scholarly journals Regional aspects of global climate change simulations : Validation and assessment of climate response over Indian monsoon region to transient increase of greenhouse gases and sulfate aerosols

MAUSAM ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 229-244
Author(s):  
K. RUPA KUMAR ◽  
R. G. ASHRIT
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
General Circulation ◽  
Regional Scale ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Change Scenario ◽  
Climate Projections ◽  
Sulfate Aerosols ◽  
Monsoon Climate

The regional climatic impacts associated with global climatic change and their assessment are very important since agriculture, water resources, ecology etc., are all vulnerable to climatic changes on regional scale. Coupled Atmosphere-Ocean general circulation model (AOGCM) simulations provide a range of scenarios, which can be used, for the assessment of impacts and development of adaptive or mitigative strategies. Validation of the models against the observations and establishing the sensitivity to climate change forcing are essential before the model projections are used for assessment of possible impacts. Moreover model simulated climate projections are often of coarse resolution while the models used for impact assessment, (e.g. crop simulation models, or river runoff models etc.) operate on a higher spatial resolution. This spatial mismatch can be overcome by adopting an appropriate strategy of downscaling the GCM output.   This study examines two AOGCM (ECHAM4/OPYC3 and HadCM2) climate change simulations for their performance in the simulation of monsoon climate over India and the sensitivity of the simulated monsoon climate to transient changes in the atmospheric concentrations of greenhouse gases and sulfate aerosols. The results show that the two models simulate the gross features of climate over India reasonably well. However the inter-model differences in simulation of mean characteristics, sensitivity to forcing and in the simulation of climate change suggest need for caution. Further an empirical downscaling approach in used to assess the possibility of using GCM projections for preparation of regional climate change scenario for India.

Regional Tropical Precipitation Change Mechanisms in ECHAM4/OPYC3 under Global Warming*

2006 ◽  
Vol 19 (17) ◽  
pp. 4207-4223 ◽  
Author(s):  
Chia Chou ◽  
J. David Neelin ◽  
Jien-Yi Tu ◽  
Cheng-Ta Chen
Keyword(s):  
Global Warming ◽  
Greenhouse Gases ◽  
General Circulation Model ◽  
General Circulation ◽  
Vertical Motion ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Additional Contribution ◽  
Tropical Precipitation ◽  
Precipitation Anomalies

Abstract Mechanisms of global warming impacts on regional tropical precipitation are examined in a coupled atmosphere–ocean general circulation model (ECHAM4/OPYC3). The pattern of the regional tropical precipitation changes, once established, tends to persist, growing in magnitude as greenhouse gases increase. The sulfate aerosol induces regional tropical precipitation anomalies similar to the greenhouse gases but with opposite sign, thus reducing the early signal. Evidence for two main mechanisms, the upped-ante and the anomalous gross moist stability (M′) mechanisms (previously proposed in an intermediate complexity model), is found in this more comprehensive coupled general circulation model. Preferential moisture increase occurs in convection zones. The upped-ante mechanism signature of dry advection from nonconvective regions is found in tropical drought regions on the margins of convection zones. Here advection in both the atmospheric boundary layer and lower free troposphere are found to be important, with an additional contribution from horizontal temperature transport in some locations. The signature of the M′ mechanism—moisture convergence due to increased moisture in regions of large mean vertical motion—enhances precipitation within strong convective regions. Ocean dynamical feedbacks can be assessed by net surface flux, the main example being the El Niño–like shift of the equatorial Pacific convection zone. Cloud–radiative feedbacks are found to oppose precipitation anomalies over ocean regions.

scholarly journals Modelling the impacts of climate change on tropospheric ozone over three centuries

2011 ◽  
Vol 11 (2) ◽  
pp. 6805-6843 ◽  
Author(s):  
G. B. Hedegaard ◽  
A. Gross ◽  
J. H. Christensen ◽  
W. May ◽  
H. Skov ◽  
...  
Keyword(s):  
Climate Change ◽  
Ozone Concentration ◽  
General Circulation ◽  
Climate Model ◽  
Transport Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
The Arctic

Abstract. The ozone chemistry over three centuries has been simulated based on climate prediction from a global climate model and constant anthropogenic emissions in order to separate out the effects on air pollution from climate change. Four decades in different centuries has been simulated using the chemistry version of the atmospheric long-range transport model; the Danish Eulerian Hemispheric Model (DEHM) forced with meteorology predicted by the ECHAM5/MPI-OM coupled Atmosphere-Ocean General Circulation Model. The largest changes in both meteorology, ozone and its precursors is found in the 21st century, however, also significant changes are found in the 22nd century. At surface level the ozone concentration is predicted to increase due to climate change in the areas where substantial amounts of ozone precursors are emitted. Elsewhere a significant decrease is predicted at the surface. In the free troposphere a general increase is found in the entire Northern Hemisphere except in the tropics, where the ozone concentration is decreasing. In the Arctic the ozone concentration will increase in the entire air column, which most likely is due to changes in transport. The change in temperature, humidity and the naturally emitted Volatile Organic Compounds (VOCs) are governing with respect to changes in ozone both in the past, present and future century.

scholarly journals Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model

2009 ◽  
Vol 6 (10) ◽  
pp. 2099-2120 ◽  
Author(s):  
P. E. Thornton ◽  
S. C. Doney ◽  
K. Lindsay ◽  
J. K. Moore ◽  
N. Mahowald ◽  
...  
Keyword(s):  
Climate Change ◽  
General Circulation Model ◽  
General Circulation ◽  
Experimental Studies ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
New Mineral ◽  
Carbon Uptake ◽  
Anthropogenic Co2 ◽  
Ocean General Circulation

Abstract. Inclusion of fundamental ecological interactions between carbon and nitrogen cycles in the land component of an atmosphere-ocean general circulation model (AOGCM) leads to decreased carbon uptake associated with CO2 fertilization, and increased carbon uptake associated with warming of the climate system. The balance of these two opposing effects is to reduce the fraction of anthropogenic CO2 predicted to be sequestered in land ecosystems. The primary mechanism responsible for increased land carbon storage under radiatively forced climate change is shown to be fertilization of plant growth by increased mineralization of nitrogen directly associated with increased decomposition of soil organic matter under a warming climate, which in this particular model results in a negative gain for the climate-carbon feedback. Estimates for the land and ocean sink fractions of recent anthropogenic emissions are individually within the range of observational estimates, but the combined land plus ocean sink fractions produce an airborne fraction which is too high compared to observations. This bias is likely due in part to an underestimation of the ocean sink fraction. Our results show a significant growth in the airborne fraction of anthropogenic CO2 emissions over the coming century, attributable in part to a steady decline in the ocean sink fraction. Comparison to experimental studies on the fate of radio-labeled nitrogen tracers in temperate forests indicates that the model representation of competition between plants and microbes for new mineral nitrogen resources is reasonable. Our results suggest a weaker dependence of net land carbon flux on soil moisture changes in tropical regions, and a stronger positive growth response to warming in those regions, than predicted by a similar AOGCM implemented without land carbon-nitrogen interactions. We expect that the between-model uncertainty in predictions of future atmospheric CO2 concentration and associated anthropogenic climate change will be reduced as additional climate models introduce carbon-nitrogen cycle interactions in their land components.

An Examination of Climate Change on Extreme Heat Events and Climate–Mortality Relationships in Large U.S. Cities

2011 ◽  
Vol 3 (4) ◽  
pp. 281-292 ◽  
Author(s):  
Scott Greene ◽  
Laurence S. Kalkstein ◽  
David M. Mills ◽  
Jason Samenow
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Large Scale ◽  
Circulation Model ◽  
The United States ◽  
Attributable Mortality ◽  
Climate Projections ◽  
Synoptic Classification ◽  
The Impact ◽  
Related Mortality

Abstract This study examines the impact of a changing climate on heat-related mortality in 40 large cities in the United States. A synoptic climatological procedure, the spatial synoptic classification, is used to evaluate present climate–mortality relationships and project how potential climate changes might affect these values. Specifically, the synoptic classification is combined with downscaled future climate projections for the decadal periods of 2020–29, 2045–55, and 2090–99 from a coupled atmospheric–oceanic general circulation model. The results show an increase in excessive heat event (EHE) days and increased heat-attributable mortality across the study cities with the most pronounced increases projected to occur in the Southeast and Northeast. This increase becomes more dramatic toward the end of the twenty-first century as the anticipated impact of climate change intensifies. The health impact associated with different emissions scenarios is also examined. These results suggest that a “business as usual” approach to greenhouse gas emissions mitigation could result in twice as many heat-related deaths by the end of the century than a lower emissions scenario. Finally, a comparison of future estimates of heat-related mortality during EHEs is presented using algorithms developed during two different, although overlapping, time periods, one that includes some recent large-scale significant EHE intervention strategies (1975–2004), and one without (1975–95). The results suggest these public health responses can significantly decrease heat-related mortality.

Impact of Orbital Parameters and Greenhouse Gas on the Climate of MIS 7 and MIS 5 Glacial Inceptions

2014 ◽  
Vol 27 (23) ◽  
pp. 8918-8933 ◽  
Author(s):  
Florence Colleoni ◽  
Simona Masina ◽  
Annalisa Cherchi ◽  
Doroteaciro Iovino
Keyword(s):  
Greenhouse Gas ◽  
General Circulation ◽  
Regional Scale ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Cold Climate ◽  
The Arctic ◽  
Orbital Parameters ◽  
The Impact ◽  
Mis 5

Abstract This work explores the impact of orbital parameters and greenhouse gas concentrations on the climate of marine isotope stage (MIS) 7 glacial inception and compares it to that of MIS 5. The authors use a coupled atmosphere–ocean general circulation model to simulate the mean climate state of six time slices at 115, 122, 125, 229, 236, and 239 kyr, representative of a climate evolution from interglacial to glacial inception conditions. The simulations are designed to separate the effects of orbital parameters from those of greenhouse gas (GHG). Their results show that, in all the time slices considered, MIS 7 boreal lands mean annual climate is colder than the MIS 5 one. This difference is explained at 70% by the impact of the MIS 7 GHG. While the impact of GHG over Northern Hemisphere is homogeneous, the difference in temperature between MIS 7 and MIS 5 due to orbital parameters differs regionally and is linked with the Arctic Oscillation. The perennial snow cover is larger in all the MIS 7 experiments compared to MIS 5, as a result of MIS 7 orbital parameters, strengthened by GHG. At regional scale, Eurasia exhibits the strongest response to MIS 7 cold climate with a perennial snow area 3 times larger than in MIS 5 experiments. This suggests that MIS 7 glacial inception is more favorable over this area than over North America. Furthermore, at 239 kyr, the perennial snow covers an area equivalent to that of MIS 5 glacial inception (115 kyr). The authors suggest that MIS 7 glacial inception is more extensive than MIS 5 glacial inception over the high latitudes.

scholarly journals Challenges in water resources of Lagos mega city of Nigeria in the context of climate change

2019 ◽  
Vol 11 (4) ◽  
pp. 1067-1083 ◽  
Author(s):  
Mohammed Sanusi Shiru ◽  
Shamsuddin Shahid ◽  
Suleiman Shiru ◽  
Eun Sung Chung ◽  
Noraliani Alias ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
General Circulation ◽  
Salt Water ◽  
Circulation Model ◽  
Environmental Crisis ◽  
Salt Water Intrusion ◽  
Climate Projections ◽  
Environmental Challenges ◽  
Groundwater Overdraft

Abstract This study assesses the water resources and environmental challenges of Lagos mega city, Nigeria, in the context of climate change. Being a commercial hub, the Lagos population has grown rapidly causing an insurmountable water and environmental crisis. In this study, a combined field observation, sample analysis, and interviews were used to assess water challenges. Observed climate, general circulation model (GCM) projections and groundwater data were used to assess water challenges due to climate change. The study revealed that unavailability of sufficient water supply provision in Lagos has overwhelmingly compelled the population to depend on groundwater, which has eventually caused groundwater overdraft. Salt water intrusion and subsidence has occurred due to groundwater overexploitation. High concentrations of heavy metals were observed in wells around a landfill. Climate projections showed a decrease in rainfall of up to 140 mm and an increase in temperature of up to 8 °C. Groundwater storage is projected to decrease after the mid-century due to climate change. Sea level rise will continue until the end of the century. As the water and environmental challenges of Lagos are broad and the changing characteristics of the climate are expected to intensify these as projected, tackling these challenges requires a holistic approach from an integrated water resources management perspective.

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