The Synthesis Report of the IPCC Fourth Assessment Report (AR4) was launched in Spain on November 17, 2007. The report synthesizes the recent advances in physical sciences, impacts, adaptation and mitigation of climate change by interlinking the greenhouse gas (GHG) emission, atmospheric GHG concentration with surface temperature. The report indicates whether the negative impacts of climate change could be minimized largely depends upon the efforts and investment in global GHG emission control in the future 20 to 30 years. It is urgent for mankind to take prompt actions in reducing the GHG emission. The synthesis report of IPCC AR4 promotes scientific guidance to the social-economy policies made by governments worldwide and the international negotiation regarding climate change.

The impact of climate warming on warm and rich-ice permafrost must be considered for engineering design in the Qinghai-Tibet Railway. In order to face climate warming and solve the roadbed stability in the regions of warm and rich-ice permafrost, the new design idea of cooling embankment to reduce the permafrost temperature under the embankment was proposed. Engineering measures controlling heat conduction, radiation and convection were proposed to achieve the objective of reducing permafrost temperature and mitigating the impact of climate warming, ensuring the roadbed stability in permafrost regions to the largest extent.

Key climate change mitigation technologies were outlined as a brief introduction. Some organizations have paid more attention to climate change mitigation technologies recently. Some important strategy plans were proposed by International Energy Agency (IEA), World Wide Fund for Nature (WWF), Global Energy Technology Strategy Program (GTSP), World Resources Institute (WRI), EU and United States. After a synthetical analysis on these strategy plans, a blue map of international climate change mitigation technology was described. The prospective contributions of climate change technologies for mitigating global warming were addressed. And also, some important related aspects that may impact the effort of climate change technology practices, efficiency, safety, environment, and public acceptability, etc., were put forward at the end of the paper.

Some studies have shown that the positive radiative forcing (0.1 W/m2) caused by black carbon (BC) could not only be an important impact factor on global warming, but also affect multiple parameters of the climate system, such as atmosphere circulation, precipitation, etc. Recently, the research of BC has extended to the fields of carbon cycle, and the interactions of BC aerosols with the abnormity of atmosphere circulation, and of the surface of BC particles with active gas species, etc. New progresses in the above research fields are reviewed in this paper.

Temperature and precipitation are the two main variables in climate change. Spatial-temporal resolutions of temperature and precipitation, and climate variability are summarized and discussed in this paper. Recent 100-year datasets are used to reveal quasi-20-year and quasi-70-year oscillations in eastern China, as well as precipitation pattern shift in China. Besides,70- to 80-year oscillations exist in eastern China, based on 500 years and 1000 years proxy and observation records. Finally, researches for future on climate change in China should be improved on data development, regularity and mechanism, prediction and service.

Daily maximum rainfall (as an index for extreme precipitation) was higher in the Jialing River basin, Taihu Lake area, the mid-lower main stream section in the 1990s, and there was a good relationship between ECHAM5/MPI-OM simulations and observed data about extreme precipitation. Under the A2, A1B, and B1 greenhouse gases emission scenarios of SRES, the extreme precipitation projected in 2000-2050 was compared, the daily maximum rainfall will be dominated by increasing trends in the upper reaches of the Yangtze River basin, with the largest magnitude of increasing tendency under the A2 scenario and the least magnitude under the A1B scenario before 2020. As for the middle and lower reaches, the daily maximum rainfall will increase prominently before 2025, and then decline slightly. There might be more floods in the south of the Yangtze River and more droughts in the north in the future.

Based on the tropical cyclone track dataset in the Northwestern Pacific from China Meteorological Administration, variations in frequencies and intensities of tropical cyclones (TCs) in the western North Pacific, affecting-China tropical cyclones (ACTCs) and landfall ones (LTCs) reaching typhoon intensity during 1957-2004 were studied. Frequencies of strong tropical cyclones showed significant decreasing trends from 1957 to 2004 and the linear trend was much larger when the intensity was strong. There were no increasing or decreasing trends in the ratios of strong tropical cyclones reaching typhoon intensity, while those reaching strong typhoon and super typhoon showed decreasing trends during 1957-2004. The maximum intensities of TCs, ACTCs and LTCs had all decreased during the period of 1957-2004. The mean intensities of TCs and ACTCs illustrated decreasing trends and the mean intensity of LTCs achieving typhoon intensity also showed decreasing trends.

Based on Shenzhen's temperature observations from 1953 to 2005, the temperature time series were represented with average, maximum and minimum temperatures. By using the statistical method, linear analysis and Mann-Kendall method, the change in temperature for Shenzhen was studied, and by contrasting the frequency and intensity during different periods before and after 1987, the change characteristics of disastrous weather and climate events were discussed. The results show that under the climate warming and the rapid development of Shenzhen, except the frequency of heavy rain events the extreme precipitation has become more serious after the 1990s. The annual number of thunderstorm days has decreased, and the haze phenomenon aggravated increasingly. The high temperature days and continuous high temperature events have obviously increased, while the low temperature and the low temperature with rainy events decreased. The frequency of the tropical cyclone influencing Shenzhen has decreased, but its impact on heavy rainfall become more serious.

Based on analyses of the meteorological data at 29 meteorological stations in Qinghai Province from 1959 to 2003, the corrected Palmer drought severity index (PDSI) was calculated and analyzed. The results show that the PDSI is more objective in comparison with Z index in dryness/wetness monitoring. Most of droughts were light in Qinghai, the interannual alternations of dryness/wetness in summer and autumn were more frequent with larger change ranges in comparison with winter and spring. The drought trend in autumn was the severest, and the probability of light drought was the largest in winter and spring. Moreover, the total drought area in Qinghai Province decreased in spring, the light drought area increased in summer, but the medium and heavy drought area decreased, and the severe drought area increased in winter and autumn during 1959-2003.

Wavelet analysis was used in this paper to study the multi-time-scale structure of the temperature and precipitation series in Guangxi Zhuang Autonomous Region in the recent century, and the coupled characteristics between the sea surface temperature of Nino3 region and the two series mentioned above were diagnosed by using singular cross-spectrum analysis (SCSA). The results indicate that the ascending trend accompanied with the quasi-biennial oscillations dominated in the temperature variation while the precipitation showed a descending trend with the 32-year and quasi-biennial oscillations. Guangxi climate was characteristic of dry-cold from 1884 to the early 1910s, wet-cold from the early 1910s to around 1930, wet-warm from around 1930 to the late 1950s, and dry-warm from the late 1950s to the early 1990s. The 3-7-year oscillation component of ENSO exerted marked influence on Guangxi climate. The coupled variations of SST in the Nino3 region and Guangxi climate were reflected on the decadal scale for temperature and interannual scale for precipitation.

Based on historical records of precipitation, temperature, sunshine duration and wind speed at 5 stations including Chongqing, Fuling, Wanzhou, Fengjie and Yichang, the changes in these climate elements in summer over the Three Gorges area during 1951-2006 were analyzed. Results show that the regional average of summer precipitation had an overall increasing trend and a jump change occurred in the end of the 1970s. Meanwhile, maximum temperature, mean temperature, sunshine duration and water surface evaporation had a declining trend and a jump change happened in the early 1980s. At the same time, minimum temperature and wind speed did not have an obvious trend. All of these variables showed obvious decadal variations.

Based on the air temperature data of Heilongjiang Province and Harbin City, the centurial variation characteristics of air temperature in Harbin were analyzed and the trend of future 50 years was projected by using the simulations of five climate models. Results show that the annual temperature in Harbin has increased by 1.4 ℃ in the 120 years of 1881-2001, and Heilongjiang climate has become warm remarkably since the 1980s, and the mean temperature of 1981-2000 over the whole Heilongjiang Province risen by 1.0 ℃ relative to that of 1951-1980. Projected results show that the temperature would rise up by 1.94℃ in 2030 and by 2.42 ℃ in 2050 in comparison with the mean temperature of 1961-1990. The accumulated temperature zone was projected to move northward by 2.5° and 5.0° latitudes in 2030 and 2050, respectively, relative to the mean position of 1951-1980. Effects of climate warming on major crops (paddy, corn, soybean and wheat) will be prominent, and except soybean other crop誷 yields will decline due to shorter growth period and earlier maturation. So the crop structure adjustment is necessary to address climate change.

The sustainability of wind energy over Hexi corridor was explored by using the wind intensive observation data of stations and wind-towers during 1970-2004. Results show that the wind speed was generally stable in the period. It is projected based on the prediction of future wind speed and the unique geographic and humanistic environments that the wind speed will be still relatively stable before 2025, and the wind energy resource in the corridor has a good sustainability.