Arctic sea ice reaches minimum extent for 2014

23 09 2014

Arctic sea ice appears to have reached its minimum for 2014, according to preliminary figures from the National Snow and Ice Data Centre (NSIDC) in the US.

The extent dropped to 5.02 million square kilometres (1.94 million square miles) on 17 September, making it the 6th lowest extent observed since satellite observations became available in 1979.

This year’s minimum is above the 2012 record low extent of 3.41 million square kilometres (1.32 million square miles), but still below the long term (1981-2010) average of 6.22 million square kilometres (2.4 million square miles).

Graph shows Arctic sea ice extent at 17 September 2014 along with daily ice extent for four previous years. Source: National Snow and Ice Data Centre

Graph shows Arctic sea ice extent at 17 September 2014 along with daily ice extent for four previous years. Source: National Snow and Ice Data Center

There is a lot of year to year variability in the Arctic ice extent, as it depends on the Arctic weather.

As the ice cover thins we expect the variability in cover to increase as larger regions of the Arctic become vulnerable to being blown by the wind or melting away completely over the summer.

Overall, the long term trend in ice cover remains downward, as illustrated by the below plot of August ice extents.

Earlier this month in the Laptev Sea, a small portion of the ice edge was within 5 degrees of the North Pole – this is the most northerly position that the ice edge has reached in this region since satellite observations began.

This year the Northern Sea Route has opened to shipping for the seventh year in succession, but the North-West Passage through the Canadian Archipelago remains blocked by ice – emphasising how Arctic summer sea-ice cover depends on the prevailing weather patterns.

The exact date on which the minimum ice extent occurs varies from year to year, depending on the weather conditions along the ice edge. The 1981-2010 average is 15th September, and the latest date so far in the records has been 23rd September.

Graph shows August Arctic sea ice extent for each year since records began as a % difference to the long-term (1981-2010) average for the month. Source: National Snow and Ice Data Center

Graph shows August Arctic sea ice extent for each year since records began as a % difference to the long-term (1981-2010) average for the month. Source: National Snow and Ice Data Center

Future of Arctic sea ice

Based on projections from current climate models, a plausible date for the earliest ice free (defined as extent less than 1 million square kilometres) summer in the Arctic would be 2025-2030.

Work continues to improve our understanding of the processes driving the ice decline and how they are represented in climate models. This may lead to revised projections of the date for an ice-free summer in the Arctic.

Impacts on UK weather

Changes in the Arctic ice cover have the potential to influence the weather further afield, by changing atmospheric circulation pattern outside the Arctic.

There is some evidence that low ice cover at the end of the summer can drive easterly winds across Europe, particularly in winter, potentially resulting in anomalously cold conditions.

The relative importance of sea ice conditions and other factors in generating cold conditions in the UK is an active research area for the Met office.





Arctic sea ice reaches minimum extent for 2013

24 09 2013

Arctic sea ice has been in the media quite a bit this month and we looked at the issue in a blog a couple of weeks ago.

Late last week there was an update to the continuing story, as the National Snow and Ice Data Center (NSIDC) in the US announced that Arctic sea ice extent had reached its summer minimum.

Figures from the NSIDC show this year extent fell to 5.10 million square kilometres on 13 September, and the ice cover  is now increasing as we head into the northern hemisphere winter.

It’s possible that a shift in wind patterns or a late season melt could push ice extent lower, but – assuming the current figure remains – this year’s minimum extent is the sixth smallest since satellite records began in late 1970s.

The five lower seasonal minimum ice extents all happened from 2007 onwards, with the record set last year. That record low was just 3.41 million square kilometres, a notably low figure that was likely to have been influenced by weather conditions over the region which accelerated ice loss.

While a detailed analysis is required to understand the exact causes of the seasonal minimum this year, the weather conditions during the summer have been less conducive to ice loss than those experienced last year.

From late May to late June a stream of storms entered the Arctic Ocean, creating cloudy conditions at the time when the sun was at its strongest.

Relatively high ice cover during June and July (compared to recent years) was likely to have delayed the warming of the upper ocean and reduced melting at the base of the ice towards the end of the melt season.

We do expect a year to year variability in sea ice extent precisely because it can be so heavily influenced by weather patterns, but there is a long-term picture of decline – as you can see in the graph of August ice extents below.

August Arctic sea ice extent

August Arctic sea ice extent

New ice thickness data from the Cryosat satellite has also been released recently, and this shows a continuing shrinkage of winter ice volume.  This provides a timely reminder that despite the modest recovery in seasonal minimum ice extent this year, the ice continues to thin and the volume of sea ice continues to shrink.





Is Arctic sea ice shrinking or expanding?

13 09 2013

The decline of Arctic sea ice is often pointed to as one of the most visible indicators of a warming world but earlier this week the Mail on Sunday published an article claiming the ice is in recovery. This was followed by similar stories in The Express and The Telegraph.

However, yesterday there were stories on BBC online and CBS News, among others, saying satellite evidence confirms the ongoing story of long-term decline. So what’s really going on?

Year to year variability

Arctic summer sea ice extent has a lot of year to year variability because it can be heavily influenced by weather patterns:

- temperatures naturally vary from one year to the next;
– the amount of cloud can affect the amount of surface melting;
– summer storms can also break up ice, which can accelerate the melting process;
– settled conditions can be more conducive to ice forming;
– winds may act to spread out the ice or push it together.

Due to this high degree of variability, it’s important to look past short term fluctuations in sea ice extent and look at the longer records.

Also sea ice extent is only one part of the story; it’s the volume of sea ice that we should also be considering that depends on ice thickness as well as extent.

The longer-term view

Satellites provide the most comprehensive measurements of sea ice extent, and have provided data since 1979. They show a long-term trend of decline in sea ice extent, at an annual rate of more than 4% per decade.

The seasonal minimum (September) ice extent has declined at the faster rate of 11% per decade, and this rate of decline has accelerated in the past 15 years.

More importantly the volume of sea ice has declined substantially since 1979, as the ice has thinned. This has made the ice much more vulnerable to stormy weather, as was the case in 2012.

How does this fit the news stories?

The Mail on Sunday article points to a big recovery in Arctic sea ice compared to last year, but this needs to be viewed in context.

Last year’s minimum sea ice extent was 3.41 million square kilometres according to the US National Snow and Ice Data Center (NSIDC), 0.76 million square kilometres lower than the previous record set in 2007.

Extent has not yet reached its minimum for 2013, so it’s too early to make any definitive judgements. However, using NSIDC data to August this year we know that while the ice cover was greater than at the same time last year, it was still ranked as the sixth lowest August extent in the 34-year record.

Ann Keen, Sea Ice Scientist at the Met Office, said: “In 2012 we saw a record low which was likely to have been influenced by a storm which swept through the region in summer, but this year’s weather conditions appear to have been less conducive to ice loss.

“We know sea ice extent is going to vary from year to year due to weather conditions and that’s not at all inconsistent with the overall decline in extent. You wouldn’t expect to see records broken year after year, so this ‘recovery’ is not unexpected.

“In fact, model simulations of sea ice suggest that a as the ice gets thinner you actually get more year to year variability in extent because larger areas of the ice are more vulnerable to melting away completely over the summer.”

The stories published yesterday use new data from a satellite named CryoSat which looks at sea ice volume, which gives a better view of the relative ‘health’ of the sea ice.

Data from this satellite shows that the ice continues to thin and the volume of sea ice continues to shrink.

So all the evidence suggests the long-term decline of Arctic sea ice continues.





Discussing the UK’s recent ‘unusual seasons’

14 06 2013

There have been some media stories this morning about a meeting due to be held next week at the Met Office to discuss the recent run of unusual seasons here in the UK.

This will draw together some experts from across UK academia to discuss what happened in three specific seasons and examine some of the potential causes behind conditions.

Workshops of this kind are held on a regular basis on a great deal of issues across weather and climate science.

Collaboration and partnership working is also an integral part of the Met Office’s work at the forefront of research on weather and climate.

Stephen Belcher, Head of the Met Office Hadley Centre and chair of next week’s workshop, said: “We have seen a run of unusual seasons in the UK and Northern Europe, such as the cold winter of 2010, last year’s wet weather and the cold spring this year.

“This may be nothing more than a run of natural variability, but there may be other factors impacting our weather. For example, there is emerging research which suggests there is a link between declining Arctic sea ice and European climate – but exactly how this process might work, and how important it may be among a host of other factors, remains unclear.

“The Met Office is running a workshop to bring together climate experts from across the UK to look at these unusual seasons, the possible causes behind them, and how we can learn more about those drivers of our weather. This will continue the UK’s world class research effort to understand more about the drivers of monthly to seasonal climate across Europe.”





What’s in store this winter? Responding to the headlines

12 11 2012

It seems that it is the time of year for colourful headlines about an impending big freeze. We had them at this time last year, which prompted our Chief Executive to write an opinion piece in The Times.

Now we have very similar stories again, with the front page of the Daily Express declaring ‘Coldest winter freeze on way’ and warning that temperatures are set to plunge as low as -15C.

There have been other stories elsewhere along similar lines, with some saying that the Met Office is briefing the Government about a cold winter ahead.

So what are the facts behind the headlines?

Some of the stories have taken a cue from parts of our current 30-day forecast. Today’s forecast for 26 November to 10 December reads as follows:

As is usual, there are uncertainties in the forecast for this period, but there are signs that the changeable conditions will continue through the start of this forecast period. There is also a signal for temperatures to be close to or just below the seasonal average. Into December, although there are no strong indications that any particular weather type is going to dominate, on balance colder, drier conditions than at present are favoured, rather than milder, wetter weather, especially across the southern half of the UK.

However, perhaps what the newspapers have failed to pick up on and report to their readers is that there is still a great deal of uncertainty about exactly what weather we will see – as there often is when looking at timescales of over five days ahead.

The science does not exist to make detailed forecasts for temperature and snowfall for the end of this month, let alone for December or even the winter as a whole.

With regards to us ‘briefing the Government on a cold winter’, this is related to our three monthly outlook for contingency planners.

This is a complex product designed to help contingency planners making long-term strategic decisions based on risk exposure. However, it’s not useful for most other people as it doesn’t give one forecast for what’s ahead – rather it outlines potential scenarios and their associated probabilities.

It’s worth noting that while contingency planners use our three month outlook to inform long-term decisions, they make their operational decisions on our five day forecasts and warnings.

These will always provide the best possible guidance on any periods of cold weather, frost or the likelihood of snow, giving detailed local information across the UK.

Ultimately, we’re heading into winter and we expect winter to be colder than the rest of the year – but it’s too early to say exactly what temperatures we can expect or where and when we might see snow.





Turning colder this weekend

22 10 2012

There have been many references in the media to the UK having an Indian summer this week, with temperatures expected to reach 20 °C. However, as forecast by the Met Office many of us woke up today to rather grey, misty and drizzly skies and although temperatures are well above average for the time of year, it certainly doesn’t look or feel summery outside for most of us. We have also seen widespread mist and fog overnight across England and Wales, which the Met Office warned for over the weekend, and further foggy conditions are expected for the next couple of nights.

This morning's satellite image

Visible satellite image from 0900 22 October 2012

So are we going to see any sunshine at all this week? Well, yes, the cloud should break in some places, and we may even see temperatures rise to the high teens along the south coast of England at times, but these temperatures will be short lived.

For most of us it will be the end of the week before the sunshine returns and when it does the weather will be far from warm.

By Friday, much colder air from the Arctic will spread across the UK, bringing drier and clearer weather but much lower temperatures. In fact, daytime highs will struggle to reach double figures by the weekend and there may even be a few wintry showers across north-eastern parts of the UK. It will be cold and frosty overnight too and for many of us this will be the first cold snap of the season.

In this video, Deputy Chief Forecaster Baden Hall explains exactly what we can expect over the next few days.

The latest information about the weather and warnings can be found on the Met Office website, iPhone and Android apps and on twitter. Cold weather can also have an impact on people’s health and you can find out more on the Met Office’s Cold weather and health web pages.





Record low for Arctic sea ice extent

29 08 2012

This week the National Snow and Ice Data Centre (NSIDC) announced that Arctic sea ice extent has reached a new record low since satellite data records began in 1979.

According to the NSIDC, observations show there were 4.1 million square kilometres (1.58 million square miles) of sea ice on 26 August.

Arctic sea ice extent  The black line shows the 1979 to 2000 median extent.  Credit: National Snow and Ice Data Center

This is 70,000 square kilometres (27,000 square miles) less than the previous record low set on 18 September 2007.

The previous record was the sea ice minimum for the year – which normally occurs at the end of summer before cooler temperatures sea ice start to form.

The July 2012 ice extent was the second lowest observed during the satellite era, following the record low observed in 2011. The synoptic conditions during the month were variable, and much of the Arctic was relatively warm with temperatures 1-3 degrees Celsius above the 1981 to 2010 average over the Beaufort Sea and regions to the north. 

By 1st August the daily extent was lower than the previous record low for the time of year recorded in 2007, and has since remained at a record low value. Between 4th and 9th August there was an extremely rapid loss of ice cover in the East Siberian Sea, coinciding with a severe storm over the Central Arctic. This rapid loss of ice cover may have been caused by ice breaking up and melting due to the strong winds generated by the storm, although it is also possible that the melt would have occurred anyway at this time as the ice concentration in this region was already low.   

With this previous record already broken in August, it’s likely this year’s sea ice extent will continue to decline into September. The NSIDC will announce when the Arctic sea ice extent has hit a minimum for this year when this occurs, most likely toward the middle of next month.

Declining trend in sea-ice

Satellite records began in 1979 and have shown a long-term decline in sea ice extent. However, the rate of decline has accelerated in the past 15 years and the last five years make up the lowest five extents in the 32-year record.

Climate models which simulate future Arctic sea ice extent show wide variations, but Met Office results suggest the area could be nearly ice-free in summer as early as 2030.

However, models do not suggest the current accelerated rate of decline would continue or that there was any ‘tipping point’ from which ice extent could not recover.

What are the impacts for the UK?

Long-term changes in Arctic sea ice are likely to have impacts locally in the Arctic as well as driving changes in European and global climate.

As the sea ice decreases, the immediate impact is for a the lower atmosphere in the Arctic to be warmed by the Arctic Ocean – which is relatively warm compared to the ice cover.

However, there is also evidence that depleted sea ice alters atmospheric circulation patterns outside the Arctic throughout the following months and into winter.

This appears to result in high pressure over the Arctic and low pressure further to the south over the mid-latitudes – which in turn tends to drive more easterly winds across Europe, particularly in winter.

While other factors are also involved in determining winter climate, this raises the risk of cold winter conditions over northern Europe.

However, the relative importance of sea ice conditions and other factors in producing cold winters is being investigated by Met Office scientists and others.

You can read more about Arctic sea ice in our research news pages.





Met Office scientists to feature in BBC Horizon programme ‘Global Weirding’

27 03 2012

BBC Horizon will broadcast ‘Global Weirding’ on BBC Two tonight at 9pm, exploring the science behind why the world’s weather seems to be getting more extreme and if these patterns are a taste of what is to come.

Horizon say: “Something weird seems to be happening to our weather – it appears to be getting more extreme. In the past few years we have shivered through two record-breaking cold winters and parts of the country have experienced intense droughts and torrential floods. It is a pattern that appears to be playing out across the globe. Hurricane chasers are recording bigger storms and in Texas, record-breaking rain has been followed by record-breaking drought.

“Horizon follows the scientists who are trying to understand what’s been happening to our weather and investigates if these extremes are a taste of what’s to come.”

The producers of the programme visited the Met Office headquarters and Operations Centre in Exeter to film for the programme at the end of last year, interviewing Adam Scaife, Head of Monthly to Decadal Forecasting and Helen Chivers, a Met Office Forecaster.  In the programme we discuss the science being undertaken here at the Met Office into the effects of Climate Change on ourt weather including the effects of Arctic sea ice depletion on European winter weather, and our role in forecasting extreme weather for the UK.

Adam Scaife and Helen Chivers from the Met Office appear in the programme

Other contributors to the programme include Mike Lockwood (University of Reading) on solar observations, Kerry Emmanuel (MIT) on hurricanes and Katharine Hayhoe (Texas Tech University) on extreme wet and dry conditions in Texas.

This weeks Radio Times also previewed the programme saying:

“This week’s Very Big Number from Horizon: the Met Office’s computer can do one hundred trillion calculations — a second. It needs to, in order to process the gouts of data gathered from satellites, data which means, we’re told, that a five-day forecast today is as accurate as a one-day forecast was 30 years ago. (Were we so long-suffering in 1982?)

All this technology isn’t to feed some quaint British obsession with weather, it’s to keep track of increasingly freakish extremes in meteorology, not just here but around the world: from record rains in Scotland to droughts in Texas and a boom in hurricanes. Scientists are trying to get to grips with it all and Horizon follows them, in one amazing scene, right into the heart of the storm.”





Arctic Conditions return to bring snow disruption and tumbling temperatures

17 12 2010

Arctic Conditions return to bring snow disruption and tumbling temperatures

Following the return of arctic conditions across the UK through yesterday, overnight temperatures tumbled across the UK as significant snowfall brought disruption to parts of Scotland, Northern Ireland and Wales.

Below is a table showing a selection of lowest temperatures observed across the UK last night.

Location Minimum Temp (deg C)
Cairngorm  Siesaws -12.2
Great Dun Fell  Siesaws -10.1
Cairnwell  Siesaws -10
Spadeadam -9.4
Carterhouse -9
Tyndrum  Cdl -8.7
Drumnadrochit -8.5
Tulloch Bridge -8.4
Drumalbin  Esaws -8.2
Bealach Na Ba -8.2
Sennybridge (Samos) -7.8
Glen Ogle  Siesaws -7.5
Warcop Range  Esaws -7.2
Woodford -7.2
Salsburgh -7.2
Redesdale Camp -7.1
Dalwhinnie  Cdl -7.1
Shap Fell  Esaws -6.9
Eskdalemuir -6.6
Leek -6.3
Winchcombe Sudeley Castle -6.3
Tredegar Bryn Bach Park No 2 -6.2
Market Bosworth -6.2
Fylingdales  Codet2 -6.1
Bingley Number 2 -6
Lyneham -5.9
Alice Holt Lodge -5.9
Newton Rigg -5.9
Aviemore -5.8
Kenley (Esaws) -5.8
Bournemouth/Hurn Airport -5.8
Albermarle -5.7
Blencathra -5.7
Loch Glascarnoch -5.6
Braemar No 2 Cdl -5.6
Astwood Bank -5.6
Carlisle  Esaws -5.5
Little Rissington -5.5
Myerscough -5.5
Wattisham -5.4
Cottesmore (Samos) -5.3
Hqstc (High Wycombe) (Samos) -5.3
Rothamstead No 2  Cdl -5.3
Monks Wood  Cdl -5.3
Westonbirt -5.3
Bradford -5.3
Nottingham/Watnall -5.2
Wittering (Samos) -5.2
Keele Cdl -5.2
High Mowthorpe -5.2
Bainbridge -5.2
Threave Cdl -5.1
Lentran -5.1
Goudhurst -5.1
Marham (Samos) -5
Benson -5
Durham  Cdl -5
Newport -5
Herstmonceux -4.9
Wick -4.9
Keswick  Esaws -4.9
Andrewsfield -4.9
Charlwood -4.9
Yeovilton  Samos -4.9
Cranwell (Samos) -4.9
Santon Downham -4.9
Wych Cross -4.9
Bedford  Esaws -4.8
Scampton -4.8
Kinbrace  Cdl -4.8
Rochdale  Cdl -4.8
Hampstead -4.8
Otterbourne Water Works -4.8
Cavendish -4.8
Edinburgh Royal Botanic Gardens -4.8
Lake Vyrnwy  Esaws -4.7
Baltasound -4.7
Coleshill -4.7
Boscombe Down  Samos -4.7
Pershore College Of Horticulture  Cdl -4.7
Norwich Airport -4.7
Craibstone -4.7
Llysdinam -4.7
Ravensworth -4.7
Odiham -4.6
Langdon Bay -4.6
Shawbury (Samos) -4.6
Pershore  Esaws -4.6
Middle Wallop (Samos) -4.6
Writtle -4.6
Leuchars -4.5
Coningsby (Samos) -4.5
Exeter Airport -4.5
Trawscoed  Esaws -4.5
South Farnborough  Esaws -4.5
Liscombe  Esaws -4.5
Wainfleet  Samos -4.5
Dishforth Airfield -4.5
Wisley -4.5

Below is a table showing snow depths recorded at 0900 this morning. With strong winds there has been significant drifting of snow and depths are likely to be significantly deeper in parts of Northern Ireland and Scotland.

Location Snow Depth (cm)
FORRES, HILLHEAD 10
LOUGH FEA 10
ALDERGROVE 9
ORKNEY: LOCH OF HUNDLAND 9
KINROSS 8
KIRKWALL 8
SENNYBRIDGE NO 2 8
CASTLEDERG 8
DYCE 7
AVIEMORE 7
DERRYGONNELLY FSC 7
LINGWOOD, STRUMPSHAW HILL 6
CROMDALE 6
FAIR ISLE 6
REDESDALE CAMP 6
SHAWBURY 5
VELINDRE 4
LERWICK 4
KINLOSS 4
DARWEN NO 2 3
MIDDLETON, HILLSIDE 3
SKYE: LUSA 3
WICK AIRPORT 3
ESKDALEMUIR 3
ROSEHEARTY 3
RONALDSWAY 3
LINTON-ON-OUSE 3
ALBERMARLE 2
YEOVILTON 2
ABERPORTH 2
DUNKESWELL 2
WATTISHAM 1
WITTERING 1
COTTESMORE 1
SPADEADAM 1

 

Map showing snow depths recorded at 0900 am on Friday 17th December

Map showing snow depths recorded at 0900 am on Friday 17th December

 

 

 

 








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