2009-08-27 11:34:36
By Judith Burns
Science and environment reporter, BBC News
Engineers say a forest of 100,000 "artificial trees" could be deployed within
10 to 20 years to help soak up the world's carbon emissions.
The trees are among three geo-engineering ideas highlighted as practical in a
new report.
The authors from the Institution of Mechanical Engineers say that without
geo-engineering it will be impossible to avoid dangerous climate change.
The report includes a 100-year roadmap to "decarbonise" the global economy.
No silver bullet
Launching the report, lead author Dr Tim Fox said geo-engineering should not be
viewed as a "silver bullet" that could combat climate change in isolation.
He told BBC News it should be used in conjunction with efforts to reduce carbon
emissions and to adapt to the effects of climate change.
Many climate scientists calculate that the world has only a few decades to
reduce emissions before there is so much carbon dioxide in the atmosphere that
a dangerous rise in global temperature is inevitable.
The authors of this report say that geo-engineering of the type they propose
should be used on a short-term basis to buy the world time, but in the long
term it is vital to reduce emissions.
They define two types of geo-engineering. Nem Vaughan of University of East
Anglia said: "The first category attempts to cool the planet by reflecting some
of the sunlight away. The problem with this is that it just masks the problem."
"The other type of geo-engineering is to remove carbon dioxide from the
atmosphere and store it."
Hundreds of options
The team studied hundreds of different options but have put forward just three
as being practical and feasible using current technology.
A key factor in choosing the three was that they should be low-carbon
technologies rather than adding to the problem.
Dr Fox told BBC News: "Artificial trees are already at the prototype stage and
are very advanced in their design in terms of their automation and in the
components that would be used.
"They could, within a relatively short duration, be moved forward into mass
production and deployment."
The trees would work on the principle of capturing carbon dioxide from the air
through a filter.
The CO2 would then be removed from the filter and stored. The report calls for
the technology to be developed in conjunction with carbon storage
infrastructure.
Dr Fox said the prototype artificial tree was about the same size as a shipping
container and could remove thousands of times more carbon dioxide from the
atmosphere than an equivalent sized real tree.
Another of the team's preferred methods of capturing carbon is to install what
they term "algae based photobioreactors" on buildings. These would be
transparent containers containing algae which would remove carbon dioxide from
the air during photosynthesis.
The third option focuses on the reduction of incoming solar radiation by
reflecting sunlight back into space. The report says the simplest way of doing
this is for buildings to have reflective roofs.
The authors stress that all of these options will require more research and
have called for the UK government to invest 10 million pounds in analysis of
the effectiveness, risks and costs of geo-engineering.
Dr Fox said: "We very much believe that the practical geo-engineering that we
are proposing should be implemented and could be very much part of our
landscape within the next 10 to 20 years."