单选题
For the first time in the scientific community,
there is total agreement that the activity of humans is at least partly
responsible for the rise of global temperature — specifically the emission of
greenhouse gases like carbon dioxide, which is released by the burning of wood,
coal and petroleum products. Reducing harmful emissions is just one area in
which the United Nations Intergovernmental Panel is decidedly optimistic. For
one thing, in the short term it might not prove that difficult. Efficiency
improvements alone could cut energy needs by as much as 30 percent at virtually
no extra cost and, in developed countries, emission reductions of up to 60
percent "are technically feasible". In the longer term, harmful emissions will
be reduced as the world changes over to cheaper, less environmentally damaging
energy sources. So, if it is economically and technically
feasible to reduce harmful emissions, why is almost nothing being done? There
are two main reasons. The first stems from the uncertainty about how hot the
planet is going to get. The current estimate is extremely broad — between 0.8
and 3.5 degrees Celsius by 2100. If the former prediction is accurate, it may be
that we can adapt to it without difficulty. If, on the other hand, the latter is
closer to reality, a complete rethink of the world's energy supplies is already
long overdue. This leads directly to the second problem — the
time scale involved. It is difficult to get people to act when predictions may
take between 50 and 100 years to materialize. For politicians, who face
elections every half decade or so. preventative action against a future threat —
the magnitude of which is still very uncertain — carries heavy political
risks. Even if politicians in the developed world were to be
forced into action, what of the developing world. which is economically
dependent on fossil fuels? Should it reduce emissions, and suffer the
consequences, because of mistakes made by the developed world? One suggestion is
that developing countries be given allowances above the current emission
standards. This would enable them to meet their industrialized needs and
ultimately help them to finance environmentally sound technologies. This would
seem the only realistic way of getting agreement from developing countries — a
vital requirement because, if preventative action is going to work, you really
do have to have everyone on board.
单选题
In the longer span of the future what is most important in reducing
harmful emissions?