Transcript Changes in Temperature, Sea Level and Northern Hemisphere

Sea Level Rise
Questions
1. Why does water take up more space as it
gets warmer?
2. Why does climate change raise sea levels?
3. How much has the ocean risen?
4. Why is melting in Greenland and Antarctica
bad?
5. What are the effects of sea level change?
Reminder
• About 70% of the Earth's
surface is water-covered
– The oceans hold about
96.5% of all Earth's water
– Other water is stored in
glaciers and groundwater
Rising Sea Levels
• As water gets warmer, it takes up more space.
– Each drop of water only expands by a little bit, but
multiplied over the entire depth of the ocean, it adds
up and causes ocean levels to rise.
– Sea level is also rising because melting glaciers and ice
sheets are adding more water to the oceans.
Climate Change
• The main cause of sea level rise is climate
change
– Greatly influenced by greenhouse gases
• A warmer climate does 2 things:
– Melt ice sheets and glaciers
– Cause water to heat up an expand
Changes in Temperature, Sea Level and Northern Hemisphere Snow Cover
Courtesy of IPCC, 2007
What’s going on now
• Over the past 100 years,
the average sea level
around the world rose by
nearly 7 inches
Greenland and the Antarctic
• The melting of
Greenland’s and Antarctic
ice sheets are particularly
dangerous
– The ice from the land flows
into the water, raising the
overall ocean level
– Ice that is already in the
ocean that’s melting won’t
raise the sea level
Arctic Sea Ice Is Disappearing At Record Rate
Summer 1979
Summer 2003
The loss poses grave environmental dangers … but not
Sea Level Rise
• Global change
- More ice on land = Lower sea level
10
Sources of Ice Melt & Potential
Impact on Sea Level
70 m
6m
Antarctica
Greenland
0.7 m
Mountain
Glaciers
Changes in sea levels
• During the last Ice Age
(10,000 years ago),
global sea levels were
130 meters (425 feet)
lower than current day
– Glacial melting has raised
the level of the ocean
• Every year, the ocean rises
1.5-4.0mm
The Future
• If our climate keeps getting warmer, the
average sea level around the world by the end
of this century (the year 2099) could be
anywhere from 7 to 23 inches higher than it
was in 1990.
– Sea level could rise even more if the big ice sheets
in Greenland and Antarctica melt faster.
Effects of Rising Waters
Effects of Sea Level Change
• No matter the cause, rising
ocean levels can cause great
damage
– Beaches are eroded
– Flooding
• Netherlands, many islands, all of
Florida and Louisiana would be
underwater
• Cities would disappear
– New York!
– Increased salinity of rivers,
bays, and groundwater table
• Estuaries would be destroyed
• Drinking water would be ruined
North America current
Source: http://geongrid.geo.arizona.edu/arcims/website/slr1kmglobal/viewer.htm
Sea level rise: Fraser Valley
scenarios
North America: 1 metre sea level rise
Sea level rise: Fraser Valley
scenarios
Africa, Asia, Europe: 1 metre rise
Sea level rise: Fraser Valley
scenarios
Africa, Asia, Europe: 6 meter rise
Sea level rise: Fraser Valley
scenarios
Coastal futures : New Orleans &
Katrina
Sea level rise: Fraser Valley
scenarios