Dr Carol McSweeney, Oxford University

Observed Data

◦ Past and Present climate 1960-2009...◦ Mainly Records from Weather stations, but also satellite data...

Is there evidence of long termWhat are the What year to year of long-term trends in the climate in recent decades?

What are the characteristics of current climate?

y yvariations are seen in ‘normal’ or current climate? E.g. El Nino....

Model data

◦ Projections of the future from Global or Regional climate models

1. Emissions Scenarios

2. GCMSimulated Climate

3. DownscalingLocal Climate

4. ImpactsScenarios Response response

p

H th ti l b t l ibl i f l b l i iHypothetical, but plausible, scenarios of global socio-economic change. ‘What will happen to the climate if...’Estimate carbon emissions based on different scenarios of societal h i d l i h l i l d lchange e.g. attitudes, population, technological developments

A1Bd

B1A2medium emissions (rapid economic growth but with

decreasing reliance on fossil fuels)

low emissions (a more environmentally

sustainable approach, lower consumption and lower

population growth.)

A2high emissions

(high population growth, strong emphasis on

economic development)) 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

•Typically 2.5˚ latitude/longitude resolution

•BUT cannot resolve many important processes at this coarse resolution e.g. St /h iStorms/hurricanes.

•Cannot represent fully the topography – mountains, l k tlakes etc

•Doesn’t give ‘local’ enough projections for

ll l li t i tsmall scale climate impact assessment

‘Downscale’ to typically 50km or higher spatial resolutionM d l ll iModel a smaller regions, given ‘boundary conditions’ from a GCMHigher resolution allows more realistic representation of physical processesphysical processes

PRECIS – driven by 2 different GCMS (ECHAM 4 dGCMS (ECHAM-4 and HadCM3)

Regional scale Country scale Destinational ScaleRegional scale

(Caribbean)

Country scale

(Jamaica) (Montego Bay and Negril

Ensemble of 15 IPCC Global

One Regional Model

Increasing model resolutionIncreasing detail in model processes and output

Models (2 driving GCMS)

Temperature (minimum, mean, maximum)Rainfall (total, intensity, number of rainy Directly( , y, ydays, timing of seasonal rainfall, length of dry spells)Humidity

Directly projected

from climate modelsu d ty

Sea-surface temperaturesWind speed Cloud cover (sunshine hours)

models

Cloud cover (sunshine hours)

Sea-level rise Additional Storm surgeStorms and Hurricanes: Frequency, intensity, paths, and timing

info required

y, p , g

Observed increase 0.14˚ per decade

2030s(+0.6) +1.0˚(+1.2)(+0.5) +1.1˚(+1.3)(+0 3) +0 8˚(+1 0)

2090s(+2.5) +3.0˚(+3.5)(+1.6) +2.6˚(+3.2)(+1 1) +1 5˚(+2 2)

Under the A2 (high emissions) Scenario...(+0.3) +0.8 (+1.0) (+1.1) +1.5 (+2.2)

No clear trend in recent observed data

Under the A2 Scenario

2030s(-35) -3 % (+17)(-32) -7 % (+9)(-20) -2 % (+10)

2090s(-65) -14 % (+3)(-36) -13 % (+11)(-30) -2 % (+22)Under the A2 Scenario... ( 20) 2 % (+10) ( 30) 2 % (+22)

Frequency of ‘Hot days’ ‘Cold days’ ‘Hot nights’Frequency of Hot days , Cold days , Hot nights and ‘Cold nights’◦ Using daily maximum and minimum temperature records,

Temperature exceeded in current climate every 1 in 10Temperature exceeded in current climate every 1 in 10 days...

◦ Different value for every region and seasonH f ill hi b d d i h f ?◦ How often will this temperature be exceeded in the future? (i.e. Might the temperature that we currently consider to be relatively ‘hot’ or ‘cold’ in current climate become more normal in future?normal in future?

Maximum 1-day and 5-day total rainfallsProportion of rainfall that occurs in ‘Heavy’ eventsProportion of rainfall that occurs in Heavy eventsNumber of consecutive dry-days

Jamaica: ‘Hot’ daysJamaica: ‘Hot’ daysJ yJ y

Under the A2 Scenario...

2060s(32) 51% (73)(36) 53% (68)

(27) +42%˚(53)

2090s(49) 78% (98)(41) 71% (96)(30) 52% (66)

Jamaica: ‘Cold’ daysJamaica: ‘Cold’ daysJ C yJ C y

Under the A2 Scenario...2060s

(0) 0% ( 3)(0) 0% (2)(0) 1% (3)

2090s(0) 0% (0)(0) 0% (1)(0) 1% (2)

Jamaica: Heavy RainfallJamaica: Heavy RainfallJ yJ y

2060s(-11) 0 6)(-13) 0 4)(-14) 0 (6)

2090s(-19) -1 (7)(-13) -1 (5)(-8) -2 (9)

Under the A2 Scenario...

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 I Sh /Gl i◦ Sea-level rise = Thermal Expansion + Ice Sheet/Glacier Melt

◦ Thermal expansion is relatively easy to predict based on global temperaturesThe response of Ice Sheets and Glaciers is much more◦ The response of Ice Sheets and Glaciers is much more difficult to predict:

◦ 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 might underestimate future sea-level rise.

Increased frequency?Increased frequency?Increased intensity?Increase in Hurricane season length?Increase in Hurricane season length?Change in path/tracks?Difficult to determine via modelsDifficult to determine via models ◦ resolution too coarse...◦ Interactions with ENSO

Combined impacts of changes in storm/h rricane characteristics and sea le elstorm/hurricane characteristics and sea-level rise◦ Changes in Storm Surge Incidence◦ Changes in Storm Surge Incidence

Estimate future changes in primary climateEstimate future changes in primary climate variables using a combination of observed data and global and regional model scenariosdata and global and regional model scenariosCombination of global and regional climate model data allows us to maximise the datamodel data allows us to maximise the data available to us◦ Regional models maximise the spatial detail andRegional models maximise the spatial detail and

realism in the models◦ Global model projections allow us to compare

multiple models to give an uncertainty range

Projections from GCMs indicate:Projections from GCMs indicate:◦ Increases in temperature of around 0.3-1.3˚ by

2030s and 1.2 to 3.5 by 2090s2030s and 1.2 to 3.5 by 2090s◦ Most models indicate decreases in rainfall –

projections range from -35% to +17% in annual rainfall by 2030s, and -65% to +22% by 2090s.◦ We may see an accelerated response in climate

extremes compared with the meanextremes compared with the meanWe still have to analyse the downscaled regional climate model outputs to look atregional climate model outputs to look at impacts at destinational scale.

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

Physical Impacts andPhysical Impacts and Vulnerabilities

Human healthAgriculture and fisheries

Linking VariablesStorm SurgeWater quality and availability Run-off and soil erosion

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

Vulnerabilities in the Tourism

SectorSector