Widening of the tropical belt in a changing climate

Seidel, Dian J.; Fu, Qiang; Randel, William J.; Reichler, Thomas

doi:10.1038/ngeo.2007.38

Cited by 807 publications

(656 citation statements)

References 27 publications

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“…It plays a central role in the earth's hydrological cycle by determining the locations of the intertropical convergence zone (ITCZ), associated with regions with the largest precipitation, as well as the large-scale subtropical dry zones, where most deserts are found. There are indications that the HC has been widening in recent decades (see, e.g., Seidel et al 2008), and this would have substantial societal impacts. It is thus of great importance to accurately project changes in the HC in the coming decades.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty in Climate Change Projections of the Hadley Circulation: The Role of Internal Variability

2013

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The uncertainty arising from internal climate variability in climate change projections of the Hadley circulation (HC) is presently unknown. In this paper it is quantified by analyzing a 40-member ensemble of integrations of the Community Climate System Model, version 3 (CCSM3), under the Special Report on Emissions Scenarios (SRES) A1B scenario over the period 2000-60. An additional set of 100-yr-long timeslice integrations with the atmospheric component of the same model [Community Atmosphere Model, version 3.0 (CAM3)] is also analyzed.Focusing on simple metrics of the HC-its strength, width, and height-three key results emerge from the analysis of the CCSM3 ensemble. First, the projected weakening of the HC is almost entirely confined to the Northern Hemisphere, and is stronger in winter than in summer. Second, the projected widening of the HC occurs only in the winter season but in both hemispheres. Third, the projected rise of the tropical tropopause occurs in both hemispheres and in all seasons and is, by far, the most robust of the three metrics. This paper shows further that uncertainty in future trends of the HC width is largely controlled by extratropical variability, while those of HC strength and height are associated primarily with tropical dynamics. Comparison of the CCSM3 and CAM3 integrations reveals that ocean-atmosphere coupling is the dominant source of uncertainty in future trends of HC strength and height and of the tropical mean meridional circulation in general. Finally, uncertainty in future trends of the hydrological cycle is largely captured by the uncertainty in future trends of the mean meridional circulation.

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Section: Introductionmentioning

confidence: 99%

Uncertainty in Climate Change Projections of the Hadley Circulation: The Role of Internal Variability

2013

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“…Warming also tends to increase the spatial variability of precipitation, leading to a drying of the subtropics and an increase in tropical and mid-latitude rainfall (Solomon et al 2007). This spatial variability in precipitation, coupled with the poleward expansion of the subtropical high pressure belt under global warming (Lu et al 2007;Seidel et al 2008), points toward an intense reduction in precipitation at subtropical dry zones. Thus, climate change involves important regional changes in addition to increases in global mean temperature.…”

Section: Regional Climatementioning

confidence: 98%

Climate Change: Evidence of Human Causes and Arguments for Emissions Reduction

2011

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In a recent editorial, Raymond Spier expresses skepticism over claims that climate change is driven by human actions and that humanity should act to avoid climate change. This paper responds to this skepticism as part of a broader review of the science and ethics of climate change. While much remains uncertain about the climate, research indicates that observed temperature increases are human-driven. Although opinions vary regarding what should be done, prominent arguments against action are based on dubious factual and ethical positions. Thus, the skepticisms in the recent editorial are unwarranted. This does not diminish the general merits of skeptical intellectual inquiry.

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“…INMCM4, HadGEM2-CC, IPSL-CM5A-MR, HadGEM2-AO, and CMCC-CM underestimate the observed precipitation and have mean biases of −50.8%, −49.1%, −32.7%, −31.5%, −34.8%, and −28.1%, respectively. ese models could probably exaggerate the effects of the dry winds from the Sahara and also the warming of the troposphere by greenhouse gases that decrease the vertical temperature gradient inducing a stable atmosphere (e.g., [54,55]). Figure 4 shows the Beijing Climate Center Climate System Model version 1.1 (BCC-CSM1.1) and the Beijing Normal University Earth System Model (BNU-ESM) underestimating the observed precipitation in the Sahel while overestimating in the Guinea Coast.…”

Section: Annual Total For Climatological Mean Biasmentioning

confidence: 99%

Evaluation of CMIP5 Global Climate Models over the Volta Basin: Precipitation

Agyekum

Annor

Lamptey

et al. 2018

Advances in Meteorology

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A selected number of global climate models (GCMs) from the fifth Coupled Model Intercomparison Project (CMIP5) were evaluated over the Volta Basin for precipitation. Biases in models were computed by taking the differences between the averages over the period of the models and the observation, normalized by the average of the observed for the annual and seasonal timescales. e Community Earth System Model, version 1-Biogeochemistry (CESM1-BGC), the Community Climate System Model Version 4 (CCSM4), the Max Planck Institute Earth System Model, Medium Range (MPI-ESM-MR), the Norwegian Earth System Model (NorESM1-M), and the multimodel ensemble mean were able to simulate the observed climatological mean of the annual total precipitation well (average biases of 1.9% to 7.5%) and hence were selected for the seasonal and monthly timescales. Overall, all the models (CESM1-BGC, CCSM4, MPI-ESM-MR, and NorESM1-M) scored relatively low for correlation (<0.5) but simulated the observed temporal variability differently ranging from 1.0 to 3.0 for the seasonal total. For the annual cycle of the monthly total, the CESM1-BGC, the MPI-ESM-MR, and the NorESM1-M were able to simulate the peak of the observed rainy season well in the Soudano-Sahel, the Sahel, and the entire basin, respectively, while all the models had difficulty in simulating the bimodal pattern of the Guinea Coast. e ensemble mean shows high performance compared to the individual models in various timescales.

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Widening of the tropical belt in a changing climate

Cited by 807 publications

References 27 publications

Uncertainty in Climate Change Projections of the Hadley Circulation: The Role of Internal Variability

Uncertainty in Climate Change Projections of the Hadley Circulation: The Role of Internal Variability

Climate Change: Evidence of Human Causes and Arguments for Emissions Reduction

Evaluation of CMIP5 Global Climate Models over the Volta Basin: Precipitation

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