latest climate scienceimplications for wales met office september 2013

Latest climate scienceImplications for Wales

© Crown copyright Met Office

Vicky Pope

Sept 2013


Latest climate scienceImplications for Wales

• Basics of climate – theory and observations

• Why has there been such extreme weather recently?

• Is this the sign of things to come? Impact on projections


Heat energy re-emitted to warm Earth

Heat energy passes through atmosphere

Heat energy radiated from Earth

Sun’s energy absorbed by atmosphere

Sun’s energy reflected by Earth

Sun’s energy reflected by clouds

Incoming energy from the sun


Water evaporates from rivers lakes and the ocean

Water condenses to form clouds

Loss of water from plants, soil, animals and people

Water returns to land as precipitation

Water carried downhill by rivers

Water seeps into ground and flows to sea


Hadley cell

Ferrel cell

Polar cell

Trade winds


Evidence: the Greenhouse effect

The average temperature of the Earth is 14 ºC. Without the blanket of greenhouse gases it would be –18 ºC.

The water vapour feedback enhances the warming due to man-made greenhouse gases


INCREASING – Atmospheric carbon dioxide

1850 1900 1950 2000

380

360

340

320

Atmospheric carbon dioxideA

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CO2 has risen by 107ppm (38%) from pre-industrial levels of 280ppm.


INCREASING – Land surface temperature

Global temperatures have increased decade on decade since the mid 20th century, consistent with the basic physics.

The water vapour feedback enhances the warming due to man-made greenhouse gases

1850 1900 1950 2000


INCREASING – Sea surface temperature

1850 1900 1950 2000


INCREASING – Tropospheric temperature

1850 1900 1950 2000


INCREASING – Specific humidty

1850 1900 1950 2000


INCREASING – Sea level

1850 1900 1950 2000


DECREASING – September Arctic sea ice extent

1850 1900 1950 2000


DECREASING – Glacier mass balance

1850 1900 1950 2000

Why has there been such extreme weather recently?

19

Christidis and Stott, Met OfficeMassey et al, University of Oxford, Met Office

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

• Unusual circulation patterns can still bring very cold winter months

UK cold winter December 2010 Coldest December on record in Wales -3.8 degCRecord minimum: -18.0 deg C at Llysdinam (Powys) 28 November 2010

Oct 2010 – March 2012 Rainfall% of 1971-2000 average

2 dry winters

Extreme weatherFrom drought...

Summer 2012 Rainfall% of 1971-2000 average

2 dry winters

Extreme weather...to flood

Wettest June on record (180% of average)

3rd wettest summer on record for Wales (240% of average)

Is this the sign of things to come? Impact on projections

Representative comparison between CMIP3 and 5

models (scaled using simple models)

Climate model projections CMIP5Global surface temperature (single study, AR5 will contain synthesised results)Knutti and Sedláček, 2013

Climate model projections CMIP5Preciptation (single study, AR5 will contain synthesised results)Knutti and Sedláček, 2013

December - February

June - August

Stippling – high robustnessHatching – no significant changeWhite – models inconsistent

Important processes for UK weather and climate

• North Atlantic weather – slow changes in ocean surface temperatures

• Tropical Pacific weather – El Nino• Arctic Sea ice retreat• Solar variability

Atlantic Multidecadal Oscillation

Video of the jet streamhttp://www.metoffice.gov.uk/learning/wind/what-is-the-jet-stream?rel=0

Low UV from the sun leads to easterly winds and cold conditions in Europe and the US

Global focus

Global average temperatures (including latest observations)

Hiatus in warming: Possible contributions Met Office Hiatus report (IPCC AR5 will contain synthesised results) http://www.metoffice.gov.uk/research/news/recent-pause-in-warming

• Natural variability: models have 10-15 year periods with no warming or even cooling

• Incoming radiation: reduction of 0.6 Wm-2 needed to explain pause. Maximum possible is 0.3 Wm-2

• Recent decrease in stratospheric water vapour: traps less heat: up to 0.1Wm-2

• Change in man-made aerosols: little net effect

• Volcanic eruptions: not enough during period

• Extended solar minimum: less than 0.2Wm-2

• Ocean changes: could be a major contributor • Ocean heat content, sea-level rise observations: Earth system continued

to absorbed heat

• Additional heat appears to have been absorbed in the ocean.

• Increased exchange to deep ocean appears to have caused at least part of the pause in surface warming,

• Observations indicate that Pacific Ocean may play a key role.

http://www.metoffice.gov.uk/research/news/recent-pause-in-warming


The impact of a global temperature rise of 4 ºC

Change in temperature from pre-industrial climate

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Current City population • 3-10 million • 10-20 million

Meltingice

OceanAcidification

Rainforestloss

Reduced crops

Forestfire

Increased drought

Stronger tropical storms

Methane release

More heatwaves

Steadily increasing CO2 (similar to BAU scenario by 2100). Excludes deforestation and fire


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

Best long-term climate models, UKCP09

State-of-art seasonal

model

Current global weather forecasting

Current UK weather

forecasting + ground-breaking

climate work

Mountains (130km grid)


1.5km resolution climate modelResolution of Welsh terrain


Mountains (1.5km grid)

Important processes

Rainfall Oct to March

Video of the jet streamhttp://www.metoffice.gov.uk/learning/wind/what-is-the-jet-stream?rel=0

Sea Ice


EP2 Headline results

latest climate scienceimplications for wales met office september 2013

Business

ocean water

office massey et

earth heat energy

extreme weather

office hiatus report

earth suns energy

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heat additional heat