Climate Change II
What is global warming?
An increase in average global temperature caused by changing concentrations of greenhouse gasses over time. Earth alternates every few million years between global warming and global cooling. Average temperatures do not fluctuate dramatically during that time.
How does global warming impact polar regions?
Atmosphere over polar regions becomes warmer. An ice-albedo feedback occurs, causing warmer oceans and land. Frozen water melts and increases ocean or lake volume. Increased evaporation rates create greenhouse gasses over polar regions. Atmosphere continuously warms and frozen water melts.
Global Impacts
Climate change over remote polar regions will create substantial global events. These include: Melting the polar ice-caps Raising global sea levels Changing ecosystem food webs
Antarctic Peninsula
Climate over the Antarctic Peninsula increased by 4.5O F over the last 50 years. Warming increased frequency of break-up of the Larsen B Ice Shelf. After the year 2002, scientists showed that glaciers near Larsen moved 8x faster than before.
Solutions
Encourage authorities to oppose legislation that allows for oil exploration in the Arctic Ocean. Ask authorities to implement sharp carbon-cuts to prevent substantial melting of polar ice-caps. Learn from indigenous people to better advocate for tribal rights and survival in the Arctic Circle. Present climate change data to public audiences so they become informed about repercussions of ice-cap melting. Develop media that highlights the importance of polar ecosystems to global ocean health.
Sea Ice Formation
Frozen seawater that forms during winter. Half of what forms later melts during summer. Ice crystals form when seawater temperature falls below -2O C. Ice crystals are devoid of salt, so liquid water within ice cracks becomes highly
Icebergs
Ice shelf collapses also create dangerously large icebergs. Iceberg B-15 broke off the Ross Ice Shelf in March 2000, and traveled around Antarctica for five years! Its presence disrupted animal migrations, human activities, and Southern Ocean processes.
Melting Ice Shelves
Ice shelves are extensions of glaciers moving towards the ocean. Typically advance over decades before breaking off to form icebergs.
indigenous people
Important resource for indigenous people isolated in the Arctic Circle. Fatty walrus meat gives tribes carbon energy and nutrients. Skin and hides used to build boats, houses, and tools. Ivory tusks carved to sell or trade at markets.
Melting Ice Caps
In the past, polar ice formations melted a bit each summer. Winter precipitation was sufficient to balance out that melting. However, higher temperatures are causing greater than average summer melting and decreases in winter precipitation. Polar ice formations are disappearing faster than they can reform.
Sea Level Rise
Initial estimates placed sea level rise at 0.13 inches per year. Most of that expansion was contributed to thermal expansion of warm oceans. Global warming has since caused meltwater to fill the oceans at an accelerated pace each year. Intergovernmental Panel on Climate Change says we can expect the oceans to rise between one to three feet by the end of the century.
What happens to polar bears if sea ice melts?
Limited food availability for seals, which impacts prey populations Seals unable to breed without sea ice, decreasing prey abundances Bears cannot 'hop' icebergs to search for potential prey Bears may desperately attack larger and more dangerous prey Bears get forced onto land year-round, entering human settlements
POLAR ECOSYSTEMS
Low precipitation, but snow remains frozen over time. Ice-shelves cover the ecosystem for most of the year. Dramatic changes in seasonality.
Polar Bear (Ursus maritimus)
Population 22,000 - 31,000 bears 800 - 1,300 lbs in weight Stand ~10 ft tall Resides in the Arctic Circle Lives on the sea ice Scavenger and active predator
Walrus (Odobenus rosmarus)
Population ~ 250,000 Weight of 1.5 tons Length of 7.25 - 11.5 ft Resides in or just below the Arctic Circle Lives on sea ice or rocky coasts Active predator Walruses use sea ice to breed, rest, and access good foraging habitats. Sea-ice offers protection from storms and predators.
Bowhead whale (Balaena mysticetus)
Population ~10,000 Weight of 100 tons Length of 46 - 59 ft Resides in or just below the Arctic Circle Lives beneath sea ice or along rocky coasts Passive predator
BOTH seals and bears rely on sea ice!
Seals breed and rest on sea ice, and forage on sympatric communities. Bears ambush seals on sea ice. Also a good place to rest between swims to icebergs.
Why care about bowhead survival?
Whales helps nourish and sustain many cultures in the Arctic Circle! Spiritual practices for indigenous tribes hunting whales. Populations are slow to recover because of longevity. Also ecosystem engineers that help other marine mammals.
How will we fare amidst sea level rise?
Shifting tidal range will increase erosion rates along coasts. Flooded estuaries and lowlands will impact food production. Seawater intrusion upriver will effect underground aquifers. Storm surge will damage subterranean, sanitation infrastructure. American metropolises will sink and displace millions of people.
Sea Ice Importance
Sympagic community resides within the sea-ice and saline channels. Photosynthetic algae attach to icy substrate Tiny animals gather at sea-ice to consume settled algae Dead algae, and tiny animals, fall as marine snow and feed benthic organisms
Why care about polar bear survival?
The polar bear is an apex predator AND keystone species! Can inform us of problems in the Artic community. Excellent representative for wildlife and used to promote environmental conservation. Also, they are cute and cuddly!
What happens to walruses if sea ice melts?
Walruses can no longer access deep water foraging habitat Walruses crowd along coastlines and create territory disputes Walrus breeding habitat becomes rare in Arctic Circle Orphaned walrus pups due to starving parents Increased interactions with apex predators, particularly poachers