The week that's gone: 27 April 2013

This is a summary of the stories we published in the week ending Saturday 27 April.

Fukushima faces long road to repair

22 April – The cleanup after the catastrophic nuclear accident two years ago at the Fukushima nuclear plant in Japan is not going well. Radioactive cooling water is leaking into the ground from at least three vast storage tanks, and the vulnerability of the plant to further accidents was revealed when a rat chewed through an electric cable, cutting off vital cooling. These setbacks come as a 12-man team from the International Atomic Energy Agency (IAEA) in Vienna tours the stricken plants to assess the country’s efforts to make safe, clean up and eventually dismantle the crippled reactors. Within Japan there is alarm at the situation and criticism of the Tokyo Electric Power Company, Tepco. Even government safety officials say the company is not demonstrating that it is competent in dealing with a problem that will probably take decades to solve, judging by other serious nuclear accidents. Spent nuclear fuel melted into lumps of unknown size will remain dangerous for hundreds of years, and so far no one has devised a method of retrieving it.

Continental climate changes vary widely

21 April – A worldwide consortium of 70 scientists has completed the most detailed climatic history of the planet so far during the last 2,000 years. They used evidence from ice cores, tree rings, preserved pollens, coral growth rings, stalagmites, lake sediments, sea bed cores, old documents and modern instruments to chart change not just of the globe itself, but of climate change in seven continental regions. Altogether, they looked at more than 500 different sets of temperature records from all the continents except Africa, where the evidence is still incomplete. The ambition united botanists from Pakistan and China, archaeologists from Norway, glaciologists from Germany and Tasmania, foresters from Japan and so on: experts who knew their field, and their territory.

Winter’s unpredictability ‘kills birds’

22 April – If the weather turns cold humans put on extra clothes while birds build a bigger, snugger nest to keep them warm while incubating their eggs. But birds have to sit on their eggs for two weeks or more to hatch them and can be caught out by rapidly changing weather conditions, badly affecting their breeding success, scientists have discovered. Researchers at the University of Lincoln in the east of England believe that climate change, with its unpredictable weather patterns, poses a serious risk for birds during this critical period. The incubating eggs have to be kept at a constant temperature if the chicks are to develop and hatch successfully. Dr Charles Deeming, senior lecturer at the University, writing in the April edition of the Society of Biology’s magazine, The Biologist, has been studying the construction of the nests of blue and great tits in nest boxes on the campus at Riseholme Park. Individual birds built completely different nests each year depending on the weather at the time of construction. In a cold spell the nest was much heavier and lined with moss or sheep’s wool, while in warm weather a light and poorly-insulated nest was regarded as adequate.

Fossil snails explain ancient transition

22 April – British and American scientists have used a new technique to pinpoint an epoch-making moment of climate change. They have used isotopes from land snails in what is now… England to reconstruct a fateful fall in carbon dioxide levels in the atmosphere, when average air temperatures fell by up to 6°C, summer freshwater temperatures plummeted 10°C and great sheets of ice began to form. Almost 34 million years ago, the late Eocene epoch gave way to the Oligocene. In a much warmer world, carbon dioxide levels in the atmosphere had reached 1,000 parts per million (ppm), and then started to fall precipitately. Within about 400,000 years huge glaciers dominated the polar regions, sea levels fell, faunas were extinguished and the world had changed forever. Palaeontologists, climate scientists and geophysicists have repeatedly tried to reconstruct the sequence of events that turned a hot, marshy world into a freezing one, but any physical evidence of ancient planetary catastrophe has been buried, or eroded, or washed away… But isotope evidence from fossil shells of the snail Viviparius lentus seems to have settled one point: the dramatic shift is firmly linked to changes in carbon dioxide levels in the atmosphere.

Warmer seas dim Antarctic clams’ ardour

23 April – Antarctic clams (Laternula elliptica) play a vital role in the ocean ecosystem, drawing down carbon into sea-bed sediments and circulating ocean nutrients. Now a new study has found that the reproductive capacity of this long-lived and abundant species – existing in the cold, oxygen-rich waters of the Antarctic – could be seriously affected by rising ocean temperatures. The study, by scientists at the British Antarctic Survey (BAS) and from the University of Kiel and the Alfred Wegener Institute in Germany and published in the journal Global Change Biology, found that young clams examined – averaging three years old – tended to try to move and bury themselves deeper when they sensed warmer ocean temperatures or reduced oxygen levels. But more mature clams – of around 18 years old – stayed put. This, say scientists, is important as it is the older clams, not the younger ones, which reproduce. If they don’t adapt, their existence could be threatened.

Benign E. coli makes biodiesel

24 April – British scientists may have found a new way to pump high quality diesel into the tractors, trucks and taxis of tomorrow. They have demonstrated that, with a little help from one of humanity’s oldest acquaintances, they can produce fuel-quality diesel without benefit of oil well or refinery. A team from the University of Exeter and from the Shell Technology Centre in Chester report in the Proceedings of the National Academy of Sciences that, with a little help from the genetic engineers, and a bit of patience in the laboratory, Escherichia coli delivered a customised biofuel almost identical to the stuff now hosed in from the petrol pump. Biodiesel from renewable sources is not new – but nor is it of sufficient quality to go straight into modern, mass-produced engines: biodiesel from plants normally has to be mixed with diesel distilled from petroleum to deliver propulsive power of the right quality. There is a saving on fossil fuels, and therefore on carbon dioxide emissions, but only of between 10 and 20%.

Black carbon flows from soil to seas

25 April – Climate scientists may have to rethink some of their old assumptions about carbon. US and European researchers have just established that black carbon, soot and biochar – the burnt remains from countless forest fires – doesn’t stay in the soil indefinitely. Around 27 million tons of the stuff gets dissolved in water and washed down the rivers into the oceans each year. Black carbon or biochar has been hailed as one possible way of limiting greenhouse gas emissions, by taking carbon out of circulation. But this study, according to a report in the journal Science, “closes a major gap in the global charcoal budget and provides critical information in the context of geo-engineering”. Forest, bush, scrub and peat fires produce somewhere between 40 and 250 million tons of black carbon every year. Had this burning been complete, this would have ended up as carbon dioxide, back in the atmosphere. So researchers have counted the biochar locked in the soil – where it enhances fertility – as carbon out of circulation for millions of years. But analysis of water from the world’s 10 largest rivers – the Amazon, the Yangtse, the Congo and so on – told a different story.

Fast-moving climate zones speed extinction

26 April – As global temperatures rise, climate zones will shift at greater speed, according to new research in Nature Climate Change. If greenhouse gas emissions carry on increasing, then about 20% of the land area of the planet will undergo change – and the creatures that have made their homes in what were once stable ecosystems will have to adapt swiftly, or face grim consequences. “The warmer the climate gets, the faster the climate zones are shifting”, says Irina Mahlstein, of the US NOAA Earth System Research Laboratory in Boulder, Colorado. “This could make it harder for plants and animals to adjust.” Such fears are not new: in the past two decades biologists and ecologists have repeatedly warned that vulnerable species were at risk from climate change. But vulnerable species are at risk anyway, just from pollution, habitat destruction and the spread of humanity across the habitable globe. What Dr Mahlstein and her colleagues have done is to look at geography’s mosaic of climates and landscapes and measure the rates of change in these.

Cut your carbon: Stay warm, lose the lawn

27 April – Here is some very limited advice on how to reduce your carbon footprint in suburban America: if you have a lawn, dig it up and plant a crop of maize. And if you live in Minneapolis, sell up and move to Miami. Two research papers in two journals have looked at two of those either/or questions that keep academics busy and dinner parties animated. Researchers at Elizabethtown College in Lancaster County, Pennsylvania, decided to look at what happens when farmland is converted to urban property. So for 10 weeks in the autumn of 2011, they visited and sampled the carbon dioxide release, soil moisture and temperatures, from urban lawns and from fields of corn, known also as Zea mays. They report in the Soil Science Society of America Journal that freshly mown grass sward won the dubious trophy for high greenhouse achievement. That is because lawns, on average, were hotter… Meanwhile, over at the University of Michigan, Ann Arbor, Michael Sivak asked himself the question: which demands more energy, air conditioning or central heating? He reports in Environmental Research Letters that he compared the costs of climate control in America’s warmest large city, and its coldest: Miami and Minneapolis respectively.