Met Office Presentation September 2013

Climate change and Wales

© Crown copyright Met Office

Professor Julia Slingo, Met Office Chief Scientist

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Changing Research Agenda

• Increasing vulnerability to hazardous weather and climate extremes demands greater preparedness and resilience now.

• Commitment to a certain level of climate change in the next 20-30 years means that adaptation in the future is unavoidable.

• Mitigation policies require a greater understanding of Earth System processes and feedbacks, and of our commitments to long-term or irreversible change.

Understanding our present climate and extremes© Crown copyright Met Office

© Crown copyright Met Office

Why was this Spring so cold?

2013 closely resembles the state of the climate system in 1962

Global rainfall anomalies (left panel) and surface air temperature anomalies (right panel) for March 1962 against the climatology for 1981-2010.

SST anomalies for March 2013 (top) and March1962 (bottom) relative to 1981-2010

Sudden Stratospheric Warming in January 2013

Atlantic Multidecadal Oscillation.

Anomalies in monthly Arctic sea ice extent from 1979

Extreme weatherNovember/December 2010

December 2010:Record minimum monthly average temperature for Wales = -3.8 degC

Record minimum Nov temperature:-18.0 °C at Llysdinam (Powys) on 28 November 2010, lowest November min. temperature in Wales on record

Extreme weatherNovember/December 2010

The odds of the cold December 2010 temperatures have halved as a result of human‐induced climate change

Dec 2010 CET

Return time of temperatures for December in 1960-1969 decade

Return time of temperatures for December in 2000-2009 decade

Predicting the Future© Crown copyright Met Office

© Crown copyright Met Office

Forecast models are huge computer codes based on fundamental mathematical equations of motion, mass continuity, moist thermodynamics and radiative transfer

These govern:

Flow of air and water - winds in the atmosphere, currents in the ocean.

Exchange of heat between the atmosphere and the earth’s surface

Release of latent heat by condensation during the formation of clouds and raindrops

Absorption of solar radiation and emission of thermal (infra-red) radiation

NB: Solar output, Earth’s rotation (and atmospheric composition) are the only imposed constraints.

Fundamentals of weather and climate modelling

© Crown copyright Met Office

Represent the earth by a grid of squares, typically of length 100 km or smaller. Atmosphere and oceans are divided into vertical slices of varying depths. 3-dimensional picture of the state of the atmosphere and oceans. Integrate equations of motion and thermodynamics forward in time. Conserve heat, moisture, salinity and momentum

Fundamentals of weather and climate modelling

Moving from uncertainty to probabilities/likelihoods

UKCIP02

Single projection

Very unlikely to be less than (10%)

UKCP09

Central estimate (50%)

Very unlikely to be more than (90%)

Su

mm

er

Ra

infa

ll 20

80’

s

© Crown copyright Met Office

Impacts

0

10

20

30

40

50

60

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2095

Sea

leve

l ris

e (r

elat

ive

1990

) [c

m]

High

Medium

Low

Sea level change – central probability estimate.

Medium emission scenario 22 cm by 2050

% change in flood frequency of 2-year return period flow

Cardiff

- Hotter, drier summers??- Milder wetter winters- Reduction in snowfall and frost- Increased frequency of intense rainfall events- Decrease groundwater levels- Increased flooding of low-lying coastal areas

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Significant step forwards:

• First to quantify uncertainties and provide probability distribution functions

• First to include feedbacks and uncertainties from carbon cycle

But……

• No wind or snow variables, only limited information on extremes – but more could be extracted from the regional climate model ensembles

• No account of the current state of the climate system

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UKCP09: The first step on a long road...

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10-year Vision: Integrated weather and climate prediction

for estimating hazards and risks

N x Global predictions at ~20km with lead

times of days to years:

Synoptic drivers

<N x Regional predictions at ~1km:

Local meteorology

Probability of local hazard:

Impacts

1.5km resolution climate modelResolution of Welsh terrain

Best long-term climate models, UKCP09

State-of-art seasonal

model configuration

Current global weather forecasting

Current UK weather

forecasting + ground-breaking

climate work

1.5 km L70 From 3 UTC 19/11

12 UTC analysis

West Wales flooding: 8-9 June 2012

1.5 km forecast model RADAR

• Same formulation as new 1.5km weather forecast model, run operationally since last year

• Spans southern England and Wales at 1.5km resolution

• Driven by 12km regional climate model at boundaries (in turn driven by reanalysis data)

• Explicitly represents convection without need for parameterisation scheme

• Completed 20 years: 1989-2008

• Just started climate change experiments using global 60km model output for boundary forcing, enabling study of climate change and extremes

1.5km resolution climate modelGround-breaking science

Environmental Prediction at Regional and Local Scales

• Established models exist for most components• Modeling scales are converging

How resilient are our assets to future change?

What future extremes should we prepare for?

How can science inform future investments?

Climate services: A revolution in the application of climate science

© Crown copyright Met Office

• From mitigation to mitigation and adaptation• Climate change to climate change and

climate variability• Global, century-scale scenarios to regional

predictions, days to decades ahead• Global climate to characteristics of

hazardous weather and climate extremes• From few to many customers – public,

governments, business and industry• Operational delivery – from IPCC

Assessment Reports to regularly updated monitoring, forecasts, products and services

© Crown copyright Met OfficeDiscussion

Opportunities for partnershipExtreme Weather Initiative Wales

• Performance of 1.5km model to represent extreme rainfall characteristics in South Wales catchments

• 20 year hourly rainfall climatology, including variability and extremes, and comparison with observations

• Grid-scale and catchment-scale analysis

• Comparison with 12km driving model to assess benefits of very high resolution modelling for Wales

• Climate change experiments at 1.5km over South Wales

• Application of HPC Wales capability

• Additional ensemble member experiments, to complement time-slice runs at Met Office, to allow climate change signal to be extracted from noise due to climate variability

• Analysis of projected changes in rainfall, limited to those metrics where 1.5km model shown to be skilful for present day

• Provision of guidance on implications for climate change advice and flood risk planning in Wales