2015 likely to be the warmest on record

25 11 2015

This year’s global average surface temperature is likely to be the warmest on record according to data from the Met Office, and is expected to continue the trend showing 15 of the top 16 warmest years have happened since 2001.

These findings concur with the World Meteorological Organisation (WMO) findings also announced today.

2015 a more ‘clear-cut’ record

Provisional figures up to the end of October show this year’s near-surface global temperature as estimated from the HadCRUT dataset has been around 0.71 ±0.1 °C above the 1961-1990 average of 14.0 °C.

This is in-line with the Met Office’s forecast, issued in December 2014, which predicted 2015 global temperatures would be between 0.52 °C and 0.76 °C* above the 1961-1990 average, with a central estimate of 0.64 °C.

In HadCRUT, this year is clearly warmer than 2014, the previous nominal warmest year in the record, which was 0.57 ±0.1 °C above the 1961-1990 average.

Global Temperature graph

Colin Morice, a climate monitoring scientist at the Met Office, said: “Last year was nominally the warmest year in our records but wasn’t much higher than the other top warmest years. This year the temperature is markedly warmer than anything we’ve previously seen in the 166-year record, meaning its position at the top of the rankings looks set to be much more clear cut.”


The HadCRUT dataset, jointly compiled by the Met Office and Climatic Research Unit at the University of East Anglia, uses data from more than 6, 000 observation sites around the world and observations from ships and buoys at sea. It is recognised as one of the world’s leading indices of global temperature.

Temperatures 1 °C above ‘pre-industrial’ for first time

2015 is set to mark the first time in the record that annual global temperatures reach 1 °C above ‘pre-industrial’ temperatures (taken here as an average of the 1850-1900 period*).

This is important because governments around the world have agreed the aim of trying to limit warming to 2 °C or less above pre-industrial to try to avoid the most dangerous impacts of climate change.

Leading independently-run datasets agree

Findings from HadCRUT are very similar to independently-run global temperature datasets compiled by the US National Oceanic and Atmospheric Administration and NASA Goddard Institute of Space Studies.

Information from all three datasets is included in an announcement from the World Meteorological Organization (WMO) on global temperature, which also concludes this year is likely to be the warmest on record.

Where did 2015’s warmth come from?

This year has seen a strong El Niño develop, with unusually warm sea surface temperatures across the Tropical Pacific, releasing heat into the atmosphere and pushing up global temperatures.

Global Temperature chart

Global Temperature chart

While this has contributed to 2015’s warmth, this is likely to be comparatively small compared to the long-term influence of warming caused by human greenhouse gas emissions.

This is backed up by research from the Met Office last year which showed global temperatures seen in recent years would be highly unlikely in a world without human influence on the climate.

What’s in store for the year ahead?

Last year saw record or near record warmth globally, this year is warmer still and the current expectation is that next year will also be warm.

This is due to two factors: firstly, the ongoing warming due to human influence, and secondly although the current El Niño is expected to peak around the end of this year, its main warming influence is usually felt in the months afterwards. For example, a strong El Niño peaked at the end of 1997 – but it was 1998 which went on to become a record (at the time) by some margin.

There are other natural factors – such as changes in longer term ocean cycles or volcanic eruptions – which could act to reduce global temperatures next year, so there will always be some uncertainty.

The Met Office will give more detail in the expected global temperature for 2016 when it publishes its forecast in the latter part of December.


* While late 19th century temperatures are commonly taken to be indicative of pre-industrial, there is no fixed period that is used as standard and a variety of other periods have been used for observational and palaeo datasets. There are limitations in available data in the early instrumental record, making the average temperature in the reference period less certain. There is not a reliable indicator of global temperatures back to 1750, which is the era widely assumed to represent pre-industrial conditions. Therefore 1850-1900 is chosen here as the most reliable reference period, which also corresponds to the period chosen by IPCC to represent a suitable earlier reference period.

So what happened to our summer?

28 08 2015

Our Chief Scientist Professor Dame Julia Slingo OBE FRS reflects on this summer’s weather and what has influenced it:

No-one can deny that we have had a pretty disappointing summer with a lot of unsettled weather and only a few warm spells, especially through July and August. Our weather has been dominated by low pressure over and to the west of the country that has brought us periods of heavy rain from the south – what we call the Spanish Plume. So what has been happening?

If we look beyond our shores there have been some big changes in the global climate this year. El Niño is in full flight, disturbing weather patterns around the world. The low pressure that has dominated our weather is part of a pattern of waves in the jet stream around the world that has brought crippling heat waves to places like Poland and Japan. And, looking back over past El Niños, you could have expected that a more unsettled summer might be on the cards for the UK. Closer to home the North Atlantic is more than 2 degrees colder than normal. It seems quite likely that the unusually cold North Atlantic has strengthened and pushed our jet stream south, also contributing to the low pressure systems that have dominated our weather.

So could all this have been anticipated? Seasonal forecasts for this summer suggested that temperatures and rainfall would be near normal. However, as the season progressed all the leading models around the world failed to capture the signal for unsettled weather over the UK. We all know that forecasting months and seasons ahead is still in its infancy and much more research needs to be done. On the other hand our day-to-day forecasts have been really successful in allowing us to warn of bad weather, highlighting yet again the benefits of our research that has delivered year-on-year and decade-by-decade improvements in forecasting skill. Our 5-day forecast is now as accurate as our 1-day forecast was when I started my career. This enables us to make so many decisions that keep us safe, protect our property, keep our infrastructure running and even when to go out and enjoy the sunshine!

All of this cannot happen without improvements to research and technology, and this week the first phase of our new supercomputer went live, five weeks ahead of schedule. This will enable us to provide even more accurate and relevant weather and climate forecasts to all of us, our government, emergency responders, and our many other customers at home and abroad.

The news that the BBC has decided that the Met Office won’t be their main weather provider when the current contract ends has raised the question of where will the new provider get their information from. It’s important to understand that no weather forecasting organization, whether it is a National Met Service like the Met Office or an independent company, can provide a service without a forecast, and that it is the leading meteorological agencies, like the Met Office, that build and deliver those forecasts. So whoever the BBC chooses to deliver their weather services in future, you can be sure that Met Office observations and forecasts will continue to be at the heart of them. We are committed to driving forward the skill and usefulness of our forecasts and ensuring that all of us benefit from the advances the Met Office makes in the coming years with our new supercomputer.

Met Office Science Camps a huge success

20 07 2015

Over 200 secondary school pupils have taken part in four Met Office Science Camps this year.

The overnight camps, held at Met Office HQ in Exeter, provided a unique opportunity for 11-13 year old to join in a selection of hands-on activities led by Met Office staff. The activities covered a wide range of topics and helped explain how we measure and forecast the weather and climate.

Science Camp May 2015

Twelve schools and three scouts/guide groups took part in the events and Director of Science at the Met Office, Andy Brown said: “As well as being fun, Met Office Science Camps engage, challenge and enthuse students, encouraging them to develop scientific skills and hopefully inspire the scientists of the future.”

As one of the UK’s top science and engineering organisations, the Met Office is continually looking at ways to engage people, young and old, in the fascinating worlds of weather and climate science.

The Met Office Science Camps are part of the Met Office STEM (Science, Technology, Engineering and Math’s) Outreach programme which aims to improve understanding of how weather and climate are measured and forecast. The programme has been awarded the European Meteorological Society Outreach and Communication Award in recognition of our outstanding efforts to engage young people.

Over the last decade or so, predicting the weather and climate has become one of the most important areas of scientific research. Work at the Met Office is incredibly varied, and this is reflected in the variety of career opportunities available, including everything from Science and Forecasting to Engineering and Business Development.

You can hear from a whole range of different people who are employed at the Met Office, from IT specialists to Climate Change scientists, in a series of podcasts.

How to Register

If your school or organisation would like to be added to our mailing list for the 2016 Met Office Science Camps, please email us at science.camp@metoffice.gov.uk with your name and the school (or organisation) that you are emailing on behalf of. We take group bookings from schools or other organisations, rather than individual campers. If you are a parent or student looking to get involved then please get in touch with a teacher at your school and ask them to contact us.

If you have any queries, please email us: science.camp@metoffice.gov.uk.

Met Office awarded for its collaborative work overseas

15 05 2015

The International Development team at the Met Office has won a prestigous award for its work helping increase the access, use and benefits of climate information services to 2.4 million people in Kenya.

The British Expertise International Award for ‘Outstanding International Collaboration’ was given to the Met Office for its work with the Adaptation Consortium delivering the ‘Mainstreaming Climate Adaptation into Planning’ project.

Other partners in the consortium are Christian Aid, the International Institute for Environment and Development, Kenya Meteorological Services and the National Drought Management Authority Kenya.

The project aims to address the underlying causes of vulnerability to climate change while strengthening adaptation to future extreme events. It has improved access to climate and other information, integrated climate change adaptation into development plans, developed better water infrastructure and training in water governance, and improved disease surveillance.

The Spectator: How accurate is the Met Office?

11 07 2013

In an article which appeared in the Spectator online today, Rupert Darwall makes a sustained attack on climate scientists and specifically on the Met Office.

His main point seems to be that the Met Office gets weather forecasts wrong. To answer that, you can see our accuracy figures online and these are regularly updated to reflect our recent performance.

At the time of writing this blog, the Met Office is beating all of its forecast accuracy targets. As an example, 87.7% of our next day maximum temperature forecasts are accurate to within 2C. The target is 80%.

The Met Office is consistently recognised by the World Meteorological Organization as one of the top two most accurate operational forecasters in the world.

No forecaster can be accurate 100% of the time and we don’t claim to be, but we are at the forefront of weather and climate science and are continuing our world class research to ensure the UK stays a leader in this field.

In the article, Rupert Darwell gives a few examples of forecast errors to back up his claims – these all refer to our long-range (three month) outlooks. This is a challenging area of forecasting and the Met Office has always been clear that these long-range forecasts are part of our ongoing research and development. We acknowledge that the public favour our short-range forecasts, which they download in their millions on iPhone, Android and now Kindle apps.

With time, continued research will hopefully yield similar improvements in our long-range outlooks as we have seen over time in our short-range forecasts. As an example of that progression, our four day forecast is as accurate today as our one day forecast was 30 years ago.

The article also talks about the Met Office ‘bracing’ the UK for a ‘decade of soggy summers’.

This is a misrepresentation of the science, as the statement refers to media reporting following a press conference hosted by the Met Office. The conference came at the end of a science workshop attended by experts from across UK academia to look at the potential causes behind the UK’s recent spell of unusual seasons.

During that press conference, scientists talked to the media about some of the latest research discussed at the meeting. This included research from the University of Reading which looked at long-term temperature patterns in the Atlantic which may impact weather patterns over Europe – potentially influencing a higher frequency of wet summers for a given period of time.

Scientists were clear to say this was early research and they were not issuing a forecast, but some parts of the media reported it that way. We issued a blog in reaction to this, to make clear that there was no expectation every summer would be wet for a decade – but The Spectator article makes the same claim again, despite all of this publicly available information to the contrary.

Apparently, “the Met Office has decided that global warming means colder summers in Britain”. This is news to the Met Office, which has been very careful to say that more research needs to be done to understand what impacts changes in our climate (such as reduced Arctic sea ice) could have on UK climate. Again, this seems to be a misinterpretation of our position.

The Met Office has already discussed the issue related to Doug Keenan, which you can also read about on our blog. You can also see a discussion paper we published on the issues he raises.

On global temperatures, you can look at our HadCRUT4 pages – which show 2010 and 2005 are respectively the first and second warmest years on record, with all the supporting data available online. You can also look at a report from the WMO released last week.

There are many other points to address in the lengthy Spectator article, too numerous to detail in this blog.

However, as a final point, Rupert Darwall says: “At the very least, the Met Office has a duty of care to the rest of us: to be balanced and objective, to admit when they’ve got it wrong, not to indulge in speculation and to tell us what they don’t know.”

The Met Office recognises this duty of care and takes it very seriously, which is why our impartial advice is based only on evidence from world class research. Our scientists have and will continue to report those findings as they are, without censorship, to enable people to make informed decisions.

The Met Office is very proud of its science and scientists. Indeed last year the Met Office published 267 peer reviewed scientific papers in academic journals and is widely recognised as one of the best geosciences institutes in the world.

Recent climate research in the news

21 05 2013

A research paper published in Nature Geoscience (Otto et al, 2013) led to a fair amount of media coverage yesterday, including articles in the Guardian, BBC and an opinion piece by Matt Ridley in The Times (this article is behind a pay wall).

The research paper looked at a ‘best estimate’ of the warming expected when the concentration of carbon in the atmosphere is doubled over pre-industrial levels (known as the Transient Climate Response).

Alexander Otto, Research Fellow in Climate Decisions at the Environmental Change Institute, University of Oxford, was the lead author of the research.

He has written an article discussing the science and the implications of the research which can be seen on the Research News pages on our website.

Here is a short extract from Alexander Otto’s article :

“We published a paper in Nature Geoscience on Sunday giving a new best-estimate of 1.3°C for the Transient Climate Response, or the warming expected at the time carbon dioxide reaches double its pre-industrial concentration, using data from the most recent climate observations.

This best-estimate is lower than the HadGEM2 [one of the Met Office climate models] TCR value of 2.5°C and it is also 30% lower than the multi-model average of 1.8°C of the CMIP5 models used in the current IPCC assessment. Does this mean that the Met Office’s advice to government is based on a flawed model? Certainly not.

It is well acknowledged by all that the HadGEM2 model is at the top end of the range of TCR values in CMIP5, but we need a diverse range of TCR values to represent the uncertainties in our understanding of climate system processes. And the Met Office’s advice to government, like any solid policy advice, is based on the range of results from different models, not just their own.

The ‘warming pause’ over the recent decade does not show that climate change is not happening. And it certainly does not mean that climate scientists are “backing away” from our fundamental understanding.

Every new decade of data brings new information that helps reduce uncertainties in climate forecasts. In some ways, the picture changes surprisingly slowly for such an intensely scrutinised problem… This study highlights the importance of continued careful monitoring of the climate system, and also the dangers of over-interpreting any single decade’s worth of data.”

Setting the record straight in the Daily Mail

8 03 2013

In response to our complaint to an article by James Delingpole in the Daily Mail on 10 January 2013 the Daily Mail has now published a response from the Met Office Chairman on its letters page.

Met Office mettle

James Delingpole’s views misrepresent the Met Office’s reputation for world-class weather and climate forecasting and research (Mail). The UK can be rightly proud that the Met Office is among the world’s top two national weather forecasting services.

We’re proud that, in independent surveys, more than 90 per cent of the public regard our warnings as useful and more than 80 per cent of the UK public trust our forecasts and warnings. This respect for our professionalism and impartiality has been built over 150 years of forecasting for the nation.

We aim to use our world leading scientific expertise to protect life and property and increase prosperity and wellbeing right across the UK. We provide impartial services ranging from forecasts and warnings to the public, services to transport operators, so we can fly, drive or sail safely, and advice to the energy, retail and health sectors so we can all go about our daily lives safely and efficiently.

Our forecasts on radio, TV, mobile phone apps and newspapers are a source of daily interest as well as essential advice to the public.

Whatever a journalist’s views are about climate change – and they have a right to air them – let’s not degrade the institutions on which the public rely.


Met Office chairman, Exeter, Devon.

Although this does not fully address all the issues we had with the original article we do accept that a published letter recognises our concerns and has taken steps to resolve some of them. The Daily Mail has also offered to append this letter to the original article.

We are grateful to the Daily Mail for dealing with our objections to the inaccuracies in the original article and the efforts made to find a constructive resolution. We are, as ever, grateful for the role the Daily Mail, and other print, online and broadcast media have in bringing key forecasts, warnings, and science to the attention of the public.

Addressing the Daily Mail and James Delingpole’s ‘crazy climate change obsession’ article

10 01 2013

An article by James Delingpole appears in the Daily Mail today under the headline The crazy climate change obsession that’s made the Met Office a menace’.

This article contains a series of factual inaccuracies about the Met Office and its science, as outlined below.

Firstly, he claims the Met Office failed to predict snow in 2010, but our 5-day forecasts accurately forecast 12 out of 13 snowfall events – as you can see in this article. In addition the Press Complaints Commission has also already addressed this fallacy with the Daily Telegraph in February of last year. As a result the newspaper published a clarification that highlighted that “the Met Office did warn the public of last winter’s [2010/11] cold weather from early November 2010.” 

Mr Delingpole also says we failed to predict flooding in November last year. Once again, our 5-day forecasts gave accurate guidance and warnings throughout the period. In just one example of feedback the Met Office has received for highly accurate forecasting and guidance throughout 2012, Assistant Chief Constable Paul Netherton, Chair for the Local Resilience Forum for Devon, Cornwall and the Isles of Scilly (which was one of the areas most affected by flooding in November), said: “[I] would like to formally thank and recognise the hard work of the Met Office over the past week. The information you provided was invaluable and enabled the responders in Devon, Cornwall and the Isles of Scilly to prepare and respond effectively to assist our communities.”

Mr Delingpole then inaccurately states that the Met Office has conceded ‘there is no evidence that ‘global warming’ is happening’. We have not said this at any point.

In fact, we explicitly say this was not the case in an article, posted on the home page of our website and widely circulated, which was written in response to articles about updates to our decadal forecast. Professor Julia Slingo, Met Office Chief Scientist, has also provided a more in depth feature on ‘Decadal Forecasting – What is it and what does it tell us?’.

Further on in the print version of the article (although amended online), Mr Delingpole says “According to the Met, Britain is apparently experiencing more rain by volume and intensity than at any time since records began.” Although he is right in saying the Met Office has published preliminary observations which show an increase in the intensity and volume of rain, we are clear that this relates to a period from 1960 onwards – not ‘since records began’ as he claims.

He also states that the Met Office was trying to defend a narrative that the “the past ten years have been the ‘wettest decade ever’”. Again, this is not something the Met Office has ever said.

Also he quotes David Whitehouse of the Global Warming Policy Foundation saying that the Met Office ‘thinks weather forecasting is beneath it’ and that ‘climate change… brings in more money’.

A cursory glance at our annual report and accounts (pdf) would reveal weather forecasting represents the vast majority of the Met Office’s contractual work on behalf of the public.

There are also a number of other accusations which cannot be substantiated.

Mr Delingpole does quote Dr Whitehouse saying “when it comes to four or five day weather forecasting, the Met Office is the best in the world.”

This supports the view of the World Meterological Organization (WMO) which consistently ranks the Met Office in the top two operational forecasters in the world.

Our reputation for forecasting accuracy is based on our commitment to provide the world’s best weather and climate service which helps protect lives and property here in the UK and around the world.

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.”

Met Office in the Media: The Sunday Times – ‘So, do we freeze or fry’

5 02 2012

Figures showing temperatures flatlining have given the climate debate fresh ferocity. Jonathan Leake, Science Editor of The Sunday Times, unpicks the row in ‘So, do we freeze or fry

John Prescott was apocalyptic. “Our polar ice caps are melting,” the then deputy prime minister thundered. “Only this weekend Mexico was hit by freak snowstorms . . . a world of drought and crop failures, rising seas, mass migration and disease . . . rising greenhouse grasses [sic] . . .”

The year was 1997 and Prescott had just come back from Kyoto in Japan to give the House of Commons his account of the latest climate talks.

Prescott’s terrifying warnings were backed by Britain’s leading climate scientists. Just before Kyoto a Met Office report warned that climate-related floods would put 50m people at risk of death from starvation in the coming decades. Whole island nations would disappear, it added, while the American Midwest, which helps to feed 100 nations, was likely to face drought and the North Pole might melt.

That was 15 years ago — what has happened to world temperatures since then? Last month came the suggestion that the answer was, embarrassingly, nothing. Research based on Met Office figures pointed to temperatures having been flat since 1997.

It was the kind of admission that those who doubt climate science pounce on. “Forget global warming,” trumpeted The Mail on Sunday, because “the planet has not warmed in 15 years”. It then cited other research, into the declining energy output of the sun, to suggest the real danger was from a big freeze, raising the prospect of a reprise of the frost fairs held on the frozen Thames in the 17th century.

Two days earlier The Wall Street Journal had published a letter from 16 scientists advancing similar arguments. It said: “The lack of warming for more than a decade . . . suggests that computer models have greatly exaggerated how much warming additional CO2 can cause.”

Since then the same cry has been taken up by innumerable bloggers, exemplified by David Whitehouse, formerly the BBC’s science editor, now an adviser to the Global Warming Policy Foundation, which frequently challenges the views of climate-change scientists. He, it turns out, was a source of the research that sparked the whole row.

“We set out to see how long it had been since the temperature had risen, and 15 years was what emerged from the data set,” he said. “It raises serious questions about how the Met Office models future climate.”
It seemed a strong argument but the climate scientists came out fighting, starting with a furious blog posted by the Met Office itself, which attacked the Mail on Sunday article as “entirely misleading”.

That was followed by another letter in The Wall Street Journal, this time signed by 35 leading climate scientists, who pointed out that few of the signatories to its sceptical predecessor were actually involved in climate research.

“Do you consult your dentist about your heart condition?” it asked, adding: “Climate experts know that the long-term warming trend has not abated in the past decade. In fact, it was the warmest on record.”

What were the rest of us meant to make of this? Some scientists appear to be warning we will fry, while other sources fear we will freeze. For the public the outcome is, increasingly, confusion. Where might the truth lie?

Perhaps the simplest first step is to put aside the arguments and get back to the data. Is it really true that global temperatures have not risen since 1997?

The simple answer is: they have risen, but not by very much. “Our records for the past 15 years suggest the world has warmed by about 0.051C over that period,” said the Met Office. In layman’s terms that is 51 thousandths of a degree.

These figures come from the Met Office HadCruT3 database, which takes readings from 3,000 land stations around the world, along with oceanic readings from a similar number of ships and buoys.

However, HadCruT3 is just one of several global temperature databases, each overseen by different scientists and calculated in slightly different ways. This allows each group to cross-check results, confirming findings or spotting errors.

One, held at the National Climate Data Centre (NCDC), run by America’s National Oceanic and Atmospheric Administration, suggests that global temperatures rose by an average of 0.074C since 1997. That’s small, too — but it is another rise.

A third and very different data set is overseen by John Christy, professor of atmospheric science at the University of Alabama in Huntsville. He gathers figures from three satellites that orbit the Earth 14 times a day. They measure the average temperature of the air from ground level to a height of 35,000ft, a method completely different from those of the Met Office and NCDC. Oddly, given his reputation as a climate sceptic, he found the biggest rise of all.

“From 1997-2011 our data show a global temperature rise of 0.15C,” he said. “What’s more, our satellites have been taking this data since 1979, and over that period [the] global temperature has risen 0.46C, so the world has been getting warmer.”

Overall, then, the world has got slightly warmer since 1997. Perhaps the real question is: why has it warmed so much less than was predicted by the climate models?

For most climate scientists the answer is simple. “Fifteen years is just too short a period over which to measure climate change,” said Peter Stott, head of climate monitoring at the Met Office. “The world undergoes natural temperature changes on all kinds of time scales from daily variations to seasonal ones. It also varies naturally from year to year and decade to decade.”

Whitehouse accepts this point. “The records do show that global temperatures have risen by about 0.4C over the past three decades, most of it in the 1990s,” he said.

“I accept that CO2 is a greenhouse gas that might warm the world but the key issue is how strong the effect is and how the data compare with the models used to predict the future.”

This is an interesting admission, turning what had appeared to be an attack on the keystones of climate science — that greenhouse gases cause global warming — into a “shades of grey” debate over whether global warming will happen slowly and steadily or in jerks, accelerating in some decades but then slowing or even reversing a little in others.

For the critics of climate science this is a crucial point — but why? The answer goes back to the 2001 and 2007 science reports from the Intergovernmental Panel on Climate Change that had predicted the world was likely to warm by an average of about 0.2C a decade. The implication was that temperatures would rise steadily, not with 15-year gaps. The existence of such gaps, the critics argue, implies the climate models themselves are too flawed to be relied on.

Other leading climate scientists have raised similar issues. One is Judith Curry, professor of atmospheric sciences at the Georgia Institute of Technology. She argues that global climate is affected by so many factors, ranging from solar output to volcanic eruptions, that predicting how the world will warm is impossible.

Crucially, however, Curry accepts that greenhouse gas emissions are likely to lead to long-term warming. She wrote on her blog: “We don’t know what the climate will be for the next several decades. In terms of when global warming will come ‘roaring back’, it is possible this may not happen for the first half of the 21st century.”

For Curry and many others one of the key unresolved issues lies in the behaviour of the sun, whose output appears to be undergoing a steady but small decline. Most scientists accept that this will reduce global warming. The debate is over just how strong this effect will be, with people such as Curry suggesting it could be powerful while others see it as small.

Among the latter is Mike Lockwood, professor of space physics at Reading University’s meteorology department, who believes the sun has been in a “grand solar maximum” since the 1960s, thought to be the longest-lived peak in its output for more than 9,000 years.

“A decline in activity is long overdue,” he said. “How deep will it go? We think there is about an 8% chance that it will drop below the famous Maunder minimum.”

This was a 60-year period, starting in about 1645, when the sun had very few sunspots; it was marked by an unusually high proportion of cold winters in Europe.

That sounds ominous but Lockwood calculates that even a decline in activity on that scale would now have little effect because the impact would be far smaller than the opposing effects of surging greenhouse gas emissions.

What about the most evocative image of all — the prediction that the Thames might freeze over? This did happen in 1963, but far upstream in the stretches around Windsor. The idea that the lower tidal reaches might be in similar danger generates little but scorn from all sides.

Lockwood said: “The disappearance of frost fairs is nothing to do with climate. It is because the old London Bridge — really more of a weir — was pulled down and the embankments were put in. So the river now flows much too fast to freeze and is also a lot saltier. Even a return to Maunder minimum solar conditions would not cause the Thames to freeze again so far downstream.”

This article first appeared in The Sunday Times on Sunday 5 February 2012.


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