The Change of North China Climate in Transient Simulations Using the IPCC SRES A2 and B2 Scenarios with a Coupled Atmosphere-Ocean General Circulation Model

This paper applies the newest emission scenarios of the sulfur and greenhouse gases, namely IPCC SRES A2 and B2 scenarios, to investigate the change of the North China climate with an atmosphere-ocean coupled general circulation model. In the last three decades of the 21st century, the global warming enlarges the land-sea thermal contrast, and hence, causes the East Asian summer (winter) monsoon circulation to he strengthened (weakened). The rainfall seasonality strengthens and the summer precipitation increases significantly in North China. It is suggested that the East Asian rainy area would expand northward to North China in the last three decades of the 21st century. In addition, the North China precipitation would increase significantly in September. In July, August, and September, the interannual variability of the precipitation enlarges evidently over North China, implying a risk of flooding in the future.

A Coupled Model Study on the Intensification of the Asian Summer Monsoon in IPCC SRES Scenarios

The Asian summer monsoon is an important part of the climate system. Investigating the response of the Asian summer monsoon to changing concentrations of greenhouse gases and aerosols will be meaningful to understand and predict climate variability and climate change not only in Asia but also globally. In order to diagnose the impacts of future anthropogenic emissions on monsoon climates, a coupled general circulation model of the atmosphere and the ocean has been used at the Max-Planck-Institute for Meteorology. In addition to carbon dioxide, the major well mixed greenhouse gases such as methane, nitrous oxide, several chlorofluorocarbons, and CFC substitute gases are prescribed as a function of time. The sulfur cycle is simulated interactively, and both the direct aerosol effect and the indirect cloud albedo effect are considered. Furthermore, changes in tropospheric ozone have been pre-calculated with a chemical transport model and prescribed as a function of time and space in the climate simulations. Concentrations of greenhouse gases and anthropogenic emissions of sulfur dioxide are prescribed according to observations （1860-1990） and projected into the future （1990-2100） according to the Scenarios A2 and B2 in Special Report on Emissions Scenarios （SRES, Nakcenovic et al., 2000） developed by the Intergovernmental Panel on Climate Change （IPCC）. It is found that the Indian summer monsoon is enhanced in the scenarios in terms of both mean precipitation and interannual variability. An increase in precipitation is simulated for northern China but a decrease for the southern part. Furthermore, the simulated future increase in monsoon variability seems to be linked to enhanced ENSO variability towards the end of the scenario integrations.

Hydrological Processes and Climate Change in Hydrographic Regions of Brazil

The objective of this work is to assess the impacts of IPCC AR5 climate change scenarios on water resources and hydrological processes across the entire Brazilian territory. Hydrological simulations are carried out in total drainage area of about 11,535,645 km2 and average stream flow of about 272,460 m3/s. The study area consists of different climates and land covers such as the Amazon Forest, Northeast Semiarid, Brazilian Savannah, Pantanal wetlands and temperate climate in the South. The atmospheric forcing to drive the large-scale hydrological model MGB-IPH is derived from the downscaling of two global climate models, HadGEM2-ES and MIROC5, by the Eta Regional Climate Model, at 20 km resolution. The Eta model provided the downscaling of the baseline (1961-1990) and three time-slices (2011-2040, 2041-2070 and 2071-2099). These projections adopted two emission scenarios, the RCP 4.5 and RCP 8.5. The change in the average and extremes of precipitation, evapotranspiration, rates of river discharge and soil moisture were assessed. The simulations showed the response of the hydrographic regions due to change of precipitation and potential evapotranspiration in the scenarios. Water availability decreases in almost the entire study area (exception for the South) and the major basins for hydroelectric power generation are affected. The Northwest, Amazon and a small area along the Northeast Atlantic coast exhibited intensification of the extremes discharges, where the anomaly is positive for high-flow (Q10) and negative for low-flow (Q95). The results highlight the most climatic sensitive regions in Brazil in terms of hydrological variables and water resources.

Numerical Simulation of Regional Climate Change under IPCC A2 Scenario in China

Regional climate change in China under the IPCC A2 Scenario, was simulated for continuous 10-yr period by the MM5V3, using the output of an IPCC A2 run from CISRO Mark 3 climate system model as lateral and surface boundary conditions. The regional climate change of surface air temperature, precipitation, and circulation were analyzed. The results showed that （1） the distribution of mean circulation, surface air temperature, and precipitation was reproduced by the MM5V3. The regional climate model was capable to improve the regional climate simulation driven by GCM. （2） The climate change simulation under the IPCC A2 Scenario indicated that the surface air temperature in China would increase in the future, with a stronger trend in winter and the increasing magnitude from the south to the north. The precipitation distribution would appear a distinct change as well. Annual mean precipitation would remarkably increase in Northeast China, Yangtze and Huaihe River Valley, and the south area of the valley. Meanwhile, rainfall would show a decreasing trend in partial areas of North China, and many regions of Southwest and Northwest China.