Invoking the oak – nature’s veteran recorder helping scientists understand the rate and scale of climate change

Ancient oak trees – individuals more than 400 years old – extend back into the deep and dark recesses of history.

During that time, these senior trees will have been surrounded by huge fluctuations in climate; to say nothing of the monumental changes in human history and how we have modified landscapes.

For those that can read them, the patterns of tree rings can provide a hint of past seasons, since the growing trees lock in valuable data about the climate for every year of their life.

Oak trees can live for centuries, providing a climate record spanning their lifetime but by monitoring the living tree and recording factors the first appearance of leaves and when the tree becomes bare can provide climatologists with a raft of data the current growing season. During 2020, the growing season for pedunculate oak was extended in the UK by 12 days. Picture: Ted Green/WTML (Woodland Trust media library).

However, that is not the only assistance that oak trees can provide to those researchers looking to understand more about our climate and how it is changing. By observing and charting the changes when individual trees come into leaf or shed their leaves, scientists and climatologists can glean valuable data about fundamental shifts in climate since individual plants respond to the shifting waves of weather and climate patterns from one year to the next.

Meteorologists have often been interested in how the weather and climate have profound impacts on phenology: the study of recurring events in nature and their relationships with climate. And indeed in 1875 the (Royal) Meteorological Society embraced the timing of natural events within the growing interest of phenology.

Dr Debbie Hemming is a Met Office scientist conducting research to improve understanding and modelling of the interactions between vegetation and climate. She said: “Trees and other species are natural data stores. They can be used in so many ways to inform us about the past and present of our changing world.”

With climate change already affecting the world, including the UK, there is a rapidly expanding interest in phenology and how the timing of natural events are responding to climate shifts, like rising temperatures and fluctuations in rainfall patterns.

For 31 years the BAMS Global State of the Climate report has been monitoring climate trends to provide a snapshot of the shifts in global and regional climate. The latest report is published today [25 August 2021] covers 2020.

Using results from phenology studies across the globe, the report states the seasonal cycle of vegetation across the Northern Hemisphere showed a generally earlier spring and later autumn (fall) in 2020 compared to recent decades. These differences were larger across Eurasia than North America.

Debbie Hemming added: “Satellite observations analysed by colleagues at the NASA Ames Research Centre, in the United States, showed that about 55 per cent of the Northern Hemisphere experienced an earlier spring and about 65 per cent a later autumn (fall) in 2020 compared to recent decades.”

Volunteer citizen scientists can make valuable contributions to the understanding of our changing climate by making phenological records. Picture: Michael Hefferman/WTML (Woodland Trust media library).

One UK study – involving citizen scientists from the Woodland Trust’s Nature Calendar project – has been charting the duration of leaves on the pedunculate oak from first leaf to bare tree. The pedunculate oak – colloquially known as the English oak – actually has a range across much of temperate Europe and Asia Minor, and it is the national tree of several European nations, not solely the UK.

Oak trees came into leaf across the UK earlier in 2020 than in any of the previous 20 years.

The average first ‘leaf date’ for the 2000–09 baseline was 26 April (day 116), and average ‘bare tree’ date was 30 November (day 334), giving a 218-day growing season.

Both events are strongly influenced by temperature; the first leaf date advances by approximately six days for every 1°C increase in mean February–April temperature; and the ‘bare tree’ date is  delayed by approximately three days for every 1°C increase in October temperature.

The year 2020, like 2019, had a very warm spring, and this resulted in the earliest United Kingdom first leaf date in the 20-year series (10 days earlier than the in-situ baseline).

October temperature was similar to recent years, and the bare tree date (note these were predicted from the temperature relationship due to COVID-19 monitoring restrictions) was approximately two days later than the baseline.

Professor Tim Sparks, speaking on behalf of the Woodland Trust, said: “The net result was a United Kingdom “oak season” 12 days longer than the baseline. The earlier spring and later autumn (fall) vegetation was associated with warmer than average temperatures during these seasons. Nature is having to keep pace with rapid changes – perhaps never more rapid.

“However, not all species are changing at the same rate. Whilst some species can take advantage of a warmer climate, for others climate change will be a further threat to their existence.”

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Met Office science at the heart of climate assessments

The Met Office Hadley Centre – which celebrated its 30th anniversary last year – has a long and proud history of working and supporting the IPCC. Indeed, one of the foremost scientists who propelled the IPCC, serving as co-chair and chairman of its scientific advisory group from its inception until 2002, was the late Sir John Houghton.

Sir John was Met Office Director General/Chief Executive from 1983-1991 and was instrumental in establishing the Met Office Hadley Centre, which was formerly opened by the then Prime Minister, Baroness Margaret Thatcher, on 25 May 1990. This was the same day that the IPCC First Assessment Report was published.

Professor Peter Stott has been working on climate research at the Met Office since 1996.

Professor Peter Stott joined the Met Office in 1996, a date which coincidentally aligned with the publication of the IPCC’s Second Assessment report. Before the days of widespread email use, Peter remembers fondly that this hefty volume arrived in a large envelope on the doormat at his home just before he started his Met Office career. He said: “Reading through the report, I immediately realised that this was the first official document to make a link between human activities and global warming, using the phrase that there was a discernible human influence on the global climate.”

The following year, Peter attended the global climate conference in Kyoto. Peter said: “Those of us who went were able to present the Met Office Hadley Centre’s work and the conclusions of that second IPCC report.

“It was an important moment because it was when governments first agreed to do something about climate change when they signed the Kyoto Protocol, based largely on the growing evidence from the IPCC’s second report.

“So it was already recognised there was a human influence of greenhouse gas emissions on the climate, but it was still very early days for putting any precision on what that may mean in terms of impacts; such as extreme weather for example.”

Peter added: “Looking back now to the late 1990s our predictions about global warming and global temperature rise were very accurate, even though we weren’t able to rely on the vast supercomputer power that we have today.

“Though, relatively speaking, the information we had from those projections and what it may mean for rising sea levels or agriculture, for example, were very broad brush.”

After two decades of scientific research and increasing technological capability, the sophistication and resolution of climate projections have increased enormously

Peter added: “It is only now with our climate models, that we can simulate climate aspects such as really heavy rainfall and extreme heatwaves at a regional level, putting a local precision on high-impact weather.”

Commenting on the current impacts of climate change, Peter Stott added: “What we are now seeing in 2021 is the very clear effects of climate change playing out in real time, with floods, wildfires and heatwaves.”

The sixth Assessment Report – published on 9 August 2021 – is the first IPCC report to state that it is unequivocal that human influence has warmed the atmosphere, ocean and land.

Peter added: “The latest IPCC report is a big step forward because it is laying out clearly the risks of climate change at least in terms of some of the irreversible impacts of climate such as sea level rise for example which will continue to rise for many centuries. We are still at the early stages of mapping out those risks.

“The better we can understand those risks the better we can mitigate them. That is a big challenge for societies now to be more resilient to heatwaves and other climate risks. The big challenges to come will include being able to provide more information about high-impact climate risks such as heavy rainfall. This is an exciting development that will help us all be better prepared for what is coming at us in the future.

“New scientific information such as the latest IPCC report also helps governments as they seek to reach international agreements to reduce greenhouse gas emissions rapidly enough to avoid the worst effects of climate change.

“This historical and continued contribution the Met Office Hadley Centre has enjoyed with the IPCC acknowledges our status as a world-leading centre for climate science research and has helped to ensure that our observational datasets, climate modelling and peer-reviewed research is incorporated into the heart of the scientific assessments.”

Chris Jones has also recently been selected as an author for a future IPCC report, due for release in 2022. Chris said: “The IPCC represents the “go to” place to understand the state-of-the-science for policy makers and scientists alike. The rigour and comprehensiveness of the assessment brings together experts from all over the world. It’s been a huge honour, and immensely enjoyable, to be a part of this community activity.”

Bringing the Met Office’s journey with the IPCC to a full circle, during the press conference for the latest Sixth Assessment Report (AR6) publication, IPCC Chair, Hoesung Lee, announced that the report is dedicated to the memory of Sir John Houghton.

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Europe needs to prepare for temperatures of 50C in future

Syracuse, in Sicily, has provisionally exceeded the previous European highest temperature with a record of 48.8°C yesterday. If the record is confirmed by the World Meteorological Organization, this temperature will break the previous record of 48.0°C in Athens in 1977.

It will also raise concerns that even higher temperatures are potential in future, possibly even exceeding 50.0C.

Professor Peter Stott is the Met Office’s lead on climate attribution. He has studied European heatwaves for nearly two decades, including the notable ones in 2003 and 2019.

He said: “Climate change is making heat-related extremes of weather more intense and when we think about those record-breaking temperature the chance of breaking temperature records – or coming close to breaking records – is greatly increased.

“Record-breaking temperatures in June 2019 saw the French temperature record exceed 45.0°C for the first time, and our analysis found that event was at least five times more likely because of climate change. Although we haven’t yet been able to run an in-depth study on the current situation, I think it’s going to be clear that climate change has made this current event more extreme.

“The chances each summer of seeing really extreme temperatures are pretty high now. We can’t say exactly when it is likely to happen, but Europe will need to prepare for the eventuality of further records being broken with temperatures above 50.0°C being possible in Europe in future, most likely close to the Mediterranean where the influence of hot air from North Africa is strongest.”

The Earth’s average surface temperature has risen by around 1.1°C since the pre-industrial period (1850-1900), but the average temperature in some regions has increased by a greater amount. The average temperature in North Africa, for example, has increased by around 2.0°C over the same period.

Potentially Syracuse has broken the European temperature record as heat builds further west into Iberia

Chris Almond is a meteorologist working with the Met Office’s Global Guidance Unit. Commenting on the conditions leading up to this event, he said: “There is a large area of high pressure in the upper atmosphere affecting much of the Mediterranean, as well as northern Africa.

“High pressure leads to sinking motion in the atmosphere which compresses the air and heats it up, and this added to the heat from the sun can lead to very high temperatures at this time of year. Also under high pressure, winds tend to be light, so the heat doesn’t get dispersed as much this also helps conditions to get hotter and hotter.

“This weather situation is not particularly unusual, high pressure often sits over these areas in the summer – it’s the temperatures which are more unusual, which are the result of many factors coming together at the same time.

“With climate change, we are expecting, and are already seeing, more frequent and severe events, and will continue to do in the future.”

The exceptional heat in the central Mediterranean is building after extreme conditions in Greece and Turkey last week.

This heat is expected to extend into Iberia and Morocco through the next couple of days. Further national records could be achieved in the coming days, including for Spain, where the current record is 47.3C in Cordoba in 2003.

Chris Almond added: “A high wildfire threat continues, which could result in the rapid spread of new fires and limit containment activities of existing fires. It will be next week before temperatures are expected to slowly decrease across the region.

“Adverse human health impacts are likely, particularly to those exposed to the extreme heat for prolonged periods or are part of vulnerable population groups. This is combined with poor air quality in some places due to ongoing wildfires and smoke.”

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Heatwave helps mark fifth warmest July on record

The mid-month heatwave has helped the UK to its joint fifth warmest July on record according to provisional Met Office figures, with Scotland and Northern Ireland recording their third warmest July, in a month where Northern Ireland also broke its all-time high temperature record, exceeding 31C multiple times.  

The mean temperature for July 2021 in the UK was 16.6°C, which put it level with July 1995’s figure, although still some way short of the record figure of 17.8C in 2006. Northern Ireland (16.4° C) and Scotland (15.1°C) saw their third warmest Julys, Wales (16.5°C) its ninth warmest and England (17.5°C) its eleventh warmest.  

A Mean temperature map of the UK for July 2021, showing above average temperatures throughout, especially in western Scotland and Northern Ireland.
July 2021 mean temperature map

While the high mean temperatures were spurred on by the mid-month heatwave, the figure was helped to its elevated position in the standings with notably high night-time temperatures recorded across the month, with the average minimum temperature for the UK putting it at joint-second for the warmest recorded in July, at 12.1°C.  

Of course, most people will remember July 2021 for the heatwave during the middle of the month, which saw the Met Office issue its first ever extreme heat warning. Western areas in particular got the most consistently hot conditions, and Northern Ireland even broke its all-time temperature record with a figure of 31.3°C recorded at Castlederg on 21st *.  

Both Scotland and Northern Ireland had average maximum temperatures for the month in their top 10 ever recorded, with 21.2°C in Northern Ireland being the fifth highest and 19.2°C in Scotland being their sixth highest.  

On a similar theme, Scotland and Northern Ireland were also far drier and sunnier than average for July. Both countries saw 25% more sunshine hours than average, with 175.6 sunshine hours for Scotland, and 175.5 for Northern Ireland. Scotland got 67% (66.4mm) of average rain in the month, while Northern Ireland got just 53% (43.3mm).  

A map of the UK showing average sunshine duration for regions versus the long term average. The map shows many western areas had above average hours of sunshine in the month, especially western Scotland. Eastern areas have closer to average sunshine hours.
July 2021 average sunshine hours map

Despite the dry month for western areas in particular, intense summer downpours affected some areas of the country and resulted in some places exceeding twice their average rainfall for July. The Isle of Wight had its seventh wettest July on record – and its wettest since 1920 – with 115.4mm of rain, while parts of London recorded more than double the average rainfall they’d expect in the month. The localised nature of some of the summer downpours meant there could be some sharp contrasts with, for example, some parts of London receiving much closer to average rainfall. 

A map showing the rainfall across the UK versus the average for July 2021. It shows many southern areas had above average rainfall, while western areas, especially Northern Ireland and western Scotland, had below average rainfall.
July 2021 rainfall amount map

In addition, despite the mid-month heatwave, some unsettled and thundery conditions were in force for much of the second part of the month, which even saw Storm Evert named and sweep across southern areas of England and Wales, bringing with it gusty winds and some persistent rain.  

Tim Legg of the National Climate Information Centre said, “Early July was relatively unsettled, with frequent heavy showers, especially over parts of England. The early subdued temperatures were replaced with a very warm spell for much of the UK as a high pressure system moved in and settled down, resulting in temperatures regularly getting in to the low 30s Celsius by day and remaining warm overnight.  

“The hot spell is largely responsible for the above average temperatures recorded for the UK, with western areas in particular reporting temperatures well above their July averages. This warm period broke down later in the month, bringing with it rain, thunderstorms and even the first storm we’ve named in July when Storm Evert crossed our shores from the 30th.” 

Provisional July 2021Mean temp (°C) Sunshine (hours) Rainfall (mm) 
 Actual Diff from avg (°C)Actual% of avgActual% of avg
UK 16.6 1.5 191.6111  72.5 93
England 17.5 1.2 200.7104 78.3 125
Wales 16.5 1.4 203.4114 79.7 86
Scotland 15.1 1.8 175.6125 66.4 67
N Ireland 16.5 1.9 175.5125 43.3 53

* A provisional temperature of 31.4 C was recorded at Armagh on 22nd July, which did not pass all subsequent verification checks.  

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COP26 – 100 days to go

COP – or Conference of Parties, is an annual United Nations climate summit where world leaders meet to discuss and make decisions on key global issues. In attendance will be countries that signed the United Nations Framework Convention on Climate Change (UNFCCC) back in 1994. This year sees the arrival of the much-awaited COP26, following postponement from November 2020 due to the COVID-19 pandemic. Every year a different nation takes on presidency of the summit, and this year’s UK presidency, in partnership with Italy, will see the conference taking place in Glasgow from 31 October to 12 November 2021. There are just under 100 days to go until COP26 begins, so we’ll be sharing lots of news in the coming weeks about our preparations here at the Met Office and how you can get involved. 

COP26 - In Partnership with Italy
COP26 is taking place in Glasgow later this year

This year’s COP is the 26th annual summit and is of particular significance as it will mark 5 years since the signing of the Paris agreement at COP21 in 2015. The Paris Agreement commits participating nations to the goal of limiting global warming to 2 degrees, preferably 1.5 degrees, above pre-industrial levels. Progress on the agreement will be reviewed every five years and updated plans laid out for the future, making this the first COP summit where progress is discussed amongst all committed nations. Following the declaration by the UK Government in 2020, that this is a “year of climate action”, there is much anticipation as to what this year’s COP will deliver.   

At COP25 back in 2019, many key issues remained without unanimous resolution. In light of this, as well as the ever-increasing threat of global warming, COP26 is considered to be an event of particular urgency, and one that experts hope will signify an acceleration of proactive global efforts to combat climate change. Over 190 world leaders are expected to attend the conference in Glasgow, where they will be joined by government representatives, businesses, non-profit organisations and citizens for 12 days of climate talks. Amongst the discussion points of the summit, there are some fundamental goals that the UK will strive to achieve. These include: 

  • securing global Net Zero emissions by the middle of the century and continuing to strive towards limiting global warming to a maximum of 1.5 degrees above pre-industrial levels; 
  • the deployment of adaptation measures to protect vulnerable communities and natural habitats from the impacts of climate change;  
  • the mobilisation of financial aid by developed countries to achieve global Net Zero; and 
  • acceleration of collaborations between governments, business and society in order to achieve ambitious climate goals.  

Preparation is well and truly underway ahead of the conference in November, with a busy timeline of events aimed to further the UK’s progress towards delivery of its goals. More information on the pre-COP26 event schedule can be found on the COP26 website.

At the Met Office, we’ve also been busy with preparations ahead of the start of the summit in just under 100 days’ time. We’ve coordinated several COP related events, such as our Climate Science Conference in May, which brought together scientists, policy makers and communicators in a virtual conference to explore how climate science and services can create a more sustainable and resilient future. The event focused on a number of climate themes, with the goal of laying out a scientific agenda to inform climate policy during the COP26 event itself and until the end of the decade. 

"We know that the climate has changed and we know it will continue to change over the next 30 years as we transition to Net Zero." - Stephen Belcher, Chief Scientist
Chief Scientist Stephen Belcher at the Climate Science Conference earlier this year

We’ve also made our own commitment towards the government’s Net Zero pledge, with our own Journey to Net Zero by 2030. As part of this commitment, we will work towards achieving Net Zero emissions through all of our activities by investing in renewable energy solutions, reducing carbon emissions and engaging in carbon offsetting schemes to counterbalance any unavoidable outputs.  

Much of our ongoing climate research informs government policy and is of particular relevance to the COP26 aims and ambitions. Our Hadley Centre Climate Programme undertakes research into climate change to determine the cause of such changes and develop services to manage climate risk. 

Albert Klein Tank, scientific director of the Met Office Hadley Centre, one of the UK’s leading climate research centres, discusses how Met Office research informs COP negotiations: 
 
“At the Met Office, the run up to COP is perhaps even more important than the event itself, where our role is less visible. In the run up to COP, the Hadley Centre keeps the government informed on the latest science and information on climate projections. We will contribute to the latest IPCC report which will come out in August, which will also inform the international negotiations. It’s really about aligning and making all of the latest evidence available so that the impacts and the local impacts of particular extreme events and how they can be attributed to climate change and to human interference is clear.” 

Some people have said that COP is a large gathering of people without much progress, but I feel much more optimistic. I think the fact that international communities and governments are coming together demonstrates that this really is at the top of their agenda, and with climate change growing and with the evidence of the impacts of climate change growing, this collaboration is really needed, and it is really timely.” 

For COP26 and future COP events, the Met Office will continue to collaborate with other research organisations, governments and policy makers on the shared goal of tackling climate change and moving towards a resilient net zero future. By working with other organisations and communicating our findings to key audiences, we hope to strengthen the UK’s position as a world leader in tackling climate change and as a key provider of robust global science. In doing this we will ensure our credibility as hosts of COP26 in November whilst also maintaining a legacy which extends into the coming decades, when a united global response to climate research will become increasingly urgent. 

You can learn more about COP26 and how the Met Office is involved through the following links: 

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Pole to pole on a tipping point journey

There is one climate topic that you’re likely to hear a lot about this year: tipping points.

In the context of climate science, a tipping point can occur when a relatively small change can have a large and irreversible effect on some of the Earth’s largest systems, such as the Antarctic ice sheets or the Amazon rainforest.

In the first post in our series on tipping points, we looked at the definition of tipping points. In the second of our series we literally go from pole to pole to examine the potential for huge change in the oceans and the cryosphere – the Earth’s wealth of ice.

Professor Tim Lenton – from the University of Exeter – is a world-renowned expert on tipping points. One tipping element (bits of the climate system that could pass a tipping point) that stands out as high risk for Professor Tim Lenton, is West Antarctica. Here there is physical evidence consistent with possibly having passed the tipping point for irreversible retreat of part of the ice sheet. Destabilization of the West Antarctica ice sheet could lead to about a three-metre sea-level-rise on a timescale of centuries to millennia. In a wider study Tim suggests that part of the East Antarctic ice sheet might similarly be unstable, with the potential to add another 3-4 m to sea level on timescales beyond a century.

He said: “We might already have committed future generations to living with sea-level rises of around 10 m over thousands of years. But that timescale is still under our control. The rate of melting depends on the magnitude of warming above the tipping point. More observational data will establish whether ice sheets are reaching a tipping point, and better developed models are needed to resolve how soon and how fast the ice sheets could collapse.” Tim.

Dr Ed Blockley, who leads the Polar Climate Group of the Met Office Hadley Centre, paints a similarly bleak picture for retreating Arctic sea ice. He explains that one challenge to understanding sea ice decline, is measuring the large seasonal and year-to-year variability against sustained long-term decline. However, over the past four decades, Arctic sea ice cover has reduced, on average, by 87,000 square kilometres, an area of more than four times the size of Wales each year. The Arctic has an important role to play in regulating climate, such as the albedo effect – where the expanses of white ice reflect the sun’s energy back into space – and atmospheric circulation patterns, which can influence the weather at lower latitudes such as in Europe.

Dr Blockley said: “One potential tipping point of Arctic sea ice is the ocean halocline, whereby cold, fresh water at the surface is less dense than warm, salty water below and currently prevents the warm water from reaching the surface and melting the sea ice. If the halocline were to collapse, this warm water, which contains enough heat to melt all the sea ice many times over, could mean that the Arctic would remain ice-free even if global warming were to be reversed.”

Tim Lenton added: “The Arctic is the place where a sort of cascade of unwelcome tipping point changes may be starting because it’s clearly the place that’s warming up two to three times as fast as the global average. We are also accumulating more evidence of casual interactions here as well, such as the role of Arctic sea-ice retreat and resultant warming in permafrost thawing. We appear to be approaching several tipping points.”

The global pattern of ocean circulation brings warm water into the North Atlantic and returns colder denser water southward. A global pump known as the Atlantic Meriodional Overturning Circulation.

Perhaps one tipping element more than any other attracts regular media headlines: the collapse of the Atlantic Meridional Overturning Circulation (AMOC). This huge conveyor belt brings warm salty water from the tropics into the northernmost reaches of the Atlantic. A weakening or collapse of this current could have devastating impacts on the climate of the northern Atlantic region, potentially switching off the transport of warm conditions to northern Europe.

Dr Richard Wood, head of cryosphere and oceans group at the Met Office Hadley Centre, explains: “If we were to add fresh water to the North Atlantic – such as from melting glaciers or increased precipitation run-off, for example – you would make the surface water fresher and less dense, weakening the ‘pump’ that drives the ocean circulation.”

Warming of the surface waters due to greenhouse gases has a similar effect of making the surface waters less dense and so weakening the ocean circulation pump. So there is a ‘double whammy’ of warming and freshening conspiring to weaken the circulation.

Dr Wood added: “Because the AMOC is a circulation that spans the whole globe, it’s a fundamental part of our climate system. We don’t think a collapse is imminent in the next decade or so, but climate models do suggest that over the 21st century, the AMOC will weaken, as greenhouse gases increase. We need to monitor for any early warning signals that the AMOC is getting near a tipping point.”

The Met Office’s second episode of our Mostly Climate podcast on Tipping Points can be found here.

Next time in the lasts of our tipping points series we’ll be travelling to the Amazon.

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Get ready for tomorrow: Met Office launches climate newsletter

Get ready for tomorrow newsletter
The email newsletter is available for anyone with an interest in the latest climate change news and debates

The Met Office is launching a new Climate Newsletter to inform decision makers, scientists and the public about the very latest climate news and debates.

The twice-monthly email newsletter will bring together the latest research, news and developments on the environment and climate change and will share knowledge around the latest scientific thinking in the area.

The first issue shines a spotlight on extreme heat and the recent record-breaking temperatures across the northern hemisphere. Lytton, in southwestern Canada, broke the country’s all-time maximum temperature record three days in a row.

In addition, the newsletter provides a one-stop-shop for the latest climate news, including information on the Climate Change Committee’s publication of their Adaptation Committee’s Independent Assessment of UK Climate Risk which set out priority climate changes risks and opportunities for the UK.

There’s also a look ahead to what’s coming up in climate news, including the Intergovernmental Panel on Climate Change being set to publish the first of three reports of its Sixth Assessment Report. 2020’s State of the UK Climate will also be published in the coming weeks.

Also, with less than 100 days to go until COP26 in Glasgow, the newsletter shares details on the Government’s publication of their COP26 Explained document, which highlights what needs to be achieved at the international climate negotiations and why.

In the foreword of the first edition of the newsletter, Director of the Met Office Hadley Centre Professor Albert Klein Tank noted, “Our climate is changing rapidly and will continue to change this century and beyond.

“Climate science is essential to help understand the challenges ahead and guide decisions to build the resilience we need to face the challenges of the future.

“As we approach the COP26 climate conference in Glasgow later this year, we will also share information on what the Met Office and others are doing ahead of these critical negotiations, including how research from our new climate science programme will address some of the key scientific challenges to inform the international climate gathering and beyond.”

You can sign up for the Get ready for tomorrow climate newsletter via GovDelivery.


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Tracking Extremes in a Changing Climate

It is often through extreme weather events, such as heatwaves and heavy rainfall, that the impacts from climate change first affect us, presenting the greatest shocks to our wellbeing, key infrastructure, the economy and our environment.

Scientists from the Met Office Hadley Centre have produced a dashboard monitoring key indicators of global climate extremes. These include changes in both high and low temperature extremes and changes in rainfall intensity extremes.

The dashboard is the result of a continuing project to present clearly and simply how climate change is affecting the planet. Using a dataset known as HadEX3, which provides historical observations of changes in temperature and precipitation extremes, it informs how the risk from extreme events has changed.

Indicators show that globally, the number of warm days has risen, with around an additional 20 “warm” days per year in the most recent decade when compared to the 1970s.

Met Office Hadley Centre global climate extremes dashboard showing high temperature extremes.

Three indicators in the dashboard monitor changes in intense rainfall globally – wettest day of the year, amount of rain falling in heavy events and the fraction of the total annual precipitation coming from heavy events. All indicators show gentle increases since the beginning of the 20th Century. On a global average, we see that on the wettest day in a year, a few more mm of rain will fall on average now than in similar events 100 years ago. Over 20mm more rain is falling on the wettest days of the year than the average over 1961-90. Nowadays, an extra 2% of the total annual rainfall is falling in these wet days, compared to 1961-90.

Met Office Hadley Centre global climate extremes dashboard showing rainfall intensity extremes.

These indices provide a different perspective on climate change, complementing other global indicators of change such as annual average temperature, CO2 concentration and Arctic Sea ice extent, which the Met Office Hadley Centre reports in its climate dashboard to provide a more complete picture of what’s happening in the climate. Dr Robert Dunn, Climate Scientist at the Met Office said: “As individual extreme and exceptional events capture the headlines, the observations in this dashboard show that across the globe extreme events are changing their character.  For example, warm nights are becoming warmer, daily rainfall more intense, and warm spells are lasting longer.  These give context to our recent, current and projected future climate.”

These historical observations form part of mounting evidence which suggests that intense rainfall and heat extremes are becoming more frequent and intense in a warming climate. Nikos Christidis is a climate attribution scientist with the Met Office who looked at the record-breaking heatwave currently devastating parts of north western North America. He said: “Without human-induced climate change, it would have been almost impossible to hit such record-breaking mean June temperatures in the Western United States as the chances of natural occurrence is once every tens of thousands of  years.”

Last year, the prolonged Siberian heat where overall temperatures were more than 5°C above average from January to June 2020 is further evidence of the extreme temperatures we can expect to see more frequently around the world in a warming global climate. Met Office Climate Attribution scientist Andrew Ciavarella said that “climate change increased the chances of the prolonged heat in Siberia by at least 600 times.”

Closer to home, October 2020 will be remembered for containing one of the wettest days on record for the UK with an exceptional average of 30mm of rain falling  across the country in a single day. The record rainfall is estimated to have become about 2.5 times more likely because of human influence on the climate.

Monitoring extreme events is a key area of science and the new Met Office Hadley Centre climate programme will look at how global warming translates into local-scale changes in weather and climate extremes. Decision makers can use this information to inform adaptation and mitigation plans for future climate risk. At the COP26 climate conference in Glasgow later this year, a clear goal is agreeing adaptation measures to protect communities and natural habitats. Only the best climate science will enable us to build the resilience we need to face the challenges of the future.

HadEX3 was released last year and developed by the Met Office in collaboration with scientists from ARC Centre of Excellence for Climate Extremes at the University of New South Wales, Environment and Climate Change Canada and Barcelona Supercomputing Centre.  We are continuing to develop our global climate extremes dashboard. Please get in touch if you have any feedback via email to knowledge.integration@metoffice.gov.uk

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Warm June heralds start of summer, despite recent unsettled weather

Summer has kicked off with a predominantly warm and sunny June compared to the long-term averages, according to provisional statistics from the Met Office.  

Although conditions have been more unsettled for some in recent weeks, the UK has had above average temperatures for the month, including particularly warm nighttime temperatures with England reporting its joint second highest average minimum temperature in June since records began in 1884, with 10.7°C.  

Map showing generally above average minimum temperatures across the UK

Although the high minimum temperatures are the most noteworthy, average maximum temperatures and mean temperatures were also more than one degree warmer than the long-term average for the UK, and each country in the UK is above the average for their temperature figures for the month. The warm conditions are in contrast to 2021’s Spring, when cooler than average temperatures were reported as May concluded with showery and cold conditions.  

The UK started to become more unsettled, and often stormy, from the middle of June. Southern areas, and particularly the southeast, have seen the heaviest rain, with London having double the amount of rain it would normally expect (97.1mm) and some locations in Hampshire and the Isle of Wight being the wettest in the whole country with over three times their average June rainfall.  

Map showing below average rainfall for large parts of central and northern areas of the UK and above average in areas of southern England, particularly the southeast.

Those figures are in stark contrast to the northern reaches of the UK, with Scotland having just 44% (39.2mm) of its expected rainfall and Northern Ireland 52% (39.3mm). Wales has also seen below average rainfall, with just 37% (32.1mm) of the average rainfall for the month. England has had 77% (47.8mm) of its average rainfall, but that’s largely accounted for by southern England seeing above average rainfall (105%, 59.4mm), while northern England had just 36% (25.7mm) of its expected rain.  

Interestingly, despite southeast England seeing well above average rainfall, the number of days that it  rained is actually fairly close to average, this is because the rainfall was heavy and persistent when it did make an appearance. Northern England, Wales and Scotland, however, had fewer days of rain than would be expected.  

Map showing average number of days of rain in the UK

Hours of sunshine across the UK has been close to or above average for most regions, with a few duller areas in the west, with Northern Ireland being the only country not to quite reach its June average with 144.8 sunshine hours (96%).  

Map showing around average sunshine for much of the UK, and slightly above average sunshine hours for central and northern areas

Dr Mark McCarthy, Scientific Manager of the National Climate Information Centre, said: “June has been warmer and sunnier than average for most of the country, with minimum temperatures being notably high as nights have remained fairly warm. 

“High pressure was the dominant feature throughout the first part of the month, with temperatures regularly in the upper 20s and particularly warm in the southeast. However, there was a shift in the weather in the middle of the month for southern England which was regularly subject to outbreaks of heavy, and often thundery, rain. Northern England and Scotland, however, largely held on to warm, sunny weather, albeit with showery rain threatening sometimes. Resulting in a sharp contrast in the rainfall statistics across the country.” 

Provisional June 2021Mean temp (°C) Sunshine (hours) Rainfall (mm) 
 Actual Diff from avg (°C)Actual% of avgActual% of avg
UK 14.2 1.2 181.9107  43.2 59
England 15.3 1.3 195.0107 47.8 77
Wales 14.1 1.0 174.1100 32.1 37
Scotland 12.5 1.2 168.2112 39.2 44
N Ireland 13.6 0.9 144.896 39.3 52
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Heatwave record for Pacific North West

A record-breaking heatwave is devastating parts of northwestern North America, and the heat is expected to continue now through much of this week.

Temperatures in parts of the northwest USA and southwest Canada are likely to reach as high as around 45.0°C by day for perhaps five or more days, with extremely warm nights in between.

In the affected area a few thunderstorms and locally gusty winds will bring wildfire risks.

Paul Hutcheon is a meteorologist with the Met Office’s global guidance unit. He said: “Many all-time long-standing station records are expected to be broken for many days in a row, some by more than 5.0°C. The all-time Canadian record was broken on Sunday, with Lytton in British Columbia recording 46.6°C (1.6°C higher than the previous record set on 5 July 1937). Less than 24 hours later, Lytton broke this record again, reaching 47.9°C on Monday To put this into context the average June maximum is around 24.3°C.”

Armel Castellan is a meteorologist with Environment and Climate Change Canada. He said: “Higher temperatures started in earnest on Friday and it will be peaking early this week for the coast and the middle of the week for the interior of British Columbia, and then the heat will be moving east into Alberta: so we are not done with this yet.

“Northwest Territories have recorded their all-time highest temperatures not just in June, but any point in the year.  We are setting records that have no business in being set so early in the season.”

The heat is also affecting northwestern United States with Seattle setting a new all-time record at 40°C and this is expected to be exceeded on Monday with 44.0°C. Portland, in Oregon, broke the record twice: 42.0°C on Saturday and 44.4°C on Sunday, according to the US National Weather Service.

During the week, the central focus of the heat dome shifts gradually eastwards away from British Columbia and into Alberta

The heat is being driven by a huge ridge of high pressure. Armel Castellan explained: “We have experienced a ridge with low pressure sandwiched on either side. And it’s really hard to move it. The jet stream isn’t moving it along. In that pattern we have essentially a heat dome. A pattern that is sticking to its guns where pollutants and heat keep adding to each other. It is compounding.

“The first day of a ridge like this is warm and we are very close to the solstice so we are dealing with the highest sun angle in the sky, and we have had many days of this in a row and each morning we wake up to a higher temperatures. This is what is dangerous and it is affecting people throughout many days where they are dehydrated and we have had many days where the temperature is higher than the day before.

“Overnight lows being higher than our average daytime highs for late June is a really big deal. Our bodies need to cool off and recover before taking on another day of high temperatures. Another thing to think about is the infrastructure. Fewer than 40 per cent of homes have air conditioning on the coast, people are having to go to libraries and shopping malls to find a couple of hours of air conditioning. I have been sleeping in a tent to get some respite from the heat.”

Even at night residents of British Columbia, including here in Vancouver, have been struggling to cope with the extreme night-time heat. Picture: Shutterstock.

The impacts from the record-breaking heat are expected to be significant. Paul Hutcheon of the Met Office added: “Significant excess human and animal mortality is likely. In this region properties are generally designed to retain heat, not to shed heat, and air conditioning is much less prevalent than in other parts of North America. These temperatures will also likely stress infrastructure in this region, for example, power and water supplies. Additionally the risk of wildfires will increase throughout this spell. The warmth may well lead to rapid melting of the some mountain snowpack across the region, which could lead to some localised avalanche, flooding, and landslides in the mountains.”

Commenting specifically on the threat of wildfire, Armel Castellan concluded: “Unfortunately the outlook is very dry, we have some thunderstorm activity that will bring some respite but  It is very dangerous to add dry lightning to a very strong drought signal: we are very susceptible to a wildfire event transpiring.”

Climate change

In a statement, the World Meteorological Organization has said: “These early summer hot weather conditions are taking place against the background of human-induced climate change with global temperatures already 1.2 C higher than pre-industrial levels.

“Heatwaves are becoming more frequent and intense as greenhouse gas concentrations lead to a rise in global temperatures. They are starting earlier and ending later and are taking an increasing toll on human health and health systems.”

Other parts of the northern hemisphere are already experiencing exceptional early hot summer conditions extending from north Africa, the Arabian Peninsula, eastern Europe, Iran and the north-western Indian continent, with maximum daily temperatures exceeding 45.0°C in several locations and reaching 50.0 C in the Sahara. Western Russia and areas around the Caspian Sea have also seen unusually high temperatures due to the continued presence of a large area of high pressure. In parts of the region including Moscow temperatures have been reaching the mid-30s°C by day, remaining above 20°C by night. Areas nearer the Caspian Sea are expected to experience temperatures reaching the mid 40s°C and remaining above 25°C at night. It is likely that some all-time temperature records will be set during this heatwave.

Nikos Christidis is a climate scientist with the Met Office. He said: “Without human-induced climate change, it would have been almost impossible to hit such record-breaking mean June temperatures in the Western United States as the chances of natural occurrence is once every tens of thousands of  years.

“In the present-day climate getting an extremely hot June is common and is likely to occur twice in three decades. However, an analysis from many computer models suggests that by the end of the century these extreme temperatures are more likely than not. Human influence is estimated to have increased the likelihood of a new record several thousand times.”

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