Gathering and analysing climate change data 1 ) Observed climate1.) Observed climate2.) Modelled climate

At (a) Regional (b) National and (c)At (a) Regional (b) National and (c) Destinational scale

Use data to identify potentialUse data to identify potential impacts and vulnerabilities on Eleuthera

Making a climate change data bank available for further impacts studiesimpacts studies

Is there evidence of long-term trends in the

What are the characteristics of current

What year-to-year or decade-to-decade variations are seen in

climate in recent decades?

of current climate? ‘normal’ or current

climate? E.g. El Nino....

◦ Observations 1900-2009...◦ Mainly records from weather◦ Mainly records from weather

stations, but also Satellite data in recent years... y

• Projections of the future from Global or Regional climate modelsRegional climate models

1. Emissions

2. GCMSimulated Climate

3. DownscalingLocal Climate

4. ImpactsScenarios Climate

ResponseLocal Climate

responseImpacts

Hypothetical, but plausible, scenarios of global socio-economic h ‘Wh t ill h t th li t if ’change. ‘What will happen to the climate if...’

Estimate carbon emissions based on different scenarios of societal change e.g. attitudes, population, technological developments

A2A1Bd

B1A2high emissions

(high population growth, strong emphasis on

economic development)

medium emissions (rapid economic growth but with

decreasing reliance on fossil fuels)

low emissions (a more environmentally

sustainable approach, lower consumption and lower

population growth.)) population growth.)

AtmosphereCloud Types

RadiativelyActive

gases and Horizontal exchange between columns of momentum, heat and moistureAtmosphere

Vertical exchange Run-off

L d h Di l d

Ice

gaerosols

↓ Precipitation

Sea

Momentum, latent and

sensible heat fluxes

Biosphere

gbetween layers of momentum, heat and moisture

Land heat and moisture storage

Diurnal and seasonal

penetration

Sea Ice

Surface Ocean Layers

2 How2 How Land surfaceE.g. Topography, Hydrology, Ice Sheets, Vegetation cover

2. How2. Howdoes a does a GCMGCM

g

O L

GCM GCM work?work? Ocean Layers

Vertical exchange of water, heat, salt, nutrients... Ocean layers

Horizontal exchange of water heat salt

work?work?

of water, heat, salt, nutrients etc

• Simulate the large scale gglobal circulation patterns that determine climate

• Cannot represent fully the topography –mountains, lakes etc

• cannot simulate land-sea interactions, sea breezebreeze

• Cannot resolve many important physical processes at this coarse resolution e.g. Storms/hurricanesStorms/hurricanes.

PRECIS - driven by 2 different GCMS (ECHAM-4 and HadCM3) INSMET, CCCCC and UWI.

‘Downscale’ to 50km and 25km spatial resolutions

Model a smaller regions, given ‘boundary conditions’ from a GCM

h l llHigher resolution allows more realistic representation of physical processes

Ensemble of Regional Gridded 15 IPCC GlobalModels

Regional Model Projections

RegionalScale

Griddedobservational

datasets

Ensemble ofNational

ScaleGridded

observationaldatasets

Ensemble of 15 IPCC GlobalModels

Regional Model Projections

Models

Destination Scale

Local Observation

Stations Regional Model

Projections(where available)

Observed increase 0.11˚ per decade

2030

2090s

(+2 3) +3 1˚(+3 5)2030s

(+0.6) +0.9˚(+1.2)

(+2.3) +3.1 (+3.5)

The Bahamas: ‘Hot’ daysThe Bahamas: ‘Hot’ daysyy

2060s(26) 40% (47)

2090s(36) 59% (67)

)

No clear trend in recent observed data

2030s(-13) -4 % (+10)

2090s(-30) -7 % (+18)

2090s

Primary Climate VariablesyTemperature, Precipitation, Evaporation ,Humidity, Wind speed, Sea Surface Temperature, Cloud cover (sunshine hours)Hurricane frequency and intensity, Sea-Level riseHurricane frequency and intensity, Sea Level rise

h l dPhysical Impacts and Vulnerabilities

Human healthAgriculture and fisheries

Linking VariablesStorm SurgeWater quality and availability Agriculture and fisheries

Run-off and soil erosionBiodiversity and habitat loss

Water quality and availabilityOcean acidityFlooding – from coasts or heavy rainfallCoastal erosionCoastal erosion

Vulnerabilities in the Tourism

SectorSector

IPCC estimate of 0.13-0.56 metres in the Caribbean by the 2090s relative to 1980-1999...

S l l i Th l E i f O I◦ Sea-level rise = Thermal Expansion of Oceans + Ice Sheet/Glacier Melt

◦ However: Recent research suggests that ice sheet melt might accelerate over the coming decades, and not to continue at the current rate and that IPCC estimates mightcontinue at the current rate, and that IPCC estimates might underestimate future sea-level rise.

◦ Several independent studies* indicate higher sea-level rise f 1 5 b h 2090of up to 1.5m by the 2090s.

* e.g. Rahmstorf 2007, Rignot et al, 2008, Rohling et al, 2008g , g , , g ,

Climate change and sea-level irise:◦ Shift in shore line◦ Exacerbated coastal erosion

E h d h i h◦ Enhanced storm surge heightsWhat is the observed rate of shoreline recession? ◦ Compare current shoreline

position with aerial photography and satellite archives

What might be the future position of the shoreline?◦ Overlay sea-level rise scenarios

onto topography◦ Identify most vulnerable regions

Ryan Sim, Josh King (Univ. Waterloo)S R ll (B h D M l )Suzanne Russell (Bahamas Dept. Meteorology)Carol McSweeney (Univ. Oxford)With help from Lionel Fernander

Storms and HurricanesStorms and HurricanesIPCC AR4: ‘Tropical storm and hurricane frequencies vary considerably from year to year, but evidence suggests substantial increases in intensity and duration since the 1970s.’

Estimating future changes in storm characteristics

IPCC AR4 Summary: ‘a likely increase of peak wind

intensities and notably whereintensities and notably, where analysed, increased near-storm precipitation in future tropical cyclones’

Storms are hurricanes operate on too small a scale to be resolved by global or regional climate models

◦ Studies based on high resolution weather models and statistical models

Storm surge model◦ Review literature to make estimates

of changes in intensity, duration, hurricane season length, and path.

Storm surge model• Add storm surge to Digital Elevation ModelModel

Carol.McSweeney@ouce.ox.ac.ukCarol.McSweeney@ouce.ox.ac.uk

R lt f b dd d hi h l ti d l dResults from embedded high-resolution models andglobal models, ranging in grid spacing from 100 km to 9 km,project a likely increase of peak wind intensities and notably,where analysed increased near storm precipitation in futurewhere analysed, increased near-storm precipitation in futuretropical cyclones. Most recent published modelling studiesinvestigating tropical storm frequency simulate a decrease inthe overall number of storms though there is less confidencethe overall number of storms, though there is less confidencein these projections and in the projected decrease of relativelyweak storms in most basins, with an increase in the numbers ofthe most intense tropical cyclonesthe most intense tropical cyclones.

Tropical storm and hurricane frequencies vary considerably from year to year, but evidence suggests substantial increases in yea to yea , but e de ce suggests substa t a c easesintensity and duration since the 1970s.In the extratropics, variations in tracks and intensity of storms reflect variations in major features of the atmospheric circulation, such as the North j p ,Atlantic Oscillation.

Temperature (minimum, mean, maximum)Rainfall (total, intensity, number of rainy days, timing of seasonal rainfall, length Directly y , g , gof dry spells)HumiditySea-surface temperatures

projected from climate

modelsSea surface temperaturesWind speed Cloud cover (sunshine hours)

Sea-level rise Water - Quality and availabilityStorm surge incidenceStorms and Hurricanes: Frequency, intensity, paths, and timing

Ocean AcidityFlooding – Surface and CoastalCoastal Erosionintensity, paths, and timing Coastal Erosion