Why officials in Labour government pushed ‘dash for diesel’

As Chancellor Philip Hammond considers tougher budget measures on diesel cars, documents obtained by the BBC reveal how the “dash for diesel” was encouraged by presentational considerations.

The shift to promoting diesel vehicles under the last Labour government can be seen as a textbook example of the law of unintended consequences.

In 2001, the then Chancellor Gordon Brown introduced a new system of car tax aimed at protecting the environment. In actual reality it fostered a popular move towards highly polluting diesel cars – a trend which according to some experts has been associated with thousands of premature deaths a year.

New light is shed on how this happened byrecords received by the BBC, after a two-year freedom of information battle with the Treasury. Some of these papers show that civil servants objected to a stronger policy to deter diesel usage on presentational grounds, because they did not want the government to be seen as “penalising” diesel drivers.

‘Overly harsh’

Mr Brown brought in a sliding scale for car tax or vehicle excise duty (VED), to make it cheaper for cars with lower emissions of carbon dioxide (CO2), a greenhouse gas which contributes to global warming. This resulted in lower VED rates generally for diesel cars, which tend to be more fuel efficient. But they emitted greater quantities of other pollutants harmful to health, nitrogen oxides and particulates.


The records confirm that ministers and civil servants in the Labour government were well aware that diesel pollution damages air quality (even if perhaps they did not appreciate the full extent). But officials preparing the 2000 Budgetargued against higher tax for diesel cars “so we are not seen as being overly harsh on diesel users”.

Advice from the Treasury’s tax policy section presented to ministers stated: “Relative to petrol, diesel has lower emissions of CO2 but higher emissions of the particulates and pollutants which damage local air quality. A diesel supplement is necessary so that we do not create incentives for people to choose diesel vehicles over similar petrol models in order to attract a lower VED rate.”

Car exhaustImage copyrightPA

But their concern was how this supplement would be perceived: “Presentationally, this should be seen as ensuring fair treatment of petrol and diesel, rather than as a penalty on diesel users.”

The officials therefore rejected imposing larger supplements on diesel cars which would have a greater deterrent effect, concluding “we would prefer the smaller £10 supplement, so we are not seen to be ‘penalising’ diesel vehicles.”

‘Dash for diesel’

They added that this could be re-visited if another budget decision on fuel duty “opens us up to criticism of doing too little on local air quality”.

In the documents released to the BBC this presentational factor was the only argument given against a higher supplement for diesels. This was advice from officials which may not have represented the motives of ministers. The Labour government’s policy followed a consultation exercise on vehicle duty and environmental concerns.

The resulting financial incentive for diesel cars helped to prompt a “dash for diesel” after it came into effect in 2001 and was extended in further years. This particularly happened within company car fleets which were responsible for a substantial proportion of new car purchases.

There are now 12 million diesel cars on Britain’s roads, while back in 2000 there were only three million. And in recent years diesels have accounted for around half the new car market, whereas in 2000 only one in seven new cars was a diesel model.

New carsImage copyrightPA

Millions of Britons switched to drive very polluting vehicles, while being told it was less damaging to the environment. Emissions of nitrogen oxides and particulates have been linked to respiratory difficulties, heart attacks and lung cancer.

The health issues affecting diesel vehicles have since been recognised and the government has pledged to tackle them. According to reports ahead of the forthcoming budget, Mr Hammond is considering extra tax on the sale of diesel vehicles and an increase in diesel fuel duty.

I first applied for relevant documents from the Treasury in October 2015, under the freedom of information law and the regulations governing environmental information. Their response to the request has involved considerable delays.


At one stage the Treasury argued that it would be against the public interest to release any information, as it would damage the policy development process and inhibit the quality of advice. It later changed its stance and said the application would be too expensive to answer. Eventually officials decided to respond partly to a narrower request.

Gordon Brown’s office declined to comment. In his memoirs published this month there is no specific reference to the diesel issue, but Mr Brown states that “our policy on fuel taxation was heavily influenced by our desire to promote cleaner fuels and vehicles”.

Paul Morozzo, clean air campaigner at Greenpeace, said: “It’s now clear politicians have known diesel is toxic to people’s health for decades. This government must not make the mistakes of the last. It must prioritise public health over the motoring lobby in next week’s budget by getting tough on diesel.”

The Treasury said that it can’t comment on decisions taken under a previous government, or on budget speculation. It refused to comment on the reasons for the FOI delays.

PS: This issue remains politically sensitive today, as illustrated by the fact the Conservatives have now picked up on this disclosure.

The Environment Secretary Michael Gove said: “The dash for diesel was pursued under a Labour government, and these documents show they knew the damage this would do to our environment. This is yet another example of a Conservative government having to clean up Labour’s mess.

“We are taking action and have put in place a £3bn plan to improve air quality and reduce harmful emissions as well as ending the sale of new diesel and petrol cars and vans by 2040.”

UK and Canada lead global alliance against coal

  1. CoalImage copyrightGETTY IMAGES
  2. The UK and Canada have launched a global alliance of 20 countries committed to phasing out coal for energy production.
  3. Members including France, Finland and Mexico, say they will end the use of coal before 2030.
  4. Ministers hope to have 50 countries signed up by the time of the next major UN conference in Poland next year.
  5. However some important coal consuming nations, including China, the US and Germany have not joined the group.
  6. Reducing global coal use is a formidable challenge, as the fuel produces around 40% of the world’s electricity at present.
  7. As a highly carbon intensive source, coal contributes significantly to the rising levels of CO2 emissions that scientists reported earlier this week.
  8. Researchers say that if the world is to curb dramatic temperature rises this century then coal use must be limited.
  9. Called the Powering Past Coal Alliance, this new initiative sees countries, regions and provinces, signing up to setting coal phase-out targets and committing to no new investments in coal-fired electricity in their national jurisdictions or abroad.
  10. No sacrifice
  11. The UK has said it will end the generation of electricity from unabated coal by 2025. Unabated means that the coal is burnt without capturing the resulting carbon emissions.
  12. Already, the move away from coal in the UK has been rapid. Around 40% of electricity was still being generated from coal in 2012 but in April this year the UK had its first full day without coal power in 135 years.
  13. “We have not sacrificed growth,” said Claire Perry, the UK’s minister for climate change and industry.
  14. “Since 1990 Britain has cut its emissions buy 42% and our economy has grown by 67%, that’s the best performance in the G7 so this is not something that’s a win-lose, it’s a win-win situation.”
  15. Energy ministersImage copyrightBEISImage captionEnergy ministers assembled at the meeting in Bonn
  16. However many of those who have signed up to the alliance have little or no coal production or consumption, among them Fiji, Niue, and Costa Rica. Many of the richer countries involved have already announced their move away from coal and taken together the grouping only represents about 2.5% of global coal consumption.
  17. There are also some significant coal consuming countries including Germany and China, absent from the list at present.
  18. The anti-coal alliance are confident that by the time of the next major UN climate conference in Poland in 2018, there will be closer to 50 countries on board.
  19. The development has been broadly welcomed by environmental groups.
  20. “This is another positive signal of the global momentum away from coal, benefitting the health of the climate, the public and the economy,” said Jens Mattias Clausen from Greenpeace.
  21. “But it also puts on notice the governments who lag behind on ending coal or those who promote it that the world’s dirtiest fossil fuel has no future.”
  22. Closest of allies
  23. Those involved in the coal industry say the alliance needs to put more efforts into developing technology that will allow coal use to continue.
  24. “With the world set to use fossil fuels, including coal, for the foreseeable future, Canada and the UK should direct efforts to advancing carbon capture and storage technology because that’s much more likely to achieve global climate objectives than unrealistic calls to eliminate coal in major emerging economies,” said Benjamin Sporton, chief executive of the World Coal Association.
  25. With Canada and the UK leading the group, it means that two of the closest allies of the US are moving away from coal at a time when President Trump is talking about a revival for the fuel.
  26. McKenna, Liebrich, PerryImage copyrightBEISImage captionFrom L-R: Catherine McKenna, Canada’s environment minister; Michael Liebreich, founder of Bloomberg New Energy Finance; Claire Perry, UK climate change and industry minister
  27. The White House has had a presence at this meeting with the President’s special adviser on climate change, George David Banks telling reporters that coal and other fossil fuels were an important part of the solution to climate change.
  28. Mr Banks believes that a so-called “clean coal alliance” involving the US, Japan and others would be something the Trump team would favour.
  29. “I would say that the administration is interested in the idea,” he told reporters.
  30. “I’m guessing that would mean a clean coal alliance that would focus on highly efficient low emission coal plants and carbon capture utilisation and storage. I think there would be interest in exploring that.”
  31. Many environmental campaigners though, believe that attempts to produce clean coal are essentially efforts to prolong the dominance of the fossil fuel industry.
  32. “People were worried that this summit would see Trump assaulting the Paris Agreement with his coal lobbyists,” said Mohamed Adow from Christian Aid.
  33. “But his actions have actually galvanised other nations into action, with a new alliance making it clear that coal’s climate change threat must be taken seriously.
  34. “The bottom line is coal is a dirty, unnecessary, polluting fuel that deserves to remain in a more ignorant and backward era. These countries are showing they understand that.”

Dinosaur sported ‘bandit mask’


A dinosaur from China sported a “bandit mask” pattern in the feathers on its face, scientists have said.

Researchers came to their conclusion after studying three well-preserved fossil specimens of the extinct creature, called Sinosauropteryx.

They were able to discern the dinosaur’s colour patterns, showing that it had a banded tail and “counter-shading” – where animals are dark on top and lighter on their underside.

The study appears in Current Biology.

The bandit mask pattern is seen in numerous animals today, from mammals – such as raccoons and badgers – to birds, such as the nuthatch.

“This is the first time it’s been seen in a dinosaur and, to my knowledge, any extinct animal that shows colour bands,” co-author Fiann Smithwick, from Bristol University, told BBC News.

Masked avengers?

There are a variety of ideas about why animals carry the bandit mask pattern. And the reasons might differ between individual species.

“In raccoons and badgers, it’s an advertisement of the fact that they’re aggressive,” said Dr Smithwick, adding: “If you’re a predator and you mess with them, they’re going to fight back.”

“We think that’s probably unlikely in Sinosauropteryx because there’s no real anatomical evidence that it could have defended itself well. It’s a small dinosaur and quite gracile (lightly built).

“It would probably have been fast-moving, but in terms of a physical deterrent that you’d need to back up a signal like that, it doesn’t really have one.

Image captionOne of the specimens used in the study

He added: “If you have a non-honest signal like that, you’re generally found out pretty quickly in evolutionary terms.”

Instead, the team thinks the bandit mask served a similar function to the one seen in modern birds – which makes sense given the evolutionary relationship between the two groups.

Scientists think one reason birds have it is to reduce glare from light reflected on feathers around the eye. This might be particularly important in environments where there’s lots of direct sunlight.

“The analogy is athletes who paint a dark stripe under their eyes… it’s really beneficial for increasing your visual acuity,” said Dr Smithwick.

But they might also camouflage the eyes, making them harder for predators to spot.

Photo inspection

Sinosauropteryx is known to have lived between 133 and 120 million years ago in north-eastern China. It was a small feathered dinosaur characterised by a long tail and short arms. The longest specimen is about a metre (three-and-a-half feet) in length.

“One of these fossils was looked at about seven years ago, by a team that found pigment preserved in the feathers – this was in the form of melanin. This was a particular type of melanin that’s known to give ‘ginger’ or ‘rusty-brown’ colours in living animals,” he explained.

Only pigmented feathers were preserved by fossilisation. So parts of the dinosaur’s body where they were not found were presumed to be white in life.

Co-author Dr Jakob Vinther, also from Bristol University, travelled to China to take very high-resolution photos of the specimens. Some of these were normally lit, but others were taken using cross-polarising filters on the light and the camera.

SinosauropteryxImage copyrightFIANN SMITHWICK
Image captionArtwork: The dinosaur had the longest tail of any known theropod dinosaur relative to its body length

These filters reduce the glare that comes off the fossil under artificial light, allowing the scientists to see in detail where the dark-pigmented areas were.

“It essentially allowed us to map out the distribution of the light and dark plumage,” said Dr Smithwick.

In addition to the bandit mask, the researchers identified counter-shading on the body and a banded tail. These patterns can tell scientists lots about the animal, its behaviour, and habitat.

Counter-shading is a common form of camouflage present in modern animals. It balances out the natural patterns of light and shade cast by sunlight, making the creature appear flatter against the background. The particular way that the dinosaur was counter-shaded suggests Sinosauropteryx lived in open habitats, rather than dense forest.

Sinosauropteryx could not have held the long tail in a perfectly horizontal position for long periods, which may explain why it’s banded rather than counter-shaded.

Artificial intelligence smart enough to fool Captcha security check

A man answers a Captcha puzzle on a laptop screen

Computer scientists have developed artificial intelligence that can outsmart the Captcha website security check system.

Captcha challenges people to prove they are human by recognising combinations of letters and numbers that machines would struggle to complete correctly.

Researchers developed an algorithm that imitates how the human brain responds to these visual clues.

The neural network could identify letters and numbers from their shapes.

The research, conducted by Vicarious – a Californian artificial intelligence firm funded by Amazon founder Jeff Bezos and Facebook’s Mark Zuckerberg – is published in the journal Science.

What is Captcha?

The Captcha test, which means the “Completely Automated Public Turing test to tell Computers and Humans Apart”, was developed in the late 1990s to prevent people from using automated bots to set up fake accounts on websites.

When logging into a website, users prove that they are human by solving visual puzzles, which requires identifying letters, digits, symbols or objects that have been distorted or animated in some way.

Computers usually struggle to pass such tests, and Google says that its reCaptcha test is so complicated that even humans can only solve it 87% of the time.

However, researchers from Vicarious claim that their computer algorithm can pick out distorted letters and digits from images.

Neural networks

To get computers to recognise images, computer scientists usually use neural networks, which are large networks of computers trained to solve complex problems.

A neural network contains hundreds of layers, inspired by the human brain, and each layer examines a different part of the problem. Eventually, the answer from all the layers is combined together to produce one final result.

However, neural networks have to be painstakingly trained using thousands of images that have been pre-labelled by humans, which makes it a very arduous task.

The team from Vicarious developed Recursive Cortical Network (RCN), a software which mimics actual processes in the human brain while requiring less computing power than a neural network.

The human brain has the ability to identify objects even if they are obscured by other objects, by recognising shapes and textures.

Vicarious has been developing algorithms for RCN that aim to identify objects by analysing pixels in an image to see if they match the outline of an object.

Captcha attacks

In 2013, Vicarious announced that it had cracked text-based Captcha testsused by Google, Yahoo, PayPal and Captcha.com with a 90% accuracy.

Since then, Captcha designers have made their tests more difficult to beat, but the researchers said in their new paper that the software was now able to pass Google’s reCaptcha test 66.6% of the time.

The RCN software was also able to solve reCaptacha tests from Captcha generator BotDetect at a 64.4% success rate, Yahoo Captchas at a 57.4% success rate and PayPal at a 57.1% success rate.

A Captcha results table

“We’re not seeing attacks on Captcha at the moment, but within three or four months, whatever the researchers have developed will become mainstream, so Captcha’s days are numbered,” Simon Edwards, a cyber-security architect for data cyber-security firm Trend Micro Europe, told the BBC.

“The very nature of big data analysis and machine learning is that if you give it enough data to play with, it will eventually work out most things.”

Mr Edwards said that typically within two months of security flaws being discovered, have-a-go hackers will start attacking every publicly-visible web server they can find, and so it is likely that Captcha tests on websites will soon be under siege.

“The technology has been around for a long time – there needs to be a better version of Captcha,” he said.

“In my mind, the best form of authentication is two-factor. It’s the only real way of getting around these problems.”

Chimpanzees among 33 breeds selected for special protection

Collage of leopard, chimpanzee and giraffe all from Getty

A UN-backed wildlife conference held in the Philippines has voted for additional protections for a list of 33 endangered species including chimpanzees, leopards and giraffes.

Whale sharks, the world’s largest fish, were also included on the list.

The six-day long Convention of Migratory Species (CMS) concluded on Saturday, demanding better protections for species that cross country borders.

The group’s executive secretary said “everybody has to pitch in” to efforts.

“It has helped to convey the message that the future of migratory wildlife is integral to our own future and that we all have the responsibility to act,” Bradney Chamber said.

Governments also made commitments to cooperate on reducing the negative impacts of marine debris, noise pollution and climate change on migratory species.

Whale shark under water pictured eating fish near Donsol town in the Philippines

More than 1,000 delegates from 129 countries debated species’ protection at the 12th conference of its kind, backed by the United Nations Environment Programme.

China is still not part of the delegation, but organisers said the country had made some advances on animal protection, such as committing to shut-down the ivory trade and banning the serving of endangered species, such as shark fin soup, at government events.

Hosts the Philippines lobbied for the inclusion of whale sharks, which have become a tourist attraction for the nation. Three other shark breeds were also included in the list.

Ten species of vultures were also singled out for special protection, alongside well-known African mammals deemed to be in danger.

Giraffes are on decline on the continent, with only 90,000 thought to be left in the wild.

Lesser-known species were also singled out for protection – including the Gobi Bear found in the Gobi desert in Mongolia and China. Organisers said only 45 of them remain in the wild.

Professor Stephen Hawking’s PhD viewed two million times

Hawking PhD

Stephen Hawking’s PhD thesis was accessed more than two million times within days of it being made available to the public, it has been revealed.

Prof Hawking’s 1966 work proved so popular on the day of its release it crashed the publications section of Cambridge University’s website.

More than 500,000 people have also tried to download the paper, titled “Properties of expanding universes”.

Dr Arthur Smith, from the university, called the figures “monumental”.

Stephen Hawking

“This is far and away the most accessed item we have in the university’s Apollo repository,” Dr Smith, deputy head of scholarly communication, said.

“I’d hazard a guess that Prof Hawking’s PhD thesis is also the most accessed item from any research repository ever. We’ve never seen numbers like this before.”

Factfile: Stephen Hawking

  • Born 8 January 1942 in Oxford, England
  • Earned place at Oxford University to read natural science in 1959, before studying for his PhD at Cambridge
  • By 1963, was diagnosed with motor neurone disease and given two years to live
  • Outlined his theory that black holes emit “Hawking radiation” in 1974
  • Published his book A Brief History of Time in 1988, which has sold more than 10 million copies
  • His life story was the subject of the 2014 film The Theory of Everything, starring Eddie Redmayne

Prof Hawking wrote the 134-page document as a 24-year-old postgraduate student while studying at Trinity Hall, Cambridge.

The astrophysicist, who has been at Cambridge University since 1962, would later go on to write A Brief History of Time, one of the most influential scientific works ever.

Since it went live at 00:01 BST on Monday, the PhD has been accessed about two million times by about 800,000 unique browsers “from every corner of the globe”, according to the university.

The next most read PhD thesis has received just 7,960 downloads in 2017.

Image captionThe opening page of Stephen Hawking’s PhD, when he was a 24-year-old studying at Trinity Hall

Previously, to read Hawking’s PhD in full, people had to pay £65 to the university library to scan a copy or physically go to the library to read it.

Cambridge University hopes to encourage its other former academics to make their work available to the public, like Prof Hawking has.

Dr Smith added: “Locking knowledge and information behind closed doors benefits no-one.”


Google DeepMind: AI becomes more alien

  • October 2017
GoImage copyrightGOOGLE
Image captionThere are many more possible moves in a Go game than a chess match

Google’s DeepMind says it has made another big advance in artificial intelligence by getting a machine to master the Chinese game of Go without help from human players.

The AlphaGo program, devised by the tech giant’s AI division, has already beaten two of the world’s best players.

It had started by learning from thousands of games played by humans.

But the new AlphaGo Zero began with a blank Go board and no data apart from the rules, and then played itself.

Within 72 hours it was good enough to beat the original program by 100 games to zero.


DeepMind’s chief executive, Demis Hassabis, said the system could now have more general applications in scientific research.

Demis HassabisImage copyrightGOOGLE
Image captionDemis Hassabis worked on video games before co-founding Deep Mind

“We’re quite excited because we think this is now good enough to make some real progress on some real problems even though we’re obviously a long way from full AI,” he told the BBC and other journalists.

The London-based artificial intelligence company’s software defeated leading South Korean Go player Lee Se-dol by four games to one last year.

In a game where there are more possible legal board positions than there are atoms in the universe, it was a triumph for machine over man and one that came much earlier than many in the AI world had expected.

AlphaGo followed this with the defeat of the world’s number one Go player, China’s Ke Jie, in May.

As with many advances in this field, the achievements required the combination of vast amounts of data – in this case records of thousands of games – and a lot of computer-processing power.

David SilverImage copyrightGOOGLE
Image captionDavid Silver also began his career in video games

David Silver, who led that effort, says the team took a very different approach with AlphaGo Zero.

“The new version starts from a neural network that knows nothing at all about the game of Go,” he explained.

“The only knowledge it has is the rules of the game. Apart from that, it figures everything out just by playing games against itself.”

What is Go?

Go is thought to date back to ancient China, several thousand years ago.

Using black and white stones on a grid, players gain the upper hand by surrounding their opponents’ pieces with their own.

The rules are simpler than those of chess, but a player typically has a choice of 200 moves at most points in the game, compared with about 20 in chess.

It can be very difficult to determine who is winning, and many of the top human players rely on instinct.

This has turned out to be far more efficient way of addressing the problem.

Whereas AlphaGo took months to get to the point where it could take on a professional, AlphaGo Zero got there in just three days, using a fraction of the processing power.

“It shows it’s the novel algorithms that count, not the compute power or the data,” says Mr Silver.

He enthuses about an idea some may find rather scary – that in just a few days a machine has surpassed the knowledge of this game acquired by humanity over thousands of years.

“We’ve actually removed the constraints of human knowledge and it’s able, therefore, to create knowledge itself from first principles, from a blank slate,” he said.

AlphaGo movieImage copyrightMOXIE PICTURES
Image captionGoogle DeepMind’s defeat of champion Go player Lee Se-dol has been made into a documentary

Whereas earlier versions quickly learned from and improved upon human strategies, AlphaGo Zero developed techniques which the professional player who advised DeepMind said he had never seen before.

Many of the team have now moved on to new projects where they are trying to take this technique to new areas. Demis Hassabis mentions drug design and the discovery of new materials as areas of interest.

Whereas some see a threat from AI, he looks ahead with optimism.

“I hope these kind of algorithms will be routinely working with us as scientific experts medical experts on advancing the frontiers of science and medicine – that’s what I hope,” he says.

But he and his colleagues are cautious about how rapidly we will see the wider application of these AI techniques – a game with clear rules and no element of luck is one thing, the messy, random, unpredictable real world quite another.

I wrote earlier this week about the tidal wave of AI hype pouring into my email inbox. AlphaGo Zero is at the other end of the spectrum – proper peer-reviewed science with a real advance in computer intelligence.

We need to keep a close eye on the ethical dilemmas involved in developing a machine that, by some definitions, can think for itself – especially when it is controlled by a giant like Google.

But for now, there are few signs that AlphaGo Zero and its ilk will either steal our jobs or threaten to make humanity obsolete.

A brief history of the Earth’s CO2

Climate change has been described as one of the biggest problems faced by humankind. Carbon dioxide is is the primary driver of global warming. Prof Joanna Haigh from Imperial College London explains why this gas has played a crucial role in shaping the Earth’s climate.

Carbon dioxide (CO2) has been present in the atmosphere since the Earth condensed from a ball of hot gases following its formation from the explosion of a huge star about five billion years ago.

At that time the atmosphere was mainly composed of nitrogen, CO2 and water vapour, which seeped through cracks in the solid surface. A very similar composition emerges from volcanic eruptions today.

As the planet cooled further some of the water vapour condensed out to form oceans and they dissolved a portion of the CO2 but it was still present in the atmosphere in large amounts.

Tomorrow’s World


What is climate change?

The first life forms to evolve on Earth were microbes which could survive in this primordial atmosphere but about 2.5 billion years ago, plants developed the ability to photosynthesise, creating glucose and oxygen from CO2 and water in the presence of light from the Sun.

This had a transformative impact on the atmosphere: as life developed, CO2 was consumed so that by around 20 million years ago its concentration was down to below 300 molecules in every one million molecules of air (or 300 parts per million – ppm).

Early EarthImage copyrightSPL
Image captionArtwork: As life developed on Earth, carbon dioxide levels plummeted

Life on Earth has evolved under these conditions – note that humans did not appear until about 200,000 years ago – and atmospheric CO2 has not exceed that concentration until the industrial revolution brought with it massive emissions from the combustion of fossil fuels: coal and oil.

CO2 plays an important role in climate because it is one of the atmospheric “greenhouse” gases (GHGs) which keep the Earth’s surface about 33 degrees warmer than the -18C temperature it would be at were they not present.

They do this by being fairly transparent to the Sun’s rays, allowing them through to warm the surface, but then absorbing the radiant heat that the surface emits, so trapping it and enhancing the warming. In the present climate the most effective GHGs are water vapour, which is responsible for about two-thirds of the total warming, and CO2 which accounts for about one quarter.

Other gases, including methane, make up the remainder. The atmospheric concentration of water vapour is less than 1% and, with CO2 making up only a few molecules in every ten thousand of air, it may be surprising that they can have such a significant impact on the surface temperature.

They are able to do this, however, because the structure of their molecules makes them especially effective at absorbing heat radiation while the major atmospheric gases, nitrogen and oxygen, are essentially transparent to it.

air sampling stationImage copyrightNOAA
Image captionThis air sampling station at Mauna Loa observatory in Hawaii recorded CO2 levels going past 400ppm

The greenhouse effect means that as the atmospheric loading of GHGs increases the surface temperature of the Earth warms. The overall increase in global temperature of about 1C over the past 150 years is almost entirely due to the human activities that have increasing amounts of atmospheric GHGs.

Most significantly, the concentration of CO2 has been rising exponentially (at a rate of about 0.17% per year) since the industrial revolution, due mainly to the combustion of fossil fuels but also to large-scale tropical deforestation which depletes the climate system’s capacity for photosynthesis.

In 2015, it passed 400ppm, more than 40% higher than its pre-industrial value of 280ppm and a level that has not existed on Earth for several million years.

While the basic science of how GHGs warm the Earth is very well understood, there are complications. The climate system responds in various ways which both enhance and ameliorate the effects of these gases.

For example, a warmer atmosphere can hold more water vapour (before it condenses out in clouds or rain) and because water vapour is a GHG, this increases the temperature rise. Another example: as the oceans warm they are less able to hold CO2 so release it, again with the result the initial warming is enhanced.

VolcanoImage copyrightGETTY IMAGES
Image captionVolcanoes can eject small particles into the upper part of the atmosphere

The global temperature record over the past century does not show the same smooth increase presented by CO2 measurements because the climate is influenced by other factors than GHGs, arising from both natural and human sources. Some particles released into the atmosphere by industrial activities reflect sunshine back to space, tending to cool the planet.

Similarly, large volcanic eruptions can eject small particles into the higher atmosphere, where they remain for up to about two years reducing the sunlight reaching the surface, and temporary dips in global temperature have indeed been measured following major volcanic events.

Changes in the energy emitted by the Sun also affect surface temperature, though measurements of the solar output show this effect to be small on human timescales.

Another important consideration in interpreting global temperatures is that the climate is inherently complex. Energy moves between the atmosphere and oceans in natural fluctuations – an example being El Niño events. This means that we cannot expect an immediate direct relationship between any influencing factor and surface temperature.

All these factors complicate the picture. Nevertheless, it is indisputable that the global temperature rise over the past century is a result of human-produced GHGs, mainly CO2.

While, until the industrial revolution, the CO2 concentration has not exceeded the 280ppm value that last occurred several million years ago, it has gone through periods when it was considerably lower.

Notably, during the ice ages which have occurred roughly every 100,000 years over at least the past half million, drops in global temperature of perhaps 5C have been accompanied by reductions in CO2 concentration to less than 200ppm.

The ice ages, and associated warmer interglacial periods, are brought about by changes in the Earth’s orbit around the Sun which take place on these long timescales. The cooling in response to a decline in solar radiation reaching the Earth’s surface results in a greater uptake of CO2 by the oceans and so further cooling due to a weakened greenhouse effect.

This is an entirely natural phenomenon and it is worth noting that such amplification of temperature fluctuations will occur in response to any initiating factor regardless of its source and including human-produced greenhouse gases.

The effects of increasing CO2 are not limited to an increase in air temperature. As the oceans warm they are expanding so producing a rise in sea level, this being exacerbated by the melting of some of the ice present on land near the poles and in glaciers. The warmer atmosphere holds more water vapour resulting in increased occurrences of heavy rainfall and flooding while changes in weather patterns are intensifying droughts in other regions.

If human emissions of GHGs into the atmosphere continue unabated then the global temperature will continue to rise and the associated weather impacts become ever more severe. The UN climate conference in Paris in December 2015, at which 195 nations unanimously agreed on an aim to restrict the temperature rise to less than 2C, or preferably 1.5C, above the pre-industrial “baseline” was an extraordinary political achievement.

To achieve this, however, will require a complete cessation of global CO2 emissions by the second half of this century and, while the world considers how this might be achieved, the crossing of the 400ppm mark in CO2 concentration has been matched by a global warming of 1C.

Stonehenge builders ‘ate food from Scotland’

Stonehenge foodImage copyrightENGLISH HERITAGE/PA

The “army of builders” of Stonehenge ate animals brought from as far away as the north east of Scotland, according to a new exhibition at the famous Neolithic site in Wiltshire.

Analysis of pig and cattle teeth has revealed some of the animals were from as far as 500 miles away.

The “Feast! Food at Stonehenge” exhibition includes the skull of an aurochs, an extinct species of cattle.

It is aimed at allowing visitors to explore diet from 4,500 years ago.

Stonehenge cattle skullImage copyrightENGLISH HERITAGE/PA

English Heritage historian Susan Greany said: “Our exhibition explores the important role feasts and food played at Stonehenge.

Raising the ancient stones was an incredible feat but so too was feeding the army of builders.

“Our exhibition reveals just how this was done.”

The displays reveal research and stories from a “feeding Stonehenge” project, which has been exploring the lives of the people who lived at the nearby settlement of Durrington Walls.

The researchers say thousands of discarded animal bones and teeth excavated at Durrington Walls suggest it was not a typical village but a site of major feasting and ceremony.

Alarm over decline in flying insects


Insect huntImage copyrightGETTY IMAGES
Image captionLosses of rare insects are well documented, but there is little research on insects as a whole

It’s known as the windscreen phenomenon. When you stop your car after a drive, there seem to be far fewer squashed insects than there used to be.

Scientists have long suspected that insects are in dramatic decline, but new evidence confirms this.

Research at more than 60 protected areas in Germany suggests flying insects have declined by more than 75% over almost 30 years.

And the causes are unknown.

“This confirms what everybody’s been having as a gut feeling – the windscreen phenomenon where you squash fewer bugs as the decades go by,” said Caspar Hallmann of Radboud University in The Netherlands.

This is the first study that looked into the total biomass of flying insects and it confirms our worries.”

The study is based on measurements of the biomass of all insects trapped at 63 nature protection areas in Germany over 27 years since 1989.

The data includes thousands of different insects, such as bees, butterflies and moths.

Scientists say the dramatic decline was seen regardless of habitat, land use and the weather, leaving them at a loss to explain what was behind it.

They stressed the importance of adopting measures known to be beneficial for insects, including strips of flowers around farmland and minimising the effects of intensive agriculture.

And they said there was an urgent need to uncover the causes and extent of the decline in all airborne insects.

“We don’t know exactly what the causes are,” said Hans de Kroon, also of Radboud University, who supervised the research.

”This study shows how important it is to have good monitoring programmes and we need more research right now to look into those causes – so, that has really high priority.”

The finding was even more worrying given that it was happening in nature reserves, which are meant to protect insects and other living species, the researchers said.

”In the modern agricultural landscape, for insects it’s a hostile environment, it’s a desert, if not worse,” said Dr de Kroon.

”And the decline there has been well documented. The big surprise is that it is also happening in adjacent nature reserves.”

Insects provide vital services like pollinationImage copyrightGETTY IMAGES
Image captionInsects provide vital services like pollination

The loss of insects has far-reaching consequences for entire ecosystems.

Insects provide a food source for many birds, amphibians, bats and reptiles, while plants rely on insects for pollination.

The decline is more severe than found in previous studies.

A survey of insects at four sites in the UK between 1973 and 2002 found losses at one of the four sites only.

Dr Lynn Dicks, from the University of East Anglia, UK, who is not connected with the study, said the paper provides new evidence for “an alarming decline” that many entomologists have suspected for some time.

“If total flying insect biomass is genuinely declining at this rate (around 6% per year), it is extremely concerning,” she said.

“Flying insects have really important ecological functions, for which their numbers matter a lot.”

The research is published in the journal Plos One.