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Sea Levels Rising
What is Sea Ice?
Frozen ocean water
• It forms, grows, and melts in ocean
Keeps polar regions cool, helps moderate global climate, supports wildlife
85% of sunlight that strikes sea ice is reflected back into space
As sea ice melts in summer, it exposes dark ocean surface
Ocean absorbs 90% of sunlight
Oceans heat up, and Arctic temperatures rise further
What is Land Ice?
Ice that has accumulated over thousands of years on land
Water from precipitation
Not found in ocean
Albedo
Measure of reflectivity of a surface
Mechanism for climate change
• When surface cover changes
Different surface coverings have different albedo
Albedo of Ice
85%-90% of sunlight that strikes ice is reflected back into space
As sea ice melts in summer, it exposes dark ocean surface
Ocean absorbs 90% of sunlight
Oceans heat up
As land ice melts, exposes dark rock or soil below….
Greenland Melting: W
​ hat’s Happening in the Arctic?
Arctic stays cold b/c of Albedo:
• white color of ice causes sun’s rays to get reflected, and makes it hard for surface to “warm up”
Surface doesn’t absorb heat because it’s too white (high albedo)
Less ice = more heat absorbed by dark colored water=warmer temperatures
• Powerful positive feedback from earth’s albedo/greenhouse effect
• Extra heat will prevent Arctic ice from forming since it won’t be cold enough for ice to form
Changes in color from white to dark amplify temperatures rising, and push climate to change even more
drastically
In fall and winters in Arctic Circle there should be thick layers of ice covering surface for algae to grow on
Algae = based of food chain
Ensures survival of all Arctic animals
Ice is also habitat for these animals
• Both above and below
• Since 1950s, thickness of ice as well as amount of water itself has decreased by 3-5 % due to global
warming
Global Warming and Greenland
GW affects Greenland in two ways:
Warming temperatures cause the ice sheets to thin and lose ice mass around the edges
Warmer temperatures also cause more snow to fall in Greenland's interior
How are Scientists Researching to Answer these Questions About Greenland’s Ice:
Variety of techniques used to measure Greenland's mass balance
• Snow pits measure snowfall
• Stations measure incoming and reflected sunlight
• Aircraft use laser altimetry to measure changes in surface elevation
• Melt areas are determined by satellites reflecting microwaves off surface
• Satellite radar measure horizontal movements of Greenland's glaciers
• In 2003, NASA launched the I​ ce, Cloud, and Land Elevation Satellite​ (ICESat), using laser altimetry to
measure changes in Earth’s surface elevation
EOS Measurements
Measurements of ice elevations are made by satellite radar altimeters or laser altimeters
NASA’s Earth Observing System (EOS)
Laser gives more accurate results over larger areas
Melting Sea Ice
No impact on sea level rise
It’s already floating in ocean
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Like ice in a glass
As it warms, ice melts but volume of water stays same
DOES contribute to climate change
Changes albedo of earth’s surface
White sea ice reflects energy
Dark open ocean absorbs energy & heats up
Raises global temps
High temps cause glaciers and ice sheets on land to melt
Changes in Sea Ice and Effects
Decrease in extent and thickness
Leads to increased warming due to positive feedbacks
• Albedo changes
Loss of habitat
Melting Land Ice
Land ice melts and flows into ocean
Increasing sea level on global scale
Changes in Land Ice and Effects
Decrease in land ice
Surface melts and calving events
Leads to changes in warming due to positive feedback
• Albedo changes
Leads to rising sea levels
Changing ocean currents
Melting Ice and Earth’s Wobble
https://www.theguardian.com/environment/2016/apr/09/melting-ice-sheets-changing-the-way-the-earth-wobbleson-its-axis-says-nasa
Greenland and Antarctica Ice
Arctic Sea Ice Decreases as Antarctic Ice Increases
Why is Sea Ice Growing in Antarctica but not the Artic?
Sea ice in Antarctica is growing
• As Earth warms, Southern Ocean is warming but slowly
Slow Warming in Southern Ocean
Decrease in Salinity of Surface Waters
• Water is diluted by melting ice on edges of continent and more precipitation; creates a surface layer with
less dense, cooler water than saltier water below.
• More stratification of water layers and less mixing
• Less heat transported to melt ice and more fresh water to freeze
• Fresh water freezes at 32 degrees Fahrenheit
• Seawater freezes at about 28.4 degrees Fahrenheit , because of salt in it
Sea Levels are Rising
Sea levels risen about 8 inches since early 1900s
Projections at 3 feet or more by end of this century
F
​ actors That Contribute to Sea Level Rise
Thermal expansion of water
Melting of land ice
Greenland and Antarctica C
​ ontain about 75% of world’s fresh water
If all melted, sea level would rise by 65 meters*
Oceans Absorb Heat
90% of extra heat trapped by increasing GHG
Rate of heat absorption doubled since early 1990s
Thermal Expansion of Water
Tendency of matter to change in volume in response to a change in temperature
50% of sea level rise due to thermal expansion
Impacts of Sea Level Rising
Ecological
• Loss of coastal habitats and shallow water ecosystems
• Inundation of groundwater reservoirs (aquifers)
Economic
• Loss of human structures
• Increased damage from storm surge
Human
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• Displaced populations (climate refugees)
Economic, Ecological, and Human Impacts
Vice (Greenland)
• https://www.youtube.com/watch?v=7Yq-sfWSWLg
Vice (Antarctica)
• https://www.youtube.com/watch?v=Kp6_sDiup6U
Greenland Ice (VICE)
• Dr. Jason Box​, glaciologist for Denmark and Greenland.
• Glacial retreat: loses over 140 billion tons of ice; net ice loss = current global sea rise
• West coast is faster b/c of warmer waters = calving
Data and Science:
• Newly de-glaciated land, covered in ice just 10 years ago (several 100 feet); supply LA with water for 2000 years
• Miles and miles thick; 80% of Greenland—3x size of Texas
• How fast is ice sheet melting: drill hole and put in 30 foot pole (flag top); leave it and come back to measure how
much pole is revealed.
• 27 feet in one year (9 meters) of ice melt (size of house)
• Particulate matter/pollution on the surface of ice; soot, particles from fire and industry; dirty ice accelerates melt
b/c color absorbs heat (3x faster than lighter ice); explains rate of melt; carried by air currents
• Climate warming creates more fire = more soot = more dark ice = more melt
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Holes or fractures from water; hydro-fracture; water drains down these holes
• Force cracks open; down into glacier and lubricates from within and break/calve into the sea
• Climate change outpaced worst case scenario by 60 years
• 21 feet of global sea level; if all of Greenland melts then 80 of 100 biggest cities will be under water
• Calving: turbulent water bubbles up and force heat exchange between warm ocean and cold ice; undercuts the ice
and promotes more calving
• Several km of calving (lost glacial ice) per year
• Hundreds of feet high; ice cliffs are continually calving into the sea
• Increased changes ahead of predictions (60 years ahead); rate of melting
• IPCC 2013 report; ahead of worst case scenario
• Dr. Gavin Schmidt,​ climatologist at NASA; IPPC 5 report discussion;
• Change is arctic sea ice projections made 5 years ago; melt on Greenland and other glaciers = sea level rise along
with heat with causes thermal expansion = more sea level rise
• Stabilize ice; cut carbon and heat in the atmosphere. Have to decrease carbon emissions by 80% in next few
decades
• Carbon emissions going up not down
• How much is man-made?
• All of it is man-made; sun, volcanoes, natural variability in ocean; no credible way to blame something else
• It won’t stop even if we stabilize temperature; sea level rise will continue but might slow.
Antarctica Ice (VICE)
• 90% of world’s ice; 70% of fresh water on earth
• West Antarctica melts = 3-5 meters of sea level
• Retreating 1 km per year; increase in retreat and in surface elevation of ice
• Mapping for 20 years (laser altimeters; can measure up to cm in changes) using tate of art technology
• Increased westerly winds and ocean currents carrying heat to ice and undercutting glaciers (rocks exposed)
• Melting glaciers add influx of cold freshwater to seas; less dense than sea water and higher freezing point;
• Pure water freezes at 32F, salt water needs to be colder before it freezes and so it usually takes longer to freeze
• The more salt in the water, the lower the freezing point (approximately 28F)
• Blogger for Climate Denial​; talking points get fed into political and media outlets
• Climate change is natural, not caused by humans; main evidence is the sea ice in Southern Hemisphere; well
above average for sea ice –since satellite monitoring began in 1979
• Sea ice and land ice are not the same thing; sea ice is thinner and seasonal. An increase in sea ice can lead to an
increase in albedo and vice versa but no effect on sea levels. Sea ice is growing in Antarctica b/c of shifting
westerly winds and cold fresh water from glacial melts is changing the freezing point and causing more ice to
form seasonally.
• Dr. Eric Renoit; University of California, Irvine researcher​; glacier retreating faster than natural cycle; last decade
more than last century
• 55 mph to 550mph on freeway; like changing speed limit
• No idea how fast systems can react to climate warming; data from 20 years showing us that reacting fast
• He says we are in big trouble with sea level rise
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Water drone at Palmer station is measuring temp, salinity changes
Less ice in future