China is the world's most populous country and a major emitter of greenhouse gases. Consequently, much research has focused on China's influence on climate change but somewhat less has been written about the impact of climate change on China. China experienced explosive economic growth in recent decades, but with only 7% of the world's arable land available to feed 22% of the world's population, China's economy may be vulnerable to climate change itself. We find, however, that notwithstanding the clear warming that has occurred in China in recent decades, current understanding does not allow a clear assessment of the impact of anthropogenic climate change on China's water resources and agriculture and therefore China's ability to feed its people. To reach a more definitive conclusion, future work must improve regional climate simulations-especially of precipitation-and develop a better understanding of the managed and unmanaged responses of crops to changes in climate, diseases, pests and atmospheric constituents.

The purpose of this study was to evaluate 10 process-based terrestrial biosphere models that were used for the IPCC fifth Assessment Report. The simulated gross primary productivity (GPP) is compared with flux-tower-based estimates by Jung et al. [Journal of Geophysical Research 116 (2011) G00J07] (JU11). The net primary productivity (NPP) apparent sensitivity to climate variability and atmospheric CO2 trends is diagnosed from each model output, using statistical functions. The temperature sensitivity is compared against ecosystem field warming experiments results. The CO2 sensitivity of NPP is compared to the results from four Free-Air CO2 Enrichment (FACE) experiments. The simulated global net biome productivity (NBP) is compared with the residual land sink (RLS) of the global carbon budget from Friedlingstein et al. [Nature Geoscience 3 (2010) 811] (FR10). We found that models produce a higher GPP (133 ± 15 Pg C yr(-1) ) than JU11 (118 ± 6 Pg C yr(-1) ). In response to rising atmospheric CO2 concentration, modeled NPP increases on average by 16% (5-20%) per 100 ppm, a slightly larger apparent sensitivity of NPP to CO2 than that measured at the FACE experiment locations (13% per 100 ppm). Global NBP differs markedly among individual models, although the mean value of 2.0 ± 0.8 Pg C yr(-1) is remarkably close to the mean value of RLS (2.1 ± 1.2 Pg C yr(-1) ). The interannual variability in modeled NBP is significantly correlated with that of RLS for the period 1980-2009. Both model-to-model and interannual variation in model GPP is larger than that in model NBP due to the strong coupling causing a positive correlation between ecosystem respiration and GPP in the model. The average linear regression slope of global NBP vs. temperature across the 10 models is -3.0 ± 1.5 Pg C yr(-1) °C(-1) , within the uncertainty of what derived from RLS (-3.9 ± 1.1 Pg C yr(-1) °C(-1) ). However, 9 of 10 models overestimate the regression slope of NBP vs. precipitation, compared with the slope of the observed RLS vs. precipitation. With most models lacking processes that control GPP and NBP in addition to CO2 and climate, the agreement between modeled and observation-based GPP and NBP can be fortuitous. Carbon-nitrogen interactions (only separable in one model) significantly influence the simulated response of carbon cycle to temperature and atmospheric CO2 concentration, suggesting that nutrients limitations should be included in the next generation of terrestrial biosphere models.

No abstract

2018) Trophic state assessment of global inland waters using a MODIS-derived Forel-Ule index.Abstract 13 Eutrophication of inland waters is considered a serious global environmental 14 problem. Satellite remote sensing (RS) has been established as an important source of 15 information to determine the trophic state of inland waters through the retrieval of 16 optically active water quality parameters such as chlorophyll-a (Chl-a). However, the 17 use of RS techniques for assessment of the trophic state of inland waters on a global 18 scale is hindered by the performance of retrieval algorithms over highly dynamic and 19 complex optical properties that characterize many of these systems. In this study, we 20 developed a new RS approach to assess the trophic state of global inland water bodies 21 based on Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and the 22Forel-Ule index (FUI). First, the FUI was calculated from MODIS data by dividing 23 2 natural water colour into 21 indices from dark blue to yellowish-brown. Then the 24 relationship between FUI and the trophic state index (TSI) was established based on in-25 situ measurements and MODIS products. The water-leaving reflectance at 645 nm band 26 was employed to distinguish coloured dissolved organic matter (CDOM)-dominated 27 systems in the FUI-based trophic state assessment. Based on the analysis, the FUI-based 28 trophic state assessment method was developed and applied to assess the trophic states 29 of 2058 large inland water bodies (surface area > 25 km 2 ) distributed around the world 30 using MODIS data from the austral and boreal summers of 2012. Our results showed 31 that FUI can be retrieved from MODIS with a considerable accuracy (92.5%, R 2 =0.92) 32 by comparing with concurrent in situ measurements over a wide range of lakes, and the 33 overall accuracy of the FUI-based trophic state assessment method is 80.0% (R 2 = 0.75) 34 validated by an independent dataset. Of the global large water bodies considered, 35 oligotrophic large lakes were found to be concentrated in plateau regions in central Asia 36 and southern South America, while eutrophic large lakes were concentrated in central 37 Africa, eastern Asia, and mid-northern and southeast North America. 38

There is profound interest in knowing the degree to which China's institutions are capable of protecting its natural forests and biodiversity in the face of economic and political change. China's 2 most important forest-protection policies are its National Forest Protection Program (NFPP) and its nationallevel nature reserves (NNRs

No abstract

Global crop production has doubled since the Green Revolution on the average, but crop yield has stagnated or even declined in some regions. In the same time, food demand has highly increased due to population growth and higher living standards. The use of pesticides and mineral fertilizers has improved crop yields but also contaminated food and the environment, thus leading to a global food crisis. Here, we reviewed the historical trends of global pesticide and fertilizer application, cereal yields, and production. Our main findings are as follows: (1) fertilizer and pesticide consumption increased for 35-40 % of the countries; (2) cereal production in 38 % of countries and yields in 47 % of countries either stagnated or decreased from 1961 to 2010; (3) countries showing stagnated or decreased yields are countries with low gross domestic product per capita, mainly situated in Africa, South America, and West Asia. Our findings thus evidence a global imbalance in food production and the usage of fertilizers and pesticides.

No abstract