Rock the Amazon at your peril

In a massive study scientists have shown that climate change could turn the Amazon rainforest from a carbon ally into a carbon criminal.

Writing in this week's Science Leeds University ecologist Professor Oliver Phillips, together with an international team of more than 60 collaborators, describes how he and his colleagues have studied 136 "plots" of rainforest to understand the impact of future climate change on the ability of the Amazon to soak up CO₂.  Specifically the team compared how the plots performed historically with the effect of a prolonged drought in 2005.

"We measured trees and wood density to calculate how much biomass was present," says Phillips.  The team found that in years leading up to 2005 the Amazon was a powerful carbon "sink", locking away more than a tonne of carbon per hectare per year.

But the drought led to the death of trees and growth arrest, turning what was a carbon sink into a carbon source with areas losing up to 2 tonnes of carbon (as carbon dioxide due to breakdown of the wood and foliage) per hectare per year.

The significance of this result is that the 2005 drought was provoked by  warmer-than-normal north Atlantic water, which also triggered Hurricane Katrina and led to the flooding parts of New Orleans.  But it had the reverse effect over the Amazon, and if global warming continues we might therefore see a drier Amazon more often.  This would mean that the billions of tonnes of carbon locked away by the rainforest every year would cease to be removed from the atmosphere and at the same time the Amazon would become a net producer of carbon.  The affect would be a dramatic acceleration of the greenhouse effect, with predictable global consequences.

"This should provoke a re-think of the political agenda," says Phillips.

8th Mar 2009

Cig addiction could be in your genes

Tobacco causes around a quarter of all cancer deaths in the UK, as well as heart disease, lung disease and other heart problems.  And it’s a fiercely addictive drug, meaning that people find it hard to give up. But some people do manage to quit the cigs relatively easily, while other fight a life-long battle.  And what makes some people become addicted after just a few puffs, while others can smoke a few cigarettes then just stop.

Now researchers from across the US have used the latest DNA analysis techniques to hunt for genes linked to smoking behaviour, with the hope of shedding light on this conundrum.

The team looked at DNA from over 2,300 men and more than 2,200 women – a mixture of smokers and non-smokers - and looked at their smoking behaviour. This included the number of cigarettes smoked per day, age they started smoking, how long they had smoked for, and pack years (for example, one pack year is the equivalent of smoking one pack  day for a year, or half a pack a day for two year). The scientists also looked at whether the people had ever smoked, or if they had managed to give up.

The researchers used so-called SNP (“snip”) analysis to track down potential genes linked to specific smoking behaviours. In total, around 2,600 of the people in the study had ever smoked. Although they didn’t find any new genes linked to smoking, the results provided more evidence to support the existence of an important gene on chromosome 15 linked to the number of cigarettes smoked per day.

The team also found evidence for variations in genes encoding nicotine receptors being involved in some smoking behaviours, as might be expected, including the number of cigs smoked per day, the number of pack years, and the age they started smoking. And they also found a link between variations in a gene region called MAOA on the X chromosome and whether people smoked more or less than 10 cigarettes per day.

This is an intriguing gene, as some studies have shown possible links with alcoholism and Parkinson’s disease, so it needs more investigation.  And another interesting result was a link between variations at alcohol dehydrogenase genes and whether a person had ever smoked, or never smoked.  So perhaps these genes are linked to whether a person actually ever starts smoking.

But the main thing the team took from their study was that the links between any of these genes and specific smoking behaviours, although it has thrown up some interesting candidates that merit further research. But the true picture is likely to be very complex, involving social as well as genetic factors.

8th Mar 2009

Hungry Jupiter

Scientists have spent a lot of time trying to simulate the birth of the solar system, partly to try and understand our solar system and partly to try and estimate how many other similar solar systems there are out there. But one thing that has confused them is Jupiter's moons - there aren't enough of them. According to all the simulations the moons of Jupiter should have made up about 10% of the total mass of Jupiter but they seem to only make up about 2%.

Robin Canup of the Southwest Research Institute, Colorado may have worked out where all those moons have gone. They have been eaten by Jupiter itself. Jupiter and its moons were formed out of a disk of gas and lumps of rock and ice orbiting itself.  This then slowly collapsed under gravity as it lost energy to friction between the lumps of material. Moons which formed very early on in this process would have been surrounded by this disc which would have slowed them down causing them to fall lower and lower until they were swallowed up by Jupiter itself.

Jupiter could have swallowed up to 5 generations of moons, with those visible today being the last ones to form as the disk finally dissipated leaving them to continue orbiting for the intervening billions of years.

8th Mar 2009

Spying on the sense of self

One of the most intriguing areas of neuroscience at the moment is the issue of the “sense of self” – basically, how we are aware of our own thoughts and personality. Previous research has shown that a few areas of the brain – the prefrontal cortex, the posterior cingulated cortex, and the parietal regions – are involved in self-reflection, and processing our sense of self.  

But can we draw a distinction between regions of the brain that are specifically involved in processing thoughts about our “self” from those that are involved in processing thoughts about people in general? New results from researchers in the Netherlands using functional MRI scanning have provided a clue – our sense of self may reside (at least partly) in a region called the anterior insula, deep in the forebrain, which is part of the brain linked to feelings and emotions.

The researchers used sixteen young male volunteers an put them in a functional MRI scanner, which looks at the activity levels of different regions of the brain. They were shown three different types of statements, and were asked to say whether they were true about them, like “I am a good friend”, about someone they knew like a team-mate or classmate, like “So-and-so talks too much”, or just a general knowledge fact like “a vertebra is a bone”.

While asking the volunteers to carry out the task, the researchers monitored their brain activity. They found that when the volunteers were considering the statements about themselves, there was activity in the anterior insula, but this wasn’t seen so much when they were thinking about the general knowledge statements. And, crucially, activity in the anterior insula wasn’t seen when they were thinking about other people.

The team found activity in regions such as the medial prefrontal cortex and the posterior insula when the volunteers were thinking either about themselves or about another person. But the scientists only saw extra activity in the anterior insula when the volunteers thought about statements related to themselves.

These kind of studies are important, not only for scientific interest, but for psychiatrists. There are several illnesses in which a person’s sense of self is disturbed, including schizophrenia. Understanding more about the parts of the brain that are involved could shed light on the roots of these complex diseases, if neuroscientists focus more on them.

8th Mar 2009

Predicting Landslides

Predicting earthquakes and avalanches is notoriously difficult, scientists have been attempting to do so for hundreds of years with very little success, and a group from imperial college london may have worked out why.

Both earthquakes and avalanches are types of critical phenomina, the classic example is slowly pouring sand onto a sand pile. The top of the sandpile slowly gets more and more unstable until something gives and you get a landslide. The problem is predicting how big the landslide is going to be. It might be tiny or the small landslide, may trigger a larger one which may trigger an even larger one, or it might not.

Henrik Jensen has been looking at a simplified version of this. He has been creating a pile of ball bearings by adding one at a time to the top of the pile. Every time he added a ball he took a photo. Occasionally there were landslides of different sizes which he tried to predict in various different ways.

He found that it was virtually impossible to predict the size of the landslide the traditional way, by looking at the size of previous landslide. But he did have more luck when he looked at the state of the pile before each ball was added.

He found that the more disordered the pile was before the next ball was added, the larger the landslip was going to be. and he could predict the size of the landslip with a 64% accuracy, and he thinks that he can get a lot better.

This sounds like a pretty abstract finding, but it does show that if you are wanting to predict avalanches or earthquakes you shouldn't be looking at previous avalanches or earthquakes, but look at the state of the hillside or tectonic plates. And possibly more importantly it means that the problem is soluble if we approach it from the right direction.

8th Mar 2009

Near Earth Objects - DD45's Near Miss

Chris - If you have been watching the news this week then you might have noticed that the Earth had a brush with a near-Earth object. You might have been forgiven for letting it pass you by which is luckily what happened to the Earth this week. But we did have a close encounter with DD45. To tell us what DD45 was here's Professor Alan Fitzsimmons from Queens University in Belfast. Hello, Alan.

Alan - Hello there.

Chris - Tell us about this object, what is it?

Alan - It's a small asteroid. It's about between 20-40m across. It was discovered only just over a week ago, on Friday 27^th February. It passed our planet by at a distance of only 72,000km on Tuesday.

Chris - That's extremely close. That's, let's put that in perspective. Satellites orbit the Earth about 25,000 miles out. That's only twice as far away as a geostationary satellite.

Alan - That's right. Occasionally we do spot these small asteroids coming past us. Objects of that size hit the earth probably about once every 2-300 years. We're not quite sure how often they hit us at the moment but they hit us on time scales of centuries.

Chris - Had this thing not been seventy thousand kilometres away and it had actually landed on the Earth what sort of damage would it have done? How would it compare with, say, the object that wiped out the dinosaurs?

Alan - Well, it's much smaller than that. The object that wiped out the dinosaurs was about ten kilometres across and had global consequences. Those objects only hit us about once ever hundred million years. An object that can cause climate change can be as small as one kilometre across, however. Even they only hit us once every million years or so. Something this size may have been similar to the object that entered our atmosphere over Tunguska in Siberia in 1908. It may have exploded low down in the atmosphere if it had entered our atmosphere and perhaps about a few kilometres up. It would have wiped out several square thousand kilometres of ground.

Chris - That's city devastating sort of level. How did we miss this kind of object? I thought we had, I was reassured to learn we had systems in place to spot these things so we could take action.

Alan - Well, it's because the systems we have in place are designed to spot the larger asteroids, the one kilometre guys and larger - the ones that would affect the entire planet. They're too small to effectively catalogue all the much smaller objects. At the moment the next generation of survey telescopes is in construction. There's something call Pan-STARRS which starts operating this year in Hawaii. Then sometime in the next decade, towards the end of the next decade something called the large synoptic survey telescope will get going in Chile. Even those telescopes won't be able to catalogue all the objects about the same size as DD45. We're just going to have to keep watching and surveying the sky.

Chris - Where did DD45 come from and given that it was so close this time round is it or is there any chance it might go round again and have another go?

Alan - The asteroid's in orbit around the sun just as everything else is in our solar system. It has an orbital period of just over 1.5 years. It's orbit just happens to have a point in it where it's very close to the Earth's orbit. Roughly once every March if the asteroid's there and the Earth is there it can come close to us. At the moment it can't hit us. The next time it will come close to us will actually be on the third of March in the year 2067 when even then it will pass by twice as far as it did this week. Over the coming centuries and thousands of years it's orbit will change slightly due to the gravitational tugs of the Earth and the other planets. It may well end up hitting us in a few thousand years' time. We don't know at the moment we haven't got enough data on it at the moment.

Chris - So unless you're Bruce Forsyth or someone who's going to live forever like that then you're probably in no danger.

March 2009

Bubbles that sink - Antibubbles

Make fascinating bubbles which rather than floating on water actually sink.

What you need

What to Do

What may Happen

On the top mostly you will produce normal drops, but sometimes you will see what look like bubbles but if you look closer they reflect light much better and they have far more momentum skittering across the surface.