James Lovelock paints a worst-case scenario
of run-away climate change and the collapse of modern civilisation before the
end of this century (January 17 Item 9). Could it happen? Lovelock’s scenario depends on strong
feedbacks to an already-warming climate – a surge in warming when polluting
aerosols are removed along with their cooling effect, increasing carbon
emissions from land as the climate warms, more absorption of solar radiation as
sea ice disappears from the Arctic Ocean. All of these effects are plausible scientifically, and the
beginnings of some are being observed now.
However, the worst of these accelerating
effects on climate won’t become important until the second half of this
century. So we probably have about 40-50
years to get the climate problem under control, about the time it takes to
transform a major piece of infrastructure like an energy system. But the
decision point to make significant changes to our energy system must come much sooner,
in the next five or ten years.
Have we already passed the point of no
return, as Lovelock claims? Probably not. But there is a very real risk that we
will later this century if we do not make deep and lasting reductions in
greenhouse gas emissions.