cbd-ts-66-en

Part I: Impacts of Climate-related Geoengineering on Biological Diversity
a given amount of CO2. However, pH reductions would still occur in large volumes of water near to such lakes,382
and mobile scavengers are likely to be attracted (and themselves deleteriously affected) by the scent of recentlykilled
organisms.383
Ecosystem services from the deep seabed are generally of an indirect nature, relating to nutrient cycling and long
term climate control. However, all deep water does eventually return to the surface and/or mix with the rest of the
ocean. The use of the deep sea for large-scale CO2 storage will therefore eventually reduce ocean pH as a whole,
with potential effects greatest in upwelling regions (currently highly productive and supporting major fisheries).
The chronic effects of direct CO2 injection into the ocean on ecosystems over large ocean areas and long time
scales have not yet been studied, and the capacity of ecosystems to compensate or adjust to such CO2 induced
shifts is unknown. Several short-term and very small field experiments (litres) have, however, been carried out,
e.g., on meiofauna,384 and peer-reviewed literature on potential CO2 leakages from geological sub-sea storage385
is also relevant.
CO2 storage in sub-surface geological reservoirs
CO2 storage in sub-surface geological reservoirs is already being implemented at pilot-scale levels, and has been used
industrially as part of enhanced oil recovery. Based in part on this experience, the risks are generally regarded as
low. However, leakage from such reservoirs could have locally significant biodiversity implications.386 It is expected
that, where CO2 storage in sub-seabed geological formations is authorized (by permit) under the London Protocol,
information on the leakage and potential impacts will be reported and amassed over time.
There is potentially reduced risk of leakage from sub-surface reservoirs if the CO2 is injected into basalt387, 388 or
other minerals rich in calcium and/or magnesium389 with which it would react—in a similar way to the enhanced
weathering reactions described in section 5.4. With pure CO2, the reactions are expected to be relatively rapid,
limited by the porosity of the rock. This process is currently being tested at commercial scale.390
5.8 SEQUESTRATION OF GREENHOUSE GASES OTHER THAN CARBON DIOXIDE
CDR techniques necessarily focus on the removal of CO2 from the atmosphere. Nevertheless, there could be
significant climatic benefits if other greenhouse gases, particularly methane (CH4) and nitrous oxide (N2O) could
also be removed.391 Techniques are understood to be under development, but have not yet been reported in peer
reviewed literature.
382 IPCC (2005a).
383 Tamburri et al. (2000).
384 Barry et al. (2004).
385 IPCC (2005a).
386 Wilson et al. (2003); Oruganti & Bryant (2009).
387 Goldberg et al. (2008).
388 Goldberg et al. (2010).
389 Matter & Keleman (2009).
390 Matter et al. (2009).
391 Boucher & Folberth (2010).
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