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Part I: Impacts of Climate-related Geoengineering on Biological Diversity 3.2 OBSERVED AND PROJECTED IMPACTS OF CLIMATE CHANGE, INCLUDING OCEAN ACIDIFICATION, ON BIODIVERSITY 3.2.1 Overview of climate change impacts on biodiversity Temperature, rainfall and other components of climate strongly influence the distribution and abundance of species; they also affect the functioning of ecosystems, through species interactions. Whilst vegetation shifts, population movements and genetic adaptation have lessened the impacts of previous, naturally-occurring climate change (e.g., during geologically-recent ice age cycles),103 the scope for such responses is now reduced by other anthropogenic pressures on biodiversity, including over-exploitation; habitat loss, fragmentation and degradation;104 the introduction of non-native species; and pollution, and the rapid pace of projected climate change. Thus, anthropogenic climate change carries a higher extinction risk,105 since the abundance (and genetic diversity) of many species is already depleted. Human security may also be compromised by climate change,106, 107 with indirect (but potentially serious) biodiversity consequences in many regions. Whilst some species may benefit from climate change, many more will not. Observed impacts and adaptation responses arising from anthropogenic climate changes that have occurred to date include the following:108 36 • Shift in geographical distributions towards higher latitudes and (for terrestrial species) to higher elevations.109 This response is compromised by habitat loss and anthropogenic barriers to range change; • Phenological changes relating to seasonal timing of life-cycle events; • Disruption of biotic interactions, due to differential changes in seasonal timing; e.g., mismatch between peak of resource demand by reproducing animals and the peak of resource availability; • Changes in photosynthetic rates and primary production in response to CO2 fertilization and increased nutrient availability (nitrogen deposition and coastal eutrophication). Overall, gross primary production is expected to increase, although fast growing species are likely to be favoured over slower growing ones, and different climate forcing agents (e.g., CO2, tropospheric ozone, aerosols and methane) may have very different effects.110 As noted above, the IPCC AR4 report estimated future global warming to be between 1.1°C to 6.4°C by 2100, with the upper part of that range becoming increasingly likely if current trajectories continue. Five reasons for concern for a similar temperature range had been previously identified in the IPCC’s Third Assessment Report,111 relating to risks to unique and threatened (eco)systems; risks of extreme weather events; disparities of (human) impacts and vulnerabilities; aggregate damages to net global markets; and risks of large-scale discontinuities. These reasons for concern were re-assessed eight years later using the same methodology,112 with the conclusion that smaller future increases in global mean temperature—of around 1°C—lead to high risks to many unique and threatened systems, such as “coral reefs, tropical glaciers, endangered species, unique ecosystems, biodiversity hotspots, small island states and indigenous communities” (Figure 3.4). 103 Jackson & Overpeck (2000). 104 Ellis (2011). 105 Maclean & Wilson (2011). 106 Barnett & Adger (2007). 107 Hsiang et al. (2011). 108 Secretariat of the Convention on Biological Diversity (2009a). 109 Cheng et al. (2011). 110 Huntingford et al. (2011). 111 Smith et al. (2001). 112 Smith et al. (2009).
Figure 3.4: Projected impacts of global warming, as “Reasons for Concern” 113 Part I: Impacts of Climate-related Geoengineering on Biological Diversity Updated “reasons for concern” plotted against increase in global mean temperature. Note that: i) this figure relates risk and vulnerability to temperature increase without reference to a future date; ii) the figure authors state that the colour scheme is not intended to equate to “dangerous climatic interference” (since that is a value judgement); and iii) there was a marked worsening of the authors’ prognosis in comparison to an assessment published 8 years earlier, 114 using the same methodologies. The relatively specific and quantifiable risk of rate of extinction was assessed by the CBD’s Second Ad hoc Technical Expert Group on Biodiversity and Climate Change, with the estimate that ~10% of species will be at risk of extinction for every 1°C rise in global mean temperature.115 A recent meta-analysis116 provides a similar, although lower, estimate, indicating that extinction is likely for 10–14% of all species by 2100. Even if such losses only occur locally or regionally rather than globally (i.e. extirpations, with species possibly “saved from extinction” in zoos, seedbanks or culture collections), biodiversity reductions at those scales must inevitably lead to severe disruptions of many ecosystems and their services,117 with serious social, cultural and economic consequences. Due to the complex nature of the climate-biodiversity link, there will inevitably be uncertainty about the extent and speed at which climate change will impact biodiversity, species interactions,118 ecosystem services, the thresholds of climate change above which ecosystems no longer function in their current form,119 and the effectiveness of potential conservation measures.120, 121 113 Smith et al. (2009). 114 Smith et al. (2001). 115 Secretariat of the Convention on Biological Diversity (2009a). 116 Maclean & Wilson (2011). 117 Isbell et al. (2011). 118 Brooker et al. (2007). 119 Pereira et al. (2010). 120 Hoegh-Guldberg et al. (2008). 121 Dawson et al. (2011). 37
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Betz G. (2011). The case for climat
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Glibert P M. (2008). Ocean urea fer
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Kasperson R.E., Renn O., Slovic P.,
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Moreno-Cruz J.B., Ricke K.L. & Keit
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Artaxo P.,Melillo J. & Morgan M.G..
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Turley C.M, Roberts J.M. & Guinotte
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PART II THE REGULATORY FRAMEWORK FO
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CHAPTER 6 CONCLUSIONS Part II: The
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ANNEX II Part II: The Regulatory Fr
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ANNEX IV Part II: The Regulatory Fr
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