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The world’s sea levels could rise twice as high this century as UN climate scientists have previously predicted, according to a study. The Intergovernmental Panel on Climate Change proposes a maximum sea level rise of 81cm (32in) this century. But in the journal Nature Geoscience, researchers say the true maximum could be about twice that: 163cm (64in). They looked at what happened more than 100,000 years ago - the last time Earth was this warm. The results join other studies showing that current sea level projections may be very conservative.Sea level rise is a key effect of global climate change. There are two major contributory effects: expansion of sea water as the oceans warm, and the melting of ice over land. In the latest study, researchers came up with their estimates by looking at the so-called interglacial period, some 124,000 to 119,000 years ago, when Earth’s climate was warmer than it is now due to a different configuration of the planet’s orbit around the Sun. That was the last time sea levels reached up to 6m (20ft) above where they are now, fuelled by the melting of ice sheets that covered Greenland and Antarctica.

‘Robust’ work

The researchers say their study is the first robust documentation of how quickly sea levels rose to that level. “Until now, there have been no data that sufficiently constrain the full rate of past sea level rises above the present level,” lead author Eelco Rohling, of Britain’s National Oceanography Centre in Southampton, said in a statement. Rohling and his colleagues found an average sea level rise of 1.6m (64in) each century during the interglacial period. Back then, Greenland was 3C to 5C (5.4F to 9F) warmer than now - which is similar to the warming period expected in the next 50 to 100 years, Dr Rohling said.

Current models of ice sheet activity do not predict rates of change this large. However, they also do not include many of the dynamic processes already being observed by glaciologists, the researchers said. “The average rise of 1.6m per century that we find is roughly twice as high as the maximum estimates in the IPCC Fourth Assessment Report, and so offers the first potential constraint on the dynamic ice sheet component that was not included in the headline IPCC values,” explained Dr Rohling. Last year, a separate study found sea level rise projections could be under-estimating the impact of human-induced climate change on the world’s oceans.

Stefan Rahmstorf, from the Potsdam Institute for Climate Impact Research, Germany, and colleagues plotted global mean surface temperatures against sea level rise, and found that levels could rise by 59% more than current forecasts.

[BBC News]

Nov. 13, 2007: Something strange is happening in the atmosphere above Africa and researchers have converged on Addis Ababa, Ethiopia, to discuss the phenomenon. The Africa Space Weather Workshop kicked off Nov. 12th with nearly 100 scientists and students in attendance.

The strange phenomenon that brings all these people together is the ion plume—”a newly discovered form of space weather,” says University of Colorado atmospheric scientist and Workshop co-organizer Tim Fuller-Rowell.

Researchers liken the plumes to smoke billowing out of a factory smokestack—except instead of ordinary ash and dust, ion plumes are made of electrified gas floating so high above ground they come in contact with space itself. “The plumes appear during geomagnetic storms and they can interfere with satellite transmissions, airline navigation and radio communications,” says Fuller-Rowell. Indeed, it is their effect on GPS signals that led to the discovery of plumes over North America just a few years ago.

Two days before this map was made, an explosion on the sun had hurled a cloud of magnetized gas—a CME—toward Earth. The plume formed when the CME hit, triggering a strong geomagnetic storm. The plume consists of ionized air at high altitude moving from Florida to Canada at a speed of 1 km/s (2200 mph).

Above: A plume of excess electron density over North America on Nov. 20, 2003. The plume was discovered and mapped by its effect on GPS signals. Credit: Courtesy of Anthea Coster and John Foster of MIT.

Ion plumes inhabit a layer of Earth’s atmosphere called the “ionosphere.” It is a broad region 85 km to 600 km above ground level where ultraviolet radiation from the sun knocks electrons off atoms and molecules, creating a layer of ionized gas or “plasma” surrounding our entire planet. As ham radio operators have known for more than 100 years, the ionosphere can bend, distort, reflect and even absorb radio waves. Plumes amplify these effects.

How important is Africa to the study of this phenomenon? “Many believe the source of the plumes is near Earth’s magnetic equator,” explains NASA heliophysicist Lika Guhathakurta who is attending the Workshop. “Africa is a great place to check this possibility because the magnetic equator passes directly over the sub-Sahara.”

Just one problem: “There aren’t enough sensors in Africa to study the phenomenon,” says Fuller-Rowell. The sensor of choice is the dual-frequency GPS receiver. “North America has an abundance of dual frequency GPS receivers—thousands of them in a network we use to monitor North American plumes. But Africa has only a few dozen.”

The purpose of the Workshop is to familiarize African space scientists with the plume phenomenon and lay the groundwork for a continent-wide GPS network. “Within a few years we hope to deploy hundreds of receivers,” he says.

The Africa Space Weather Workshop is organized under the auspices of the 2007 International Heliophysical Year (IHY), continuing the tradition of international research and cooperation begun during the International Geophysical Year (IGY) of 1957. To learn more about the IHY on the web, click here.

[via Science@NASA]

WorldCoolers/Gristmill have produced a long list of articles on “How to Talk to a Climate Skeptic,” a series by Coby Beck containing responses to the most common skeptical arguments on global warming. There are four separate taxonomies; arguments are divided by:

• Stages of Denial,
• Scientific Topics,
• Types of Argument, and
• Levels of Sophistication.

Individual articles will appear under multiple headings and may even appear in multiple subcategories in the same heading. An excellent resource dealing with many aspects of climate change.

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This brainworks series looks at what is reality, and the conclusion so far is: whatever we make it to be. This post looks at another example of reality as brain (mind?) creation: even when we think we act act consciously, it seems that more often than not does our subconscious sit in the driver’s seat.

The groundbreaking research that put a question behind free will took place in 1983 at the University of California. Benjamin Libet set up an experiment in which participants were asked to make voluntary movements whenever they liked, such as lifting a finger. Using an EGG to monitor brain activity, he found that the subjects became aware of their intention to act only a few hundred milliseconds after their brain had initiated the movement. Libet was forced to conclude that what feels like a conscious decision may in fact be nothing of the sort (Brain, vol 106, p 623). Today it is an established theory in neuroscience that a major proportion of our thoughts and actions - even things we believe we are in conscious control of - actually take place in your unconscious. Most of the time we are essentially operating on autopilot.

We don’t need an EGG to test this theory; instead we can trigger at home what is known as the ideomotor effect, a psychological phenomenon wherein a subject acts without conscious awareness (examples for the ideomotor effect range from welling up tears to people responding to stage hypnotist’s suggestions; automatic writing, dowsing, facilitated communication, and Ouija boards have also been attributed to the effect of this phenomena). The idea behind this concept is that people’s actions originate solely from within themselves, at least in the vast majority of cases (which makes claims about divination etc. in most cases highly questionable).

In our case, we need to create a pendulum (e.g. with a piece of thread and a paper clip) and ask simple yes/no questions like “Do I own a car?” or “Am I at home?”. Tell yourself that if the pendulum swings clockwise, the answer is yes, while anticlockwise means no. While it seems quit spooky that the pendulum will rotate in the direction of the correct answer, there is nothing supernatural about it. The unconscious brain fires up motor preparation circuits in anticipation of the answer it expects to see. These circuits initiate subtle muscle movements that we are not normally aware of - except when they are amplified by a pendulum (or dowsing stick or Ouija board). This is your unconscious brain in action. (People being able to successfully dowse for water also demonstrate that we know much more than we are aware of; it’s all hidden in the subconscious).

Another area of subconscious reality creation is what is called ‘implicit assumptions’. Our subconscious does not only plan and execute actions, it also spends a great deal of time analysing the world around us. The conclusions it comes to are called ‘implicit assumptions’, subtle prejudices about people and events. In evolutionary terms they serves us well - most of the time. Sometimes though they can actually conflict with our conscious values and beliefs, leading for example to racist, sexist or ageist undertones in how we judge the world. Brian Nosek at the University of Virginia and colleagues have devised a test as a way to access implicit assumptions - it’s well worth taking it at https://implicit.harvard.edu/implicit).

The next post will look at how we pay attention; the previous one dealt with the curious consequences of having a split brain.

[Source: New Scientist]