CHINA’S WILD WEST - Wildlife Conservation in China: Preserving the Habitat of China's Wild West - page 32

have short and cold growing seasons to begin with. Is such a warming likely to exacer-
bate desiccation or promote more vigorous growth? At least on the Tibetan Plateau, it is
possible that warming, despite its overall dangers for humanity, may enhance grassland
growth. A group of Japanese and Chinese scientists speculated that “climate warming may
promote vegetation growth on the Tibetan Plateau.” 26 More persuasively, a group from
Beijing University seems to have data that support this: based on remote sensing data
during the period 1982-99, they documented an increase of roughly 1 percent annually
in net primary productivity as averaged over all of Qinghai and Tibet. 27
One additional potential interaction between grassland degradation in western China's
coldest regions and recent climate change that deserves consideration is the reduction in
extent and depth of permafrost. There are reliable data that overall warming has reduced
the extent of permafrost that underlies much of the Tibetan Plateau and nearby moun-
tain ranges at least seasonally, and increased the depth of its active layer (i.e., ground
that freezes and thaws seasonally). These trends would tend to allow surface water to
infiltrate into soils too deeply to be useful for plants, thus producing drier soils even
without desiccation from the atmosphere. There are weak signals that this may indeed
be occurring, at least locally. But even here, the issue is far from simple. Data collected
and models constructed thus far suggest that such effects should be observed mostly in
the highest, coldest sedge-dominated meadows (i.e., pastoral summer ranges), but much
grassland degradation has occurred on lower elevation winter ranges. Further, degradation
of permafrost and warmer surface soils can be caused by vegetation removal (i.e., human
activities) as well as by globally-initiated warming. 28 While plausible, studies have yet to
show that site-specific, climate-induced permafrost reduction is an important contributor
to range degradation (although future studies might).
If there is so little clear evidence for a general drying trend in western China, why,
then, does the claim so often reappear in Chinese documents? There appear to be three
reasons. First, some publications provide no data themselves but simply accept and repeat
the conclusions of other papers (the details of which are hidden from the reader). Writing
in the Swedish publication Ambio, Wang Xiuhong and Fu Xiaofeng uncritically repeated
the claim that summer precipitation had decreased by 0.65mm/year since 1961 in southern
Qinghai in concluding that “Regional climate change is not suitable for the growth of
alpine meadows.” 29 Yang and colleagues asserted, “in the past decades, due to the climate
warming, the climate condition [on the] . . . Tibet Plateau has been relatively dry,” but
failed to back this up with any citation of data or analyses. 30 Similarly, a livestock special-
ist working for a local livestock development center in Lhasa concluded that “climatic
warming increases evaporation, which results in a negative trend of drought condition,
and a worse environment for grass growth,” without citing references on temperature,
precipitation, or their interaction on vegetation in the area studied. 31 A press release issued
in September 2004 by China Science and Technology Daily gained considerable attention
by proclaiming the “Drying of the Qinghai-Tibet Plateau,” based on a general increase in
temperature of 0.336°C per decade (a figure that accords generally with other published
information), but then providing no data at all to link the temperature rise (which, as
explained earlier, was primarily an increase in winter minimums) with rangeland desic-
cation. The problem was later compounded when this press release was translated into