19. UK cold winter December 2010
Coldest December on record in Wales -3.8 degC
Record minimum: -18.0 deg C at Llysdinam (Powys) 28 November 2010
• 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
Christidis and Stott, Met Office
Massey et al, University of Oxford, Met Office
19
21. Extreme weather
...to flood
Wettest June on record
(180% of average)
2 dry winters
Summer 2012 Rainfall
% of 1971-2000 average
3rd wettest summer on
record for Wales
(240% of average)
22. Is this the sign of things to come?
Impact on projections
23. Climate model projections CMIP5
Global surface temperature (single study, AR5 will contain synthesised results)
Knutti and Sedláček, 2013
Representative comparison
between CMIP3 and 5
models (scaled using simple
models)
24. Climate model projections CMIP5
Preciptation (single study, AR5 will contain synthesised results)
Knutti and Sedláček, 2013
December - February
June - August
Stippling – high robustness
Hatching – no significant change
White – models inconsistent
25.
26. Important processes for UK
weather and climate
•
•
•
•
North Atlantic weather – slow changes in ocean surface temperatures
Tropical Pacific weather – El Nino
Video of the jet stream
http://www.metoffice.gov.uk/le
Arctic Sea ice retreat
arning/wind/what-is-the-jetstream?rel=0
Solar variability
Atlantic Multidecadal Oscillation
27. Low UV from the sun leads to easterly winds
and cold conditions in Europe and the US
30. 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.
35. 1.5km resolution climate model
Resolution of Welsh terrain
Mountains
Mountains
(130km grid)
(60km grid)
Best longterm climate
models,
UKCP09
State-of-art
seasonal
model
Mountains
(25km grid)
Current
global
weather
forecasting
Mountains
(1.5km grid)
Current UK
weather
forecasting
+ groundbreaking
climate work
36. Important processes
Rainfall Oct to March
Video of the jet stream
http://www.metoffice.gov.uk/le
arning/wind/what-is-the-jetstream?rel=0
485 mm rainfall for Wales summer 2012
Average – 270.6mm
Wettest June on record – 205mm (avg 86.2mm)
Multi-model mean relative precipitation change for two seasons (December–February, DJF, and June–August, JJA) and one 20-year time periods centred around 2090, relative to 1986–2005, for CMIP5 (left) and CMIP3 (right). Stippling marks high robustness, hatching marks no significant change and white areas mark inconsistent model responses (
Figure 1. Individual and MEM projections of GTE (m) under (a) RCP2.6, (b) RCP4.5 and (c) RCP8.5. The curves show
the GTE relative to 2006. Thick black lines indicate the MEM. The discontinuity at 2100 is due to the change of ensemble
size.
Guest blog – How the Atlantic may influence wet summers
This morning there has been a lot of media coverage following a workshop held here at the Met Office HQ in Exeter on a recent run of unusual seasons in the UK.
Much of this centred around recent research by the University of Reading, presented at the workshop yesterday, which suggested Atlantic ocean cycles – specifically one known as the Atlantic Multidecadal Oscillation (AMO) – can have an influence on UK summer weather.
Here Professor Rowan Sutton, from the University of Reading, explains that research in a bit more detail:
“Last year, Buwen Dong and I at the National Centre for Atmospheric Science published a paper in Nature Geoscience about the link between slow changes in the temperature of the North Atlantic Ocean and weather patterns.
In particular, we presented evidence of a link between warm surface temperatures in the North Atlantic and a higher frequency of wet summers in the UK and Northern Europe.
This research built on earlier research I published with another colleague, Dan Hodson, in Science in 2005 and an important study by Jeff Knight and colleagues at the Met Office, which was published in 2006.
In our 2012 paper we showed that a rapid warming of the North Atlantic Ocean which occurred in the 1990s coincided with a shift to wetter summers in the UK and northern Europe and hotter, drier summers around the Mediterranean. The pattern identified matched that of summer 2012, when the UK had the wettest summer in 100 years.
Observational records show that the surface temperature of the North Atlantic has swung slowly between warmer and cooler conditions, and the present warm phase has a similar pattern to warm conditions that persisted throughout the 1930s, 40s and 50s. During the 1960s, 70s and 80s cooler conditions prevailed.
Computer simulations suggest that these changes in ocean temperature affect the atmosphere above. Warmth in the North Atlantic causes a trough of low pressure over western Europe in summer and steers rain-bearing weather systems into the UK.
An important question of interest to many people is how long will the current pattern of wet summers in northern Europe persist? This is a key research question and we don’t yet have precise answers.
In our 2012 paper we stated: “Our results suggest that the recent pattern of anomalies in European climate will persist as long as the North Atlantic Ocean remains anomalously warm.”
How long might this be? There is strong evidence linking the swings in the Atlantic Ocean surface temperature to the “overturning” or “thermohaline” circulation of the Atlantic.
This circulation appears to have intensified in the 1990s. Following such a strengthening, a subsequent weakening is expected, as various feedbacks exert their influence.
For example, the surface warm waters transported northward by the overturning circulation have relatively low density which inhibits their tendency to sink, and acts to slow the circulation. Such a slowing cools the North Atlantic.
The time scales involved are in the range between a few years and a decade or two. Progress in Decadal Forecasting, such as the pioneering work at the Met Office, and critical observations such as from the NERC-funded “RAPID” array, should help us to reduce this large range of uncertainty, but it is a challenging problem and advances may take some years.”
What the map shows
Average of models1 when they reach 4 ºC
With no mitigation there is +4 ºC rise by 2100
Some of the human impacts
Highlights some UK research since IPCC
Assume consistent population growth (A1B)
What the map does not show
Not particular time
Likelihood of this happening
No assumptions about adaptive capacity
Non-climate drivers excluded
1Met Office Hadley Centre HadCM3 QUMP ensemble model runs (A1B and A1FI scenarios)
Future forest fraction under an idealised scenario of steadily increasing carbon dioxide (roughly corresponding to the end of the century under a business as usual emissions scenario), from the old (top) and new (bottom) Met Office models. These results exclude the effects of deforestation and fire. Some forest dieback is found in the new model as forest adjusts over longer timescales
Climate Change Adaptation Planning Guide: This schematic gives the user a guide to when the energy industry should plan and adapt to climate change, based on the results of this project. The assessment is based on a judgement of the level of risk posed by climate change across the UK. In practice, adaptation plans will need to be location specific and should take in to account the resilience of the existing infrastructure.
Examples of EP2 achievements:
Investigated future wind resource, enabling the industry to understand the continued uncertainty of future wind power. This will assist risk management and investment decisions.
Modelled future soil conditions and their impact on cables. This has helped companies understand the cost and benefits of installing cables for a more resilient future network.
Built a tool to enable UK coastal and marine sites of interest to be screened to assess if sea level rise should be considered in more detail.
Investigated how the urban heat island effect may change in the future, so that network companies can develop plans for their infrastructure in cities.
Examples of some of the project’s findings:
With a few exceptions, such as the thermal ratings of equipment and apparatus, there is currently no evidence to support adjusting network design standards. For example, existing design standards for overhead line conductors do not require change.
Soil conditions will change — higher temperatures and seasonal differences in soil moisture are expected. Future conditions could be included in cable rating studies by increasing average summer soil temperatures in the models by approximately 0.5 °C per decade.
The output of thermal power stations (and in particular combined cycle gas turbines) could be suppressed, with higher air temperature meaning lower air density and lower mass flow. Conditions at each location should be considered, especially during redesign or new build and, if appropriate, adaptation planned.
Historical climatologies are no longer valid because climate is not stationary. The new climatologies that take account of climate change are already being adopted and will improve demand forecasting and planning out to 10 years ahead.