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Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
Further Reading: Detailed Notes Posted on Class Web Sites
Outline
- global climate models
- the next two decades
- 21st century projections
- summary of changes from IPCC 2007
Apr-20-07
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Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
Apr-20-07
(2 of 10)
Introduction
The purpose of this chapter is to assess and quantify projections of possible future climate
change from climate models.
The Climate System
Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Global Climate Models
Global climate models (GCMs) include as
central components atmospheric and ocean
general circulation models, as well as
representation of land surface processes,
and sea-ice.
Myneni
L30: Projections of Future Climate Change
Apr-20-07
(3 of 10)
Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
Apr-20-07
(4 of 10)
The Next 2 Decades
For the next two decades a warming of about 0.2°C per decade is
projected for a range of emission scenarios.
Even if the concentrations of all greenhouse gases and aerosols had
been kept constant at year 2000 levels, a further warming of about
0.1°C per decade would be expected.
Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
21st Century- Global Average Temperature
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B1: Low emissions, A2: High Emissions
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Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
21st Century - Temp and Sea Level Rise
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Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
Apr-20-07
(7 of 10)
21st Century - Pattern of Warming
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Projected surface temperature changes for the early and late 21st
century relative to the period 1980– 1999
Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
Apr-20-07
(8 of 10)
21st Century - Precip Patterns
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Relative changes in precipitation (in percent) for the period 2090–2099,
relative to 1980–1999. Values are multi-model averages based on the
medium emission scenario for December to February (left) and June to
August (right).
Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
Apr-20-07
(9 of 10)
21st Century - IPCC 2007 Projections-1
Continued greenhouse gas emissions at or above current rates would
cause further warming and induce many changes in the global climate
system during the 21st century that would very likely be larger than
those observed during the 20th century.
Warming is expected to be greatest over land and at most high northern
latitudes, and least over the Southern Ocean and parts of the North
Atlantic ocean.
Snow cover is projected to contract. Sea ice is projected to shrink in
both the Arctic and Antarctic under all emission scenarios. In some
projections, Arctic late-summer sea ice disappears almost entirely by
the latter part of the 21st century.
Natural Environments: The Atmosphere
GE 101 – Spring 2007
Boston University
Myneni
L30: Projections of Future Climate Change
Apr-20-07
(10 of 10)
21st Century - IPCC 2007 Projections-2
Increases in the amount of precipitation are very likely in high
latitudes, while decreases are likely in most subtropical land regions
(by as much as about 20%), continuing observed patterns in recent
trends.
It is very likely that hot extremes, heat waves, and heavy precipitation
events will continue to become more frequent.
Based on a range of models, it is likely that future tropical cyclones
(typhoons and hurricanes) will become more intense, with larger peak
wind speeds and more heavy precipitation associated with ongoing
increases of tropical SSTs.