Tuesday, July 5, 2011
CLIMATE CHANGE AFFECTS BIODIVERSITY
The link between climate change and biodiversity has long been established. Although throughout Earth’s history the climate has always changed with ecosystems and species coming and going, rapid climate change affects ecosystems and species ability to adapt and so biodiversity loss increases.
Biodiversity and Climate Change, Convention on Biological Diversity, December, 2009
From a human perspective, the rapid climate change and accelerating biodiversity loss risks human security (e.g. a major change in the food chain upon which we depend, water sources may change, recede or disappear, medicines and other resources we rely on may be harder to obtain as the plants and forna they are derived from may reduce or disappear, etc.).
The UN’s Global Biodiversity Outlook 3, in May 2010, summarized some concerns that climate change will have on ecosystems:
Climate change is already having an impact on biodiversity, and is projected to become a progressively more significant threat in the coming decades. Loss of Arctic sea ice threatens biodiversity across an entire biome and beyond. The related pressure of ocean acidification, resulting from higher concentrations of carbon dioxide in the atmosphere, is also already being observed.
Ecosystems are already showing negative impacts under current levels of climate change … which is modest compared to future projected changes…. In addition to warming temperatures, more frequent extreme weather events and changing patterns of rainfall and drought can be expected to have significant impacts on biodiversity.—
Secretariat of the Convention on Biological Diversity (2010), Global Biodiversity Outlook 3, May, 2010, p.56
Some species may benefit from climate change (including, from a human perspective, an increases in diseases and pests) but the rapid nature of the change suggests that most species will not find it as beneficial as most will not be able to adapt.
Climate change impacts on biodiversity in the Arctic
The Arctic, Antarctic and high latitudes have had the highest rates of warming, and this trend is projected to continue, as the above-mentioned Global Biodiversity Outlook 3 notes (p. 56).
In the Arctic, it is not just a reduction in the extent of sea ice, but its thickness and age. Less ice means less reflective surface meaning more rapid melting. The rapid reduction exceeds even scientific forecasts and is discussed further on this site’s climate change introduction.
In terms of biodiversity, “the prospect of ice-free summers in the Arctic Ocean implies the loss of an entire biome”, the Global Biodiversity Outlook notes (p. 57).
In addition, “Whole species assemblages are adapted to life on top of or under ice — from the algae that grow on the underside of multi-year ice, forming up to 25% of the Arctic Ocean’s primary production, to the invertebrates, birds, fish and marine mammals further up the food chain.” The iconic polar bear at the top of that food chain is therefore not the only species at risk even though it may get more media attention.
Note, the ice in the Arctic does thaw and refreeze each year, but it is that pattern which has changed a lot in recent years.
The extent of floating sea ice in the Arctic Ocean, as measured at its annual minimum in September, showed a steady decline between 1980 and 2009.
Source: National Snow and Ice Data Center, graph compiled by Secretariat of the Convention on Biological Diversity (2010) Global Biodiversity Outlook 3, May 2010.
It is also important to note that loss of sea ice has implications on biodiversity beyond the Arctic, as the Global Biodiversity Outlook report also summarizes:
•Bright white ice reflects sunlight.
•When it is replaced by darker water, the ocean and the air heat much faster, a feedback that accelerates ice melt and heating of surface air inland, with resultant loss of tundra.
•Less sea ice leads to changes in seawater temperature and salinity, leading to changes in primary productivity and species composition of plankton and fish, as well as large-scale changes in ocean circulation, affecting biodiversity well beyond the Arctic.—
Secretariat of the Convention on Biological Diversity (2010), Global Biodiversity Outlook 3, May, 2010, p.57
FOR MORE LINKS TO THIS ISSUE: