caribbean climate in the future :results from the precis rcm

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. MonaDepartment of Physics

University of the West Indies, Mona

2080’s

Industrial sized AC unit

Large Water Storage Tank

Support Wires

Additional Foliage

Why?

Why the need for any change?

Why the need for these changes?

Why do we think Caribbean climate will change at all?

What does PRECIS suggest the future Caribbean climate will be like?

The earth has warmed over the last century

Why a change

?

'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 mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.

- IPCC (2007)

Caribbean climate seems to be changing too.

Why a change

?

# 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)

The earth will likely continue to warm

Why a change

?

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.

The earth will likely continue to warm

Why a change

?

Global climate modeling (computer based simulations) has advanced significantly.

The global climate models (GCMs) are run for varying storylines (scenarios) into the future to produce pictures of the future climate.

Storylines grouped in families according to emphasis of storyline and emission gases produced.

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.

B1

A1B

A2

The global models suggest Caribbean climate will change as

wellWhy a change

?

The GCMs can give a good first guess about what is likely to happen in the Caribbean.

BUT

•Resolution is coarse so Caribbean islands often not represented.

Nonetheless

GCMs suggest that Caribbean not immune to the climatic changes that rest of globe likely to experience.

We must adapt!!!

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.

Hotter

Wett

er

PRECIS provides a little more detailed look on the future

Why this

change?

•PRECIS is a regional model (15 km - 50 km).

•Run over a Caribbean domain exclusively

•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

•Run for baseline (1960-1990) to evaluate change.

•Done as part of a collaborative project (Cuba, Belize, Barbados)

Heard about PRECIS in previous talk, won’t repeat the model details.

On this basis of the PRECIS results I am modifying my dwelling structure!!

Why this

change?

Why this

change?

Why this

change?

TemperaturesWhy this

change?

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.

TemperaturesWhy this

change?

Warming is year round.

Nowhere and at no time in the year is the Caribbean cooler than present.

Summer warming greatest.

Under A2 warming up to 5oC in larger islands

Sea surface temperatures also warmer

DJF

JJA

RainfallWhy this

change?

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

PrecipitationWhy this

change?

Southern Caribbean dry year round.

Far north Caribbean wetter between December and March

Drying in late season (when normally get most rain) most severe.

DJF

JJA

ClimatologyWhy this

change?

Still retain the climatology – e.g. MSD

All months hotter and drier than baseline in both scenarios.

JJA and SON indistinguishable

Early and late season peak in rainfall identical

0

2

4

6

8

10

12

14

16

18

20

22

24

24 25 26 27 28 29 30 31

T E MP E R AT UR E ºC

PR

EC

IPIT

AT

ION

(

cm)

D J F MAM J J A

S ON A2 S c enario B 2 S c enario

B as eline

Today

January

MSD

Future

Wett

er

Hotter

Vertical ShearWhy this

change?

Annual

SON

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.

Pattern consistent with rainfall changes.

Pattern for A2 most severe.

Strengthening at lower levels evident (not shown)

Cloud CoverWhy this

change?

Jan

Sept

General reduction in cloud cover year round in main Caribbean basin.

Pattern consistent with rainfall changes.

Reduction for A2 most severe.

But before you build…

Why this

change?

Why this

change?

Why this

change?

Why this

change?

Hotter

Wetter

Windier

Less cloudy

2080’s

PRECIS represents one set of model realizations

Some proviso

s!

Remember that PRECIS is forced by one GCM (Hadley Centre).

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.

ALLALL

ONEONE

NONNONEE

There is natural variabilitySome

provisos!

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.

Precipitation Change (B2) – Annual Mean


provisos!




provisos!



Temperature Change (B2)

There is still lots to doSome

provisos!

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

caribbean climate in the future :results from the precis rcm

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