(August 4, 2015) Continuing
current carbon dioxide (CO2) emission trends throughout this century and beyond
would leave a legacy of heat and acidity in the deep ocean. These changes would
linger even if the atmospheric carbon dioxide concentration were to be restored
to pre-industrial levels at some point in the future, according to a new Nature
Climate Change paper from an international team including Carnegie’s Ken
Caldeira. This is due to the tremendous inertia of the ocean system.
Greenhouse gases emitted by human activities not only cause
rapid warming of the seas, but also an unprecedented rate of ocean
acidification. Ocean acidification occurs when atmospheric carbon dioxide is
absorbed by the ocean and forms carbonic acid, inhibiting coral reef growth and
threatening marine life.
Some experts propose that climate and chemical damage due to
high levels of greenhouse gases could be avoided by removing active carbon
dioxide from the atmosphere, processes broadly called CDR for carbon dioxide
removal. One idea is that fast-growing trees such as poplars, which consume a
great deal of carbon dioxide during growth, could be farmed and then burned in
bioenergy plants where their carbon dioxide would captured and stored
underground instead of released back into the atmosphere. However, none of the
proposed removal-and-storage strategies have been proven at an industrial scale
yet, and ideas such as poplar farming would have to be carefully balanced
against land use for food production.
Using computer modeling to investigate the success of CDR
strategies, the team discovered that the clock is ticking for CDR to
substantially reduce risks to much marine life. If these processes are applied
too late, they might as well not be applied at all, as far as ocean
acidification is concerned, the team found.