Dr Carol McSweeney, Oxford University
Jan 19, 2017
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