Climate Change Projections in CESM1(CAM5) Compared to CCSM4

2013 ◽  
Vol 26 (17) ◽  
pp. 6287-6308 ◽  
Author(s):  
Gerald A. Meehl ◽  
Warren M. Washington ◽  
Julie M. Arblaster ◽  
Aixue Hu ◽  
Haiyan Teng ◽  
...  
Keyword(s):  
Climate Change ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
First Century ◽  
System Model ◽  
Future Climate Change ◽  
System Response ◽  
Climate Change Projections ◽  
Model Version ◽  
Twenty First Century

Abstract Future climate change projections for phase 5 of the Coupled Model Intercomparison Project (CMIP5) are presented for the Community Earth System Model version 1 that includes the Community Atmospheric Model version 5 [CESM1(CAM5)]. These results are compared to the Community Climate System Model, version 4 (CCSM4) and include simulations using the representative concentration pathway (RCP) mitigation scenarios, and extensions for those scenarios beyond 2100 to 2300. Equilibrium climate sensitivity of CESM1(CAM5) is 4.10°C, which is higher than the CCSM4 value of 3.20°C. The transient climate response is 2.33°C, compared to the CCSM4 value of 1.73°C. Thus, even though CESM1(CAM5) includes both the direct and indirect effects of aerosols (CCSM4 had only the direct effect), the overall climate system response including forcing and feedbacks is greater in CESM1(CAM5) compared to CCSM4. The Atlantic Ocean meridional overturning circulation (AMOC) in CESM1(CAM5) weakens considerably in the twenty-first century in all the RCP scenarios, and recovers more slowly in the lower forcing scenarios. The total aerosol optical depth (AOD) changes from ~0.12 in 2006 to ~0.10 in 2100, compared to a preindustrial 1850 value of 0.08, so there is less negative forcing (a net positive forcing) from that source during the twenty-first century. Consequently, the change from 2006 to 2100 in aerosol direct forcing in CESM1(CAM5) contributes to greater twenty-first century warming relative to CCSM4. There is greater Arctic warming and sea ice loss in CESM1(CAM5), with an ice-free summer Arctic occurring by about 2060 in RCP8.5 (2040s in September) as opposed to about 2100 in CCSM4 (2060s in September).

scholarly journals Climate System Response to External Forcings and Climate Change Projections in CCSM4

2012 ◽  
Vol 25 (11) ◽  
pp. 3661-3683 ◽  
Author(s):  
Gerald A. Meehl ◽  
Warren M. Washington ◽  
Julie M. Arblaster ◽  
Aixue Hu ◽  
Haiyan Teng ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Sea Ice ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
First Century ◽  
The Arctic ◽  
System Response ◽  
Transient Climate Response ◽  
Climate System Model ◽  
Twenty First Century

Results are presented from experiments performed with the Community Climate System Model, version 4 (CCSM4) for the Coupled Model Intercomparison Project phase 5 (CMIP5). These include multiple ensemble members of twentieth-century climate with anthropogenic and natural forcings as well as single-forcing runs, sensitivity experiments with sulfate aerosol forcing, twenty-first-century representative concentration pathway (RCP) mitigation scenarios, and extensions for those scenarios beyond 2100–2300. Equilibrium climate sensitivity of CCSM4 is 3.20°C, and the transient climate response is 1.73°C. Global surface temperatures averaged for the last 20 years of the twenty-first century compared to the 1986–2005 reference period for six-member ensembles from CCSM4 are +0.85°, +1.64°, +2.09°, and +3.53°C for RCP2.6, RCP4.5, RCP6.0, and RCP8.5, respectively. The ocean meridional overturning circulation (MOC) in the Atlantic, which weakens during the twentieth century in the model, nearly recovers to early twentieth-century values in RCP2.6, partially recovers in RCP4.5 and RCP6, and does not recover by 2100 in RCP8.5. Heat wave intensity is projected to increase almost everywhere in CCSM4 in a future warmer climate, with the magnitude of the increase proportional to the forcing. Precipitation intensity is also projected to increase, with dry days increasing in most subtropical areas. For future climate, there is almost no summer sea ice left in the Arctic in the high RCP8.5 scenario by 2100, but in the low RCP2.6 scenario there is substantial sea ice remaining in summer at the end of the century.

scholarly journals Climate Change Projection in the Twenty-First Century Simulated by NIMS-KMA CMIP6 Model Based on New GHGs Concentration Pathways

2021 ◽  
Author(s):  
Hyun Min Sung ◽  
Jisun Kim ◽  
Sungbo Shim ◽  
Jeong-byn Seo ◽  
Sang-Hoon Kwon ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Changes ◽  
Scientific Information ◽  
Earth System Model ◽  
First Century ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Future Projections ◽  
Twenty First Century

AbstractThe National Institute of Meteorological Sciences-Korea Meteorological Administration (NIMS-KMA) has participated in the Coupled Model Inter-comparison Project (CMIP) and provided long-term simulations using the coupled climate model. The NIMS-KMA produces new future projections using the ensemble mean of KMA Advanced Community Earth system model (K-ACE) and UK Earth System Model version1 (UKESM1) simulations to provide scientific information of future climate changes. In this study, we analyze four experiments those conducted following the new shared socioeconomic pathway (SSP) based scenarios to examine projected climate change in the twenty-first century. Present day (PD) simulations show high performance skill in both climate mean and variability, which provide a reliability of the climate models and reduces the uncertainty in response to future forcing. In future projections, global temperature increases from 1.92 °C to 5.20 °C relative to the PD level (1995–2014). Global mean precipitation increases from 5.1% to 10.1% and sea ice extent decreases from 19% to 62% in the Arctic and from 18% to 54% in the Antarctic. In addition, climate changes are accelerating toward the late twenty-first century. Our CMIP6 simulations are released to the public through the Earth System Grid Federation (ESGF) international data sharing portal and are used to support the establishment of the national adaptation plan for climate change in South Korea.

scholarly journals An Assessment of Recent and Future Temperature Change over the Sichuan Basin, China, Using CMIP5 Climate Models

2017 ◽  
Vol 30 (17) ◽  
pp. 6701-6722 ◽  
Author(s):  
Daniel Bannister ◽  
Michael Herzog ◽  
Hans-F. Graf ◽  
J. Scott Hosking ◽  
C. Alan Short
Keyword(s):  
Climate Change ◽  
Sichuan Basin ◽  
Climate Models ◽  
Distribution Functions ◽  
Future Climate ◽  
First Century ◽  
Future Climate Change ◽  
Change Scenario ◽  
The Sichuan Basin ◽  
Twenty First Century

The Sichuan basin is one of the most densely populated regions of China, making the area particularly vulnerable to the adverse impacts associated with future climate change. As such, climate models are important for understanding regional and local impacts of climate change and variability, like heat stress and drought. In this study, climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are validated over the Sichuan basin by evaluating how well each model can capture the phase, amplitude, and variability of the regionally observed mean, maximum, and minimum temperature between 1979 and 2005. The results reveal that the majority of the models do not capture the basic spatial pattern and observed means, trends, and probability distribution functions. In particular, mean and minimum temperatures are underestimated, especially during the winter, resulting in biases exceeding −3°C. Models that reasonably represent the complex basin topography are found to generally have lower biases overall. The five most skillful climate models with respect to the regional climate of the Sichuan basin are selected to explore twenty-first-century temperature projections for the region. Under the CMIP5 high-emission future climate change scenario, representative concentration pathway 8.5 (RCP8.5), the temperatures are projected to increase by approximately 4°C (with an average warming rate of +0.72°C decade−1), with the greatest warming located over the central plains of the Sichuan basin, by 2100. Moreover, the frequency of extreme months (where mean temperature exceeds 28°C) is shown to increase in the twenty-first century at a faster rate compared to the twentieth century.

scholarly journals Reversibility of Historical and Future Climate Change with a Complex Earth System Model

2021 ◽  
Author(s):  
Shili Yang ◽  
Di Tian ◽  
JieMing Chou ◽  
Ting Wei ◽  
Xian Zhu ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Earth System Model ◽  
Meridional Overturning Circulation ◽  
System Model ◽  
Convective Precipitation ◽  
Future Climate Change ◽  
Earth System ◽  
Initial Values ◽  
Precipitation Total

Abstract The reversibility of a wide range of components of the earth system was investigated by comparing forward and time-reversed historical and future simulations of a coupled earth system model known as the Beijing Normal University earth system model. Many characteristics of the climate system, including the surface temperature, ocean heat content (OHC), convective precipitation, total runoff, ground evaporation, soil moisture, sea ice extent and Atlantic Meridional Overturning Circulation, did not fully return to their initial values when the historical or future natural and anthropogenic forcing agents were reversed. The surface temperature and OHC declines lagged behind the decline in greenhouse gases (GHGs). Reverses in other variables occurred in direct response to the decline in GHGs. The sea level increased, even after all of the forces returned to the original values. Furthermore, most of the climate variables did not return to their original values because of thermal inertial. The end states of variables, other than those related to thermal storage, mainly depended on the original state of the natural and anthropogenic forces, and were unaffected by the future growth rate of the GHGs. The climate policy implication of this study is that climate change cannot be completely reversed even if all the external forces are returned to their initial values.

Climate Change Projections for the Twenty-First Century and Climate Change Commitment in the CCSM3

2006 ◽  
Vol 19 (11) ◽  
pp. 2597-2616 ◽  
Author(s):  
Gerald A. Meehl ◽  
Warren M. Washington ◽  
Benjamin D. Santer ◽  
William D. Collins ◽  
Julie M. Arblaster ◽  
...  
Keyword(s):  
Climate Change ◽  
Twentieth Century ◽  
Sea Ice ◽  
Sea Level Rise ◽  
Sea Level ◽  
Climate System ◽  
First Century ◽  
Change Scenario ◽  
Climate System Model ◽  
Twenty First Century

Abstract Climate change scenario simulations with the Community Climate System Model version 3 (CCSM3), a global coupled climate model, show that if concentrations of all greenhouse gases (GHGs) could have been stabilized at the year 2000, the climate system would already be committed to 0.4°C more warming by the end of the twenty-first century. Committed sea level rise by 2100 is about an order of magnitude more, percentage-wise, compared to sea level rise simulated in the twentieth century. This increase in the model is produced only by thermal expansion of seawater, and does not take into account melt from ice sheets and glaciers, which could at least double that number. Several tenths of a degree of additional warming occurs in the model for the next 200 yr in the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) B1 and A1B scenarios after stabilization in the year 2100, but with twice as much sea level rise after 100 yr, and doubling yet again in the next 100 yr to 2300. At the end of the twenty-first century, the warming in the tropical Pacific for the A2, A1B, and B1 scenarios resembles an El Niño–like response, likely due to cloud feedbacks in the model as shown in an earlier version. Greatest warming occurs at high northern latitudes and over continents. The monsoon regimes intensify somewhat in the future warmer climate, with decreases of sea level pressure at high latitudes and increases in the subtropics and parts of the midlatitudes. There is a weak summer midlatitude soil moisture drying in this model as documented in previous models. Sea ice distributions in both hemispheres are somewhat overextensive, but with about the right ice thickness at the end of the twentieth century. Future decreases in sea ice with global warming are proportional to the temperature response from the forcing scenarios, with the high forcing scenario, A2, producing an ice-free Arctic in summer by the year 2100.

scholarly journals An integrated assessment modeling framework for uncertainty studies in global and regional climate change: the MIT IGSM-CAM (version 1.0)

2013 ◽  
Vol 6 (6) ◽  
pp. 2063-2085 ◽  
Author(s):  
E. Monier ◽  
J. R. Scott ◽  
A. P. Sokolov ◽  
C. E. Forest ◽  
C. A. Schlosser
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Climate System ◽  
System Model ◽  
System Response ◽  
Continental Scale ◽  
Climate Parameters ◽  
Precipitation Changes

Abstract. This paper describes a computationally efficient framework for uncertainty studies in global and regional climate change. In this framework, the Massachusetts Institute of Technology (MIT) Integrated Global System Model (IGSM), an integrated assessment model that couples an Earth system model of intermediate complexity to a human activity model, is linked to the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). Since the MIT IGSM-CAM framework (version 1.0) incorporates a human activity model, it is possible to analyze uncertainties in emissions resulting from both uncertainties in the underlying socio-economic characteristics of the economic model and in the choice of climate-related policies. Another major feature is the flexibility to vary key climate parameters controlling the climate system response to changes in greenhouse gases and aerosols concentrations, e.g., climate sensitivity, ocean heat uptake rate, and strength of the aerosol forcing. The IGSM-CAM is not only able to realistically simulate the present-day mean climate and the observed trends at the global and continental scale, but it also simulates ENSO variability with realistic time scales, seasonality and patterns of SST anomalies, albeit with stronger magnitudes than observed. The IGSM-CAM shares the same general strengths and limitations as the Coupled Model Intercomparison Project Phase 3 (CMIP3) models in simulating present-day annual mean surface temperature and precipitation. Over land, the IGSM-CAM shows similar biases to the NCAR Community Climate System Model (CCSM) version 3, which shares the same atmospheric model. This study also presents 21st century simulations based on two emissions scenarios (unconstrained scenario and stabilization scenario at 660 ppm CO2-equivalent) similar to, respectively, the Representative Concentration Pathways RCP8.5 and RCP4.5 scenarios, and three sets of climate parameters. Results of the simulations with the chosen climate parameters provide a good approximation for the median, and the 5th and 95th percentiles of the probability distribution of 21st century changes in global mean surface air temperature from previous work with the IGSM. Because the IGSM-CAM framework only considers one particular climate model, it cannot be used to assess the structural modeling uncertainty arising from differences in the parameterization suites of climate models. However, comparison of the IGSM-CAM projections with simulations of 31 CMIP5 models under the RCP4.5 and RCP8.5 scenarios show that the range of warming at the continental scale shows very good agreement between the two ensemble simulations, except over Antarctica, where the IGSM-CAM overestimates the warming. This demonstrates that by sampling the climate system response, the IGSM-CAM, even though it relies on one single climate model, can essentially reproduce the range of future continental warming simulated by more than 30 different models. Precipitation changes projected in the IGSM-CAM simulations and the CMIP5 multi-model ensemble both display a large uncertainty at the continental scale. The two ensemble simulations show good agreement over Asia and Europe. However, the ranges of precipitation changes do not overlap – but display similar size – over Africa and South America, two continents where models generally show little agreement in the sign of precipitation changes and where CCSM3 tends to be an outlier. Overall, the IGSM-CAM provides an efficient and consistent framework to explore the large uncertainty in future projections of global and regional climate change associated with uncertainty in the climate response and projected emissions.

scholarly journals The Community Climate System Model Version 3 (CCSM3)

2006 ◽  
Vol 19 (11) ◽  
pp. 2122-2143 ◽  
Author(s):  
William D. Collins ◽  
Cecilia M. Bitz ◽  
Maurice L. Blackmon ◽  
Gordon B. Bonan ◽  
Christopher S. Bretherton ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Climate System ◽  
System Model ◽  
Ice Dynamics ◽  
Community Climate System Model ◽  
Climate System Model ◽  
Model Version ◽  
Systematic Biases ◽  
Community Climate

Abstract The Community Climate System Model version 3 (CCSM3) has recently been developed and released to the climate community. CCSM3 is a coupled climate model with components representing the atmosphere, ocean, sea ice, and land surface connected by a flux coupler. CCSM3 is designed to produce realistic simulations over a wide range of spatial resolutions, enabling inexpensive simulations lasting several millennia or detailed studies of continental-scale dynamics, variability, and climate change. This paper will show results from the configuration used for climate-change simulations with a T85 grid for the atmosphere and land and a grid with approximately 1° resolution for the ocean and sea ice. The new system incorporates several significant improvements in the physical parameterizations. The enhancements in the model physics are designed to reduce or eliminate several systematic biases in the mean climate produced by previous editions of CCSM. These include new treatments of cloud processes, aerosol radiative forcing, land–atmosphere fluxes, ocean mixed layer processes, and sea ice dynamics. There are significant improvements in the sea ice thickness, polar radiation budgets, tropical sea surface temperatures, and cloud radiative effects. CCSM3 can produce stable climate simulations of millennial duration without ad hoc adjustments to the fluxes exchanged among the component models. Nonetheless, there are still systematic biases in the ocean–atmosphere fluxes in coastal regions west of continents, the spectrum of ENSO variability, the spatial distribution of precipitation in the tropical oceans, and continental precipitation and surface air temperatures. Work is under way to extend CCSM to a more accurate and comprehensive model of the earth's climate system.

scholarly journals Identification of Nonlinear Behavior in Transient Climate Change Projections of Soil Moisture over the United States

2009 ◽  
Vol 13 (1) ◽  
pp. 1-13
Author(s):  
Bruce T. Anderson ◽  
Catherine Reifen ◽  
Ralf Toumi
Keyword(s):  
Climate Change ◽  
United States ◽  
Soil Moisture ◽  
Nonlinear Behavior ◽  
The United States ◽  
Climate System ◽  
Future Climate Change ◽  
Climate Change Projections ◽  
Climate System Model

Abstract While most projections of climate change and its regional impacts focus on overall changes in the state of the climate system, useful information can also be found in the evolution of the climate system from one state to another. Here the authors introduce one method for identifying regions in which significant and systematic long-term nonlinear evolutions may be present, even given quasi-linear anthropogenic forcing. Using climate change projections taken from simulations of NCAR’s Community Climate System Model, version 3 (CCSM3), the authors then employ the technique to isolate systematic nonlinear behavior of soil moisture variations over the United States. While the projections presented here only represent the results from one model system, it is argued that such nonlinear behavior is an important characteristic of future climate change that should be considered when discussing both short-term and long-term impacts of anthropogenic climate forcing.

Terrestrial Carbon Cycle Dynamics under Recent and Future Climate Change

2005 ◽  
Vol 18 (10) ◽  
pp. 1609-1628 ◽  
Author(s):  
H. Damon Matthews ◽  
Andrew J. Weaver ◽  
Katrin J. Meissner
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Future Climate ◽  
First Century ◽  
Future Climate Change ◽  
Cycle Model ◽  
Terrestrial Carbon ◽  
Carbon Cycle Model ◽  
Terrestrial Carbon Cycle ◽  
Twenty First Century

Abstract The behavior of the terrestrial carbon cycle under historical and future climate change is examined using the University of Victoria Earth System Climate Model, now coupled to a dynamic terrestrial vegetation and global carbon cycle model. When forced by historical emissions of CO2 from fossil fuels and land-use change, the coupled climate–carbon cycle model accurately reproduces historical atmospheric CO2 trends, as well as terrestrial and oceanic uptake for the past two decades. Under six twenty-first-century CO2 emissions scenarios, both terrestrial and oceanic carbon sinks continue to increase, though terrestrial uptake slows in the latter half of the century. Climate–carbon cycle feedbacks are isolated by comparing a coupled model run with a run where climate and the carbon cycle are uncoupled. The modeled positive feedback between the carbon cycle and climate is found to be relatively small, resulting in an increase in simulated CO2 of 60 ppmv at the year 2100. Including non-CO2 greenhouse gas forcing and increasing the model’s climate sensitivity increase the effect of this feedback to 140 ppmv. The UVic model does not, however, simulate a switch from a terrestrial carbon sink to a source during the twenty-first century, as earlier studies have suggested. This can be explained by a lack of substantial reductions in simulated vegetation productivity due to climate changes.

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