Tuesday, November 27, 2007

Facilitating Species Migration: Adapting to Climate Change & Benefiting Biodiversity

IPCC's recently completed Fourth Assessment Report paints a grim picture of climate change impacts (the summary of the synthesis report is available here). IPCC Working Group II’s contribution estimates: “on average 20% to 30% of species assessed are likely to be at increasingly high risk of extinction from climate change impacts possibly within this century as global mean temperatures exceed 2°C to 3°C relative to pre-industrial levels.” With a rise of 4°C or more above pre-industrial levels, models suggest 40-70% extinction rates. Popular media, such as Scientific American, also highlight the biodiversity impacts of climate change.

Hopefully, the completion of the IPCC report will spur significant advances in the international legal response to climate change, as previous reports have. Because existing mechanisms for combating biodiversity loss have proven largely ineffective, the climate change regime presents one of the best hopes for near-term action to stem global biodiversity loss from both climate and non-climate causes.

Without intervention, climate change will enhance other factors driving biodiversity loss. For example, climate change in fragmented ecosystems will likely favor those species that move with relative ease – the same weedy species that are already speeding the depletion of biodiversity.

One element of adaption to climate change must be combating habitat fragmentation to allow species to respond through migration, or range shifts, as has occurred in previous periods of climatic change (discussed here and here). In general, this requires a reassessment of protected area priorities to combat fragmentation and ensure that as species find current ecosystems uninhabitable, they will have somewhere to run. Focus on improving protected areas in a climate regime is a sensible response to climatic impacts on biodiversity. It also provides a route to combat habitat destruction – currently the primary driver of species loss.

At the domestic level, preserving habitat for migration might be integrated into Endangered Species Act implementation through critical habitat designations, as J.B. Ruhl notes in an article on FWS’ options for responding to climate change. At the international level, providing migration options could be combined with efforts to preserve or reinvigorate forests as a means of storing or sinking carbon dioxide.

Channeling some of the funds and initiatives aimed at climate change toward activities benefiting biodiversity can create incentives for developing countries that will seek compensation for loss of development opportunities (as Indonesia and Ecuador plan to do, for example). This might be achieved through more directly valuing biodiversity benefits in CDM projects that facilitate sustainable development. Likewise, carbon credits with enhanced value for projects providing biodiversity benefits would allow industrialized countries to benefit from investing in projects that foster species adaption while reducing greenhouse gas emissions.

Even with increased legal and policy support for preserving habitat to facilitate migration, several scientific limitations complicate prediction of migration options for species threatened by climate change. First, substantial uncertainty remains in identification of areas that can provide future range to species requiring migration to survive climate changes. Second, some recent scientific literature suggests that current species richness is strongly correlated with historic climactic conditions, particularly for species with limited range. If so, a significant proportion of species may be unable to migrate to more suitable conditions as the climate changes. Accordingly, assisted migration options should be developed to sustain such species.

Despite these limitations, working fragmentation concerns into the climate change regime offers a way to foster natural species adaption, preserve options for assisted migration and address other root causes of biodiversity loss. It can be factored into the value of credits for CDM projects or carbon storage in forests, or other compensation provided for forgoing deforestation. In this way, perhaps the momentum on climate change can be harnessed to jumpstart international biodiversity preservation.



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