| 英文摘要: |
The rate of increase of atmospheric carbon dioxide (CO2)
over the past 70 years is nearly 100 times larger than
that at the end of the last ice age. As far as direct and
proxy observations can tell, such abrupt changes in
the atmospheric levels of CO2 have never before been
seen. The figure on the left shows the CO2 atmospheric
content at the end of the last ice age, and the figure
on the right shows recent atmospheric CO2 content
[1]. The thin grey area on the left figure, which looks
like a vertical line, corresponds to a similar period of
70 years as depicted on the right figure for modern
times. Rapidly increasing atmospheric levels of CO2 and
other greenhouse gases (GHGs) have the potential to
initiate unpredictable changes in the climate system,
because of strong positive feedbacks, leading to severe
ecological and economic disruptions. The WMO Global
Atmosphere Watch (GAW) Programme tracks the
changing levels of GHGs and serves as an early warning
system by detecting changes in these key atmospheric
drivers of climate change. |
