Fifth consecutive ‘failed’ rainy season in East Africa predicted

Meteorological and climate projection expertise at the Met Office is not just confined to the UK, we have a number of experts working in regions around the world. A key region where this expertise is vital is Eastern Africa, where the population is particularly vulnerable to environmental fluctuations. In this blog, Met Office Scientific Manager (Seasonal to Climate Applications) Tammy Janes explains what the Met Office does in the region and why it is so important with the prospect of a fifth consecutive ‘failed’ rainy season.  

What the Met Office does in East Africa

Met Office scientists like myself have been working alongside colleagues in the Greater Horn of Africa (GHA) for over a decade to better understand and predict key rainy seasons for the region, helping to develop the skill of local seasonal forecasters and decision-makers to deliver actionable seasonal advice for the protection of lives and livelihoods.

We work in collaboration with the IGAD Climate Prediction and Applications Centre (ICPAC) which is the designated Regional Climate Centre for the World Meteorological Organization (WMO). Along with counterparts from 11 National Meteorological Services, ICPAC lead the production of seasonal forecasts based on an analysis of several global climate model predictions customised for the Greater Horn of Africa.

A key focus point of our work here is a triannual summit called the Greater Horn of Africa Climate Outlook Forum (GHACOF) which brings together a range of seasonal climate specialists as well as stakeholders from across sectors including agriculture, energy, water and many more.

Our support to the GHACOF process has involved delivering training programmes, engaging with sector-users, and promoting the use of robust and verifiable scientific methods in the forecasting process. The latest GHACOF meeting took place in Mombasa just last week (23-26 August 2022) and I was there in person with my colleague Scott for the first time since January 2020. We attended alongside colleagues from the Met Office-managed Weather and Climate Information Services (WISER) programme, which has supported over 3.3 million households to better access weather and climate information services in the region for the past seven years, helping to improve resilience to weather and climate related shocks.   

GHACOF-62 was a fantastic opportunity to strengthen existing relationships and build new ones. We were involved in some of the side events at the conference and Scott delivered a key talk on the current and predicted state of climate drivers that are well known to impact the upcoming ‘short rains’ during October to December.

Met Office Scientist Scott Burgan presenting at GHACOF-62

What the latest outlooks are saying

The latest outlook released by ICPAC is showing a high likelihood of below normal rainfall for East Africa during the upcoming October to December short rains, particularly in the drought affected regions of Ethiopia, Kenya, and Somalia. This is largely being driven by the combined effect of a predicted continuation of current La Niña conditions and a negative Indian Ocean Dipole (IOD). The ICPAC outlook is consistent with the Met Office seasonal outlook for Africa which has also just been updated.

This outlook is so important because parts of the region, including coastal Kenya, central/southern Somalia and central Ethiopia, have experienced four consecutive ‘failed’ rainy seasons since 2020, and a fifth ‘failed’ October-December rainy season would drive further deterioration of an already stressed humanitarian system.

Unprecedented situation

The October to December season in the equatorial parts of the Greater Horn of Africa contributes up to 70% of the annual total rainfall, particularly in eastern Kenya. The consecutive below average, or ‘failed’ rains are causing an unprecedented situation in what has been the longest drought in 40 years, suggesting that extreme weather and climate events are getting more extreme

The fear is that the strategies that have been put in place previously to cope with these sorts of events may not be enough to protect the lives and livelihoods of vulnerable communities in the Greater Horn of Africa with year-on-year deterioration.

Dire consequences

The impacts of prolonged lower than average rainfall are varied and significant. The predicted below-average October-December season would drive a deterioration of an already dire food security and malnutrition situation in 2023. Over 50 million people are expected to face high levels of food insecurity.

Irrespective of rainfall between October and December, conditions will not recover quickly enough to see food security improvements before mid-2023. A rapid scaling up of action is needed now to save lives and avert starvation and death. Dr.Guleid Artan, Director of ICPAC, said, “In Ethiopia, Kenya, and Somalia, we are on the brink of an unprecedented humanitarian catastrophe”.

A recent statement from the Food and Agriculture Organization (FAO) of the UN highlighted that “current appeals to respond to the drought remain well underfunded” and that the “drought response needs to be increased immediately to prevent the already severe food emergency, including a risk of famine in Somalia, from deteriorating into an even more dire situation.”

Ongoing support

Alongside other science colleagues at the Met Office, we will continue working with our African partners to provide important support to help decision makers and humanitarian organisations act on what is ahead.

At COP26 in Glasgow last November, the UK Government’s Foreign, Commonwealth and Development Office (FCDO) announced additional funding for the WISER programme in Africa.

WISER has worked in East Africa and the Sahel to deliver transformational change in the access and use of weather and climate information services to people and organisations including National Meteorological and Hydrological Services (NMHSs). It delivered over £200million in socio-economic benefits during that time, including enabling improved protection of property, livelihoods and even saving lives through its projects.

The WISER programme is now expanding into additional regions through its WISER Africa programme, including West and Southern Africa, as well as the Middle East and North Africa (MENA) through WISER MENA. It is currently in its scoping phase, with projects expected to begin in early 2023. To find out more about WISER, visit the WISER webpages on the Met Office website.

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Pakistan flooding – ‘worst’ in decades

Relentless monsoon rain has left 33 million people across Pakistan affected by flooding, according to Pakistan’s Federal Minister for Climate Change, Senator Sherry Rehman. Although very little rain is expected through the coming weeks the levels of the Indus and Kabul Rivers will continue to leave many lives and livelihoods at risk.  

The Asian summer monsoon season runs from June to the end of September, and much of south Asia depend on this rainfall following the dry season. However, this year Pakistan has seen this rain come in unmanageable volumes.  

Deputy Chief Meteorologist at the Met Office, Ele Hands, said: “Pakistan started the season with its wettest July on record, followed by a very wet August. These added together means that they have already seen three times the average monsoon rainfall, and more locally areas have received up to five times the amount of rain they would usually see, and we still have another month of the monsoon season left.” 

River levels are slowly retreating from that of a 1 in 100-year event, very little rainfall is expected this week, but levels are forecast to be that of a 1 in 20-year event even into this weekend.  

The Indus River rises in Tibetan Plateau, while the Kabul River rises in the Hindu Kush mountains in Afghanistan. The Indus drains an enormous area of Pakistan, and extreme rainfall has resulted in the main river channel becoming overwhelmed. Mountain glaciers to the north feed these large rivers flowing south, and during mid-July to mid-August peak snow melt and rainfall coincide to result in the highest river levels. 

The drivers of flooding 

Throughout July and August, a succession of monsoon depressions tracked west across India and into Pakistan bringing waves of very heavy rain. This weather pattern is typical during monsoon season, but the frequency has changed this year. 

Monsoon conditions are driven by a simple mechanism that drive a dramatic change, every year. Heat builds up across the Tibetan Plateau through the spring and summer months causing air to rise. This means low-pressure depressions develop at the surface. These depressions drag in moist southwesterly air which lead to heavy rainfall.  

Ele explained: “In a typical monsoon season, we would expect around four waves of this heavy rain but there have been eight of them so far. These waves have moved into a similar area each time and that means the rain has accumulated over the same areas.”  

Not only have these pulses of rain arrived at an unmanageable rate, but they have also pushed into more northern parts of Pakistan. The increase in spatial coverage means that far more people compared to usual as well as other extreme monsoons events, have been affected.

Is this climate change?

The south Asian monsoon is known to exhibit a high degree of natural variation with some extreme years producing much higher rainfall totals across the region, and the ongoing La Nina conditions are likely to be a contributing factor to the wetter-than-average season. 

The natural variability creates challenges for climate scientists trying to examine the impacts of climate change on this weather system. This is largely because the differences between extreme wet and dry years can be larger than any influence that could be expected from climate change at this stage. 

We know that a warmer atmosphere holds more moisture, so this could be a contributing factor affecting those years which would already have been extremely wet. It is likely human influence has led to intensification of heavy precipitation across Asia but adding glacial and snow melt into the picture complicates the relationship between the south Asian monsoon and downstream flooding events. Any changes in land management of the catchments of southern Asia’s great rivers provides an extra complication which needs to be considered. Ongoing research into the evolution of the Indian Summer Monsoon is therefore vital to better understand what the future holds.   

Impacts 

In 2010, an extreme monsoon caused devastating flooding to the Indus River in Pakistan. It was estimated that 20 million people were affected, so far, the 2022 monsoon has affected 33 million people. Human fatalities are currently estimated to be around 1000, so far less than the total from 2010. But the impacts from this year’s monsoon season are expected to continue well after the peak rainfall, as the rivers continue to react.  

Flooding is always expected during monsoon season but this year’s flooding will leave damage that will take years to recover from. UN (United Nations) Secretary General Antonio Guterres has said “the people of Pakistan face the unrelenting impact of heavy rains and flooding – worst in decades.” On Tuesday, the Government of Pakistan and the United Nations launched a Floods Response Plan in the backdrop of devastating rains, floods, and landslides that have destroyed homes, caused over 735,000 livestock to perish, impacted two million acres of crops, and caused severe damage to communications infrastructure.

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Future summers could last longer hints Met Office research

Small White butterfly enjoying the autumn sunshine

A Small White butterfly enjoys the autumn sunshine. Picture: Grahame Madge

UK autumns are likely to become drier on average and more ‘summer-like’ with increasing climate change according to new research from the Met Office.

Daniel Cotterill is the lead scientist behind the study, which focusses on the projected likelihood of occurrence of weather patterns, of which there are 30 standard types. He said: “Each weather pattern over the UK brings certain characteristics, whether that’s rainfall or temperature.

“Using climate models and the UK Climate Projections, our research found that the largely ‘summer-like’ weather patterns -bringing drier conditions – will begin to extend into the start of autumn. And weather patterns such as those dominated by large low-pressure systems, will tend to occur slightly less in autumn in future.

“Although we don’t expect to see this shift in pattern imminently, a key finding from this study is that from the mid-2020s warmer and drier autumns following hotter and drier summers could increase drought risk.”

The strength of the shift in weather patterns is dependent upon the rate of greenhouse gas emissions are emitted into the atmosphere. Climate scientists refer to these different rates as emissions’ pathways. Daniel added: “Our research compares a very low-emissions pathway to a very high-emission scenario. What we see is these effects are a lot stronger in the high-emissions scenarios, and this suggests that these changes in weather patterns are due to human influence and the resulting effect of warming on atmospheric circulation.”

The study shows that we’re likely going to see less rain in autumn on average. But, backing up other studies, it signalled the potential for extreme rainfall events to be interspersed between the drier spells.

Daniel added: “This is a signal we’ll start to perhaps see over the next ten years. We’re likely to see a 4 to 12% reduction in rainfall in English regions in the future in autumn. And this depends very much on the greenhouse gas emission scenarios. One of the things we are already seeing in autumn as average seasonal temperatures rise is an increase in the number of extreme rainfall events. But in future, we’re likely to see this drying effect as well.

“UK Climate Projections have shown for some time that we can expect hotter, drier summers and warmer and wetter winters. Our study shows we are likely to see hotter and drier autumns on average too.

Daniel added: “To see how situations might unfold we could consider the autumn of 2020. On 3 October we saw the UK’s wettest day on record and the volume of rainfall which fell on the UK that day could have filled Loch Ness. However, if you look at the overall rainfall for that autumn, it’s actually only 6% above average and that is because of a drier September and November that year.”

The paperFuture extension of the UK summer and its impact on autumn precipitation – is published in the journal Climate Dynamics.

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How many days of thunder do we have in the UK? 

The heatwave ended with a bang for many of us earlier this week as thunderstorms hit the UK after several weeks of record-breaking hot and dry weather. According to the Met Office’s next generation lightning location system, there were 26,718 lightning strikes over UK land between Sunday and Wednesday, which equates to more than half of all UK lightning strikes (49,439) during the past twelve months.  

These thunderstorms produced torrential downpours in some parts, leading to surface-water flooding and travel disruption, with much of the rainwater unable to permeate the hard ground. Lightning can also cause wildfires, damage to infrastructure and even fatalities. Due to these impacts, it’s important to understand how frequently thunderstorms happen and how that has changed over time.  

Thunderstorms can bring torrential rain leading to flooding.

How do we detect thunder and lightning? 

We can calculate how far away lightning is by counting the number of seconds between the flash of lightning and the sound of thunder, and then dividing by five. That gives us the distance in miles from the lightning: 1 mile for every five seconds.  

The Met Office has operated some form of long-range very low frequency lighting location network to detect and locate the source of lightning events since the 1940s. Nowadays it can obtain data about thunder and lightning from observation stations and voluntary observers, as well as from its lightning location system.  

This data helps meteorologists provide warnings for the public, the aviation sector and other industries of hazardous weather associated with thunderstorms and potential impacts. But it doesn’t help to determine long-term trends accurately for the whole of the UK, because of data limitations and changes to the location of sensors over time.  

Lightning is a huge electrical discharge that flows between clouds, from a cloud to air, or from a cloud to the ground.

Days of Thunder study  

The Met Office recently conducted a Days of Thunder (DoTs) climatology study to show how the frequency of thunderstorms varied over a 30-year period for the UK from 1990 to 2019 per month, season and year.  

The National Climate Information Centre at the Met Office has a database of DoTs per month from volunteer observer stations, dating back to 1949. But the number of stations have varied from eight in 1949 to around 500 at its peak. The study was based on 25 stations that continuously reported DoTs between 1990 and 2019, alongside lightning location data generated from long-range lightning location networks. 

The thunderstorm study introduced a new method of normalising the long-range lightning location data using observations of audible thunder. It was also the first thunderstorm study to generate a gridded dataset for such a long time period, focusing exclusively on the UK. The study could be extended beyond 2019, as more data becomes available, allowing trends to be analysed in the future.   

The  figure shows the 30-year average days of thunder separated by season, with the colour scales showing the number of days of thunder per year.

How frequently do we get thunderstorms in the UK? 

Overall, there was a reduction in the number of days of thunder in the UK per year between 1989 and 2019, according to the study. Thunderstorms increased in the north of the UK and decreased in the south. Summer was the most active thunderstorm season and the winter the least active.  

Met Office Observations Scientist, Ed Stone, who led the study said: “Our study has shown that in the United Kingdom we are less likely to see a thunderstorm today than we were 30 years ago. Although we have not attempted to investigate the changes shown, is possible that some of the trends seen are due to decadal-scale oscillations in the atmosphere.  

“The findings may also help us to predict future lightning activity as part of climate change. We hope that the methods presented can support significant further research using other climatological data.”  

These graphs show how the average number of days of thunder has changed during the 30-year period year. The solid grey line is UK land and sea area; the solid black line is all UK land area, and the dashed grey line is UK sea area. The black dotted line and black dashed line are south UK Land and North UK Land area respectively.

What is the relationship between lightning and climate?  

The relationship between lightning and climate change is still being studied by climate and weather scientists. A Science study in 2014 predicted that global warming will increase the frequency of lightning strikes by about 12% for every degree rise in global temperature. 

Between the two 30-year periods 1961-1990 and 1991-2020, the mean temperature of the UK rose by 0.8C from 8.3C to 9.1C. Scientists will need to undertake further research to understand why the increase in the UK’s mean temperature appears not to have led to a corresponding increase in lightning activity; in contrast to the 2014 study. 

Ed Stone of the Met Office added: “Thunderstorms are among the most impactful elements of weather in the UK. Understanding more about their frequency has important implications for increasing our knowledge of future climate change and severe weather events.”

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Monitoring and responding to sea level rise  

In our recent blog post, we introduced our August climate theme of sea level rise, explored some of the different aspects, and looked at how climate change can influence sea levels at a global and regional scale. In this blog, we will be taking a closer look at this topic to find out how sea levels are monitored and the actions that can be taken in response to changing sea levels.  

Monitoring sea level rise  
Climate scientists monitor sea levels to understand how they have changed over time, and to inform projections of how they might change in the future and the impacts that these changes might cause. Sea level is monitored by tide gauges and from space by satellites.   
  
The Global Climate Indicators are a set of parameters that describe the changing climate, looking beyond temperature as the only indication of climate change. They comprise key information for the most relevant domains of climate change: temperature and energy, atmospheric composition, ocean and water as well as the cryosphere. These indicators provide additional information and allow a more detailed picture of changes to our climate.  

The Met Office climate dashboard provides a comprehensive way to stay up to date on the current state of the climate by providing data based on observations of these key global climate indicators, one of which is sea level rise.   
  
Nick Rayner, who leads the Met Office’s Climate Monitoring team said of the dashboard:  
“Observations from coastal tide gauges show sea levels rose by nearly 200mm between 1900 and 2000. However, by building in projections of sea level rise linked to different scenarios for future greenhouse gas emissions, you can easily see what we are already committed to and the need for urgent action to minimise further changes.”   

You can view the sea level dashboard here.  

How much could sea levels rise?  
In August 2019, the Met Office Hadley Centre produced a set of UK- focused sea level projections for a report which was published by the Environment Agency. The projections demonstrated that under all emissions scenarios, sea levels would continue to rise well beyond the year 2100, although the rate and severity of the rise would depend on the level of emissions.   

Figure 1. Time series of the time-mean relative sea level change for UK capital cities based on the nearest Class A tide gauge location (indicated in brackets). Notes: Solid lines indicate the central estimate and dashed lines indicate the 5th to 95th percentile range for each RCP scenario as indicated in the legend (top left panel). All projections are presented relative to a baseline period of 1981 to 2000.Source: UKCP18 Marine Report (Palmer et al. 2018b, Figure 3.1.4)  

Matt Palmer, who leads the sea level projection work at the Met Office said: “As part of the UKCP18 national climate projections, we developed a new set of sea level projections with information available all the way to 2300. These longer time horizons are needed to fully appreciate the future sea level rise we will need to adapt to under different amounts of future climate change. Even under immediate and sustained reductions of greenhouse gas emissions, the UK will need to be prepared for 1-2 m of future sea level rise.”   
  
Sea level rise impacts   
Rising sea levels can cause a myriad of impacts, from changing the shape of our coastline and beaches, to threatening infrastructure and the homes of people who live in coastal communities. Rising sea levels can also threaten the survival of already fragile wildlife habitats.  

As the sea level rises around the UK it exposes more areas of coastal land to larger and more frequent storm surges and wind-driven wave impacts. In February 2014, a storm destroyed a section of the seawall in Dawlish, Devon, leaving the railway line suspended in mid-air. This line was the only one linking Cornwall to the rest of the country, so its damage caused significant travel disruptions. Reconstruction of the sea wall and train line cost millions of pounds, and it wasn’t until April 2014 that the line was reopened.  

Major infrastructure close to the sea such as the main Devon to Cornwall rail link at Dawlish will be increasingly vulnerable to rising sea levels and storm surges.

Tackling sea level rise – a combined approach  
Research tells us that climate change influences sea level rise, and we know that even if we were to curb emissions of greenhouse gases, we are already committed to substantial sea level rise over the coming century and beyond, based on the concentration of greenhouse gases that are already in the atmosphere. With this in mind, how can we respond to the threat of rising sea levels, and is there anything that can be done to limit this progress? The answer lies in a combined approach.

Mitigation will be a vital strategy in stabilising the rate of climate change-induced sea level rise. Climate change mitigation involves finding ways to limit the progress of climate change and its resulting impacts. Methods of mitigation include investment in renewable energy sources, carbon-neutral schemes and a reduction in carbon emissions.

Dr Helene Hewitt OBE, Met Office sea level rise expert, said, “Without strong action to tackle climate change we could see global sea levels rise by a metre by 2100, depending on the greenhouse gas emission scenario: that could be up to five times the rate or more in the next 100 years, compared with the previous century. Even with aggressive action to cut greenhouse gas emissions, global sea levels will continue to rise.”  
  
Climate change adaptation involves finding ways to adapt to the impacts of climate change that are already happening. Given that we are already committed to substantial future sea level rise, it is important that decision makers consider adaptation alongside mitigation in order to minimise the impacts that we experience.

Adaptation strategies should be informed by regional climate modelling and risk analysis, and flood modelling of how climate change will affect future flood risk so appropriate adaptation measures can be designed for at-risk areas. Environment Agency guidance, including Flood risk assessments: climate change allowances and Flood and coastal risk projects, schemes and strategies: climate change allowances, can be used to help with flood modelling and assessment.  

Another possible nature-based adaptation strategy is managed realignment. This involves using natural coastal landforms to act as a defence against coastal erosion and flooding, as opposed to the use of artificial structures like sea walls. An example of managed realignment is the creation of “inter-tidal zones” – areas of low-lying land on the coast that are allowed to flood with the advancing tide, forming mudflats which serve to protect inland areas.  

How can the UK adapt to sea level rise?  
In January 2022, the UK Government published the UK’s Third Climate Change Risk Assessment (CCRA3) which sets out the risks and opportunities facing the UK from climate change. This was informed by the Climate Change Committee’s independent advice report, which identified sixty-one UK-wide climate risks and opportunities cutting across multiple sectors of the economy.   

Of these sixty-one risks or opportunities, the risk assessment concludes that thirty-four are ranked as ‘more action needed’ including risks to people, communities and buildings from coastal flooding and sea level rise.   

Earlier this year, the Environment Agency published their Flood and Coastal Erosion Risk Management Strategy Roadmap to 2026 which provides a plan to deliver its strategy’s vision for a nation ready for, and resilient to, flooding and coastal change – today, tomorrow and to the year 2100. The roadmap sets out the practical actions to achieve the ambitions in the strategy and tackle the growing threat of flooding from rivers, the sea and surface water as well as coastal erosion. It also delivers a host of wider benefits, including local nature recovery, carbon reduction, more integrated water management, and improved forecasting of flood events. These actions will increase our resilience to flooding events for homes, businesses and infrastructure across the country.  

During August, we will be exploring the topic of sea level rise and its wider impacts, both here in the UK and from a global perspective. Follow #GetClimateReady on Twitter as we explore this theme.  

Get ready for tomorrow #GetClimateReady  
 

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How will the summer end: ‘bang’ or ‘whimper’?

The summer 2022 has been remarkable on many fronts, says Paul Davies Met Office Fellow (Meteorology).

We exceeded the 40°C threshold for the first time ever, and for England the January-July period has had 69% of average rainfall making it the ninth driest in a series from 1836, and the driest such period since 1976.

July was also the driest July for England since 1935 and the driest on record for East Anglia, southeast and southern England. Some locations, such as Odiham in Hampshire, have received little or no rain since 30th June.

What does this mean for the rest of summer and beyond? Is there anything we can glean from previous heatwaves or long-lasting periods of dry weather?

Below is a plot of rolling rainfall accumulation from 1 June to 31 October for the five driest summers on record (1913, 1976, 1983, 1995, 2018) compared to the average for the period 1991-2020. Meteorologists refer to this as the climatological average.

1976 and 1995 were notable for having a sharp transition to wet conditions in September, and to a slightly lesser extent 2018 in July and August. It is also noticeable how quickly rainfall recovered to average during early autumn 1976, and the preceding heavy rain and excessive flooding from mid-August.

Why do we see these sudden changes in weather patterns? To help us explain this we need to see the weather world through regimes. A regime is a persistent state of the atmospheric circulation which can be ascribed to a weather type, for example a regime may consist of a strong Atlantic Jet bringing a series of low-pressure systems, wind, and rain across the UK. Storms Dudley, Eunice, and Franklin were classic examples. Or it might be an area of high pressure leading to long periods of dry conditions and warmth.

In 1976, the regime pattern got stuck, with a persistent area of high pressure locked in across the UK for most of the summer. But then, remarkably, the regime abruptly changed within a few days to a more unsettled type with rain and thunderstorms. High pressure – with its associated heatwaves – has been the dominant regime affecting the UK during this summer, but what does the future hold as we transition into autumn.

To try to answer these and similar questions, the Met Office has been developing a tool, called Decider to identify and forecast regimes.

Decider is based on our ensemble system – which produces multiple forecasts with different starting points aiming to capture the ‘chaotic’ nature of the weather and express the answer as probabilities.

Using Decider, we can infer the regime type for this and the following week in the plot below. It suggests a change of regime next week from hot and dry associated with a high pressure regime (red colours) towards a pattern that is typically associated with low pressure (blue): less hot with a chance of showers and thunderstorms. The numbers in the boxes representing the probability and therefore reflecting the confidence in how one regime changes to another. So, what does that mean for the UK?

(Above) The output from the Met Office Decider system helps forecasters understand when a weather regime change is most likely to occur. The reds for high pressure are clearly most likely to give way to a regime dominated by low pressure into next week.

Based on today’s Decider forecast and medium-term forecasts, there is an increased chance of rain from early next week onwards. However, there is a question mark on duration, intensity and whether the wet pattern will continue into autumn.

For areas that have received none or very little summer rain, the question on what type of rain can we expect is important too. Especially as the Environment Agency has today confirmed drought status for eight of its 14 areas in England.

Will the rainfall suggested by the forecast be sufficient to shorten the duration of the drought? We will have to see, but the door is open to a forecast with more rainfall for southern England than we have seen since early June.

In the next seven days the forecast though has a lot more certainty. Providing the Met Office with sufficient confidence to issue thunderstorm warnings covering the greater part of the UK. The rain could be of sufficient intensity to result in high-velocity flows, flash flooding and debris as slow-moving thunderstorms deposit rain onto baked, hardened surfaces with water running off into potential downstream deluges.

This will it be a ‘hit-and-miss’ affair with locations only a few miles apart receiving no rain while others seeing extreme rainfall and flooding.

Before assessing the longer-range forecast into the rest of August and September, we may have to wait until the Atlantic Jet strengthens. This will be driven in part by the decaying remnants of hurricanes entering our latitude; driven in turn by an anticipated active hurricane season. At this range, indications remain mixed, highlighted in lower probabilities in the Decider plot above, but there are signs for further spells of wind and rain across the UK, especially across more northern and western areas with occasional incursions further south and east.

Back to the question: how will the summer end?

For some next week the summer will end with a ‘bang’ as intense thunderstorms are forecast for early next week, while others who miss the rain will perceive the change as a ‘whimper’.

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Get ClimateReady – What is meant by sea level rise?

This month, as part of our Get ClimateReady campaign, we will be exploring the theme of sea level rise, a topic which has been of significant interest this year. Simply put, “sea level rise” refers to the rise in the ocean surface as a result of climate change. Rising sea levels can cause significant impacts for infrastructure, coastal communities and wildlife across the globe, and it is clear that a combined approach, implementing both mitigation and adaptation measures, is necessary to avoid the worst of these impacts. Understanding the changes in sea level – what causes them, why, and how quickly they occur, is imperative if we are to adopt the most effective solutions.  

There are two main aspects of sea level rise that are of particular interest to climate scientists: 
 
Global and regional mean sea level 
Increases in global mean sea level are caused by two main processes; thermal expansion of oceans as they increase in temperature due to global warming, and the addition of more water to the oceans – mostly from melting ice sheets and glaciers.  

Whilst the total increase in ocean volume relates to global mean sea level rise, regional sea level can be influenced by additional factors such as changes in ocean currents, the distant effects of land ice melt and the rise and fall of land masses. These factors affect sea level rise around the UK.  For example, while the land is rebounding in Scotland after the last ice age, in southern England it is sinking, which affects the sea level rise experienced in these regions.  

Similarly, gravitational effects can influence sea level at a regional scale. The large amount of ice in the Greenland and Antarctic ice sheets means that water is pulled towards them by gravity. As this ice melts, the gravitational attraction decreases, which leads to a drop in sea level near the ice sheet and a rise much further away. Areas that are in between the areas of fall and rise experience very little sea level rise from the ice sheet melt. Due to its geographic location, melting of the Greenland ice sheet will have a much lesser effect of UK sea level rise than melting of the Antarctic ice sheet.  

In this article from the Guardian, Met Office Climate Scientist Dr Matt Palmer explains more about the gravitational effects which influence sea levels. 

Extreme sea level 
Extreme sea level typically refers to the maximum sea level that is experienced during a storm. Storm surges can contribute to significant extremes in sea level, occurring when sea levels rise due to a combination of a reduction in atmospheric pressure, water being forced onto the coast by the wind, and in some cases funnelling by the local bathymetry (variations in the ocean floor). 

Climate change and sea level 
As the planet warms, so too do our oceans, directly contributing to thermal expansion and the melting of ice sheets and glaciers, which lead to increases in global and regional mean sea level rise. The slow response of the oceans and ice sheets to climate change mean that sea level will continue to rise for centuries, even under scenarios where future temperature rise is stabilised/stopped. 
 
The Intergovernmental Panel on Climate Change (IPCC) is the United Nation’s body for assessing the science related to climate change. In August 2021, the IPCC published the Working Group 1 (WG1) contribution to the Sixth Assessment Report (AR6), a peer-reviewed publication which examines the physical science of climate change, based on contributions from thousands of international scientists. The report confirmed that global mean sea level has increased by 20cm since the early 20th century and that human influence was the main driver of these increases since at least the 1970s. Extreme sea level events are also expected to become more frequent in the future and IPCC assessed that, compared to the recent past, extreme sea levels will occur about 20 to 30 times more frequently by the year 2050.


Dr Helene Hewitt, of the Met Office, was a co-ordinating lead author on the chapter covering Oceans, Cryosphere and Sea Level. In an article exploring the findings of the IPCC’s report, Helene took a closer look at what we know about past and future sea level rise, and examined projections for the future, based on different climate scenarios.  
 
Speaking about the report, she said:  
“This report demonstrates that oceans are continuing to warm, ice is melting and sea level is rising. Many of these changes will not stop immediately if we reduce emissions but they can be slowed down and crucially, we will limit the risk of rapid ice loss from Antarctica which otherwise could lead to additional metres of sea level rise over the coming centuries”. 
 

More recent climate reports provide further clear evidence to support the fact that climate change is influencing sea levels, both around the UK and across the globe. Published in May, the World Meteorological Organisation’s State of Climate report found that global mean sea level reached a new record high in 2021. The report confirmed the IPCC’s findings that the rate of sea level rise had increased, estimating that sea level has risen at an average rate of 4.5mm per year over the period 2013 – 2021, more than double of that between 1993 – 2002. Such an increase can be attributed to the accelerated loss of ice mass from ice sheets.  

The increasing rate of sea level rise seen in the global mean is also apparent in regional sea level around UK. The latest State of the UK Climate report for 2021 by the Met Office, found that the rate of sea level rise around the UK is increasing, with selected locations seeing a sea level increase of 3.0-5.2mm per year, compared to around 1.5mm per year in the 1900s.  

The National Oceanography Centre (NOC) provided the input for the sea level section of the State of the UK Climate report. 
 
Dr Svetlana Jevrejeva, a Principal Research Scientist at the NOC, said: 
“Our long-term records show that over the past few decades, rate of sea level rise in the UK is increasing. As sea levels rise there can be greater impacts from storm surges. Last year storm surges of over 1.5 m were seen during Storm Arwen, but extreme sea levels were avoided as this occurred during low water and a neap tide”. 
 
Throughout August we will be continuing to explore the topic of sea level rise and its wider impacts. In our next blog, we’ll be taking a closer look at sea level rise – how it is monitored, the impacts it can cause, and the different approaches that can be taken to mitigate these, both here in the UK and from a global perspective. Follow #GetClimateReady on Twitter as we explore the topic of ‘sea level rise’. 

Get ready for tomorrow #GetClimateReady 

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Climate study backs up Met Office research

A study published today [Friday 29 July] by World Weather Attribution supports a previous Met Office study that was published before this summer and which looked at the prospect of 40°C in the UK.

The UK record temperature was reached on 19 July 2022

The UK’s temperature record was broken on 19 July 2022 when 40.3C was recorded at Coningsby in Lincolnshire. Picture: Shutterstock

The Met Office study found that the likelihood of seeing 40°C in the UK has been rapidly increasing and what would once have been an extremely unlikely event without climate change has now become a distinct possibility. Both the Met Office and WWA studies found that human-caused climate change has made the chance of 40°C in the UK about ten times more likely when compared with the pre-industrial climate. Taken together, the Met Office research carried out ahead of this summer’s heatwave and the WWA study conducted shortly afterwards, this research underscores the importance of needing to adapt to such extreme temperatures.

While current calculations indicate that the chance of 40°C temperatures occurring in the UK is around a 1% chance every year, Met Office research shows that this could increase with further greenhouse gas emissions. In the most extreme emissions case considered this could reach around 33% chance every year but current international efforts to reduce greenhouse gas emissions may reduce this to 5-6% in any given year. Further emission reductions inline with the Paris agreement (CoP26) climate temperature goals could reduce the yearly chance further.

The Met Office study was published in 2020 in a paper by Nikos Christidis, Mark McCarthy and Peter Stott in Nature Communications. At the time, Nikos Christidis said: “Our paper shows that the likelihood of hitting 40°C is rapidly increasing. In a ‘natural’ climate without human-caused climate change, the event would have been exceptionally rare.”

It is clear that temperature extremes of 40°C or more have been unlikely in the historic climate and are still unlikely today. Different studies show some variation but all agree that events of this magnitude are unlikely in the current UK climate but that the chances are growing all the time

Professor Jason Lowe OBE said: “The potential for a temperature of 40°C or more for the UK’s current climate is captured within computer models and the output from the UK Climate Projections (UKCP18).”

It is not inconceivable that we could get another forecast of 40°C for the UK later this summer. Professor Peter Stott – a globally recognised authority on heatwaves, added: “The heat which brought these record-breaking temperatures to our shores is still in place in south western Europe, prompting the risk of further extremely hot temperatures.”

The heatwave in the UK fits into a global pattern of weather this summer. As well as the exceptionally high temperatures in Western Europe, China has endured three heatwaves so far this summer and the US has experienced exceptionally high temperatures, particularly in the South-West. This is part of a naturally-occurring wave-like pattern in the atmosphere around the Northern Hemisphere. When combined with a warming climate and localised effects that can enhance the heat even further, the result is a widespread pattern of heatwaves across the planet.

Peter Stott concuded: “These searing temperatures across the globe, not just this year but in the last few years, show how temperature records are not just being broken but are being shattered. The climate science community remains focussed on establishing where these events fit into our climate modelling and predictions, and continuing research to enhance our understanding of how these elements come together as the climate continues to change.”

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Climate adaptation monitoring – a necessary challenge 

In May 2021, we brought scientists, policymakers, community representatives and climate communicators from around the globe together at our virtual Climate Science Conference. Its aim was to set out a vision for how climate science and services can be harnessed in support of the ambitions of diverse societies worldwide to build a more sustainable, more resilient low carbon future. Following robust discussions and valuable insights from speakers and delegates, nine key recommendations were developed, three of which focused on climate monitoring, our climate theme for this month. 

As well as highlighting a need to accurately monitor greenhouse gas emissions from different countries, it was also concluded that an integrated monitoring, attribution and prediction system is urgently needed to provide monitoring of extreme weather events and their impacts, and to provide early warning of incremental change and high impact low likelihood events (tipping points). The science behind the development of such a system is the subject of a World Climate Research Programme (WCRP) Lighthouse activity. 

Monitoring adaptation 

The third recommendation centred around adaptation and the need for measures to be monitored so that their effectiveness can be assessed. Professor Charlotte Watts, Chief Scientific Adviser and Director for Research and Evidence in the Foreign, Commonwealth & Development Office (FCDO), spoke at the conference, saying, “Climate science for adaptation is not just about hypotheses of what futures might look like but it’s about how do we inform real action now to improve lives today and tomorrow.”  

Professor Brian O’Neill also spoke in his role as Atmospheric Science & Global Change Manager at the Pacific Northwest National Laboratory. He commented that, “When thinking about our possible futures for climate change risks…we’re going to need to understand how climate change development pathways and adaptation and mitigation responses will interact together to determine the risks we face and the most effective solutions.”  

Baroness Brown of Cambridge, Chair of the UK’s Climate Change Committee (CCC) Adaptation Sub-Committee, also referenced the need for mitigation and adaptation to go hand in hand: “Significant adaptation is required to deliver nature-based solutions for achieving Net Zero emissions. We must use nature that will work in the climate in 80 years’ time.” 

Around the world, adaptation monitoring is a big gap in the policies of many countries, with monitoring and evaluation of adaptation more difficult to measure than the qualitative data available when considering emissions and mitigation. Brendan Freeman, Senior Analyst, Climate Change Committee, said: “Measurement is fundamental to understanding if adaptation is working. However, current indicators for measuring progress and the effectiveness of adaptation actions are inadequate. There is an urgent need, therefore, for Government to fund work to develop new indicators to support the comprehensive assessment of adaptation progress.” 

Adapting for tomorrow now 

In the UK, the Department for Environment, Food and Rural Affairs (Defra) is the lead Government department for domestic climate adaptation. It’s a statutory requirement under the Climate Change Act of 2008 to plan how the UK will adapt to climate change. In 2023, Defra will release the new National Adaptation Programme (NAP), which will highlight the ways that the UK is planning to adapt to climate change in the next five years. The government’s ambition for NAP3 is to have a clear set of objectives for adaptation, and policies, programmes and investments to meet those objectives, with metrics and timelines linked to the 61 risks set out in the third Climate Change Risk Assessment (CCRA3) published in January.   

Climate science and services 

UK urban park

Effective climate services are an important component in informing climate change adaptation measures. As a climate service provider our role is to translate our leading scientific research into user-driven climate services, enabling users to better understand & manage the risks & opportunities arising from climate variability & change.

One of the outputs from the UK Climate Resilience Programme (UKCRP), funded by the UK Government’s Strategic Priorities Fund, are the city packs. Developed by the Met Office, they use the latest UK Climate Projections (UCKP18) to provide high-level, non-technical local summaries of a city’s future climate. The city packs use graphics and tables to communicate scientific research in an accessible way, providing robust climate information to help city decision makers at local and city councils plan for the future, enabling our towns and cities to become more resilient to climate change. 

In Manchester, one of the risks facing the city is flooding, due to the warmer, wetter winters that we expect to experience in the future. Following our work with Manchester City Council, they’re working on adaptation measures which provide co-benefits in local communities. For example, nature-based solutions are a key element used within a park in the West Gorton community area in Greater Manchester. Permeable paving and vegetation reduce flooding and storm water run-off and act as a cool area in heatwaves, helping with multiple impacts of climate change. The park has multiple uses for the community including for sport and recreation, improving wellbeing and benefitting local biodiversity and air quality.  

Dr Rosie Oakes, Met Office Climate Scientist, commented recently in the Mostly Climate podcast, “When you think about climate change, it can be so scary and overwhelming. But as soon as you envisage a future world which is actually better than the one you live in right now because of the adaptation that you put in place, it makes me feel more hopeful at least.” 

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July 2022: a dry run for UK’s future climate? 

So far July 2022 has been the driest July in England since 1911. Up to 26 July there has been only 15.8mm of rain averaged across England; this is only 24% of the amount we would expect in an average July. 

At this stage in the month we would expect to have seen well over three-quarters of the month’s rain to have already fallen in an average July. 

The situation for the UK is a little better. As it stands, July 2022 is still the eighth driest July since 1836. With only 37.7mm of rain having fallen so far it is the driest July since 1984. Scotland has been closer to average in the north and west, but drier conditions have prevailed for south and east Scotland. Overall Scotland (71%), Wales (39%) and Northern Ireland (43%) have been dry, but the most extreme conditions are in East Anglia and southeast England. 

As frequently happens there is a contrast between the northwest of the UK, where some regions, in the far north of Scotland, have already reached around average rainfall – and the southeast which are looking extremely dry indeed. 

Dry month

With a little way to run before the end of the month, there is still time for the situation to shift slightly. However, with little significant rain forecast for south and east England, there is scant prospect of a significant improvement within the next week or two at least. For all July 2022 will be remembered as a dry month and is prompting some in the media to consider the prospect of drought. 

Drought isn’t within the Met Office’s remit; instead, the Environment Agency takes the lead on drought in England, with Natural Resources Wales taking responsibility in Wales; NIEA in Northern Ireland and SEPA in Scotland. There are many factors beyond rainfall, such as water demand and the extent of previous rainfall, that drought planners have to consider. 

Mark McCarthy, Head of the Met Office National Climate Information Centre, said: “It is not just July that has been dry. Since the start of the year, all months apart from February have been drier than average in the UK too. The result of this is that the winter, spring and summer of 2022 have all seen less than the UK average seasonal rainfall.  

“England has seen the lowest levels during these periods and, rainfall totals for the first six months of the year are around 25% below their long-term average, with the driest regions in the east and southeast.” 

A graph showing 2022 2022 monthly rainfalls for England compared to average. The graph shows that every month other than February have seen below average rainfall.
2022 monthly rainfalls for England compared to average

Drier than 1976?

The lack of rainfall through sequential months and seasons becomes significant when looking back over the years as the 8-month period from November 2021 to June 2022 has been the driest in England since 1975/76, with an average of 421mm of rain falling in England, 74% of the 1991-2020 long-term average of 568 mm.   

However, the year so far cannot be compared too closely to 1976, as despite the dry trend England had 30% more rain during the first six months of the year than in 1976. Though the statistics do not necessarily need to be historical to have effects and the Environment Agency has advised ‘There are currently no plans for restrictions on essential water use, we can all do our bit by reducing unnecessary water consumption and following advice from our water company to ensure this remains the case whilst our rivers are exceptionally low.’  

Map of rainfall amounts compared to average between November 2021 and June 2022. The Map shows very dry conditions for the majority of the UK, especially in the south.
Map of rainfall amounts compared to average between November 2021 and June 2022
Map of rainfall amounts compared to average between November 1975 and June 1976. The map shows drier conditions than 21/22 for much of England and Wales.
Map of rainfall amounts compared to average between November 1975 and June 1976

Climate change

Mark McCarthy continued: “Met Office climate change projections highlight an increasing trend towards hotter and drier summers for the UK, with the driest regions anticipated to be in the south and east. While trends in summer temperature and heatwaves are very apparent in the climate records of recent decades, the large variability in our rainfall means that it is too soon to be able to detect the pattern in summer rainfall.” 

Persistent high pressure has not only brought a lot of dry weather this month, it has also resulted in a warmer month so far too. Since around the 6th temperatures have generally been above average. Heatwave conditions were experienced around 10th-13th and again from the 16th with an exceptional hot spell during the 18th and 19th July. And so early provisional stats for July show, the average maximum temperature across the UK currently stands at 21.5°C, 2°C higher than the UK average for the month and it currently sits within the top five warmest Julys on record. The current warmest July on record was in 2006 when the average maximum temperature for the UK was 23.3°C.  

July’s full provisional weather and climate statistics will be published on 1 August.

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