Climate Change Scenario Analysis in the Future Over Climate Change Scenario Analysis in the Future Over western of China Ying Xu Xuejie Gao Yun Gao National Climate Centre, China AIACC workshop, Philippines Nov. 04, 2004

Outline Part I: Possible Climate Change in Western China due to human activities by AOGCM Part II: Possible Climate Change in Western China due to human activities by RegCM (1) Climate Change in the future over China due to GHG (2) Impacts of Land-use Change on Climate in China Part III: next step work plan

Part I : Possible Climate Change in Western China due to human activities by GCM

Models Description A2: SRES scenario — A2 B2: SRES scenario — B2

The change of temperature over western of China in 21 st century (unit: ℃ ) A2 B2 Red: 5 model mean Dark blue: Hadley Sky blue: CCSR Green: CCCma Yellow: CSIRO Pink: NCC/IAP For 5 models mean, the temperature will increase about 8 ℃ under A2 scenario in the end of 21st century, increasing is about 5 ℃ under B2 scenario.

Annual change of temperature over western China (Unit : ℃ )

The change of precipitation over western of China in 21 st century (unit: %) A2 B2 Red: 5 model mean Dark blue: Hadley Sky blue: CCSR Green: CCCma Yellow: CSIRO Pink: NCC/IAP For 5 models mean, the Pr. will increase about 10% under A2 scenario in the end of 21st century, it will increase 8% under B2 scenario.

Annual change of precipitation over westarn China (Unit : %)

The seasonal precipitation change over western of China in 21 st century (unit: %) A2B2 Red: annual mean Dark blue: Spring Sky blue: Summer Green: Autumn Yellow: Winter The Pr. increasing is greater in winter and spring, change is little in summer and autumn under A2 and B2 scenarios.

The distribution of annual mean temperature change over western of China (2070~2099) (unit: ℃）

The distribution of annual mean precipitation change over western of China (2070~2099) (unit: % ）

Warming is obviously in western of China, warming is exceed China mean value. Compared A2 scenario with B2, it shows a majority of warming under A2 scenario than B2, So depend on different greenhouse gases emission scenario, the climate will have different change in the future. The annual mean precipitation will increase in the end of 21st century. For different season, most obvious rainfall increase occurs in winter and spring ， the increase in autumn and summer are little. For the spacial distribution, The precipitation has an increasing trend, especially in the Western China and North- western China region, while the increase is not so obvious in the Southwestern China Part I : Conclusions

Part II Possible Climate Change in Western China due to the effect of human activities by RegCM

Observed CO 2 Concentration GCM Run 5 year RCM CTL 12 h 5 year GCM CTL 5 year RCM 12h 5 year GCM Model output was interpolated to 160 stations of China (1) Possible Climate Change in China Part Ⅱ

Annual mean Ts Change in China (unit: ℃ ) Increase all over the area, with a higher increase in North China, it is obviously in western of China Part Ⅱ

Annual mean Pr Change in China (unit: %) Increase in most areas, higher in NW Part Ⅱ

Change of Annual mean rain days (%) ● ： -20 ～ 0 ● ： 0 ～ 10 ■ ： 10 ～ 20 Part Ⅲ

Conclusions : Ts in China will remarkably rises by 2.5 o C, with higher increase western of China Pr will also increase by about 25%. Increase of rain days in western of China. Part Ⅱ

(2) Impacts of Land-use Change on Climate in China Land-use changes a lot in China for its long agriculture history and present big population pressure Part Ⅳ

Landuse Change in China ▼ : tree → shrub ▲ : tree → irrigated crop farming ● : semi desert → desert ■ : tree → crop/mixed farming ◆ : grass → rop/mixed farming Areas of no change: 2: short grass 3: evergreen needleleaf tree 5: deciduous broadleaf tree 6: evergreen broadleaf tree 7: tall grass 8: desert Part Ⅳ

Experiment Design: 5 year RegCM2 run driven by 5 year CTL run of AOGCM Exp 1. With potential vegetation cover Exp 2. With present vegetation cover Exp2 - Exp1, was thought as the impact of landuse change on climate Plotted and analysed in 160 station positions Part Ⅳ

Change of Annual mean Ts ( ℃ ) ● ： -1.5 ～ 0 ■ ： 0 ～ 1.5 Part Ⅳ

Change of Annual mean Pr (%) ■ ： <-20% ■ ： -20% ～ 0 ● ： 0 ～ 20% ● ： >20% Part Ⅳ Dotted spots are stations with change passed 90% t - test, same as below

Change of Summer Tmax ( ℃ ) ● ： -2.4 ～ 0 ■ ： 0 ～ 2.4 ■ ： 2.5 ～ 4.4 ◆： >4.5 Part Ⅳ

Change of Winter Tmin ( ℃ ) ● ： <-2.4 ● ： -2.4 ～ 0 ■ ： 0 ～ 2.4 ■ ： >2.5 Part Ⅳ

Change of Annual mean Soil moisture (%) ■ ： -20 ～ 0 ● ： 0 ～ 20 Part Ⅳ

Conclusions : Current Landuse in China, may caused: Less rainfall in NW; Temperatures increasing is in Sichuan basin and part of NW area; Increasing of summer Tmax in many places, Increasing of winter Tmin in NW; Decrease of Soil moisture in many places, including western of China; Same landuse can cause different climate effect, depends on the geography character in the area. Part Ⅳ

Part III Next step work Using dynamical downscaling is going to coutinue simulate various episodes in 21st Century with the regional climate model with the boundary conditions provided by the global model. To apply the simulation results of the global and regional climate models into a hydrological model, to simulate the future hydrological cycle over the Western of China. To provide the projected climate change simulations over the Northwestern China to the relative research groups for impacts and adaption.

The End