Our Common Future Under Climate Change

International Scientific Conference 7-10 JULY 2015 Paris, France

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Thursday 9 July - 11:30-13:00 UNESCO Fontenoy - ROOM XII

L3.4 - Ecosystem-based Adaptation and Biodiversity Conservation

Large Parallel Session

Chair(s): R. Scholes (University of Witwatersrad, Johennesburg, South Africa), M. Araujo

11:30

Ecosystem-based adaptation to climate change

V. Kapos (UNEP-WCMC, Cambridge, United Kingdom)

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Ecosystem-based adaptation to climate change
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11:50

Strategic approaches for enhancing climate change adaptation of species and ecosystems

W. Foden (Global Change and Sustainability Research Institute, Gauteng, South Africa)

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Strategic approaches for enhancing climate change adaptation of species and ecosystems

W. Foden (1)
(1) Global Change and Sustainability Research Institute, University of the Witwatersrand, Gauteng, South Africa

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Even under best case mitigation scenarios, most species and ecosystems must undergo adaptation if they are to avoid extinction and maintain their functions under climate change. Published observations of such adaptation now number in the thousands and include shifts in species’ distributions and the timings of seasonal activities such as animal migrations and plant phenology.  A large literature is also emerging, however, on the negative impacts of climate change on less adaptive species and ecosystems. The broad spectrum of impacts includes physiological stress and mortality, population and distribution declines, food web disruptions, and increased competition with dispersive ‘climate change immigrants’. Climate change challenges conservation strategies to make a strong shift from traditional preservationist approaches towards promoting adaptive changes while minimising negative impacts. Here I discuss emerging approaches for enhancing climate change adaptation of species and ecosystems and outline some of the key gaps and challenges in this field.

Projecting climate change impacts on species and ecosystems is an important early step in effective adaptation planning. This has driven rapid development of a suite of approaches and methods for assessing the vulnerability of species and ecosystems to climate change, generally by co-opting methods used for other purposes.  Each differs in its strengths, weaknesses, resource requirements and suitability to different contexts, and no single one has emerged as clearly superior, nor seems likely to do so in the near future. This introduces a considerable challenge for conservation practitioners, who must select between and learn to apply sometimes complex methods for their focal areas, ecosystems or species. Although filled in part by the forthcoming IUCN SSC guidelines for assessing species’ vulnerability to climate change, the gap between academic developments and their accessibility to practitioners remains a concerning challenge. Equally, assessing how human responses to climate change will impact on natural systems (e.g., changes in agriculture and new infrastructure such as dams and sea walls) is an important gap for species-focused climate change vulnerability assessment in particular.

A range of approaches have emerged for enhancing climate change adaptation of species and ecosystems. These include those focused on landscapes (e.g., increasing protected area connectivity and permeability), sites or site networks (e.g., creating habitat refuges and decreasing non-climatic stressors), and species (e.g., enhancing evolutionary potential through translocation or ex situ conservation). Most are extensions or modifications of existing conservation approaches and, to date, there has been little investigation of their effectiveness for minimising climate change impacts, nor of their potential unforeseen maladaptive effects. Since conservation under climate change is unprecedented, we can expect errors and failures along with successes. Development of an evidence base from which we can learn will facilitate the rapid advancements needed in this important emerging field, and will help to avoid both potentially negative actions and wasted resources. Even while climate change adaptation strategies and our skill at implementing them improve, their potential to minimise losses of ecosystem function and extinction is finite. Reducing greenhouse gas emissions and thereby limiting the rate and magnitude of climate change are vital for the success of climate change adaptation initiatives.

12:10

Operational interventions to assist the adaptation of terrestrial biodiversity to climate change

G. Midgley, (Stellenbosch University, Stellenbosch, South Africa)

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Operational interventions to assist the adaptation of terrestrial biodiversity to climate change

G. Midgley, (1)
(1) Stellenbosch University, Stellenbosch, South Africa

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The rate and extent of projected anthropogenic climate change over the next century may be unprecedented in several million to tens of millions of years. This perturbation to the climate system is occurring during an inter-glacial phase, which is a naturally warm phase in the context of the Pleistocene epoch, which prior to the Holocene Epoch of the past 12000 years, has predominantly (more than 80% of the time) seen global temperatures of roughly 5°C cooler than the Holocene, and atmospheric CO2 levels of 180 to 200 ppm vs the 280 ppm CO2 of the Holocene prior to the onset of the Anthropocene. Scenarios of 500+ ppm CO2 and possible warming in excess of 3°C represent a fundamental ecological shock to terrestrial ecosystems globally, especially in the light of the much cooler planetary history of the Pleistocene. Nonetheless, ecosystems and their component biodiversity have been exposed to repeated warming and cooling cycles and have clearly coped with these, indicating the potential for substantial natural adaptive capacity, and inherent resilience.

 

One clear adaptive response has involved geographic range shifts, especially at higher latitudes in the northern Hemisphere where temperature exerts a dominant control on growing season, biome distributions, and the geographic distribution of species. This observation, together with observations of incipient range shift responses has led to the application of a paradigm largely of “passive” adaptive planning. That is, using projected geographic shifts of species in response to future change, the spatial planning of areas that anticipate the direction and preferred routes for range shifts to facilitate receptive landscapes. Under extreme scenarios involving high rates of climate change on flat landscapes with a high “climate velocity” more active approaches have also been explored, including assisted migration. A final safety-net approach of gene or seed-banking has also been proposed. Such approaches seem relevant for low temperature ecosystems that are rapidly experiencing warming, and may reach levels that could exceed existential tolerance limits established during Pleistocene times.

 

However, in the subtropics and tropics, where water availability and disturbance regimes exert control over ecosystem structure and function, it is far less clear how important range shifts have been for natural adaptation. In these ecosystems, for example, the past changes in atmospheric CO2 levels have had critical direct impacts on ecosystem distribution, with tropical forests losing significant areal coverage due to the limiting effect of low atmospheric CO2 on tree production. This may have interacted with the fire regime to allow flammable grasslands to expand and dominate tropical regions, possibly enhanced by an ascendant grazing vs diminishing browsing fauna.

 

Under these conditions, ecosystems respond according to changing disturbance rules, and not climate rules, and thus individual range shifts may be less important, but community effects may be more important as entire ecosystems may change their structure and function over large areas, thus changing habitat conditions for consumers, and indeed interacting with consumer responses. With future atmospheric CO2 projected to approach levels not seen for more than 20 million years, direct CO2 impacts may strongly influence ecosystem and habitat shifts due to changing fire regime and water use efficiency in water-limited ecosystems, potentially encouraging the re-establishment of more woody biomes. This opens the potential for active management response versus the passive landscape planning approach. Active management would involve strategic decisions about desired future states, achievable through the use of fire and graze/browse management responses.

 

Conservation practitioners would benefit by considering both active and passive adaptive strategies for biodiversity conservation, as both may have relevance, albeit with different emphases, in low and high latitude situations. Much can be learned from experience in active interventions long practiced in tropical and sub-tropical situations involving fire management, browse-graze manipulation, and translocation/reintroduction of animal species. An urgent effort is also required to understand the strength of the CO2 fertilization effect on water-limited ecosystems, and the potential of this process to transform the structure and function of fire and grazing-controlled ecosystems.

12:30

Q&A session

M. Araujo, R. Scholes (University of Witwatersrad, Johennesburg, South Africa)

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Q&A session
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