With rapid socio-economic development over the past three decades in China, adverse effects of human activities on the natural ecosystem are particularly serious in arid regions where landscape ecology is fragile due to limited water resources and considerable interannual climate variability. Data on land use, surface and ground water, climate, gross domestic product (GDP) per capita from the middle Heihe River Basin were used to (i) examine changes in water consumption, land use composition, and vegetation cover; (ii) evaluate the effectiveness of short-term management strategies for environmental protection and improvement, and (iii) apply and extend the environmental Kuznets curve (EKC) framework to describe the relationship between economic development and environmental quality in terms of the normalized difference vegetation index (NDVI). The results showed that with rapid development of agriculture and economy, land use change for the period 1986–2000 was characterized by the expansion of constructed oases, considerable contraction of oasis-desert transitional zone and natural oases. This has led to a decrease in ecosystem stability. Since 2001, effective basin management has brought about improved environment conditions, with a more optimal hierarchical structure of vegetation cover. The original EKC model could not explain most of the observed variation in NDVI (R2 = 0.37). Including additional climate variables, the extended EKC model to explain the observed NDVI was much improved (R2 = 0.78), suggesting that inclusion of biophysical factors is a necessary additional dimension in the relationship between economic development and environmental quality for arid regions with great climate variability. The relationship between GDP per capita and NDVI, with the effect of precipitation and temperature taken into consideration, was adequately described by an N-shaped curve, suggesting that the relationship between society and the environment followed a process of promotion, contradiction, and coordination.
oped countries. They illustrate how multiple driving forces interact to determine the proximate human causes of global change and why systematic social analysis is necessary for understanding how human actions cause it. In the section that follows, we discuss the interrelationships among the driving forces at a more theoretical level.
In 1985, the head of the British Antarctic Survey, Joseph Farman, reported that his team had discovered a heretofore unobserved atmospheric phenomenon: a sudden springtime thinning of the ozone layer over Antarctica, allowing ultraviolet radiation to reach the ground much more intensely than was ordinarily the case (Farman et al., 1985). Subsequent scientific investigations soon led to what is now the most widely accepted explanation of what was happening. Chlorine compounds derived mostly from chlorinated fluorocarbon gases (CFCs), mass-produced by industrial societies for a variety of purposes, reacted in the stratospheric clouds over Antarctica during the cold, dark, winter months to produce forms of chlorine that rapidly deplete stratospheric ozone when the first rays of the Antarctic spring sunlight arrive (Solomon, 1990). Massive destruction of ozone followed very quickly, until natural circulation patterns replenished the supply and closed what came to be known as ''the ozone hole.'' Human activities in distant areas of the planet had brought a sudden and potentially devastating change to the Antarctic and its ecosystems, a change that did not bode well for the ozone layer in other parts of the planet (Stolarski, 1988).
To understand this event and the political controversies that followed in its wake, one has to reach back through almost a century's worth of history, long before CFCs existed. Until almost the end of the nineteenth century, refrigeration was a limited technology, based almost entirely on natural sources of supply. Urban Americans who could afford to drink chilled beverages relied on metropolitan ice markets, which cut ice from local ponds in the winter and stored it in warehouses for use during the warm months of the year. Breweries and restaurants were the heaviest users of this stored winter ice, which was sometimes shipped hundreds of miles to provide refrigeration. Boston ice merchants, for instance, were regularly delivering ice to consumers in Charleston, South Carolina, and even the Caribbean by the fourth decade of the nineteenth century (Hall, 1888; Cummings, 1949; Lawrence, 1965).