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 as shown by this graph:

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:

(This site’s intro to climate change and Arctic geopolitics has more about the impact to the Arctic.)

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Increasing ocean acidification

Although it has gained less mainstream media attention, the effects of increasing greenhouse emissions — in particular carbon dioxide — on the oceans may well be significant.

Scientists have found that oceans are able to absorb some of the excess CO₂ released by human activity. This has helped keep the planet cooler than it otherwise could have been had these gases remained in the atmosphere.

However, the additional excess CO₂ being absorbed is also resulting in the acidification of the oceans: When CO₂ reacts with water it produces a weak acid called carbonic acid, changing the sea water chemistry. As the Global Biodiversity Outlook report explains, the water is some 30% more acidic than pre-industrial times, depleting carbonate ions — the building blocks for many marine organisms.

In addition, concentrations of carbonate ions are now lower than at any time during the last 800,000 years. The impacts on ocean biological diversity and ecosystem functioning will likely be severe, though the precise timing and distribution of these impacts are uncertain. (See p. 58 of the report.)

Although millions of years ago CO₂ levels were higher, today’s change is occurring rapidly, giving many marine organisms too little time to adapt. Some marine creatures are growing thinner shells or skeletons, for example. Some of these creatures play a crucial role in the food chain, and in ecosystem biodiversity.

Some species may benefit from the extra carbon dioxide, and a few years ago scientists and organizations, such as the European Project on OCean Acidification, formed to try to understand and assess the impacts further.

One example of recent findings is a tiny sand grain-sized plankton responsible for the sequestration of 25–50% of the carbon the oceans absorb is affected by increasing ocean acidification. This tiny plankton plays a major role in keeping atmospheric carbon dioxide (CO2) concentrations at much lower levels than they would be otherwise so large effects on them could be quite serious.

Other related problems reported by the Inter Press Service include more oceanic dead zones (areas where there is too little oxygen in the sea to support life) and the decline of important coastal plants and forests, such as mangrove forests that play an important role in carbon absorption. This is on top of the already declining ocean biodiversity that has been happening for a few decades, now.

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Coral reefs threatened by climate change

Around the world, coral reefs have been dying largely due to climate change.

At the beginning of September, 2009, the Australian agency looking after the Great Barrier Reef released an outlook report warning the Great Barrier Reef is in trouble.

But it is not just the Great Barrier Reef at risk. All of them are at risk, says Charlie Veron, an Australian marine biologist who is widely regarded as the world’s foremost expert on coral reefs.

The future is horrific, he says. There is no hope of reefs surviving to even mid-century in any form that we now recognize. If, and when, they go, they will take with them about one-third of the world’s marine biodiversity. Then there is a domino effect, as reefs fail so will other ecosystems. This is the path of a mass extinction event, when most life, especially tropical marine life, goes extinct.

Coral reefs provide many ecosystem services to humans as well, for free. This site’s page on coral reefs goes into these issues in more depth.

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Lizards threatened by climate change

What the BBC described as a global-scale study published in the journal Science found that climate change could wipe out 20% of the world’s lizard species by 2080.

Global projection models used by the scientists suggested that lizards have already crossed a threshold for extinctions caused by climate change.

The fear of lowland species moving to higher elevations has long been predicted as an effect of climate change. This has been observed with lizard populations too, as the leader of the research team told the BBC: We are actually seeing lowland species moving upward in elevation, slowly driving upland species extinct, and if the upland species can’t evolve fast enough then they’re going to continue to go extinct.

Why are lizards so sensitive to climate change? The BBC summarizes:

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Other examples

The above areas of biodiversity affected is by no means exhaustive. Other areas affected by climate change include terrestrial animals, and forests, water sources and related ecologies, and so on. For more information on those areas, see this site’s sections on

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