Astronomer royal calls for 'Plan B' to prevent runaway climate change

Launching mirrors into space,
triggering algal blooms in the oceans
and seeding clouds are among
experimental "Plan B" schemes world
leaders would have to consider if the
rise in carbon emissions cannot be
curbed within a couple of decades,
according to one of Britain's most
senior scientists.
Hacking the planet's climate through
geoengineering, though controversial
and "an utter political nightmare",
would buy time to develop cleaner
sources of energy, the astronomer
royal Lord Rees will say in a speech
to the annual British Science Festival
in Newcastle on Thursday.
Rees, who is a former president of the
Royal Society and a cosmologist at
Cambridge University, will close the
festival with a wide-ranging lecture
covering everything from astronomy
and global health to the place of
science in culture.
On climate change, Rees will say he is
pessimistic that global carbon dioxide
emissions can be reduced to safe
levels within the next 20 years, which
means that concentrations of the gas
in the atmosphere will rise above 500
parts per million (ppm) by the end of
the century. This level could mean a
rise in average temperatures of up to
6C, major melting of the ice caps and,
potentially, the triggering of tipping
points in the global environment that
would accelerate dangerous climate
change. The level of CO2 in the
atmosphere passed 400ppm in May.
"If the effect is strong, and the world
consequently seems on a rapidly
warming trajectory into dangerous
territory, there may be a pressure for
'panic measures'," he will say. "These
would have to involve a 'Plan B' –
being fatalistic about continuing
dependence on fossil fuels, but
combating its effects by some form of
geoengineering."
Geoengineering involves deliberate
planet-scale interventions to
counteract global warming.
Techniques suggested include placing
mirrors in space that reflect sunlight
away from the Earth and fertilising
the oceans with iron to encourage the
growth of algae that can soak up
atmospheric carbon dioxide. Other
options include Rees's preference – to
seed clouds in the upper layer of the
Earth's atmosphere to bounce some of
the sun's energy back into space.
The idea of firing particles into the
stratosphere to reduce temperature
was inspired by natural events. When
Mount Pinatubo in the Philippines
erupted in 1991, for example, global
temperatures dropped by 0.5C the
following year due to the dust it
released into the atmosphere.
But enacting such plans would not be
without social problems.
"Geoengineering would be an utter
political nightmare: not all nations
would want to adjust the thermostat
the same way," Rees will say. "There
could be unintended side-effects.
Regional weather patterns may
change. Moreover, the warming
would return with a vengeance if the
countermeasures were ever
discontinued; and other consequences
of rising CO2 – especially the
deleterious effects of ocean
acidification – would be unchecked."
In 2009, the Royal Society published a
report into geoengineering in which it
called for experiments in the various
techniques to ensure that their effects
and limitations are better understood
and the technologies are available as
a safety net in case global talks to
combat climate change fail.
Doug Parr, Greenpeace's chief
scientist, said Rees was right about the
many downsides and unknowns of
geo-engineering. "Yet [he] advances it
as a last resort, despite the obvious,
much safer things we can do now.
"It shows the recurrent mirage of a
silver bullet solution to climate
change is often a sign of despair at
world leaders' unwillingness to
seriously tackle CO2 emissions.
"Every new technology in this field
comes with issues, and if they become
an excuse for more foot-dragging on
slashing carbon pollution they will be
harming the climate before even
research is done."
However, Rees will insist that
considering geoengineering would
not be a get-out for reducing carbon
emissions. He will say the world also
needs to make a commitment to
developing clean energy – extracting
and storing power from wind, tides,
biofuels, solar or nuclear – that
matches the ambition of the
Manhattan project in the 1940s to
develop the first nuclear bomb or
Nasa's Apollo moon landings in the
1960s and 1970s. "It may take 50
years to decarbonise the world's
power generation, but this could be
achieved if we start now."
Looking ahead in his own field of
astronomy, Rees will say he is excited
by the regular discovery of planets
orbiting other stars. In the past
decade, space telescopes such as
Nasa's Kepler have pushed the
number of planets scientists know
about into the thousands, but they
predict there are probably many
billions in our galaxy alone, and
some of them could be twins of Earth.
With ever-improving instruments, he
will say, scientists who are now at the
start of their careers may be able to
answer the question of whether or
not there is life beyond Earth.
Back on our own planet, Rees will
also call for a more brotherly
attitude from his fellow scientists to
those of faith. Science, he will say, is
the one culture that is truly global
and should transcend all barriers of
nationality and religion.
"The scientists who attack
mainstream religion, rather than
striving for peaceful coexistence with
it, damage science, and also weaken
the fight against fundamentalism," he
will say. "But that's a theme for
another talk."