as well as the PRISM3D reconstructions of the mid-Pliocene climate. In some regions even qualitative agreement between model results and paleodata are an improvement over past studies, but the dramatic warming in the North Atlantic and Greenland-Iceland-Norwegian Sea in these new simulations is by far the most accurate portrayal ever of this key geographic region by the GISS climate model. Our belief is that continued development of key physical routines in the atmospheric model, along with higher resolution and recent corrections to mixing parameterizations in the ocean model, have led to an Earth System Model that will produce more accurate projections of future climate.

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Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-5045-2011 ◽

2011 ◽

Vol 11 (10) ◽

pp. 5045-5077 ◽

Cited By ~ 60

Author(s):

K. Semeniuk ◽

V. I. Fomichev ◽

J. C. McConnell ◽

C. Fu ◽

S. M. L. Melo ◽

...

Keyword(s):

Solar Cycle ◽

Radiative Forcing ◽

Climate Model ◽

Middle Atmosphere ◽

High Energy ◽

Galactic Cosmic Rays ◽

Particle Precipitation ◽

Solar Cycle Variation ◽

Cycle Variation ◽

The Impact

Abstract. The impact of NOx and HOx production by three types of energetic particle precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

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The UVic earth system climate model: Model description, climatology, and applications to past, present and future climates

ATMOSPHERE-OCEAN ◽

10.1080/07055900.2001.9649686 ◽

2001 ◽

Vol 39 (4) ◽

pp. 361-428 ◽

Cited By ~ 499

Author(s):

Andrew J. Weaver ◽

Michael Eby ◽

Edward C. Wiebe ◽

Cecilia M. Bitz ◽

Phil B. Duffy ◽

...

Keyword(s):

Climate Model ◽

Model Description ◽

Earth System

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The influence of global climate changes on Western Siberia climate in the first half of XXI century

Вычислительные технологии ◽

10.25743/ict.2018.23.16505 ◽

2018 ◽

Author(s):

А.А. Лагутин ◽

Н.В. Волков ◽

Е.Ю. Мордвин

Keyword(s):

Radiative Forcing ◽

Climate Changes ◽

Western Siberia ◽

Climate Model ◽

Global Climate ◽

Regional Climate ◽

First Century ◽

Global Climate Changes ◽

Rcp 8.5

Представлены результаты исследований влияния глобальных климатических изменений системы Земля на климат Западной Сибири. Для установления зон региона, в которых к середине XXI в. прогнозируются изменения, использовались модельные данные региональной климатической модели RegCM4 и принятые в этом классе задач стандартизованные евклидовы расстояния между характеристиками климата для двух состояний климатической системы — современного и будущего. Установлены зоны Западной Сибири, в которых в рамках сценариев RCP 4.5 и RCP 8.5 возможной эволюции глобальной системы к 2050 г. прогнозируются изменения климата. Purpose. An analysis of the influence of a global climate changes on the climate of Western Siberia, determination of zones of the region where changes are expected in the middle of the twenty-first century. Methodology. Results obtained using the model data of the regional climate model RegCM4 and the standardized Euclidean distances between climate characteristics. Findings, originality. Simulations of the climate characteristics for the two states of the climate system — contemporary and future — have been carried out. The zones of Western Siberia region, in which climate change is expected in the framework of RCP 4.5 and RCP 8.5 radiative forcing scenarios by the 2050, have been determined.

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