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'Taste test' for Neanderthal DNA

'Alien scene' of tadpoles' feast

The appliance of science? The questions that baffle parents

Unique species of Galápagos Islands threatened by mosquitoes

• Giant tortoise and marine iguana may be at risk
• Excess of tourists raises fear of 'ecological disaster'

Unique species on the Galápagos Islands are under threat from mosquitoes introduced by tourist planes and boats, according to research published today.

The southern house mosquito, Culex quinquefasciatus, capable of carrying West Nile fever and avian malaria, is being transported from mainland Ecuador and breeding with existing populations on the islands, prompting fears of disease outbreaks.

The Galápagos giant tortoise and marine iguana, which are unique to the archipelago, may now be at risk, say scientists from the University of Leeds and the Zoological Society of London (ZSL), who carried out the research in conjunction with the Galápagos national park and Charles Darwin Foundation.

Endemic birds, including the waved albatross, red-footed booby and flightless cormorant, may also be vulnerable.

Dr Simon Goodman, from Leeds University, said that while fumigation measures had been introduced on planes, their success had yet to be evaluated. He said that to prevent the mosquito spreading both cargo and tourists boats should also be regularly treated with insecticide and boat lights changed to ones less likely to attract flying insects.

The Galápagos – an archipelago of volcanic islands in the Pacific ocean – are particularly well-known for their huge number of endemic species, and the number of visitors to the island chain has increased from 40,000 in 1990 to more than 170,000 last year.

Tourism is a major source of income for the Galápagos and Ecuador. In 2007 there were 2,194 flights to the islands, and an estimated 363,000 passenger days on boats.

"Few tourists realise the irony that their trip to the Galápagos may actually increase the risk of an ecological disaster," said Goodman.

Arnaud Bataille, a Leeds-ZSL PhD student, said: "Our research consisted of looking for insects in aircraft holds and genetic analysis of the mosquito populations. The former allows us to quantify the arrival rates of mosquitoes on aeroplanes, and the latter allows us to estimate how many survive and spread around the islands once in Galápagos.

"On average the number of mosquitoes per aeroplane is low, but many aircraft arrive each day from the mainland in order to service the tourist industry, and the mosquitoes seem able to survive and breed once they leave the plane."

The introduction of the southern house mosquito to Hawaii in the 19th century devastated the islands' endemic birds.

Goodman added: "That we haven't already seen serious disease impacts in Galápagos is probably just a matter of luck. The Ecuadorian government recently introduced a requirement for all aircraft flying to Galápagos to have insecticide treatment, but the effectiveness hasn't yet been evaulated, and similiar measures still need to be introduced for ships.

"With tourism growing so rapidly, the future of Galápagos hangs on the ability of the Ecuadorian government to maintain stringent biosecurity protection for the islands."

Earlier this year, on the 200th anniversary of the birth of Charles Darwin – who developed his theory of evolution after visiting the islands – the Darwin Foundation warned that an ecological disaster might only be a decade away.

The influx of visitors has caused a sharp spike in alien species, which now seriously threaten the fragile ecosystem of the island chain. In 1900 just 112 alien species were recorded, compared with 1,321 in 2007.

While programmes are already in place to remove pests such as feral goats, pigs, cats and dogs, insects such as mosquitoes and the fire ants that have also been imported to the island are more difficult to eradicate.

Andrew Cunningham, a senior scientist at ZSL said: "Our research has shown that everything is in place for a similiar disaster to occur in Galápagos as occurred in Hawaii."

History Offers Hope Swine Flu Won’t Gain Strength in Fall

So far, H1N1 swine flu virus hasn’t been as deadly as many experts feared. But some say that’s because we’ve only experienced the “spring wave” of influenza that foreshadows a more devastating stage of pandemic virus in the fall.

Now, two infectious disease experts from the National Institutes of Health question the idea that severe pandemics are usually preceded by a milder wave of disease. After analyzing 15 pandemics from the last 500 years, including the catastrophic influenza pandemic of 1918, they say the pattern doesn’t hold up.

Although outbreaks of mild flu occurred in late 1917 and early 1918, the researchers say there’s no convincing evidence that the spring outbreaks were caused by the same virus responsible for the pandemic later in the year. They also found no reason to believe that the 1918 flu virus became progressively more deadly as the pandemic continued.

“Considering the long and confusing track record of pandemic influenza,” the scientists wrote Wednesday in JAMA, “it is difficult to predict the future course of the present H1N1 pandemic.”

Flu outbreaks certainly follow a seasonal pattern, and the researchers agree that summer weather may be slowing down the current spread of swine flu in the Northern Hemisphere. But even if the spread of the virus spikes again in the fall or winter, they say there’s no reason to assume that the virus will become more deadly or more contagious.

Because swine flu isn’t spreading very fast, and because it surfaced in the Northern Hemisphere just as the weather started to warm up, the researchers say there’s plenty of hope that this pandemic won’t be as deadly as those in the past.

We’ll keep our fingers crossed that they’re right.

See Also:

• Old People May Be Immune to Swine Flu
• Swine Flu Ancestor Born on U.S. Factory Farms
• Swine Flu: Just the Latest Chapter in a 91-Year Pandemic Era
• Google Could Have Caught Swine Flu Early
• Swine Flu Genes From Pigs Only, Not Humans or Birds

Image: Masked doctors treat a flu patient in the fall of 1918/ U.S. Naval Historical Center.

WATCH: Storm Damage Detailed by Light

Groups push for special wolf protections (AP)

Mars Meteorite Reveals Clues Into Planet's Past (SPACE.com)

SPACE.com - A meteorite the size of a huge watermelon on Mars is revealing new clues to the planet's environment.

Hunter-Gatherer House Reveals Stone Age Lifestyle

Satellites Track, Improve French Wine Crop

‘Flying Frog’ and Miniature Deer Discovered in Himalayas

Biggest Meteor Shower of the Year Peaks Tuesday Night

Stay up past midnight, grab a blanket and go stargazing tonight: The year’s most spectacular meteor shower is expected to peak Wednesday morning around 1 a.m. (your local time), and then again just before dawn.

The Perseid meteor shower happens every year in August, when the Earth travels through a cloud of debris left by the periodic comet Swift-Tuttle, which last approached the Earth in 1992. Under optimal conditions, up to 80 shooting stars can be seen every hour, although how many you’ll see tonight depends on cloud cover, the brightness of the moon and the proximity of city lights.

The Perseids get their name because meteors appear to shoot out from the arm of the Y-shaped constellation Perseus, named after the Greek hero famous for slaying Medusa.

Tuesday night, because of glare from the 55 percent gibbous moon, it may be easiest to spot shooting stars early in the night when the moon sits low in the sky. Between 9 p.m. and 11 p.m. (local time wherever you are), meteors will be less frequent but may look brighter than during the shower’s peak. NASA scientists say that’s also the best time to spot a stunning “Earthgrazer,” which is a meteor that skims close to the Earth’s atmosphere and generates a long, colorful tail.

The first Perseids have been visible since late July, and many Flickr photographers have already captured beautiful images of the meteors. If you want to take your own photos, check out our how-to wiki on photographing the stars. You can also submit your images to the wiki site — if we get enough good ones, we’ll compile them into a gallery on Wired Science.

See Also:

• July 16, 1862: This Comet Has Earth Written All Over It
• Meteor Watching By Balloon
• Best Meteor Shower of 2008 Predicted for Friday
• Coming Soon: Spectacular Meteors
• Best Seats For Meteor Shower Tonight? At 47000 Feet

Image 1: Flickr/Tommy Huynh, 2007. Image 2: Wikipedia Commons.

Key to Affordable Health Care: Healthier Lifestyles

Always look on the bright side of life ...

You won't only feel better, you might get to live longer too, if the latest research is to be believed

Is it possible that having a sunny outlook on life can be good for your health? Plenty of self-help guides claim that positive thinking can improve wellbeing, but is there any scientific evidence for this?

A huge new study in the US found that optimists were less likely than pessimists to develop coronary heart disease (CHD) and less likely to die of any cause over the course of the eight-year trial. Hilary Tindle and colleagues looked at 97,253 postmenopausal women, all of whom were free of cancer and cardiovascular disease when they took personality tests at the start of the study.

When the researchers compared the most optimistic 25% of their subjects with the most pessimistic 25%, they found that out of every 10,000 optimists, 43 developed CHD and overall 46 died, while for every 10,000 pessimists there were 60 cases of CHD and 63 deaths overall. Women who scored highly for "cynical hostility" were also more likely to develop CHD or die. The study was published this week in Circulation, a journal of the American Heart Association.

This isn't the first study to find a link between optimism and good health.

Psychologists distinguish two different kinds of optimism. "Dispositional optimism" is the general belief that good things will happen. On the other hand a person is said to have an optimistic "explanatory style" if they blame bad things on temporary, external factors; and a pessimistic explanatory style if they believe bad things happen because of their own fault or unchangeable, global factors.

One study, reported in 1988, looked at 99 Harvard graduates from the classes of 1942-1944, all of whom filled in questionnaires that determined their explanatory style at the age of 25. When doctors examined their physical health over the next 35 years, they found that those who were pessimistic when they left university were more likely to experience poor health between the ages of 45 and 60, taking into account their physical and mental health at 25.

A study in 2001 of 1,306 men found that those whose explanatory style was most optimistic were less than half as likely to develop coronary artery disease compared with those who were most pessimistic.

A Dutch study of 941 subjects aged 65-80, published in 2004, found that those of a pessimistic disposition were 55% more likely to die during the nine-year follow-up period, independent of other factors such as education, smoking and alcohol consumption. The effect was particularly strong in men.

A study in the US in 2006 looked at 6,958 students who had taken a psychological test when they enrolled at the University of North Carolina in the 1960s. Among the most pessimistic third of the subjects, the death rate over the next 40 years was 42 per cent higher than among the most optimistic third.

Dispositional optimism has also been linked with improved recovery rates after surgery and improved cancer survival rates.

We shouldn't leap to the conclusion that being optimistic makes people healthier. It could be that good health is what is making people optimistic in the first place, and not the other way around. Healthier people are certainly likely to be more optimistic, but studies have generally accounted for this and still found a positive result, so it doesn't seem to be the whole story. When subjects have been followed for several decades after the original questionnaire, we can be even more confident that the bad health wasn't there to begin with.

Another possibility is that optimists lead healthier lifestyles, as Dr Tindle points out. "In our study," she told me, "optimists tended to be slightly younger, more educated and wealthier, more physically active and closer to healthy body weight." But other studies have still found optimism to have a beneficial effect even after adjusting for known cardiovascular risk factors.

Although Dr Tindle stressed that her study could not identify the physiological link between optimism and health, she did suggest that optimists might have better ways of coping with stress. "This could mean not as much of a rise in blood pressure, stress hormones, or heart rate," she said.

Perhaps our genes could also be playing a role. It might be that the same genes that confer an optimistic disposition also predispose to good health.

To demonstrate a causal relationship between optimism and health, you'd need to do a randomised trial in which a group of pessimists was somehow turned into optimists, and then wait and see whether they fared any better than a control group.

As things stand, it's still unclear whether adopting a more positive outlook on life can reduce your likelihood of falling ill or dying. But it certainly won't hurt – and it might put a smile on your face. Who could argue with that?

Quakes and Typhoons: What's Up with Mother Nature?

Men Not Choosy in One-Night Stands

Pitcher plants In Pictures

SLIDE SHOW: Typhoon Devastates East Asia

How the humble leaf could power the planet

Researchers at Imperial College London embark on 'artificial leaf' project to produce power by mimicking photosynthesis

It is one of evolution's crowning achievements - a mini green power station and organic factory combined and the source of almost all of the energy that fuels every living thing on the planet.

Now scientists developing the next generation of clean power sources are working out how to copy, and ultimately improve upon, the humble leaf. The intricate chemistry involved in photosynthesis, the process where plants use sunlight to convert water and carbon dioxide into sugar, is the most effective solar energy conversion process on Earth. And researchers believe that mimicking parts of it could be the ticket to a limitless supply of clean power.

The untapped potential for using the sun's rays is huge. All human activity for a whole year could be powered by the energy contained in the sunlight hitting the Earth in just one hour. Harnessing even a small amount of this to make electricity or useful fuels could satisfy the world's increasing need for energy, predicted to double by 2050, without further endangering the climate.

Most solar power systems use silicon wafers to generate electricity directly. But although costs are coming down, these are still too expensive in many cases when compared with fossil fuels such as coal, oil and gas. Scientists are keen to develop more efficient and cheaper alternatives sources of energy.

At Imperial College London, researchers have embarked on a £1m project to study, and eventually mimic, photosynthesis. Part of a project called the "artificial leaf", involves working out exactly how leaves use sunlight to make useful molecules. The team then plans to build artificial systems that can do the same to generate clean fuels such as hydrogen and methanol. These would then be used in fuel cells to make electricity or directly to power super-clean vehicles.

Similar projects are gathering pace around the world: the US is poised to approve a federal research budget of around $35m a year for ideas that could create fuels from sunlight and the Dutch government has allocated €40m for similar research.

According to James Barber, a biologist at Imperial College London and leader of the artificial leaf project, if artificial photosynthesis systems could use around 10% of the sunlight falling on them, they would only need to cover 0.16% of the Earth's surface to satisfy a global energy consumption rate of 20 terawatts, the amount it is predicted that the world will need in 2030. And unlike a biological leaf, the artificial equivalent could be placed in the arid desert areas of the world, where it would not compete for space agricultural land.

Ultimately, Barber hopes to improve on nature's own solar cell. "If the leaf can do it, we can do it but even better," he said. "[But] it doesn't mean that you try to build exactly what the leaf has. Leonardo da Vinci tried to design flying machines with feathers that flapped up and down. But in the end we built 747s and Airbus 380s, completely different to a bird and, in fact, even better than a bird."

Photosynthesis starts with a chemical reaction where sunlight is used to split water into hydrogen and oxygen. The oxygen is released into the atmosphere while the hydrogen is used to create sugars and other organic molecules for the plant. The aim of Barber's artificial leaf project is to find an efficient way of mimicking that water-splitting reaction to create a clean and limitless source hydrogen. Unlike normal leaves, the new devices would not suck CO2 out of the atmosphere.

Hydrogen is a clean, energy-rich fuel that could be used in fuel cells to make electricity or else combined with carbon dioxide from the atmosphere (or from the exhaust of fossil-fuel power stations) to make methanol, a fuel that could be dropped into vehicles without the need for any engine modifications. "The challenge is to get hydrogen out of water using a ready supply of energy," said Barber.

For domestic purposes, Dan Nocera, a chemist at the Massachusetts Institute of Technology, has calculated that using artificial leaf to split a few litres of water a day into hydrogen and oxygen would be enough to supply all a home's energy needs.

Scientists can already produce hydrogen by splitting water but current techniques are expensive, use harsh chemicals and need carefully controlled environments in which to operate. The critical part of the artificial leaf project is developing catalysts made from cheap materials that can be used to split water in everyday conditions.

John Loughhead, executive director of the UK Energy Research Centre, described the artificial leaf idea as very promising because "we know that plants have already evolved to do it and we know that, fundamentally, it's a workable process on a large scale."

He added: "Ultimately, the only sustainable form of energy we've got is the sun. From a strategic viewpoint, you have to think this looks really interesting because we know we're starting from a base of feasibility."

Barber's colleagues at Imperial, led by chemist James Durrant, have recently developed a catalyst from rust that carried out part of the water-splitting reaction. So far the process is not very efficient, so Durrant's team is looking at improving this by engineering the surface of the rust. "We're looking at adding small catalytic amounts of cobalt onto the surface of the iron oxide to make it more efficient."

Nocera is also working on a catalyst made from cobalt and phosphorus that can split water at room temperature. Speaking last year, when he published his preliminary results in the journal Science, he said efficient water-splitting technology would be useful as a way of storing solar energy,which is a major problem for anyone who wants to use large amounts of solar power. During the day, an artificial leaf could use sunlight to split water and, at night, the stored hydrogen would be used to make electricity as it was needed. Chemical fuels such as hydrogen can store far more energy per unit mass than even the most advanced batteries.

Both Durrant's and Nocera's catalysts are many years from becoming commercial products.

Drug experts to urge ban on 'herbal high'

Legal smoking mixture contains chemicals that mimic effects of cannabis, government advisers warn

The government's drug experts will tomorrow recommend banning Spice, a herbal smoking mixture thought to be as strong as some strains of skunk cannabis.

The decision, which the home secretary, Alan Johnson, is expected to endorse, will mark the first official move to curb a burgeoning market in "legal highs". Sales of herbal drug subsitutes have grown rapidly through a network of online sites and backstreet "head shops".

The government's Advisory Council on the Misuse of Drugs (ACMD) is to warn that Spice Gold, which is advertised as a herbal high and an "aromatic potpourri", is in reality far from innocuous. They will say it contains synthetic chemicals that mimic the effects of some of the more powerful active ingredients in cannabis.

The council's advice follows a request from the former home secretary Jacqui Smith to investigate the product in March.

She voiced her concern over the "wide and largely unregulated market in the sale of psychoactive legal alternatives to illegal drugs, particularly as they are actively marketed to young people in head shops and via websites.

"Advice on the availability and harms of these so called 'legal highs', with a particular focus on protecting young people, will be very useful in informing future government policies," Smith told the ACMD.

Spice Gold has been around since 2006, when it was first imported from China. The smoking mixture costs £20 for a 3gram pouch, and contains mostly unidentified herbal matter, with ingredients such as dried flowers, leaves and aroma extracts listed on the packet. It is sold in various"flavours", with Arctic, Diamond and Silver promising different strengths.

The Trojan Horse properties of Spice were only identified last December, by the THC Pharm laboratory in Germany, which is developing medicinal cannabis. The research led to a ban in Germany and Austria in January this year. France followed suit in February.

Martin Barnes, the chief executive of the drugs information charity DrugScope, said making Spice products illegal would be a "pre-emptive measure", although the limited available research did suggest there were "potential harms" attached to their use.

"Exploring control options for the substances could remove the incentive for the manufacture and supply of Spice, as it would no longer be available as a 'legal' alternative to cannabis," said Barnes. "While consistent with the aims of the Misuse of Drugs Act, a recommendation to make Spice illegal would be a pre-emptive measure and unusual in that it would be based on evidence of potential harms to individuals and society rather than proven actual harms."

Professor Leslie Iverson, chairman of the ACMD committeethat drew up the report on Spice, stated his concerns: "It's a very clever product, sold as a herbal smoking mixture from China, but containing chemicals which can be a lot more potent than cannabis," he told his local paper, the Oxford Mail. "Users have no idea what they are taking. As a result, they are running a considerable risk of overdosing, which is not only unpleasant but potentially quite dangerous."

It is expected that the ACMD will move on, after tackling Spice, to consider the position of other "legal highs" including Salvia divinorum, commonly known as magic mint or Mexican sage. An official consultation over plans to ban two synthetic party drugs, GBL and BZP – also known as "herbal ecstasy" – is due to end on Thursday.

Swamp halts Africa's parliament

Causing a stink

Spoon-bending for beginners

Why introduce students to a field of psychology investigating claims that fly in the face of mainstream science? Chris French can think of several good reasons

From next month, potentially thousands of teenagers at schools and colleges throughout the UK will start lessons that deal with telepathy, psychokinesis, psychic healing, near-death experiences and talking to the dead. Surely the minds of the nation's youth will be corrupted by all this mumbo-jumbo?

Don't panic. I believe this is a development to be warmly welcomed, although I should declare a vested interest. From September, anomalistic psychology will be offered as an option on the A2 psychology syllabus for A-level students from the Assessment and Qualifications Alliance, the largest of the three English exam boards. For several years I have been teaching a course on anomalistic psychology at Goldsmiths, University of London, as part of our BSc in psychology. I have also been trying, along with others, to raise the academic profile of the discipline through the work of the Anomalistic Psychology Research Unit at Goldsmiths and am therefore delighted by this latest development.

What exactly is anomalistic psychology and why should it be taught in our schools and colleges? This is the definition offered on our website:

Anomalistic psychology may be defined as the study of extraordinary phenomena of behaviour and experience, including (but not restricted to) those which are often labelled "paranormal". It is directed towards understanding bizarre experiences that many people have without assuming a priori that there is anything paranormal involved. It entails attempting to explain paranormal and related beliefs and ostensibly paranormal experiences in terms of known psychological and physical factors.

Given its focus upon ostensibly paranormal events, it is important to distinguish anomalistic psychology from the closely related discipline of parapsychology. This is the scientific investigation of the "paranormal" – phenomena that cannot be explained in terms of currently accepted scientific theories.

Most parapsychologists focus on three main areas: extrasensory perception (ESP), psychokinesis and evidence relating to the possibility of life after death. Alleged ESP includes telepathy (direct mind-to-mind contact), clairvoyance (picking up information from remote locations without the use of the known sensory channels) and precognition (foretelling the future). Psychokinesis is the alleged ability to influence the outside world by willpower alone – everything from subtle effects upon random events at a subatomic level through psychic healing to spoon-bending and levitation.

Anomalistic psychologists are interested in claims relating to all of these areas, but they are also interested in attempting to explain beliefs and experiences that fall outside this strict definition of paranormal, including alien abduction claims, astrology, the Bermuda triangle, dowsing and so on – in other words, all things weird and wonderful.

Another difference between parapsychologists and anomalistic psychologists is that, in practice, the former tend to focus most of their efforts upon trying to produce evidence in support of the existence of paranormal forces whereas the latter tend to be sceptical regarding the very existence of such forces, mainly focusing instead upon non-paranormal explanations of ostensibly paranormal events.

So why should psychologists expend any effort attempting to explain such experiences? The most obvious reason is that if psychologists cannot explain such phenomena, they will have nothing to say about an important aspect of the human condition. These beliefs are widespread and deep-seated. An opinion poll published by Readers Digest in 2006, for example, found that of 1,006 British adults surveyed, 43% claimed to have experienced telepathy, more than half said they had experienced precognition, a fifth said they had seen a ghost, and 29% believed near-death experiences were evidence that there was an afterlife.

Similarly high levels of belief and experience are found all over the world and throughout recorded history. To me, this can mean only one of two things.

It might be an indication that, contrary to accepted scientific opinion, paranormal forces really do exist. If this is the case, then the scientific community must learn to overcome its prejudice towards paranormal claims and embark upon the serious and sustained investigation of paranormal forces.

But what if conventional scientists are right to reject paranormal claims? If so, psychologists can learn much of value by exploring the ways in which people often believe they have experienced a paranormal event when in fact they haven't. The challenge facing anomalistic psychologists is to explain the full range of ostensibly paranormal experiences in purely psychological terms.

It is important to realise that at this stage we cannot say with certainty whether paranormal forces exist or not. But until parapsychologists produce a robust and replicable demonstration of paranormal effects, it is perfectly legitimate for the wider scientific community to express scepticism regarding such claims.

Even if parapsychologists ultimately succeed in producing proof of such phenomena, anomalistic psychologists would still have performed a valuable service by helping them to sort the genuine psychic stuff from the stuff that simply isn't. Personally, I'm not holding my breath. After well over a hundred years of systematic research into allegedly paranormal phenomena, I do not get the sense that ultimate proof of the paranormal is anywhere nearer than it was at the outset.

Chris French is a professor of psychology at Goldsmiths, University of London, where he heads the Anomalistic Psychology Research Unit. He also edits the [UK] Skeptic magazine

Next month, Professor French explains how studying anomalistic psychology can help hone critical thinking skills, and challenges the "intellectual snobbishness" of some of his fellow psychologists

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Climate change press coverage gets weird

The paleocene-eocene thermal maximum (PETM) was a very weird period around 55 million years ago. However, the press coverage and discussion of a recent paper on the subject was weirder still. From RealClimate, part of the Guardian Environment Network

For those of you not familiar with this period in Earth's history, the PETM is a very singular event in the Cenozoic (last 65 million years). It was the largest and most abrupt perturbation to the carbon cycle over that whole period, defined by an absolutely huge negative isotope spike. Although there are smaller analogs later in the Eocene, the size of the carbon flux that must have been brought into the ocean/atmosphere carbon cycle in that one event, is on a par with the entire reserve of conventional fossil fuels at present. A really big number – but exactly how big?

The story starts off innocently enough with a new paper by Richard Zeebe and colleagues in Nature Geoscience to tackle exactly this question. They use a carbon cycle model, tuned to conditions in the Paleocene, to constrain the amount of carbon that must have come into the system to cause both the sharp isotopic spike and a very clear change in the "carbonate compensation depth" (CCD) – this is the depth at which carbonates dissolve in sea water (a function of the pH, pressure, total carbon amount etc.). There is strong evidence that the the CCD rose hundreds of meters over the PETM – causing clear dissolution events in shallower ocean sediment cores. What Zeebe et al. come up with is that around 3000 Gt carbon must have been added to the system – a significant increase on the original estimates of about half that much made a decade or so ago, though less than some high end speculations.

Temperature changes at the same time as this huge carbon spike were large too. Note that this is happening on a Paleocene background climate that we don't fully understand either – the polar amplification in very warm paleo-climates is much larger than we've been able to explain using standard models. Estimates range from 5 to 9 deg C warming (with some additional uncertainty due to potential problems with the proxy data) – smaller in the tropics than at higher latitudes.

Putting these two bits of evidence together is where it starts to get tricky.

First of all, how much does atmospheric CO2 rise if you add 3000 GtC to the system in a (geologically) short period of time? Zeebe et al. did this calculation and the answer is about 700 ppmv – quite a lot eh? However, that is a perturbation to the Paleocene carbon cycle – which they assume has a base CO2 level of 1000 ppm, and so you only get a 70% increase – i.e. not even a doubling of CO2. And since the forcing that goes along with an increase in CO2 is logarithmic, it is the percent change in CO2 that matters rather than the absolute increase. The radiative forcing associated with that is about 2.6 W/m2. Unfortunately, we don't (yet) have very good estimates of background CO2 levels in Paleocene. The proxies we do have suggest significantly higher values than today, but they aren't precise. Levels could have been less than 1000 ppm, or even significantly more.

If (and this is a key assumption that we'll get to later) this was the only forcing associated with the PETM event, how much warmer would we expect the planet to get? One might be tempted to use the standard 'Charney' climate sensitivity (2-4.5ºC per doubling of CO2) that is discussed so much in the IPCC reports. That would give you a mere 1.5-3ºC warming which appears inadequate. However, this is inappropriate for at least two reasons. First, the Charney sensitivity is a quite carefully defined metric that is used to compare a certain class of atmospheric models. It assumes that there are no other changes in atmospheric composition (aerosols, methane, ozone) and no changes in vegetation, ice sheets or ocean circulation. It is not the warming we expect if we just increase CO2 and let everything else adjust.

In fact, the concept we should be looking at is the Earth System Sensitivity (a usage I am trying to get more widely adopted) as we mentioned last year in our discussion of 'Target CO2'. The point is that all of those factors left out of the Charney sensitivity are going to change, and we are interested in the response of the whole Earth System – not just an idealised little piece of it that happens to fit with what was included in GCMs in 1979.

Now for the Paleocene, it is unlikely that changes in ice sheets were very relevant (there weren't any to speak of). But changes in vegetation, ozone, methane and aerosols (of various sorts) would certainly be expected. Estimates of the ESS taken from the Pliocene, or from the changes over the whole Cenozoic imply that the ESS is likely to be larger than the Charney sensitivity since vegetation, ozone and methane feedbacks are all amplifying. I'm on an upcoming paper that suggests a value about 50% bigger, while Jim Hansen has suggested a value about twice as big as Charney. That would give you an expected range of temperature increases of 2-5ºC (our estimate) or 3-6ºC (Hansen) (note that uncertainty bands are increasing here but the ranges are starting to overlap with the observations). ALl of this assumes that there are no huge non-linearities in climate sensitivity in radically different climates – something we aren't at all sure about either.

But let's go back to the first key assumption – that CO2 forcing is the only direct impact of the PETM event. The source of all this carbon has to satisfy two key constraints – it must be from a very depleted biogenic source and it needs to be relatively accessible. The leading candidate for this is methane hydrate – a kind of methane ice that is found in cold conditions and under pressure on continental margins – often capping large deposits of methane gas itself. Our information about such deposits in the Paleocene is sketchy to say the least, but there are plenty of ideas as to why a large outgassing of these deposits might have occurred (tectonic uplift in the proto-Indian ocean, volcanic activity in the North Atlantic, switches in deep ocean temperature due to the closure of key gateways into the Arctic etc.).

Putting aside the issue of the trigger though, we have the fascinating question of what happens to the methane that would be released in such a scenario. The standard assumption (used in the Zeebe et al paper) is that the methane would oxidise (to CO2) relatively quickly and so you don't need to worry about the details. But work that Drew Shindell and I did a few years ago suggested that this might not quite be true. We found that atmospheric chemistry feedbacks in such a circumstance could increase the impact of methane releases by a factor of 4 or so. While this isn't enough to sustain a high methane concentration for tens of thousands of years following an initial pulse, it might be enough to enhance the peak radiative forcing if the methane was being released continuously over a few thousand years. The increase in the case of a 3000 GtC pulse would be on the order of a couple of W/m2 – for as long as the methane was being released. That would be a significant boost to the CO2-only forcing given above – and enough (at least for relatively short parts of the PETM) to bring the temperature and forcing estimates into line.

Of course, much of this is speculative given the difficulty in working out what actually happened 55 million years ago. The press response to the Zeebe et al paper was, however, very predictable.

The problems probably started with the title of the paper "Carbon dioxide forcing alone insufficient to explain Palaeocene–Eocene Thermal Maximum warming" which on it's own might have been unproblematic. However, it was paired with a press release from Rice University that was titled "Global warming: Our best guess is likely wrong", containing the statement from Jerry Dickens that "There appears to be something fundamentally wrong with the way temperature and carbon are linked in climate models".

Since the know-nothings agree one hundred per cent with these two last statements, it took no time at all for the press release to get passed along by Marc Morano, posted on Drudge, and declared the final nail in the coffin for 'alarmist' global warming science on WUWT (Andrew Freedman at WaPo has a good discussion of this). The fact that what was really being said was that climate sensitivity is probably larger than produced in standard climate models seemed to pass almost all of these people by (though a few of their more astute commenters did pick up on it). Regardless, the message went out that 'climate models are wrong' with the implicit sub-text that current global warming is nothing to worry about. Almost the exact opposite point that the authors wanted to make (another press release from U. Hawaii was much better in that respect).

What might have been done differently?

First off, headlines and titles that simply confirm someone's prior belief (even if that belief is completely at odds with the substance of the paper) are a really bad idea. Many people do not go beyond the headline – they read it, they agree with it, they move on. Also one should avoid truisms. All 'models' are indeed wrong – they are models, not perfect representations of the real world. The real question is whether they are useful – what do they underestimate? overestimate? and are they sufficiently complete? Thus a much better title for the press release would have been more specific ""Global warming: Our best guess is likely too small" – and much less misinterpretable!

Secondly, a lot of the confusion is related to the use of the word 'model' itself. When people hear 'climate model', they generally think of the big ocean-atmosphere models run by GISS, NCAR or Hadley Centre etc. for the 20th Century climate and for future scenarios. The model used in Zeebe et al was not one of these, instead it was a relatively sophisticated carbon cycle model that tracks the different elements of the carbon cycle, but not the changes in climate. The conclusions of the study related to the sensitivity of the climate used the standard range of sensitivities from IPCC TAR (1.5 to 4.5ºC for a doubling of CO2), which have been constrained – not by climate models – but by observed climate changes. Thus nothing in the paper related to the commonly accepted 'climate models' at all, yet most of the commentary made the incorrect association.

To summarise, there is still a great deal of mystery about the PETM – the trigger, where the carbon came from and what happened to it – and the latest research hasn't tied up all the many loose ends. Whether the solution lies in something 'fundamental' as Dickens surmises (possibly related to our basic inability to explain the latitudinal gradients in any of the very warm climates) , or whether it's a combination of a different forcing function combined with more inclusive ideas about climate sensitivity, is yet to be determined. However, we can all agree that it remains a tantalisingly relevant episode of Earth history.

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