Clive Cookson

Painting urban roofs white is perhaps the simplest and most benign of the various schemes that have been proposed to fight climate change through geo-engineering.

Steven Chu, the US energy secretary, advocated white roofs last year but some experts doubted whether the idea would make enough impact to be worth pursuing.

Now the first computer modelling study to simulate the impact of white roofs on cities worldwide, carried out at the US National Center for Atmospheric Research, has confirmed that they could significantly cool urban areas and mitigate some effects of global warming. The study will be published in Geophysical Research Letters.

“Our research demonstrates that white roofs, at least in theory, can be an effective method for reducing urban heat,” says NCAR scientist Keith Oleson. “It remains to be seen if it’s actually feasible for cities to paint their roofs white, but the idea certainly warrants further investigation.”

The study team used a new computer model to simulate the amount of solar radiation absorbed or reflected by urban surfaces. The simulations, which provide an idealized view of different types of cities around the world, indicate that, if every roof were entirely painted white, the urban heat island effect could be reduced by 33 percent.

While the model did not have enough detail to capture individual cities, it did show the change in temperatures in larger metropolitan regions. The New York area, for example, would cool in summer afternoons by around 1 degree centigrade.

White roofs are evidently not going to save the planet on their own but it does sound as though we should be considering a painting programme.

Clive Cookson

Many scientists are on the look-out for links between persistent man-made chemicals and ill health in people.

The latest identification of a possible association is published today in the journal Environmental Health Perspectives.

Toxicologists at Exeter University and the Peninsular Medical School found that people with higher blood concentrations of perfluorooctanoic acid (PFOA) had higher rates of thyroid disease. PFOA is a persistent organic chemical used in industrial and consumer goods including nonstick cookware and stain- and water-resistant coatings for carpets and fabrics. The analysis used almost 4,000 samples from the US National Health and Nutrition Examination Survey.

“There have long been suspicions that PFOA concentrations might be linked to changes in thyroid hormone levels,” said study co-author David Melzer of the Peninsula Medical School. “Our analysis shows that in the ‘ordinary’ adult population there is a solid statistical link between higher concentrations of PFOA in blood and thyroid disease.”

The findings may be important because persistent perfluoroalkyl acids (PFAAs) such as PFOA are found in water, air and soil worldwide. But the mechanism by which they might cause thyroid problems is not known.

Independent experts urged people to treat the report with caution. Although the link found by the Exeter researchers seemed significant – people with the highest 25% of PFOA concentrations were more than twice as likely to report current thyroid disease than those with the lowest 50% of PFOA – many “confounding factors” might have caused the association.

Much more research will be needed to show whether or not there is a causal link.

By Joseph Milton, FT science intern

Members of the public, environmentalists, scientists and businessmen will be asked for their opinions on new types of biofuels as part of a consultation launched today by an independent body that examines the ethics of biology and medicine.

Just a few years ago, biofuels were being trumpeted as a possible panacea for global warming – here was a green, renewable and sustainable source of power. And biofuels would not just help to mitigate climate change, they would offer energy security and aid agriculture and economies in the developing world. But these hopes were dashed as the darker side of the first generation of biofuels was revealed.

Land grabs and deforestation increased in some countries as the rich and powerful saw a chance to make a quick buck. Vast swathes of once biologically rich forest were replaced with palm monocultures and large numbers of people were displaced to make way for plantations.

Biofuels were also produced from food crops, contributing to the food-price spike of 2008, which in turn led to food riots in poorer countries. Mexican unrest was directly related to US maize farmers who turned from food to biofuel production, encouraged by large government subsidies.

So first generation biofuels are at best ethically dubious and, at worst, ethically atrocious, but the rehabilitation of biofuels is beginning.

The prospect of a second generation of biofuels, derived from waste materials rather than food crops or palm oil, has recently been raised. It is this new generation which the consultation by the Nuffield Council on Bioethics aims to explore.

Second generation biofuel production is likely to be based on a range of technologies under development – from harvesting oils produced by seaweed to collecting ethanol produced from food waste by genetically modified bacteria.

There are plans to use waste wood and the fibrous, inedible parts of crops to produce fuel, and genetically modify fuel-specific crops to increase yields and introduce tolerance of high salinity and drought – allowing growth on land unsuitable for agriculture.

The team at Nuffield think these methods could cut greenhouse gas emissions by 80-90 per cent compared with fossil fuels, and hope biofuel production will present opportunities for income generation in developing countries, without affecting food supplies or contributing to deforestation.

They hope to gather a wide range of opinions on issues ranging from intellectual property rights for GM, which tends to be controlled by big agri-business because of the development costs, to the rights of farmers and workers in the developing world. Those wishing to participate in the consultation can do so online.

When the consultation is complete, late next year, the council will develop a set of ethical guidelines to advise government.

However, developing the new generation of biofuels will not be cheap. With the world unsure where it stands in terms of emission targets after the disappointment that was COP15, that investment may have just become harder to find.

Once again, hopes are high for biofuels. Let’s hope the investment is forthcoming, and this time the optimism is justified.

By Joseph Milton, FT science intern

Simulations run by a team at the University of Bristol suggest that the melting of the Greenland ice sheet could be prevented by reflecting sunlight from the earth’s surface, a geoengineering technique.

Geoengineering offers radical solutions to climate change, involving large-scale alterations to the environment, directly affecting the climate. Discussion of these potentially risky procedures is increasingly common as many scientists reach the conclusion that CO2 emission reduction targets are not being met, and are unlikely to be. The Royal Society recently invited a panel of scientists to look into the subject and produce a report: Geoengineering the climate: science, governance and uncertainty.

The research at Bristol, led by Peter Irvine and published today in Environmental Research Letters, found that the temperature of the planet could be reduced to pre-industrial levels, saving the ice sheet, by reflecting 4.2 per cent of incident sunlight back into space.

But reflecting such a high percentage of sunlight, while doing nothing to reduce atmospheric CO2 levels, could reduce rainfall and change weather patterns, so the team also investigated reflecting 2.5 per cent of sunlight. They found this reduced the undesired side effects, but still cooled the planet enough to avoid the collapse of the ice sheet.

The Bristol team suggest sunlight could be deflected using geoengineering techniques known as solar radiation management. One option is the use of space reflectors – trillions of tiny reflective particles at the Lagrange point, the point in space at which the Earth and the Sun’s gravitational fields cancel each other out.

Professor Peter Cox at the University of Reading, who worked on the Royal Society report, says it might work: “It would be like just turning the sun down a bit.” But obviously there are technical considerations. As Professor Joanna Haigh of Imperial College, another of the report’s authors, points out: “The costs and the timescales involved would be absolutely enormous.” Neither thinks this technique is feasible in the near future.

Another option suggested by the Bristol team involves the addition of sulphate particles to the atmosphere, where they would reflect solar radiation. Prof. Cox says this is more difficult to rule out than he had imagined before the report was written, but Prof. Haigh is less convinced: “Who knows what the knock-on effects would be?” she says.

Solar radiation management is one of two broad categories of geoengineering techniques. The second is carbon dioxide removal, recently suggested as a possible complement to mitigation actions by Rajendra Pachauri, head of the Intergovernmental Panel on Climate Change.

Removing CO2 from the atmosphere would be a better long-term solution to global warming, as it would tackle not just global temperatures but other problems associated with high levels of greenhouse gases too, such as ocean acidification. But it would be very slow to affect the climate. On the other hand, the effects of reflecting sunlight could be seen within a few years.

Peter Irvine stressed that geoengineering should only be regarded as an emergency response: “It is no substitute for reductions in the emission of CO2,” he said.

Clive Cookson

British scientists are beginning work on a selective pesticide that would kill aphids while sparing bees and other benign insects. 

The project at Rothamsted Research in Hertfordshire, one of the UK’s largest agricultural science centres, follows the recent completion of an international effort to decode the entire genetic sequence of the aphid or greenfly.

Professor Lin Field of Rothamsted told the British Science Festival in Guildford yesterday that new insecticides were needed desperately – and not just for gardeners to spray greenfly infestations on their roses.

“Aphids are the most important insect crop pests in Europe,” she said. Almost every vegetable and fruit is vulnerable to aphids, which spread plant viruses as they suck sap.

Sustained attack with pesticides over the past 50 years has led to the evolution of chemical-resistant aphids. Only one class of insecticides still works reasonably effectively against aphids, the neonicotinoids – which are very toxic to honeybees and have been blamed for the recent collapse of bee numbers in some parts of the world.

Knowing the whole DNA sequence of the aphid (500m chemical ‘letters’ altogether) is opening new avenues of attack, said Prof Field, who is also President of the Royal Entomological Society.

Rothamsted scientists are concentrating on the aphid’s “sodium channel” which is vital for nerve function. They have identified the gene responsible for the sodium channel and discovered the mutations that cause resistance to pesticides.

The honeybee genome has also been decoded, Prof Field added. “There is now the prospect of looking at the differences in sodium channels between aphids and honeybees and thinking of how a compound might be designed to bind to the aphid protein and not that of the bee, thus creating selective insecticides.”

Several years of research and development will be needed, in collaboration with the agrochemical industry, before farmers and horticulturalists can attack aphids with a new generation of selective pesticides. These might then move quickly into garden centres.

A potentially more controversial way of defending crops against aphids is also under development at Rothamsted. It uses the “alarm pheromone”, a biochemical warning that the insects give when attacked by predators such as ladybirds.  

“We have transferred the gene for the aphid alarm pheromone into a plant,” said Prof Field. The idea is to put the insects off feeding on crops that give an alarm signal.

“We’ve got funds for a field trial but it’s a GM technology and that’s not very popular,” she said.

Clive Cookson

Hydrofluorocarbons or HFCs were introduced to save the ozone layer in the upper atmosphere from destruction. When the world agreed in 1987 to phase out chlorofluorocarbons (CFCs) through the Montreal Protocol, the chemical industry came up with HFCs as a replacement in applications such as refrigeration, air conditioning and making insulating foams.

While HFCs do not initiate ozone-destroying chemical reactions in the upper atmosphere, like CFCs, they turn out to be extremely powerful greenhouse gases – and now the environmental movement is rightly alarmed that growing use of HFCs could seriously exacerbate global warming.

Individual HFC molecules have a greenhouse effect many hundreds of times greater than carbon dioxide. At present they are present in the atmosphere only in small traces, so their total contribution to global warming is less than 1 per cent that of carbon dioxide.

But projections for the future see a huge increase in HFC use over the next few years, mainly for refrigeration and air conditioning in the developing world. A recent study by scientists at the US National Oceanic and Atmospheric Administration (NOAA) showed that, without restrictions, annual HFC emissions could heat the atmosphere by as much as 8bn tonnes of carbon dioxide by 2050.

So pressure is building for HFCs to be phased out too. The Environmental Investigation Agency (EIA), a green NGO, is leading a campaign for them to be banned under the Montreal Protocol, whose member countries are meeting in Geneva later this week.

The move has support from Achim Steiner, executive director of the UN Environment Programme, who said: “Action to freeze and then reduce this group of gases could buy the world the equivalent of a decade’s worth of carbon dioxide emissions.”

Campaigners point out that it may be easier to use the existing machinery of the Montreal Protocol, which regulates chemicals very similar to HFCs, than to try to include HFCs in climate change treaties which concentrate on carbon dioxide.

Clive Cookson

I have always been enchanted by butterflies – and in recent years have felt depressed by the evident decline in the numbers I see fluttering around English gardens and countryside. The news from official butterfly conservation bodies has been grim too, with most British species in retreat.

So I was thrilled by the research published today in the journal Science, showing the triumphant reintroduction of the large blue into its old haunts on the chalk downs of south-west England. The last native colony of large blues died out in Devon in 1979 – just as Jeremy Thomas of the Centre for Ecology and Hydrology in Oxfordshire was discovering the extraordinary details of the butterfly’s life cycle.

Females lay their eggs on thyme flowers, which caterpillars eat for three weeks before falling to the ground. Red ants recognise the caterpillar as one of their own, because it secretes a special cocktail of odour chemicals identical to an ant grub, and take it underground into their nest. It lives there for 10 months, feeding on ant grubs before forming a pupa at the top of the nest and finally crawling to the surface as an adult butterfly.

Although naturalists had known the general principles of the parasitic relationship between butterfly and ant for many years, Thomas made the key discovery that only one species of ant, Myrmica sabuleti, would nourish the large blue; other red ants ate its grubs. Unfortunately changing agricultural practices were reducing M sabuleti to unsustainable numbers.

His findings – particularly the need for short, tightly grazed grass – came just too late to save the native large blue. The same species, Maculinea arion, was in steep decline elsewhere in Europe but after scouring the continent for a suitable population Thomas and colleagues found one in Sweden. From there they imported eggs into Somerset grassland where the habitat was specially prepared to suit the butterflies and their ant hosts.

Since the original reintroduction in 1984, large blues have colonised 33 sites in south-west England, from chalk downs to railway embankments. (A dozen institutions, from the National Trust to Network Rail, are collaborating to re-establish the butterfly.)  Thomas, who remains the overall mastermind of the project, says its success has followed almost exactly his original mathematical models of the 1980s.

Meanwhile more details have emerged of the astonishing way the large blue has evolved to live with its hosts. Not only do the caterpillars smell exactly like ant grubs but they also make the same clicking sounds in the nest as queen ants.

It sounds like a precarious survival strategy – and so it is when land use changes substantially – but Thomas remarks that in a relatively stable environment an ant’s nest can make a safe predator-free home for the growing caterpillar.

Most large blue sites are still closed to the public but one, the National Trust’s Collard Hill in Somerset, welcomes visitors. If Sunday, June 21, is fine that would be a good day to go, because the Trust is holding a special large blue open day then. As large blue numbers increase, the butterfly could become a vehicle for encouraging tourism in the south-west.

Large blue on bracken (courtesy of David Simcox, CEH)

Large blue on bracken (courtesy of David Simcox, CEH)

Clive Cookson

To St James’s Palace for a press briefing at the end of the Nobel Laureate Symposium on Climate Change, hosted by the Prince of Wales.

The symposium, attended by 20 Nobel Prize winners and dozens of climate experts, produced a strong closing declaration in keeping with its strangely compelling motto, “The fierce urgency of now”.

The declaration made three demands of world leaders:

1. “An effective and just global agreement” on fighting global warming. This would require a commitment at December’s UN conference in Copenhagen to achieve a peak in global emissions of greenhouse gases before 2015 and a 50 per cent cut by 2050. Given that developing country emissions will continue rise, such an agreement requires industrialised nations to aim for a 25-40 per cent reduction by 2020.

2. Deliver a low-carbon infrastructure – including “smart grids” to connect renewable power sources over large areas – through an unprecedented partnership between governments and business.

3. Protect and restore tropical forests. (This is a pet cause of Prince Charles; as he says, without a solution to rainforest protection there is no solution to tackling climate change.)

It would be easy for a cynic to attack the Nobel Laureate symposium for the way it appeals to snobbery – scientific snobbery by inviting so many laureates and playing up their participation for all it’s worth in publicising the event, and royal snobbery by arranging for a prince to hold it in his palace.

Of course some Nobel laureates are indeed knowledgeable about climate science and involved in the fight against global warming – notably Steven Chu, the US energy secretary. It is not clear what some of the other Nobel attendees contributed, though the idea that laureates as a body constitute some sort of eminent high court of science is an interesting one.

In the end, however, I agree so strongly with the aims of the symposium and its closing declaration that I give it my wholehearted support (for what it is worth). Let us hope governments take the same attitude.

Clive Cookson

Everyone interested in renewable energy has a favourite, which he or she may feel is unjustifiably neglected in the competition between alternative sources. With solar, wind, wave, tidal, hydro, biomass, geothermal and many others vying for investment, I have long believed the heat beneath our feet provides a huge energy store that deserves more public attention.

So I was delighted to attend a briefing organised by the Royal Academy of Engineering in London, at which geologists and engineers called for more investment both in ground source heat pumps, which extract energy from near the surface for individual buildings, and in deeper geothermal projects, which involve drilling down to 1,000 metres.

“We are a sitting on top of a gigantic free reservoir of natural heat in the ground – ubiquitous and potentially available to all,” says David Banks, a heat source expert. “All we need to access it is a hole in the ground (a trench or borehole) and a pump, to lift it from a low temperature, typically 10-14ºC in the UK, to a high temperature at which it can be distributed and used to provide space heating.”

Banks says heat pumps are beginning to take off in Britain, with the market doubling every year. But the total installed base in the UK, which he estimates at 6,000 units, is still far smaller than in Scandinavia and north America.

In Sweden 350,000 units are installed, providing more than 10 per cent of heating in homes and offices. The US accounts for about half the world’s total ground source heating capacity, with 80,000 units installed every year.

Heat pumps have struggled because the initial capital costs of installation are high – typically £10,000-£15,000 for a 6 kilowatt domestic system – and natural gas is still relatively cheap in Britain. But they could pay off within 10 or 15 years for households in rural areas who have no mains gas supplies and enough space to lay the 100 metres of pipes required to extract heat from the ground. For commercial and public buildings, the economic returns are better.

While heat pumps extract low-level heat always available in the ground for use in buildings, some parts of the world have easy access to much more intense heat. This may be a blessing in energy terms but it often comes at a price because such places are vulnerable to volcanic activity and earthquakes. Iceland and the Geysers geothermal field in California are good examples.

Britain’s geology is not so favourable for geothermal energy but hot rocks are down there if you drill deep enough. The country’s only operational scheme has provided hot water to homes and offices in the centre of Southampton for more than 20 years, but David Manning, director of Newcastle University’s Institute for Research on Environment and Sustainability, says a recent project in Weardale, County Durham, shows the potential for geothermal energy in north-east England.

Prof Manning and colleagues supervised the drilling of a test borehole 1 km deep at Eastgate, which produced plentiful supplies of hot water at 40ºC – see picture below. It is expected to create a spa and heat buildings in a new “renewable energy village“.

The same geological formation of hot granite hundreds of metres deep extends up to the Tyne Valley. Geologists are now planning another borehole on the old Newcastle Brewery development site.

The world of research

The science blog is no longer updated but it remains open as an archive.

Clive Cookson, the FT's science editor, picks out the research that everyone should know about, in fields from astronomy to zoology. He also discusses key policy issues, from R&D funding to science education. He'll cover the weird and wonderful, as well as the serious side of science.