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Estimated sea level rise from 1910 to 1990.
(a) The thermal expansion, glacier and ice cap,
Greenland and Antarctic contributions
resulting from climate change in the 20th
century calculated from a range of
AOGCMs. Note that uncertainties in land
ice calculations have not been included.
(b) The mid-range and upper and lower
bounds for the computed response of sea
level to climate change (the sum of the
terms in (a) plus the contribution from
permafrost). These curves represent our
estimate of the impact of anthropogenic
climate change on sea level during the 20th
century.
(c) The mid-range and upper and lower
bounds for the computed sea level change
(the sum of all terms in (a) with the
addition of changes in permafrost, the
effect of sediment deposition, the longterm adjustment of the ice-sheets to past
climate change and the terrestrial storage
terms).
•
•
•
•
•
•
•
Glacier
– A mass of land ice flowing downhill (by internal deformation and sliding at the
base) and constrained by the surrounding topography. A glacier is maintained by
accumulation of snow at high altitudes, balanced by melting at low altitudes or
discharge into the sea.
Ice cap
– A dome shaped ice mass covering a highland area that is considerably smaller in
extent than an ice sheet.
Ice sheet
– A mass of land ice which is sufficiently deep to cover most of the underlying
bedrock topography, so that its shape is mainly determined by its internal
dynamics (the flow of the ice as it deforms internally and slides at its base).
– There are only two large ice sheets in the modern world, on Greenland and
Antarctica.
Ice shelf
– A floating ice sheet of considerable thickness attached to a coast (usually of great
horizontal extent with a level or gently undulating surface); often a seaward
extension of ice sheets.
Thermal expansion refers to the increase in volume (and decrease in density) that results
from warming water
Ocean thermal expansion leads to an increase in ocean volume (at constant mass).
The mass of the ocean, and thus sea level, changes as water is exchanged with glaciers
and ice caps.
Estimated rates of sea level rise components from observations and
models averaged over the period 1910 to 1990.
Thermal expansion
Glaciers and ice caps
Greenland Р 20th century effects
Antarctica Р 20th century effects
Ice sheets Р adjustment since LGM
Permafrost
Sediment deposition
Terrestrial storage (not directly from climate change)
Total
Estimated from observations
Minimum
(mm/yr)
Central Value
(mm/yr)
Maximum
(mm/yr)
0.3
0.2
0.0
-0.2
0.0
0.00
0.00
-1.1
-0.8
1.0
0.5
0.3
0.05
-0.1
0.25
0.025
0.025
-0.35
0.7
1.5
0.7
0.4
0.1
0.0
0.5
0.05
0.05
0.4
2.2
2.0
20th century effects: Greenland - changes in precipitation and runoff ; Antarctica - increased precipitation
Ranges of uncertainty for the average
rate of sea level rise from 1910 to 1990
and the estimated contributions from
different processes.
Climate System / Component Response Time
• the time needed to re-equilibrate to a new state, following
a forcing resulting from external / internal processes or
feedbacks
• very different for various components of the climate
system
– the atmosphere
troposphere - days to weeks
stratosphere - typically a few months
– oceans: typically decades, but up to centuries or millennia
• Due to their large heat capacity
– the strongly coupled surface-troposphere system: slow, mainly
determined by the oceans
– the biosphere: may respond fast, e.g. to droughts, but also very
slowly to imposed changes
All
All the
All the
All
All
All
All
All
All
All
All
All
Widespread Water Concerns
Drought is an important concern in every region.
Snowpack changes are especially important in the West,
Pacific Northwest, and Alaska.
Water Issues in the United States
Region
Northeast
Southeast
Midwest
Great Plains
West
Northwest
Floods
Drought
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Alaska
Islands
X
Snowpack/
Snowcover
X
X
X
X
X
X
Groundwater
X
X
X
X
X
X
Lake, river, and Quality
reservoir levels
X
X
X
X
X
X
X
X
X
X
Source: Climate Change Impacts on the United States: The P otential Consequences of Climate
Variability and Change, National Assessment Overview, Cambridge University Press, 2000.
Widespread Water Concerns
Drought is an important concern in every region.
Snowpack changes are especially important in the West,
Pacific Northwest, and Alaska.
Water Issues in the United States
Region
Northeast
Southeast
Midwest
Great Plains
West
Northwest
Floods
Drought
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Alaska
Islands
X
Snowpack/
Snowcover
X
X
X
X
X
X
Groundwater
X
X
X
X
X
X
Lake, river, and
reservoir levels
X
X
X
X
Quality
X
X
X
X
X
X
Source: Climate Change Impacts on the United States: The P otential Consequences of Climate
Variability and Change, National Assessment Overview, Cambridge University Press, 2000.
Ecosys tem
Goo ds
Forests
timber, fuelwood,
food (e.g., honey,
mushrooms, fruits)
Fres hwater
Syst ems
Gras slands
Coas tal
Syst ems
Agro ecosyst ems
Servi ces
purify air and water, generate soil, absorb
carbon, moderate weather extremes and
impacts, and provide wildlife habitat and
recreation
drinking and irricontrol water flow, dilute and carry away
gation water, fish,
wastes, and provide wildlife habitat,
hydroelectricity
transportation corridors, and recreation
livestock (food,
purify air and water, maintain biodiversity,
game, hides, fiber), and provide wildlife habitat, employment,
water, genetic
asthetic beauty, and recreation
resources
fish, shellfish, salt, buffer coastlines from storm impacts,
seaweeds, genetic maintain biodiversity, dilute and treat wastes,
resources
and provide harbors and transportation
routes, wildlife habitat, employment, beauty,
and recreation
food, fiber, crop
Build soil organic matter, absorb carbon,
genetic resources
provide employment, and provide habitat for
birds, pollinators, and soil organisms
Source: Climate Change Impacts on the United States: The P otential Consequences of Climate
Variability and Change, National Assessment Overview, Cambridge University Press, 2000.
Ecosystem
Type
Forests
Grasslands
Grasslands
Semi-arid/Arid
Semi-arid
and Arid
Impacts
Changes in tree species
composition and alteration of
animal habitat
Displacement of forests by open
woodlands and grasslands
under a warmer climate in
which soils are drier
Displacement of grasslands by
open woodlands and forests
under a wetter climate
Increase in success of nonnative invasive plant species
Increase in woody species and
loss of desert species under
wetter c limate
NE
SE
MW
X
X
X
GP
W
NW
AL
IS
X
X
X
X
X
X
X
X
X
X
Source: Climate Change Impacts on the United States: The Potential Consequences of Climate
Variability and Change, National Assessment Overview, Cambridge University Press, 2000.
X
Ecosystem
Type
Tundra
Impacts
Loss of alpine meadows as their
species are displaced by lowerelevation species
NE
SE
MW
GP
X
W
NW
AL
X
X
X
Loss of northern tundra as trees
migrate poleward
Freshwater
X
Changes in plant community
composition and alteration of
animal habitat
Loss of prairie potholes with
more frequent drought
conditions
Habitat changes in rivers and
lakes as amount and timing of
runoff changes and water
temperatures rise
IS
X
X
X
X
X
X
X
X
Source: Climate Change Impacts on the United States: The Potential Consequences of Climate
Variability and Change, National Assessment Overview, Cambridge University Press, 2000.
Ecosystem
Type
Coastal &
Marine
Impacts
NE
SE
Loss of coastal wetlands as sea
level rises and coastal
development prevents landward
migration
X
X
Loss of barrier islands as sealevel rise prevents landward
migration
X
X
Changes in quantity and quality
of freshwater delivery to
estuaries and bays alter plant
and animal habitat
X
X
Loss of coral reefs as water
temperature increases
Changes in ice location and
duration alter marine mammal
habitat
MW
GP
W
NW
X
X
X
X
AL
IS
X
X
X
X
X
X
Source: Climate Change Impacts on the United States: The Potential Consequences of Climate
Variability and Change, National Assessment Overview, Cambridge University Press, 2000.