cbd-ts-66-en

Part I: Impacts of Climate-related Geoengineering on Biological Diversity
terrestrial, freshwater and marine biodiversity are essential for the overall goals of both the CBD and UNFCCC,
not only on account of ecosystems’ active role in global cycles but also in supporting adaptation to climate change.
Carbon is naturally captured and stored by terrestrial and marine ecosystems, through biologically-driven
processes. The amount of carbon in the atmosphere, ~750Gt, is much less than the ~2,500 Gt C stored in terrestrial
ecosystems;155 a further 1,000 Gt C occurs in the upper layer of the ocean, and an additional ~37,000 Gt C is stored
in the deep ocean, exchanging with the atmospheric over relatively long time scales. On average ~160 Gt C exchange
annually between the biosphere (both ocean and terrestrial ecosystems) and atmosphere. Proportionately small
changes in ocean and terrestrial carbon stores, caused by changes in the balance of exchange processes, might
therefore have large implications for atmospheric CO2 levels. Such a change has already been observed: in the past
50 years, the fraction of CO2 emissions that remains in the atmosphere each year has slowly increased, from about
40% to 45%, and models suggest that this trend was caused by a decrease in the uptake of CO2 by natural carbon
sinks, in response to climate change and variability.156
42. It is therefore important to improve our representation of biogeochemical feedbacks (mostly driven by plants
and microbes, on land and in the ocean) in Earth system models—not just climate models—in order to understand
how biodiversity may influence, and be influenced by, human activities. The range of non-climatic factors important
in this context, as direct and indirect drivers of biodiversity change, and the range of ecosystem goods and services
that are involved are summarised in Figure 1.1.
3.4 PROJECTED SOCIO-ECONOMIC AND CULTURAL IMPACTS OF CLIMATE CHANGE, IN
BIODIVERSITY CONTEXT
The scientific literature on the societal implications of projected climate change is vast, and a detailed assessment is
inappropriate here. Nevertheless, a very brief overview of the socio-economic consequences of current trajectories
(in the context of biological diversity and ecosystem processes) is necessary, to complete the conceptual picture of
linkages between climate, biodiversity, non-marketed goods and services, and human well-being. Such considerations
provide important context for the discussion of how geoengineering (with its own impacts) might be used to
counteract climate change. Chapter 6 gives additional attention to CBD-relevant socio-economic and cultural
aspects of geoengineering.
The Stern Review157 estimated that, without action, the overall costs of climate change would be equivalent to a
future annual loss of 5–20% of gross domestic product. Although that analysis was much discussed158 and criticised
by some economists, projected economic impacts of climate change of similar range and scale were identified in
the IPCC Fourth Assessment Report (AR4, Working Group II). Table 3.1 summarises those findings on a regional
basis, with emphasis on environmental impacts. The IPCC Fifth Assessment Report, AR5 now nearing completion,
will provide additional, updated information, using improved projections (e.g., for sea level rise) and a wider range
of impacts (e.g., including ocean acidification).
155 Ravindranath & Ostwald (2008).
156 Le Queré et al. (2009).
157 Stern (2006).
158 Barker et al. (2008).
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