Latest climate science Implications for Wales Met Office September 2013
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This document summarizes the latest climate science from the Met Office and its implications for Wales. It discusses increasing global temperatures, rising carbon dioxide levels, extreme weather events, and projections showing continued warming if emissions are not reduced. Climate models are improving but still have uncertainties around factors like ocean heat uptake. The impacts of 4°C warming could include drought, flooding, reduced crops, and effects on billions of people. Improving model resolution helps understand regional implications like for Welsh terrain and rainfall.
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Latest climate science Implications for Wales Met Office September 2013
- 1. Latest climate science Implications for Wales Vicky Pope Sept 2013 © Crown copyright Met Office
- 2. Latest climate science Implications 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 © Crown copyright Met Office
- 3. © Crown copyright Met Office © Crown copyright Met Office
- 4. Incoming energy from the sun Sun’s energy reflected by clouds Sun’s energy reflected by Earth Sun’s energy absorbed by atmosphere Heat energy radiated from Earth Heat energy passes through atmosphere Heat energy re-emitted to warm Earth © Crown copyright Met Office © Crown copyright Met Office
- 5. 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 © Crown copyright Met Office © Crown copyright Met Office
- 6. Hadley cell Ferrel cell Polar cell Trade winds © Crown copyright Met Office © Crown copyright Met Office
- 7. © Crown copyright Met Office © Crown copyright Met Office
- 8. © Crown copyright Met Office © Crown copyright Met Office
- 9. 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 © Crown copyright Met Office
- 10. Atmospheric carbon dioxide (parts per million) INCREASING – Atmospheric carbon dioxide 380 Atmospheric carbon dioxide 360 340 320 1850 1900 1950 2000 CO2 has risen by 107ppm (38%) from pre-industrial levels of 280ppm. © Crown copyright Met Office
- 11. INCREASING – Land surface temperature 1850 1900 1950 2000 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 © Crown copyright Met Office
- 12. INCREASING – Sea surface temperature 1850 © Crown copyright Met Office 1900 1950 2000
- 13. INCREASING – Tropospheric temperature 1850 © Crown copyright Met Office 1900 1950 2000
- 14. INCREASING – Specific humidty 1850 © Crown copyright Met Office 1900 1950 2000
- 15. INCREASING – Sea level 1850 © Crown copyright Met Office 1900 1950 2000
- 16. DECREASING – September Arctic sea ice extent 1850 © Crown copyright Met Office 1900 1950 2000
- 17. DECREASING – Glacier mass balance 1850 © Crown copyright Met Office 1900 1950 2000
- 18. Why has there been such extreme weather recently?
- 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
- 20. Extreme weather From drought... 2 dry winters Oct 2010 – March 2012 Rainfall % of 1971-2000 average
- 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
- 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
- 28. Global focus
- 29. Global average temperatures (including latest observations)
- 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.
- 31. The impact of a global temperature rise of 4 ºC Change in temperature from pre-industrial climate 1 2 3 Ocean Acidification Rainforest loss © Crown copyright Met Office 5 6 7 8 9 10 11 12 13 14 15 16 Methane release Melting ice More heatwaves 4 Increased drought Forest fire Reduced crops Stronger tropical storms Current City population • 3-10 million • 10-20 million
- 33. Steadily increasing CO2 (similar to BAU scenario by 2100). Excludes deforestation and fire
- 34. Fundamentals of weather and climate modelling 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. © Crown copyright Met salinity and momentum Conserve heat, moisture,
- 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
- 37. Sea Ice
- 38. EP2 Headline results © Crown copyright Met Office
Editor's Notes
- 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.