Study blames plasma flow for quiet sun

Our sun is maintained by converting gravitational energy into electromagnetic energy (e.g., visible and invisible radiations). The temperature is so high that the solar matter exists only in gas of light ions and electrons. These are charged particles. Their motions may take the form of the so-called 'plasma', which has these charges moving in a coherent and collective way, appearing as waves. The dynamics are quite nonlinear and intricate. Associated with such plasma, the electromagnetic fields will also change, and have been well known following a very regular pattern. One way to notice this pattern is by counting the intensity of the so-called sunspots, which are caused by pop-ups of strong magnetic energy flow from interior to the surface, like a cork decorated with flares carrying a huge amount of energy that may partly reach the earth. The latest solar cycle peaked in 2001 and was supposed to end in 2008. However, there is something unusual with this cycle: the sun appears too sluggish, with an extra number of spotless days. Now researchers came up with an explanation, which seems under debate [http://www.wired.com/wiredscience/2011/03/spotless-sun-model/]:

Now, Dibyendu Nandy of the Indian Institute of Science Education and Research and colleagues offer an explanation: A “conveyor belt” of plasma inside the sun ran quickly at first and then slowed down.

Nandy and colleagues at Montana State University and the Harvard-Smithsonian Center for Astrophysics ran a computer simulation of magnetic flow inside the sun for 210 sunspot cycles. They randomly varied the speed of plasma flow around a loop called the meridional circulation, which carries magnetic fields from the sun’s interior to its surface and from the equator to the poles.

Observations suggest that the fastest flow runs around 22 meters per second (49 miles per hour). Nandy’s model looked at speeds between 15 and 30 meters per second (33 to 67 miles per hour).

The model found that a fast flow followed by a slow flow reproduced both the weak magnetic field and the dearth of sunspots observed in the last solar minimum.

....

Unfortunately, observations of the sun’s surface seem to directly contradict the new model.

“We’re in this quandary, this clash between theory and observations,” said NASA astronomer David Hathaway, who analyzed 13 years of data from the Solar and Heliospheric Observatory (SOHO) that tracked the movement of charged material near the surface of the sun.

Hathaway agrees that a fast flow can cause weak magnetic fields and fewer sunspots. But his observations, published March 12, 2010 in Science, suggest that the meridional flow was slow in the first half of the last solar cycle, from about 1996 to 2000. Only after the solar maximum did the flow speed up.

“That’s where there’s a problem,” Hathaway said. “We see one thing, they want the opposite to explain the observations.”

Nandy and colleagues point out that the SOHO observations only see plasma moving at the surface of the sun, not in the deep interior where sunspots are born. The surface flows might not reflect what’s going on underneath, he says.

“In an analogy that you might be able to relate to, one could ask, do ripples on the surface of the sea indicate how ocean currents determine the migration of aquatic animals deeper inside?” Nandy said.

Hathaway argues that changes in the surface should be transmitted to the interior at the speed of sound, and should reach the creation zone in half an hour or less. The disagreement between theory and data means there must be a problem with the models, he says.

Trends: Climate Modelling

Brad Marston [Physics, 4:20(2011)] suggests physicists think about tackling climate problems, e.g., how to model climate. He wrote, "In this article, I discuss specific advances in nonequilibrium statistical physics that have direct applications on efforts to understand and predict the climate. (For an excellent introduction to the general science of climate change, see David Archer’s Global Warming: Understanding the Forecast [3].) But first, let’s look at the sort of question a statistical description of the climate system would be expected to answer."

CO2 as the climate control knob

Ample physical evidence shows that carbon dioxide (CO₂) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere. This is because CO₂, like ozone, N₂O, CH₄, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO₂ and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.

http://www.sciencemag.org/cgi/content/full/330/6002/356

The role of earth: sink or source ?

Precise predictions regarding the future of terrestrial climate requires accurate understanding of the CO2 dynamics on both local and international scale. This is very difficult. But there are progress recently made:

One key to accurately predicting future levels of atmospheric carbon dioxide (CO₂) is understanding how land and atmosphere exchange CO₂. Each year, photosynthesizing land plants remove (fix) one in eight molecules of atmospheric CO₂, and respiring land plants and soil organisms return a similar number. This exchange determines whether terrestrial ecosystems are a net carbon sink or source. Two papers in this issue contribute to understanding the land-atmosphere exchange by elegantly analyzing rich data sets on CO₂ fluxes from a global network of monitoring sites. On page 834, Beer et al. (1) estimate total annual terrestrial gross primary production (GPP) in an approach more solidly based on data than previous simple approximations. On page 838, Mahecha et al. (2) assess how ecosystem respiration (R) is related to temperature over short (week-to-month) and long (annual) time scales, and find a potentially important but difficult-to-interpret relationship.

REPORTS
Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate

Christian Beer, Markus Reichstein, Enrico Tomelleri, Philippe Ciais, Martin Jung, Nuno Carvalhais, Christian Rödenbeck, M. Altaf Arain, Dennis Baldocchi, Gordon B. Bonan, Alberte Bondeau, Alessandro Cescatti, Gitta Lasslop, Anders Lindroth, Mark Lomas, Sebastiaan Luyssaert, Hank Margolis, Keith W. Oleson, Olivier Roupsard, Elmar Veenendaal, Nicolas Viovy, Christopher Williams, F. Ian Woodward, and Dario Papale (13 August 2010)
Science 329 (5993), 834. [DOI: 10.1126/science.1184984]

REPORTS
Global Convergence in the Temperature Sensitivity of Respiration at Ecosystem Level

Miguel D. Mahecha, Markus Reichstein, Nuno Carvalhais, Gitta Lasslop, Holger Lange, Sonia I. Seneviratne, Rodrigo Vargas, Christof Ammann, M. Altaf Arain, Alessandro Cescatti, Ivan A. Janssens, Mirco Migliavacca, Leonardo Montagnani, and Andrew D. Richardson (13 August 2010)
Science 329 (5993), 838. [DOI: 10.1126/science.1189587]

Climate chief admits error over Himalayan glaciers

The head of the Intergovernmental Panel on Climate Change (IPCC) has been forced to apologise for including in its 2007 report the claim that there was a "very high" chance of glaciers disappearing from the Himalayas by 2035.

Rajendra Pachauri, the chairman of the IPCC, conceded yesterday that "the clear and well-established standards of evidence required by the IPCC procedures were not applied properly" when the claim was included in the 900-page assessment of the impacts of climate change.

The paragraph at issue reads: "Glaciers in the Himalaya are receding faster than in any other part of the world and, if the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high."

Single source

The report's only cited source was a 2005 report by the environment group WWF, which in turn cited a 1999 article in New Scientist.

The New Scientist article quoted senior Indian glaciologist Syed Hasnain, the then vice-chancellor of Jawaharlal Nehru University in New Delhi, who was writing a report on the Himalayas for the International Commission for Snow and Ice. It said, on the basis of an interview with Hasnain, that his report "indicates that all the glaciers in the central and eastern Himalayas could disappear by 2035". The claim did not, however, appear in the commission's report, which was only made available late last year.

This week a group of geographers, headed by Graham Cogley of Trent University at Peterborough in Ontario, Canada, have written to the journal Science pointing out that the claim "requires a 25-fold greater loss rate from 1999 to 2035 than that estimated for 1960 to 1999. It conflicts with knowledge of glacier-climate relationships, and is wrong."

The geographers add that the claim has "captured the global imagination and has been repeated in good faith often, including recently by the IPCC's chairman". The IPCC's errors "could have been avoided had the norms of scientific publication, including peer review and concentration upon peer-reviewed work, been respected", they say.

Several of those involved in the IPCC review process did try to question the 2035 date before it was published by the IPCC. Among them was Georg Kaser, a glaciologist from the University of Innsbruck, Austria, and a lead author of another section of the IPCC report. "I scanned the almost final draft at the end of 2006 and came across the 2035 reference." Kaser queried the reference but believes it was too late in the day for it to be reassessed.

Publicly available IPCC archives of the review process show that during the formal review, the Japanese government also questioned the 2035 claim. It commented: "This seems to be a very important statement. What is the confidence level/certainty?" Soon afterwards, a reference to the WWF report was added to the final draft. But the statement otherwise went unchanged.

Grey literature

One of the IPCC authors, Stephen Schneider of Stanford University, California, this week defended the use of so-called "grey" literature in IPCC reports. He told New Scientist that it was not possible to include only peer-reviewed research because, particularly in the chapters discussing the regional impacts of climate change, "most of the literature is not up to that gold standard".

The Himalaya claim appeared in the regional chapter on Asia. "There are only a few authors in each region, so it narrows the base of science," Schneider says.

This week Hasnain has claimed, for the first time, that he was misquoted by New Scientist in 1999.