Thursday, 28 February 2008

Palaeoclimate: The rhythm of the rains

The Asian monsoon influences a vast area. Understanding how it has changed in the past explains a great deal about climate change, the landscape of the Asian continent, and also cultural adaptation to these environments...

Deposits in a Chinese cave tell the story of the region's climate stretching back more than 200,000 years, well past the last interglacial warm period — an invaluable resource for understanding the Asian monsoon.

In the quest to understand past climate change, and thus to anticipate future trends, records from cave deposits — speleothems — are increasingly taking centre stage. Wang et al.1 present a virtuoso study: a 224,000-year chronicle of the past variability of the East Asian monsoon, recorded in the oxygen isotope ratios of stalagmites built up from the floor of the Sanbao Cave in eastern central China. This is the latest in a series of records2, 3, 4, 5, 6, 7 from Chinese caves that has illuminated the workings of the East Asian monsoon, over timescales ranging from thousands of years to tens of millennia. Much remains to be understood, but the significance of this work extends well beyond the caves and the monsoon that feeds them. It provides yet more backing for a once-daring hypothesis: that wobbles in Earth's passage around the Sun are a prime mover of long-term monsoon variation.

As Earth moves around the Sun, its orbital eccentricity (the deviation of its path from a perfect circle) and its obliquity (the tilt of its rotational axis) vary slowly over time. The axis of its rotation also wobbles like that of a spinning-top, a phenomenon known as precession. These effects combine to induce a 23,000-year quasi-periodicity in the distribution of incoming solar radiation (insolation). At different stages of this slow precessional cycle, insolation at a particular place on Earth's surface may be strongest during winter, summer, or somewhere in between.

In 1981, John Kutzbach recognized8 that the changing seasonal contrast in insolation might have a significant effect on the Asian monsoon, which is driven by different rates of seasonal heating over the continents and the oceans. By taking the values for the amount of radiation hitting Earth 9,000 years ago — when the Northern Hemisphere was closer to the Sun in summer than it is today, and the influence of glacial ice from the preceding ice age had all but disappeared — and plugging them into a climate model, he calculated that the Asian monsoon circulation must have been more intense at that time than it is today. That result matched observations that rainfall was greater in many areas of the tropics between 10,000 and 5,000 years ago. Various data sets have since been used to establish the details of this relationship over many precessional cycles.

Compared with other stalwart proxies of palaeoclimatology — records from tree-rings, sediments, ice cores, corals and the like — speleothems are relative newcomers. Like many proxies, they record the ratios of different oxygen isotopes in material laid down over time. These ratios are sensitively linked to the composition of precipitation, and thus to the prevailing climate. There are valuable examples of speleothem records from most continents, from mid-latitudes into the tropics, but few regions have proved to be as fertile as eastern China. Among the exciting records stored here are several from the Dongge Cave that span the Holocene, the interglacial period from 11,550 years ago to the present3, 6. These complementary records elegantly confirm the orbital theory of monsoon variability, but also reveal decade- to century-scale variability that differs between geological formations (Fig. 1).

A comparison of oxygen isotope ratios (expressed as delta18O) from Sanbao1 (two records) and Dongge3, 6 caves in eastern China over the Holocene period yields clear trends in agreement with millennial-scale decline in insolation16 (in July at 30° N; pink line), caused by variations in Earth's orbit. The mean values are offset between the two caves owing to differences in elevation and temperature1. Century-scale variance is not always consistent among the records, highlighting the need for replication to isolate climate signals that are uniform over whole regions.High resolution image and legend (47K)

Speleothems work best when there are consistent conduits for moisture to work its way through soil and rock into a relatively closed cave where, drip by drip, it contributes to the build-up of stalagmites. As carbon dioxide is lost from this dripwater, calcium carbonate (CaCO3) precipitates. Many factors, including evaporation in soil and the nature of the cave environment, can change the oxygen isotope composition of the water after it leaves the atmosphere9, 10, interfering with the primary climatic signal. The robustness of a speleothem as a climate record thus depends on a large signal-to-noise ratio and on replication and/or calibration to identify clear climate signals.

Wang and colleagues' Sanbao Cave record1 shows that essential aspects of past monsoon variability can be replicated not just within a single cave, but also between widely spaced caves in the same region: the monsoon signal swamps non-climatic and local noise over the long timescales of orbital change. What emerges is a record of monsoon variation unprecedented in its detail and chronology stretching back 224,000 years. The primacy of orbital precession in driving the monsoon with a quasi-periodic beat of approximately 23,000 years is nicely revealed, as are details of millennial monsoon variability that show the influence of changed ocean circulation in the North Atlantic during glacial periods.

These results bring into sharp relief the true power of speleothems: the ability to date their records precisely. This is made possible by measuring the growth of the isotope thorium-230 from the slow radioactive decay of uranium, which is incorporated in trace amounts in the speleothem deposits. This method works for samples hundreds of thousands of years old, far beyond the limit of about 50,000 years that radiocarbon dating allows. Until now, the best well-dated, high-resolution records of climate variability from the Northern Hemisphere have been those from the long cores extracted from the remote Greenland ice cap. These justly famous records extend back only into the last interglacial period, less than 125,000 years ago, and uncertainties in the models used to date the cores remain above the precision possible with uranium–thorium dating11.

The Sanbao Cave record reveals that there is more to monsoon variability than a simple linear response to precessional climate effects. Precession unsurprisingly controls the largest changes in amplitude in the Asian monsoon, by altering the supply of latent heat from the Southern Hemisphere or the amount of heating over the adjacent, 5,000-metre-high Tibetan Plateau, or possibly both8, 12, 13. But the maximum-insolation peak during the last interglacial seems to have produced a weaker monsoon than smaller insolation maxima during the glacial period that preceded it. The monsoon response is also far less uniformly sinusoidal than the precession-induced variation in insolation, making it hard to judge the true nature of the phasing between the two effects. Work to unravel these mysteries will have to tap a variety of proxy sources and elaborate on the mechanisms linking monsoon variability to broader climate variability14, 15.

The smaller-amplitude, higher-frequency variations of the monsoon that occurred during both glacial and interglacial periods are even more of a challenge: here, the discrepancies between individual Sanbao records, just as with the Dongge data, indicate that details may be clouded by the smaller apparent signal-to-noise ratio (Fig. 1). Is the problem related to noise associated with cave processes? Or is it simply that smaller changes in climate forcing yield a monsoon response that varies more from place to place than is supposed? The answer will come from continuing to build up a network of data from different proxy sources, such as speleothems and lake and marine sediments, that covers the most recent glacial cycle, and especially the past 10,000 years.

The foremost goal is, of course, to anticipate how the Asian monsoon might change in the future. One thing seems certain: the monsoon is sensitive to climate changes, and if the future brings a sufficiently large net increase in summer heating of the Tibetan Plateau, its response could be large and relatively homogeneous. That could be good for those living in the shadow of the monsoon who need more rainfall. But a stronger monsoon would be hard on those in parts of south and east Asia already plagued by summer flooding. As sea levels rise along with monsoon floodwaters, the low-lying areas draining monsoon Asia could be especially at risk.

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The aftermath of independence

Not everyone is happy with Kosovo's independence...

The formerly Serbian province of Kosovo unilaterally declared its independence on 17 February. Some 10,000 Serbian students and academics live in enclaves in the ethnically divided city of Kosovska Mitrovica in the north of the new country dominated by Kosovar Albanians. Endocrinologist Aleksandar Jovanovic, vice-rector for science and international relations at the University of Mitrovica, discusses recent events.

What is the University of Mitrovica's set-up?

We were the University of Priština, but during the war in 1999 the university was split, and the main Serbian part was re-established in Mitrovica in 2001 [where it goes by the protracted name of the University of Priština in Kosovska Mitrovica]. The university is licensed by the United Nations Mission in Kosovo and funded by the Serbian government, at a cost of around €10 million (US$14.8 million) per year, which is spent mostly on salaries. We have around 10,000 students and 700–800 professors, who are paid a 100% 'Kosovo bonus' to work and teach here. The university has ten departments including faculties for science, medicine, engineering, economics and agriculture.

How did you react to the declaration of independence?

It is our clear wish to stay with Serbia. There is no way that professors or students here would teach, or get taught, in a Kosovar-Albanian-led educational system. It just wouldn't work. We have very different traditions, and we haven't had any contact with the Kosovar Albanian academic community for years. Unfortunately, there are broader political interests that are currently a higher priority than university affairs.

What are your main concerns?

In an independent Kosovo we're expecting all kinds of difficulties. Luckily, Serbia says it will continue to support our work. We need to remain a Serbian institution, otherwise this university will just cease to exist. We cannot survive without Serbian support. At the moment our main concern is security. There haven't been major clashes since March 2004, when there were attacks on the Serbian communities in Kosovo. The unilateral declaration of Kosovo's independence means that there is potential for violent conflict once more. Political rhetoric is up, anything can happen.

Students are leading the protests in Mitrovica against Kosovar independence. Is the university term being interrupted?

We're midway through the spring term and we're doing our best to carry on teaching. Student protests began on 18 February, the day after the declaration of independence, and have been going on every day since. But lectures are taking place as usual. There are courses until noon, then the students — between 3,000 and 5,000 each day — take to the streets until 3 p.m., and then everybody comes back for the afternoon classes. We must keep up the work, or we will pay the price later. When we allowed protesting students to proceed to the next term without any exams in 1996, it took several years to return to academic order.

Has there been violence?

The student protests have mostly been peaceful. There was one incident on Saturday [23 February] when some radicals tried to provoke police, throwing bottles and fake bombs. We don't know whether there were any students involved, though.

Why is the university so important for the Serbs in Kosovo?

It is vital for the Serbian enclaves in northern Kosovo. It is the only strong economic factor in a region where just 8% of the economy is private sector. Without the university, the 100,000-strong Serbian minority would further evaporate. We need the students, and we hope that many will stay here after graduation and help keep the economy alive.

Is any scientific research now going on at the university?

We're mostly just teaching. There are 46 small scientific projects, many of which were started before we moved from Priština in 1999. We have a collaboration in material sciences with Queen's University in Ontario, Canada, and we have partnerships with universities in Serbia, Macedonia, Greece and Bosnia. We're also hoping to launch a collaboration with the University of Grenoble in France. Health and environmental issues related to the mining activities in the region could be a priority for future research activities.

What difficulties do you face?

We're working under chaotic conditions. The biggest problem is that our infrastructure is devastated and that our labs are very poorly equipped. There is a lack of everything, from lighting, to computers, to chemicals. Part of our equipment, such as computers and lab tools, are locked in Priština. We have been trying to get it back or be reimbursed, but so far without success.

Is there any contact between Serbian and ethnic Albanian scientists in Kosovo?

There hasn't been any cooperation between the universities of Priština and Mitrovica since the Serbian community had to leave Priština in 1999. I hope that in the future we will collaborate with Albanian-language scientists and academics again.

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Monday, 25 February 2008

This is Radio lab from new york public radio

This episode was from mid last year and about time, Brendan and Eamon perhaps worth a listen as a follow up to our last show.

Monday, 18 February 2008

Funny how physics balances out

Part of the 'simplicity' or physics is that things always seem to be balancing themselves out. Gravitational mass is the same as inertial mass for example. When scientists filled a pool with slime and timed swimmers they discovered that the speed was the same as in water - the greater amount of force produced by the push was counterbalanced by the increasing difficulty in advancing.

Now while looking for the answer to 'why does the 'right amount of water to build a sandcastle' have such a large range, scientists have discovered that while the wa­ter’s “stick­i­ness,” or abil­ity to bind sand grains to­geth­er, de­creases as its amount in­creases; in­creas­ing the amount of wa­ter makes up for the de­creas­ing stick­i­ness, as long as more of each sand grain is wet.

crazy world.

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sQuba car

A car that swims underwater! Science meets cool...

I'll put it on my 'wish list' :P

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Tuesday, 12 February 2008

Happy Birthday Charles Darwin

Evolutionary biologists will want to remember Charles Darwin today.

Next year on this day will be his 200th birthday.

Why I left science

Apparently having a social life negatively impacts your production output and performance as an ecologist ;)

A possible role of social activity to explain differences in publication output among ecologists
Tomáš Grim, Dept of Zoology, Palacký Univ., tr. Svobody 26, CZ-771 46 Olomouc, Czech Republic.

Publication output is the standard by which scientific productivity is evaluated. Despite a plethora of papers on the issue of publication and citation biases, no study has so far considered a possible effect of social activities on publication output. One of the most frequent social activities in the world is drinking alcohol. In Europe, most alcohol is consumed as beer and, based on well known negative effects of alcohol consumption on cognitive performance, I predicted negative correlations between beer consumption and several measures of scientific performance. Using a survey from the Czech Republic, that has the highest per capita beer consumption rate in the world, I show that increasing per capita beer consumption is associated with lower numbers of papers, total citations, and citations per paper (a surrogate measure of paper quality). In addition I found the same predicted trends in comparison of two separate geographic areas within the Czech Republic that are also known to differ in beer consumption rates. These correlations are consistent with the possibility that leisure time social activities might influence the quality and quantity of scientific work and may be potential sources of publication and citation biases.

Any comments?

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Friday, 8 February 2008

Ecologists turn an eye to cities

The ASC list sure gives us access to some pretty interesting articles. When I was in Paris a couple of years back, there was a conference on 'biodiversity of cities' to try to point out to people that ecology wasn't just a matter of looking at tiny parcels of "untouched" land. So I welcome this article in Science :)

Ecologists must join humanity's rush to the cities

Cities are responsible for so many of the sustainability challengesfaced by our urbanising world, but urban ecologists can help unlock the benefits of city living, say researchers in today's issue of Science.

Urban environments act as microcosms of the challenges faced globally,which makes them real world laboratories for understanding andresponding to change, concludes a team of ecologists from CSIRO, ArizonaState University and the New Zealand Centre for Ecological Economics.

"As ecologists, the natural environment has traditionally been our mainconcern, but cities affect and are affected by changes in climate, landuse, water and biodiversity," says CSIRO's Xuemei Bai, co-author of thepaper.

"Cities are more than just planned spaces. Planners, engineers andarchitects should be working with urban ecologists to design, developand redevelop projects suited to these complex, adapting and evolvingenvironments.

"Because cities are largely designed ecosystems, we have an opportunityto use ecological principles in creating urban living and workingspaces, housing developments, open spaces, and aquatic environments thatcan sustain biodiversity and ecosystem function, while also providingimportant ecosystem services on which the city's population depends."

More than 60 per cent of Australia's population now lives in our fivelargest cities. Although urban population growth over the past centuryoccurred on less than three per cent of the Earth's surface, the impacthas been global, with 78 per cent of carbon emissions, 60 per cent ofresidential water use, and 76 per cent of wood used for industrialpurposes attributed to cities.

Original, effective responses to our urban environments - humanity'sprimary home - are urgently needed, and urban ecologists are uniquelyplaced to take us forward.

Publication: N.B. Grimm, S.H. Faeth, N.E.Golubiewski, C.L. Redman, J.Wu, X. Bai and J.M. Briggs. "Global Change and the Ecology of Cities."Science, February 8, 2008.
Image available at:
Further Information: Xuemei Bai, CSIRO Sustainable Ecosystems interviews available in English, Chinese and Japanese 02 6242
Media Assistance: Matthew Levinson, CSIRO Sustainable Ecosystems02 94905437; 0406 314 450

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Saturday, 2 February 2008

Inbreeding is good?

OK so people might still be scarred from our talk about incest a coupe of weeks ago, where among other things I mentioned that the taboo might not be completely of biological origin. Many species interbreed, and providing you produce enough offspring, chances are they will be healthier than you (purging of the genetic load).

As Guiseppe Passarino of the University of Calabria in Rende, Italy, says in the New Scientist coming out this week:

“Everyone knows that inbreeding is bad – it increases your chances of catching a range of diseases,” he says. “But on the other hand, our study suggests that if inbreds don’t get those diseases when they’re young, they might have a better chance of long life.”

He has been studying centenarians in remote villages in Italy for years. He was part of the study that looked at genes that are more prevalent among old people, and found they were also prevalent among early deaths from disease (a.k.a. if you have the gene you're on a lottery ticket for an earlier or a much later death, see

The study points out that "in a small, inbred community, the gene pool remains the same and it is more likely that an individual will be “homozygous” –with two identical copies of a gene. “Longevity seems to be linked to homozygosity,” Passarino says. This may be because certain copies of some genes boost lifespan, and carrying two of them doubles the effect. A number of DNA analyses have located regions of the genome where centenarians show an unusually high level of homozygosity, he says."
The bad news girls? Apparently this only really works for men. "Passarino says it may be because the genetic component of longevity plays a more important role in men, whereas in women, environmental factors come to the fore."For example, places that have better healthcare tend to dramatically improve women's longevity but less so men (in Denmark "the number of male centenarians is 10 times as high because of better healthcare, but the number of females is 50 times higher")

And of course this doesn't mean you should really be marrying your sister...
"Bruce Carnes of the University of Oklahoma cautions against marrying a relative, however. “Homozygosity is typically a very bad thing,” he says. “Almost every discussion of inbreeding that I have ever read has emphasised its downside.” You only have to look at the Spanish line of kings - )

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Friday, 1 February 2008

Seeing new dimensions

Particle accelerator may reveal shape of alternate dimensions

When the world's most powerful particle accelerator starts up later this year, exotic new particles may offer a glimpse of the existence and shapes of extra dimensions.

Exotic particles makes me think of those cartoons of anthropomorphised atoms we had in high school. And the shapes of extra dimensions? That just plays with my mind!

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