climate change and conservation – part ii. arctic ocean ice cover

Climate Change and Conservation – Part II

Arctic Ocean Ice Cover

Loss of Arctic Ocean Ice

Polar Bear (Usinus maritimus)

Polar Bear as Indicators

• In 2007, the US Fish and Wildlife Service listed the polar bear as a threatened species

• The polar bear is a significant seal predator and depends on ice as a platform to hunt seals

• There are three distinct subpopulations that will be differentially affected by changing sea ice

• Projected reductions in arctic sea ice will result in the loss of 2/3 of the population by 2050

Global Change and Antarctic Food Webs

• Changing sea temperatures can have numerous impacts on food webs

• Ice cover and melting influences light and nutrient levels and phytoplankton growth

• Phytoplankton blooms fuel zooplankton like krill that feed cetaceans, pinnipeds, fishes, etc.

• Krill have been influenced by local climate changes

Western Antarctic Peninsula

Global Change in Polar Regions

Global Change and Krill

Global Change in Polar Regions

Climate Change and the California Current

• Changes in winds and water temperature will affect the food web of the California Current System

• Upwelling is a critical driver for the pelagic marine food web

• Upwelled water brings nutrients and fuels higher trophic levels

• Climate change can influence winds and currents associated with upwelling

Coastal Upwelling

Ekman Transport

Climate Change and the Calfornia Current

• Several studies (Sydeman et al. 2006 and Lee et al. 2007) have documented changes in populations of sea birds

• Cassin’s auklet is a planktivorous bird that is a good indicator of changes

• Long-term data link declines in upwelling and warming sea surface temperatures with declining popuaation

Cassin’s Auklet

Cassin’s Auklets

California Current and Cassin’s Auklets

Cassin’s Auklets

Climate Influences

Other Seabirds

Climate Change in Tropics

Impacts on Coral Reefs


Hoegh-Guldberg1999

Long-Term Trends

Ocean Acidification

• Increasing CO2 can lead to changes in the oceans concentration of calcium carbonate

• Increased CO2 will increase the amount dissolved in ocean water

• This will increase carbonic acid and lower the ocean’s pH

• This will reduce the amount of aragonite in the water possibly to below saturation

• This will make it more difficult for corals and other organisms that use calcium carbonate

Ocean Acidification

Changes in Calcification

Bond et al.2001

Millenial Cycles

Decadal Cycles

Fligge and Solanki2001

Decadal Cycles

Larsen 2005

Methane Hydrates

• Heating of the deep ocean may have released large amounts of methane from methane clathrates

• Methane hydrates or clathrates are ice compounds filled with methane gas that remains solid at low temperature

• Typically in moderate depths 300-2000 m and temps near 2oC

• At higher temperature they can release lots of methane, which is a much more efficient green house gas

Methane Hydrates

Figure 1. Stability field (temperature and pressure) of methane hydrates (Dickens et al., 1995). Note the effect of warming by about 4oC from an initial deep water temperature around 11oC, leading to dissociation of hydrates over an ocean-wide zone of several hundreds of m thick.

Methane Hydrates

• End of the Paleocene about 60 million years ago, the earth’s ocean suddenly warmed (Late Paleocene Thermal Maximum)

• Associated with ocean warming of 4-6 degrees C

• Complete extinction of unicellular eukaryotes like foraminifera

• The oceans went anoxic

Late Paleocene Thermal Maximum

Methane and Thermal Increase

Ocean Temperatures

Methane HydratesFigure 2. Sizes of organic carbon reservoirs (Kvenvolden, 1998).

Burning Ice

climate change and conservation – part ii. arctic ocean ice cover

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