The Greening of China as Seen from Satellites

According to Peng et al. (2011), "using satellite-derived normalized difference vegetation index (NDVI) datasets, previous studies have found that vegetation growth significantly increased in most areas of China during the period 1982-99 and that the increased vegetation growth was significantly correlated with increased temperature (e.g., Zhou et al., 2001; Piao et al., 2003)." In addition, they report that "the increased temperature boosted vegetation growth through an increase in growing season length and enhanced photosynthesis (e.g., Zhou et al., 2001; Slayback et al., 2003; Piao et al., 2006)."

Against this backdrop Peng et al. used NOAA/AVHRR NDVI composites at a spatial resolution of 0.083° and 15-day intervals that were produced by the Global Inventory Modeling and Mapping Studies (GIMMS) program, as described by Tucker et al. (2005), to explore vegetation activity over the whole of China for the period 1982-2010, noting that "the GIMMS NDVI datasets have been corrected to minimize the effects of volcanic eruptions, solar angle and sensor errors and shifts," as described by Zhou et al. (2001) and Slayback et al. (2003), and citing the fact that these datasets have also proved to be "one of the best products to depict the temporal change of vegetation growth," as demonstrated by Beck et al. (2011).

According to the nine researchers who conducted the study, at the national scale, for the average growing season (April-October), a linear regression model predicts a significant increasing NDVI trend of 0.0007/year from 1982 to 2010, with an R² value of 0.40 and P < 0.001. And they say that they also found increasing trends for all three sub-sets of the growing season: April-May, June-August and September-October. Yet again, therefore, the Greening of the Earth continues,compliments of the growth-enhancing and water-conserving effects of atmospheric CO₂ enrichment, periodic global warming, and the ever-improving husbandry techniques of man.

Additional References
Beck, H.E., McVicar, T.R., van Dijk, A.I.J.M., Schellekens, J., de Jeu, R.A.M. and Bruijnzeel, L.A. 2011. Global evaluation of four AVHRR-NDVI data sets: intercomparison and assessment against Landsat imagery. Remote Sensing of the Environment 115: 2547-2563.

Piao, S.L., Fang, J.Y., Zhou, L.M., Ciais, P. and Zhu, B. 2006. Variations in satellite-derived phenology in China's temperate vegetation. Global Change Biology 12: 672-685.

Piao, S.L., Fang, J.Y., Zhou, L.M., Guo, Q.H., Henderson, M., Ji, W., Li, Y. and Tao, S. 2003. Interannual variations of monthly seasonal normalized difference vegetation index (NDVI) in China from 1982 to 1999. Journal of Geophysical Research 108: 4401-4413.

Slayback, D.A., Pinzon, J.E., Los, S.O. and Tucker, C.J. 2003. Northern Hemisphere photosynthetic trends 1982-99. Global Change Biology 9: 1-15.

Tucker, C.J., Pinzon, J.E., Brown, M.E., Slayback, D.A., Pak, E.W., Mahoney, R., Vermote, E.F. and El Saleous, N. 2005. An extended AVHRR 8-km NDVI dataset compatible with MODIS and SPOT vegetation NDVI data. International Journal of Remote Sensing 26: 4485-4498.

Zhou, L.M., Tucker, C.J., Kaufmann, R.K., Slayback, D., Shabanov, N.V. and Myneni, R.B. 2001. Variations in northern vegetation activity inferred from satellite data of vegetation index during 1981 to 1999. Journal of Geophysical Research 106: 20,069-20,083.