Transcript Why this change? - The University of the West Indies at Mona

Caribbean climate in the future :Results from the PRECIS RCM
Dr. Michael Taylor
A Future Caribbean Climate from PRECIS
Michael A. Taylor and Jayaka D. Campbell
Climate Studies Group. Mona
Department of Physics
University of the West Indies, Mona
Today
2080’s
Additional
Foliage
Large Water Storage Tank
Support
Wires
Industrial sized AC unit
2080’s
Additional
Foliage
Large Water Storage Tank
Support
Wires
Industrial sized AC unit
Why?
Why the need for any change?
Why do we think Caribbean
climate will change at all?
Why the need for these changes?
What does PRECIS suggest the
future Caribbean climate will be
like?
Why a
change?
The earth has warmed over the
last century
'Warming of the climate
system is unequivocal, as
is now evident from
observations of increases in
global average air and ocean
temperatures, widespread
melting of snow and ice, and
rising global average sea
level.'
'Most of the observed
increase in globally averaged
temperatures since the mid20th century is very likely
due to the observed
increase in
anthropogenic
greenhouse gas
concentrations.
- IPCC (2007)
Why a
change?
The earth has warmed over the
last century
'Warming of the climate
system is unequivocal, as
is now evident from
observations of increases in
global average air and ocean
temperatures, widespread
melting of snow and ice, and
rising global average sea
level.'
'Most of the observed
increase in globally averaged
temperatures since the mid20th century is very likely
due to the observed
increase in
anthropogenic
greenhouse gas
concentrations.
- IPCC (2007)
Why a
change?
Caribbean climate seems to be
changing too.
# Warm days and nights are
increasing!!
# Cool days and nights are
decreasing!!
Peterson, T. C., M. A. Taylor, et al., 2002: Recent changes in climate extremes in the Caribbean region, J.
Geophys. Res., 107(D21)
Why a
change?
The earth will likely continue to
warm
For the next two decades a
warming of about 0.2oC
per decade is projected
for a range of SRES
scenarios.
Even if the concentrations of
all greenhouse gases and
aerosols had been kept
constant at year 2000 levels,
a further warming of 0.1oC
per decade would be
expected.
- IPCC (2007)
Projected surface temperature changes for the early and late 21st century relative to
the period 1980 to 1999. The left and right panels show the AOGCM multi-model
average projections (°°C) for the B1 (top), A1B (mmiddle) and A2 (bbottom) SRES
scenarios averaged over the decades 2020-2029 and 2090-2099.
Why a
change?
The earth will likely continue to
warm
Global climate
modeling (computer
based simulations) has
advanced significantly.
B1
The global climate
models (GCMs) are run
for varying storylines
(scenarios) into the
future to produce pictures
of the future climate.
A1B
Storylines grouped in
families according to
emphasis of storyline and
emission gases produced.
A2
Projected surface temperature changes for the early and late 21st century relative to
the period 1980 to 1999. The left and right panels show the AOGCM multi-model
average projections (°°C) for the B1 (top), A1B (mmiddle) and A2 (bbottom) SRES
scenarios averaged over the decades 2020-2029 and 2090-2099.
Why a
change?
The global models suggest Caribbean
climate will change as well
The GCMs can give a good
first guess about what is
likely to happen in the
Caribbean.
Wetter
BUT
•Resolution is coarse so
Caribbean islands often not
represented.
Hotter
Model-simulated temperature/ precipitation response to forcing scenario. Scenario is
depicted by colour of the point (A1FI - red, A2 - grey, B1 - green and B2 - violet). Ovals
show 95% Gaussian contour ellipses of the natural internal tridecadal variability.
Nonetheless
GCMs suggest that
Caribbean not immune to
the climatic changes that
rest of globe likely to
experience.
We must adapt!!!
Why this
change?
Why this
change?
PRECIS provides a little more detailed
look on the future
Heard about PRECIS in previous talk, won’t repeat the model details.
•PRECIS is a regional model (15 km - 50 km).
•Run over a Caribbean domain exclusively
Why this
change?
•Forced at boundaries by GCMs
•Performs reasonably well with current climate.
•Run for a time slice in the future (2070-2099), A2,
B1 and B2 scenarios
Why this
change?
•Run for baseline (1960-1990) to evaluate change.
•Done as part of a collaborative project (Cuba, Belize,
Barbados)
On this basis of the PRECIS results I am modifying my dwelling structure!!
Why this
change?
Temperatures
Irrespective of
scenario the
Caribbean expected
to warm.
Warming between 1
and 5oC
Warming greater
under A2 scenario.
Warming consistent
with projections for
other parts of globe.
Why this
change?
Temperatures
DJF
Warming is year
round.
Nowhere and at no
time in the year is
the Caribbean cooler
than present.
Summer warming
greatest.
JJA
Under A2 warming
up to 5oC in larger
islands
Sea surface
temperatures also
warmer
Why this
change?
Rainfall
For both scenarios
Caribbean is in
general drier.
Up to 30% drier.
Drying more severe
under A2 scenario
Far north Caribbean
however could be
wetter
Why this
change?
Precipitation
DJF
Southern Caribbean
dry year round.
Far north Caribbean
wetter between
December and March
JJA
Drying in late season
(when normally get
most rain) most
severe.
Why this
change?
Climatology
24
Today
22
20
Still retain the
climatology – e.g.
MSD
MSD
All months hotter
and drier than
baseline in both
scenarios.
16
14
Wetter
P R E C IP IT A T ION
(c m)
18
12
10
8
January
JJA and SON
indistinguishable
6
4
2
Future
Hotter
0
24
25
26
DJ F
S ON
B as eline
27
28
MAM
T E A2
MPSE cRenario
AT UR E ºC
29
JJA
B 2 S c enario
30
31
Early and late season
peak in rainfall
identical
Why this
change?
Annual
Vertical Shear
In the mean there is
stronger shear in
main Caribbean
basin, particularly
across the main
development region
(MDR)
In wet season, the
change in shear is
positive and high.
SON
Pattern consistent
with rainfall changes.
Pattern for A2 most
severe.
Strengthening at
lower levels evident
(not shown)
Why this
change?
Jan
Cloud Cover
General reduction in
cloud cover year
round in main
Caribbean basin.
Pattern consistent
with rainfall changes.
Sept
Reduction for A2
most severe.
Hotter
Why this
change?
Wetter
Why this
change?
Why this
change?
Why this
change?
Windier
Less
cloudy
2080’s
But before you build…
Some
provisos!
PRECIS represents one set of
model realizations
Remember that PRECIS is
forced by one GCM (Hadley
Centre).
ALL
ONE
NONE
Until we have other GCM
data to force PRECIS, this at
least gives us an idea of
what to expect.
This is one of the reasons for
doing multiple scenarios i.e.
A2 B2, etc.
Future results expressed as
range
We can also take the
consensus of the runs.
Some
provisos!
There is natural variability
Precipitation Change (B2) – Annual Mean
We must always
remember that our
climate system does vary
naturally (i.e. has cycles
of hot and cold, dry and
wet).
Must attempt to separate the
climate change signal from
that which might have
occurred naturally.
Some
provisos!
There is natural variability
We must always
remember that our
climate system does vary
naturally (i.e. has cycles
of hot and cold, dry and
wet).
Must attempt to separate the
climate change signal from
that which might have
occurred naturally.
Some
provisos!
There is natural variability
Temperature Change (B2)
We must always
remember that our
climate system does vary
naturally (i.e. has cycles
of hot and cold, dry and
wet).
Must attempt to separate the
climate change signal from
that which might have
occurred naturally.
Some
provisos!
There is still lots to do
PRECIS is a good start
but….
•
Doesn’t tell about sea level
rise
•
Need to analyse extreme
weather in PRECIS e.g.
Hurricanes
•
Need more details about
changes to Daily extremes
•
Other significant climate
variables to be analysed.
Conclusions
• PRECIS offers a glimpse into the future Caribbean
Climate.
• PRECIS simulations done for the A2 and B2
scenarios.
• By 2080’s Caribbean 2-5oC warmer.
• Warming everywhere, and year round.
• By 2080’s Caribbean generally drier.
• Drying more severe southern Caribbean and during
peak rainy season.
• By 2080’s cloud cover is less than present.
• By 2080’s winds stronger.
Final words
• Remember the provisos.
• If changes are inevitable (as thought) there is
need to mitigate and adapt.
• PRECIS Future data can be accessed via web:
http://precis.insmet.cu/Precis-Caribe.htm
• Some of these results are presented in a
publication entitled: Glimpses of the Future: A
Briefing from the PRECIS Caribbean Project.
Thank You