There’s good news ahead for dark sky supporters – a real prescription for light pollution. It’s called Resolution 516: Advocating and Support for Light Pollution Control Efforts and Glare Reduction for Both Public Safety and Energy Savings. What’s it all about and how did it turn out? Then step inside… Where it’s dark at last. Continue reading “Prescription For Light Pollution”
More Atmospheric CO2 Today Than in the Past 2.1 Millions Years
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Researchers have been able to determine the atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet by analyzing the shells of single–celled plankton. Their findings shed new light on CO2’s role in the earth’s cycles of cooling and warming, confirming many researchers’ suspicions that higher carbon dioxide levels coincided with warmer intervals during the study period. But it also rules out a drop in CO2 as the cause for earth’s ice ages growing longer and more intense some 850,000 years ago.
The study, published in the June 19 issue of the journal Science shows that peak CO2 levels over the last 2.1 million years averaged only 280 parts per million; but today, CO2 is at 385 parts per million, or 38% higher. This finding means that researchers will need to look back further in time for an analog to modern day climate change.
In the study, Bärbel Hönisch, a geochemist at Lamont-Doherty Earth Observatory, and her colleagues reconstructed CO2 levels by analyzing the shells of single-celled plankton buried under the Atlantic Ocean, off the coast of Africa. By dating the shells and measuring their ratio of boron isotopes, they were able to estimate how much CO2 was in the air when the plankton were alive. This method allowed them to see further back than the precision records preserved in cores of polar ice, which go back only 800,000 years.
Around 850,000 years ago, the climate cycles on Earth switched from being dominated by 40,000 year cycles, to the stronger 100,000 year cycles of the more recent times. The time period from 800 – 1,000 kyr ago is called the mid-Pleistocene transition, and since the rhythms of the Earth’s orbit didn’t change, some scientists have attributed that shift to falling CO2 levels. But the study found that CO2 was flat during this transition and unlikely to have triggered the change.
“Previous studies indicated that CO2 did not change much over the past 20 million years, but the resolution wasn’t high enough to be definitive,” said Hönisch. “This study tells us that CO2 was not the main trigger, though our data continues to suggest that greenhouse gases and global climate are intimately linked.”
The timing of the ice ages is believed to be controlled mainly by the earth’s orbit and tilt, which determines how much sunlight falls on each hemisphere. Two million years ago, the earth underwent an ice age every 41,000 years. But some time around 850,000 years ago, the cycle grew to 100,000 years, and ice sheets reached greater extents than they had in several million years—a change too great to be explained by orbital variation alone.
A global drawdown in CO2 is just one theory proposed for the transition. A second theory suggests that advancing glaciers in North America stripped away soil in Canada, causing thicker, longer lasting ice to build up on the remaining bedrock. A third theory challenges how the cycles are counted, and questions whether a transition happened at all.
The low carbon dioxide levels outlined by the study through the last 2.1 million years make modern day levels, caused by industrialization, seem even more anomalous, says Richard Alley, a glaciologist at Pennsylvania State University, who was not involved in the research.
“We know from looking at much older climate records that large and rapid increase in C02 in the past, (about 55 million years ago) caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic,” he said. “We’re heading in that direction now.”
The idea to approximate past carbon dioxide levels using boron, an element released by erupting volcanoes and used in household soap, was pioneered over the last decade by the paper’s coauthor Gary Hemming, a researcher at Lamont-Doherty and Queens College. The study’s other authors are Jerry McManus, also at Lamont; David Archer at the University of Chicago; and Mark Siddall, at the University of Bristol, UK.
Source: EurekAlert
History of Iron Yields New Insight Into Earth’s Deepest Reaches
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Earth may have given up its innermost secrets to a pair of California geochemists, who have used extensive computer simulations to piece together the earliest history of our planet’s core.
This schematic of Earth’s crust and mantle shows the results of their study, which found extreme pressures would have concentrated iron’s heavier isotopes near the bottom of the mantle as it crystallized from an ocean of magma.
By using a super-computer to virtually squeeze and heat iron-bearing minerals under conditions that would have existed when the Earth crystallized from an ocean of magma to its solid form 4.5 billion years ago, the two scientists — from the University of California at Davis — have produced the first picture of how different isotopes of iron were initially distributed in the solid Earth.
The discovery could usher in a wave of investigations into the evolution of Earth’s mantle, a layer of material about 1,800 miles deep that extends from just beneath the planet’s thin crust to its metallic core.
“Now that we have some idea of how these isotopes of iron were originally distributed on Earth,” said lead study author James Rustad, “we should be able to use the isotopes to trace the inner workings of Earth’s engine.”
A paper describing the study by Rustad and co-author Qing-zhu Yin was posted online by the journal Nature Geoscience on Sunday, June 14, in advance of print publication in July.
Sandwiched between Earth’s crust and core, the vast mantle accounts for about 85 percent of the planet’s volume. On a human time scale, this immense portion of our orb appears to be solid. But over millions of years, heat from the molten core and the mantle’s own radioactive decay cause it to slowly churn, like thick soup over a low flame. This circulation is the driving force behind the surface motion of tectonic plates, which builds mountains and causes earthquakes.
One source of information providing insight into the physics of this viscous mass are the four stable forms, or isotopes, of iron that can be found in rocks that have risen to Earth’s surface at mid-ocean ridges where seafloor spreading is occurring, and at hotspots like Hawaii’s volcanoes that poke up through the Earth’s crust. Geologists suspect that some of this material originates at the boundary between the mantle and the core some 1,800 miles beneath the surface.
“Geologists use isotopes to track physico-chemical processes in nature the way biologists use DNA to track the evolution of life,” Yin said.
Because the composition of iron isotopes in rocks will vary depending on the pressure and temperature conditions under which a rock was created, Yin said, in principle, geologists could use iron isotopes in rocks collected at hot spots around the world to track the mantle’s geologic history. But in order to do so, they would first need to know how the isotopes were originally distributed in Earth’s primordial magma ocean when it cooled down and hardened.
Yin and Rustad investigated how the competing effects of extreme pressure and temperature deep in Earth’s interior would have affected the minerals in the lower mantle, the zone that stretches from about 400 miles beneath the planet’s crust to the core-mantle boundary. Temperatures up to 4,500 degrees Kelvin in the region reduce the isotopic differences between minerals to a miniscule level, while crushing pressures tend to alter the basic form of the iron atom itself, a phenomenon known as electronic spin transition.
The pair calculated the iron isotope composition of two minerals under a range of temperatures, pressures and different electronic spin states that are now known to occur in the lower mantle. The two minerals, ferroperovskite and ferropericlase, contain virtually all of the iron that occurs in this deep portion of the Earth.
The calculations were so complex that each series Rustad and Yin ran through the computer required a month to complete.
Yin and Rustad determined that extreme pressures would have concentrated iron’s heavier isotopes near the bottom of the crystallizing mantle.
The researchers plan to document the variation of iron isotopes in pure chemicals subjected to temperatures and pressures in the laboratory that are equivalent to those found at the core-mantle boundary. Eventually, Yin said, they hope to see their theoretical predictions verified in geological samples generated from the lower mantle.
Source: Eurekalert
Life on Earth — and Other Worlds — Could Last Longer Than Expected
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Most scientists predict that in about a billion years, the sun’s ever-increasing radiation will have scorched the Earth beyond habitability. The breathable air will be toast, the carbon dioxide that serves as food for plant life will disappear, the oceans will evaporate; and all living things will disappear. Or maybe not. A group of researchers from Caltech have studied a mechanism which would cause any planet with living organisms to remain habitable longer than originally thought, perhaps doubling the lifespan. This sounds like good news for future inhabitants of Earth, but also, this mechanism could increase the chance that life elsewhere in the Universe might have the time to progress to advanced levels.
The researchers say that atmospheric pressure is a natural climate regulator for a terrestrial planet with a biosphere. Currently, and in the past, Earth has maintained its surface temperatures through the greenhouse effect. There used to be greater amounts of CO2 and other greenhouse gases in the atmosphere 1 billion years ago, which was a good thing. Otherwise, the Earth might have been a frozen ice cube. But as the sun’s luminosity and heat increased as it has aged, Earth has naturally coped by reducing the amount of greenhouse gases in the atmosphere, thus reducing the warming effect and making the surface of the planet comfortably habitable.
Opposite of what most scientists claim however, Caltech professor Joseph L. Kirschvink says that Earth may be nearing the point where there’s not enough carbon dioxide left to regulate temperatures using that same procedure. But not to fear, there’s another mechanism underway that may work even better to regulate temperatures on Earth, keeping our home planet comfortable for life even longer than anyone ever predicted.
In their paper, Kirschvink and his collaborators Caltech professor Yuk L. Yung, and graduate students King-Fai Li and Kaveh Pahlevan show that atmospheric pressure is a factor that adjusts the global temperature by broadening infrared absorption lines of greenhouse gases. Their model suggests that by simply reducing the atmospheric pressure, the lifespan of a biosphere can be extended at least 2.3 billion years into the future, more than doubling previous estimates.
The researchers use a “blanket” analogy to explain the mechanism. For greenhouse gases, carbon dioxide would be represented by the cotton fibers making up the blanket. “The cotton weave may have holes, which allow heat to leak out,” explains Li, the lead author of the paper.
“The size of the holes is controlled by pressure,” Yung says. “Squeeze the blanket,” by increasing the atmospheric pressure, “and the holes become smaller, so less heat can escape. With less pressure, the holes become larger, and more heat can escape,” he says, helping the planet to shed the extra heat generated by a more luminous sun.
The solution is to reduce substantially the total pressure of the atmosphere itself, by removing massive amounts of molecular nitrogen, the largely nonreactive gas that makes up about 78 percent of the atmosphere. This would regulate the surface temperatures and allow carbon dioxide to remain in the atmosphere, to support life.
This wouldn’t have to be done synthetically – it appears to happen normally. The biosphere itself takes nitrogen out of the air, because nitrogen is incorporated into the cells of organisms as they grow, and is buried with them when they die.
In fact, “this reduction of nitrogen is something that may already be happening,” says Pahlevan, and that has occurred over the course of Earth’s history. This suggests that Earth’s atmospheric pressure may be lower now than it was earlier in the planet’s history.
Proof of this hypothesis may come from other research groups that are examining the gas bubbles formed in ancient lavas to determine past atmospheric pressure: the maximum size of a forming bubble is constrained by the amount of atmospheric pressure, with higher pressures producing smaller bubbles, and vice versa.
If true, the mechanism also would potentially occur on any extrasolar planet with an atmosphere and a biosphere.
“Hopefully, in the future we will not only detect earth-like planets around other stars but learn something about their atmospheres and the ambient pressures,” Pahlevan says. “And if it turns out that older planets tend to have thinner atmospheres, it would be an indication that this process has some universality.”
The researchers hope atmospheres of exoplanets can be studied to see if this is occurring on other worlds.
And if the duration of habitability could be longer on our own planet, this might have implications for finding intelligent life elsewhere in the Universe.
“It didn’t take very long to produce life on the planet, but it takes a very long time to develop advanced life,” says Yung. On Earth, this process took four billion years. “Adding an additional billion years gives us more time to develop, and more time to encounter advanced civilizations, whose own existence might be prolonged by this mechanism. It gives us a chance to meet.”
Sources: Paper, Atmospheric pressure as a natural climate regulator for a terrestrial planet with a biosphere, Caltech
With Moon Rocks in Hand, Parazynski Reaches Mt. Everest Peak
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We’ve been following former astronaut Scott Parazynski’s attempt to climb Mt. Everest, and now comes the news that he has successfully reached the summit, one year after a back injury forced him to give up his climb. “It was a wonderful experience, though and through,” Parazynski said in a Skype interview with Miles O’Brien, “and certainly the most challenging thing I’ve ever done in my life, both physically and mentally.” Parazynski brought several objects with him to the world’s highest summit, including rocks from the Moon, and remembrances of fallen astronauts. Parazynski is the first astronaut to summit Mt. Everest.
During the climb, Parazynski was doing research. “We’ll be collecting data for astrobiologists, looking for extremophile life,” Parazynski told Universe Today in an interview before he left for Mt. Everest. “If you understand how extremophiles live, you might be able to understand how life may have once evolved on Mars, or may still exist on Mars.”
Parazynski tested NASA-derived hardware, taking along a prototype lunar geology camera and other hardware for extreme environments. “Up high on the mountain there are limestone formations, which are wonderful places to look for fossilized life,” he said,” and we’ll also look for melt water and primitive forms of life there; algae lichens, etc. If liquid water exists even for brief periods on Mars it may be in similar conditions to what we’ll find on Mt. Everest. We hope to bring samples back for scientists to look at.”
Now that he has successfully reached the summit, Parazynski said he won’t return to Everest. “Once is enough,” he said, adding that his family is glad he now has the bug to climb Everest out of his system.
Check out all the videos of Parazynski’s climb at Miles O’Brien’s blog at True/ Slant, as well as more images from Keith Cowing at On Orbit.com. Congratulations to Scott Parazynski!
And I just had to share this image of Parazynski on the summit after the sun rose. It looks just like Luke Skywalker on the planet Hoth at the beginning of “The Empire Strikes Back.”
Look for an upcoming special on the Discovery channel about Parazynski’s climb.
Cosmic Rays too Wimpy to Influence Climate
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People looking for new ways to explain climate change on Earth have sometimes turned to cosmic rays, showers of atomic nuclei that emanate from the Sun and other sources in the cosmos.
But new research, in press in the journal Geophysical Research Letters, says cosmic rays are puny compared to other climatic influences, including greenhouse gases — and not likely to impact Earth’s climate much.
Jeffrey Pierce and Peter Adams of Carnegie Mellon University in Pittsburgh, Pennsylvania, point out that cycles in numerous climate phenomena, including tropospheric and stratospheric temperatures, sea-surface temperatures, sea-level pressure, and low level cloud cover have been observed to correlate with the 11-year solar cycle.
However, variation in the Sun’s brightness alone isn’t enough to explain the effects and scientists have speculated for years that cosmic rays could fill the gap.
For example, Henrick Svensmark, a solar researcher at the Danish Space Research Institute, has proposed numerous times, most recently in 2007, that solar cosmic rays can seed clouds on Earth – and he’s seen indications that periods of intense cosmic ray bombardment have yeilded stormy weather patterns in the past.
Others have disagreed.
“Dust and aerosols give us much quicker ways of producing clouds than cosmic rays,” said Mike Lockwood, a solar terrestrial physicist at Southampton University in the UK. “It could be real, but I think it will be very limited in scope.”
To address the debate, Pierce and Adams ran computer simulations using cosmic-ray fluctuations common over the 11-year solar cycle.
“In our simulations, changes in [cloud condensation nuclei concentrations] from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties,” they write, “consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change.”
The results have met a mixed reception so far with other experts, according to an article in this week’s issue of the journal Science: Jan Kazil of the University of Colorado at Boulder has reported results from a different set of models, confirming that cosmic rays’ influence is similarly weak. But at least one researcher — Fangqun Yu of the University at Albany in New York — has questioned the soundness of Pierce and Adams’ simulations.
And so, the debate isn’t over yet …
Sources: The original paper (available for registered AGU users here) and a news article in the May 1 issue of the journal Science. See links to some of Svensmark’s papers here.
European, Chinese Satellites Watch Solar Storms Pummel Earth
Scientists have long understood that satellites are at risk from bombardment by solar storms. Now, they’ve gotten a closer look at how the storms are punishing Earth’s magnetosphere, leaving satellites exposed.
The movie above, and the solar flare video below, were released by the European Space Agency today, along with descriptions of two solar eruptions spotted using ESA’s four Cluster satellites and the two Chinese/ESA Double Star satellites.
Under normal solar conditions, satellites orbit within the magnetosphere — the protective magnetic bubble carved out by Earth’s magnetic field. But when solar activity increases, the picture changes significantly: the magnetosphere gets compressed and particles get energized, exposing satellites to higher doses of radiation that can perturb signal reception.
Scientists have found that extreme solar activity drastically compresses the magnetosphere and modifies the composition of ions in the near-Earth environment. They are now challenged to model how these changes affect orbiting satellites, including the GPS system.
During two extreme solar explosions, or solar flares, on January 21, 2005 and December 13, 2006, the Cluster constellation and the two Double Star satellites were favorably positioned to observe the events on a large scale.
During both events, the velocity of positively charged particles in the solar wind was found to be higher than 900 km (559 miles) per second, more than twice their normal speed. In addition, the density of charged particles around Earth was recorded at five times higher than normal. The measurements taken in January 2005 also showed a drastic change in ion composition.
The second explosion in December 2006 released extremely powerful high-energy X-rays followed by a huge amount of mass from the solar atmosphere (called a coronal mass ejection). During the event, GPS signal reception on ground was lost.
Typical nose-like ion structures in near-Earth space were washed out as energetic particles were injected into the magnetosphere. These nose-like structures, that had formed earlier in the ‘ring current’ in the equatorial region near Earth, were detected simultaneously on opposite sides of Earth. Measurements of the ring current showed that its strength had increased.
These factors together caused the magnetosphere to be compressed. Data show that the ‘nose’ of the dayside magnetopause (the outer boundary of the magnetosphere), usually located about 60,000 km (40,000 miles) from Earth, was only 25,000 km (15,000 miles) away.
About five hours after the coronal mass ejection hit Earth’s magnetosphere, a Double Star satellite observed penetrating solar energetic particles on the night side. These particles are hazardous to astronauts as well as satellites.
“With these detailed observations, we’ll be able to plug in data and better estimate what happens to the inner magnetosphere and near-Earth space during such explosions on the Sun,” said Iannis Dandouras, principal investigator of the Cluster Ion Spectrometer and lead author on a paper about the findings.
“Looking at such a large-scale physical phenomena with a single satellite is akin to predicting the impact of a tsunami with a single buoy,” added Matt Taylor, ESA’s Project Scientist for Cluster and Double Star. “With Cluster and Double Star we have monitored both sides of Earth simultaneously, and obtained valuable in-situ data.”
The results appear in the February 2009) issue of Advances in Space Research. The abstract is available here.
Source: ESA
Submit Your Questions for Scott Parazynski and Keith Cowing
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Former astronaut Scott Parazynski is making an attempt to climb Mt. Everest, and has been sharing his adventures via Twitter, and his blog on OnOrbit.com. As we reported in in our article about Parazynski in March, he wants to share his experiences with as many people as possible. Earlier today, his “media sherpa,” Keith Cowing from NASA Watch.com joined Parazynski at base camp and both Cowing and Parazynski have agreed to take questions from readers of Universe Today and answer them during their time on Mt. Everest. Parazynski has been blogging and Twittering during his preparations for the climb, and he even wants to Twitter from the summit. “I want to tell the story of exploration here on Earth and the corollaries it has with space exploration,” Parazynski told Universe Today before he left for Kathmandu, Nepal. “The intent is to share the story with as many people as we can, particularly young people.”
So submit your questions in the comments section and we’ll relay them on. Questions can be about mountain climbing or space exploration.
For more information about check out Scott’s Twitter feed, and the OnOrbit blog, and you can even track Parazynski with his SPOT GPS locator system — which is kind of interesting to look at, as you can see how he has been going up and down the mountain the past couple of weeks to acclimate his body to higher elevation.
Despite Global Warming, Wildfire Frequency Does Not Increase
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As global average temperatures rise, it is widely believed the frequency of wildfires will increase. However, this may not be the case. According to analysis of sediment from lake beds in Northern Alaska, the frequency of wildfires didn’t relate to changes in temperature variation over the last few thousand years. This is strange, surely a warmer climate will dry out vegetation faster, creating more fuel for fires to ignite and spread? Apparently not, there appears to be a far more potent controlling factor at play…
In Southern California, the temperatures easily hit 95°F (35°C) today and I noticed the entire neighbourhood pumping a small reservoir’s-worth of water into their manicured lawns (creating an impressive river down the street). Our garden looks a little dry in comparison, I refuse to turn the sprinklers on until we really need it (for now, the hose will do). Summer appears to have arrived early, making me slightly nervous; the wildfires that blighted this region over the the last few years are sure to return. To make matters worse, we had a surprisingly wet winter, helping the spring growth of vegetation. It may be nice and green now, but all I see is surplus firewood.
However, as the last few thousand years have shown us, no matter how hot it gets, the frequency of wildfires may actually decrease.
Using samples from sediment cores at the bottom of Alaskan lakes, climatologist Philip Higuera of Montana State University has discovered it could be the type of vegetation that grows in response to temperature increases that affects the frequency of subsequent wildfires. There is little indication to suggest the frequency of wildfires increased as global average temperatures increased over the past 15,000 years. This might be counter-intuitive, but it would appear nature has an automatic fire-retardation mechanism.
“Climate is only one control of fire regimes, and if you only considered climate when predicting fire under climate-change scenarios, you would have a good chance of being wrong,” Higuera says. “You wouldn’t be wrong if vegetation didn’t change, but the greater the probability that vegetation will change, the more important it becomes when predicting future fire regimes.”
Using radiocarbon dating techniques, Higuera’s team were able to accurately date the different layers in the metre-long sediment samples. From there, they analysed the charcoal deposits, therefore deriving the wildfire frequency in North Alaska woodlands. In addition, they analysed pollen content to understand what species of plant were predominant over the past 15,000 years. Then, using known climate data for the same period, the researchers were able to correlate the fire frequency with plant species and then relate the whole lot with trends in climate change. The results are very interesting.
One of the key discoveries was that climate change a was less important factor than vegetation changes when related to frequency of wildfires. According to sediment samples over the millennia, despite very dry periods in climate history, wildfire frequency decreases sharply. It appears that during periods of temperature increases, vegetation species change from flammable shrubs to fire-resistant deciduous trees.
“Climate affects vegetation, vegetation affects fire, and both fire and vegetation respond to climate change,” Higuera adds. “Most importantly, our work emphasizes the need to consider the multiple drivers of fire regimes when anticipating their response to climate change.”
Although we may not escape the clutches of wildfires in Southern California this year, the last 15,000 years have shown us that this may gradually change as vegetation adapts to hotter conditions, becoming more fire-resistant…
Source: Physorg.com
Where is the Most Remote Location on Earth?
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According to a new study, less than 10% of the world’s land is more than 48 hours of travel from the nearest city. This doesn’t include air travel, it is ground-travel only (i.e. on foot, train, car, boat, bike, horse, donkey). So no matter where you are in the world, there’s a good chance you can get to somewhere substantially populated within two days. At face-value, this might not seem very important, but when you look at the maps, you see many wilderness locations aren’t quite as remote as we once thought they were. The Amazon Rainforest for example is surprisingly well connected (rivers are quite useful in that respect), and the remote deserts of Africa have a pretty efficient road network.
So, where is the most remote location on Earth? How long would it take to get there?
I can happily say that for 5 months I lived in one of the most remote places in the world. The Norwegian archipelago of Svalbard in the High Arctic turns out to be a very extreme place even if you put the polar bears and -30°C temperatures to one side. No matter how hard you try, it would take 2-3 days by boat to travel from Longyearbyen (on the main island of Spitsbergen) to the Norwegian mainland city of Tromsø. Unfortunately, the number of places around the globe that can boast this are rapidly shrinking.
The fact is, the travel time of any point from the nearest settlement of over 50,000 people using only ground-travel is decreasing rapidly. Transportation infrastructures are spreading and population density is increasing, meaning more people are making bigger cities closer together.
Based on a computer model that calculates the journey time to the nearest city of 50,000+ people taking only land or water. The variables included in this complex model are types of terrain, road, rail and river network access, altitude, terrain steepness and obstacles (such as border crossings). The key conclusions the researchers gained are that less than 10% of the planet’s landmass is more than 48 hours ground-travel away from the nearest city. The Amazon, for example, only has 20% of its landmass more than 2 days away from the nearest Brazilian city (owed primarily to its vast network of rivers).
The most striking maps include the plotting of the busiest waterways (the English Channel, Mediterranean and South China Seas are the most crowded) and the scope of the world’s road network. In fact, it is little wonder the international community is worried about the increasing numbers of Somalian pirate attacks; another very busy shipping lane is sandwiched between Somalia and Yemen (the key route from the Indian Ocean to the Mediterranean).
It is hoped these maps will serve as a baseline for future studies, showing how nations deal with population growth, how nature is being eroded and possibly providing some insight as to how to manage the planet a little better than we are at present…
Source: New Scientist