Under pressure:
Earth science

A bunch of agencies and scientific departments have encouraged leading Earth science boffins to bang their heads together to identify the 10 most pressing Earth science questions of the 21st century. This week we continue with the second part of the top ten list released in a new report by the NRC

By Rusty Rockets

(Part II)

ToThis week we continue with the second part of the top ten list of urgent Earth science questions devised by a group of leading Earth science experts at the behest of the National Research Council (NRC). The 10 "big picture" questions raised are ones that have been difficult to answer in the past, but are nonetheless questions that Earth scientists must face this century if we are to protect the planet and its inhabitants.

Why does the Earth have plate tectonics and continents?

When did Earth's continents first form, and what will their movements be in the future? These are questions that don't have exact answers as yet, but answering them may provide further clues to such fundamental questions as why Earth has plate tectonics at all.

Serious attempts at explaining the existence of continents and how they shift have been kicking around since the late 16th century, when cartographer Abraham Ortelius - and a string of other luminaries including Francis Bacon and Ben Franklin - first pondered the possibility of continental drift. But it wasn't until 1912 that a theory of continental drift - as well as the theory that all of Earth's continents once formed a giant land mass called Pangaea - was properly fleshed out by German interdisciplinary scientist and meteorologist Alfred Wegener.

But Wegener's theories were to remain supposition right up until 1947. During this year, a team of scientists studying the Atlantic Ocean found differences in seabed foundations, and variations in oceanic crust thickness that indicated Wegener's theory was likely correct. Unfortunately, however, Wegener died in 1930, and missed the opportunity to bask in the kudos he was due.

Contemporary plate tectonic theory is now very robust in regard to the mechanisms behind plate movements. So much so that research has now turned to discovering links between plate tectonics and Earth's water supplies, continent creation, oceans, and life itself. According to the authors of the NRC report, answering such questions would be extremely useful, as the continental crust is known to play a key role in regulating Earth's climate.

What causes the climate to change - and how much can it change?

The authors of the NRC report acknowledge that out of all the Earth systems they discuss, climate is the most widely (and heatedly) discussed topic within the public arena. A situation that has no doubt been fuelled by its politicisation, and the subsequent media interest - often provoking controversy where none previously existed - that has arisen as a consequence. At the heart of climate change research lays the question: what causes the climate to change?

Referring to the 2007 IPCC report on climate change, the authors of the NRC report say that it is now "widely recognized" that Earth's surface temperatures have increased since the beginning of the industrial age, and that CO2 is "at least partly, if not wholly, responsible" for this rise. Even if you're an anthropogenic climate change sceptic, it doesn't change the fact that our climate is changing.

For now, scientists search for clues in ice cores, sediments, fossils, and rocks, which show how Earth's climate has changed over the past four billion years. Such samples provide a glimpse at the Earth's geological record that may allow researchers to make predictions about the Earth's climate in the future. According to the report, researchers have already identified some of Earth's more extreme and abrupt climate changes, and their possible causes. Periods of abrupt climate change in Earth's history include the Permian-Triassic boundary, the Paleocene-Eocene Thermal Maximum, and Dansgaard-Oeschger events in the more recent Pleistocene Epoch. The latter of these are abrupt climate fluctuations that occurred every 1,500 years during the last ice age. "Each oscillation is characterised by gradual cooling followed by abrupt warming, typically over just a few decades," write the NRC report authors. "Even though these changes are rapid, their magnitude is large - annual temperature swings of up to 16∞C are recorded in Greenland ice cores."

How are Earth processes controlled by material properties?

From little things, big things grow; seems to be the key to this question. While the ten big Earth science questions have so far tackled the macroscale behaviours of plate tectonics and mantle convection, these large behaviours are themselves the result of microscale properties of Earth materials - down to the atomic level. This may seem obvious, but sometimes it takes a while before the simplest of concepts becomes clear. According to the report, research exploring the atomic structure of Earth materials will be crucial to understanding Earth's macroscale history, and how Earth processes may unfold into the future. 

How do fluid flow and transport affect the human environment?

The Earth is not a bottomless waste dump, and what we discard will in some form or another come back to haunt us - usually via waterways on which we are heavily dependent. As a result, scientists have made it a priority to model fluid movements at the surface level; observing rivers and streams, how stream erosion and sediment transport can change landscapes, and how human activity affects the evolution of these waterways. Modelling subsurface fluid movements is equally as important, though here has been some difficulty in this department.

Efficient management of natural resources (like water) requires a sound knowledge of the behaviour of both surface and subsurface fluids, which allows scientists to predict fluid movements and their interactions with the environment. But creating a mathematical model representing these fluid movements has been problematic.

How has life shaped Earth - and how has Earth shaped life?

Put another way, this question seeks to illuminate how biology and geology interact. But no matter how you want to put it, scientists are still in the dark as to the exact nature of this relationship. Nonetheless, there are many points of interest currently under investigation, including how biological processes oxygenate Earth's atmosphere, and how geological processes affect climate. And on a much grander scale, scientists are also keen to understand how geological events caused mass extinctions, which in turn shaped the course of evolution.

Geological and biological interactions are of great interest to scientists because their interactions produce a cyclical chain of events that, as the question suggests, shape one another.

Other sub-questions pertinent to the research of Earth's geo-biological processes - which is a multidisciplinary investigation, involving fields such as inorganic chemistry, physics, and hydrology - include how long life has fostered a habitable surface environment, how organisms influenced the oxygenation of the atmosphere and oceans, and what factors govern the history of Earth's biological diversity. These questions, together with the rest of the "big ten", highlight the complexity inherent in the interactions between macro and micro processes, and emphasize how difficult it is to find causes to events that are geo-biological in nature, such as mass extinctions.

But now armed with a clearly defined set of probing questions, perhaps a clear history of Earth's evolution will become apparent to Earth scientists over the coming decades.

"To keep the field moving forward," writes geochemist professor Donald J DePaolo, the NRC report's committee chairman, "we have to look to the past and ask deeper fundamental questions, about the origins of the Earth and life, the structure and dynamics of planets, and the connections between life and climate."

Our future survival may

depend on it.

Baby galaxy cluster discovered

A cluster of galaxies in a very early stage of formation that is 11.4 billion light years from Earth has been detected. These galaxies are so distant that the universe was in its infancy when their light was emitted...

Irvine scientists have discovered a cluster of galaxies in a very early stage of formation that is 11.4 billion light years from Earth - the farthest of its kind ever to be detected. These galaxies are so distant that the universe was in its infancy when their light was emitted.

The galaxy proto-cluster, named LBG-2377, is giving scientists an unprecedented look at galaxy formation and how the universe has evolved. Before this discovery, the farthest known event like this was approximately nine billion light years away.

"When you observe objects this far away, you are actually seeing the universe as it was a very long time ago," said Jeff Cooke, a McCue Postdoctoral Fellow in physics and astronomy at UCI and lead author of this study. "It is as if a timeline is just sitting out there in front of you. These galaxies represent what the universe looked like well before the Earth existed."

Using the Keck Telescope in Hawaii, Cooke detected LBG-2377 while looking for single galaxies. At first, it appeared to be a bright, single object. But after analysing the wavelengths of its light (galaxies emit light with telltale colours) he discovered it was three galaxies merging together, and likely two additional smaller galaxies.

Scientists use light to look back in time. Because light takes a measurable amount of time to travel, detecting it on Earth today allows scientists to view the source, as it was billions of years ago. In the case of LBG-2377, scientists believe the light has been travelling for 11.4 billion years, beginning just a few billion years after the Big Bang when the universe was only 15 percent of its current age. By comparison, the Earth was formed about 4.5 billion years ago.

The process of galaxy formation largely is a mystery. Current theory is that large galaxies formed over time from the interaction and merging of smaller galaxies. This process began more than 12 billion years ago, shortly after the Big Bang. Scientists have observed galaxies merging over a large range of distances and time, providing hard evidence to reinforce the theory. However, using current technology, it is difficult to detect this process at the most extreme distances, when galaxy formation was in its infancy.

Scientists believe galaxy clusters form in a similar manner. As galaxies congregate and interact in large, dense regions of space, the cluster grows with time. Witnessing this process first-hand helps scientists confirm their theory and deepen their understanding of the universe. Galaxy clusters can be detected at extreme distances with current technology because they are bright, but they are difficult to find.

Clusters closer to Earth contain upwards of 1,000 galaxies. Our Milky Way galaxy belongs to a lesser grouping of galaxies called the Local Group, which contains more than 35 galaxies, but only a few bright ones.

"We believe LBG-2377 is a seed that eventually will grow into a massive galaxy cluster," said James Bullock, director of the Centre for Cosmology at UCI and a study co-author.

"Our finding suggests that this is a monster structure being born in a very bright, catastrophic event with a lot of gas and matter collapsing at once," Bullock said. "We are not just seeing one solitary galaxy. We are seeing a bunch of bright galaxies coming together at the dawn of structure formation in the universe."

Scientists Elizabeth Barton and Kyle Stewart of UCI, along with Arthur Wolfe of the University of California, San Diego, worked on this study.

--www.msnbc.com

Emission reduction assumptions
for carbon dioxide overly optimistic

Reducing global emissions of carbon dioxide over the coming century will be more challenging than society has been led to believe

Reducing global emissions of carbon dioxide (CO2) over the coming century will be more challenging than society has been led to believe, according to a research. The authors, from the University of Colorado at Boulder, the National Centre for Atmospheric Research (NCAR) in Boulder, and McGill University in Montreal, said the technological challenges of reducing CO2 emissions have been significantly underestimated by the Intergovernmental Panel on Climate Change (IPCC).

The study concludes the IPCC is overly optimistic in assuming that, even without action by policymakers, new technologies that will result in dramatic reductions in the growth of future emissions will be developed and implemented.

Titled "Dangerous Assumptions", the Nature commentary is co-authored by scientists Roger Pielke, Jr., of CU-Boulder, Tom Wigley of NCAR and economist Christopher Green of McGill University.

"This welcome commentary is an indication that the science policy discussions have shifted from 'is there global warming?' to 'how does society respond?'" said Cliff Jacobs of the National Science Foundation (NSF)'s Division of Atmospheric Sciences, which funds NCAR.

"In the end, there is no question whether technological innovation is necessary--it is," write the authors. "The question is to what degree should policy focus explicitly on motivating such innovation?"

"The IPCC plays a risky game in assuming that business-as-usual advances in technological innovation will carry most of the burden of achieving future emissions reductions, rather than focusing on those conditions that are necessary and sufficient for those innovations to occur."

Recent changes in "carbon intensity"--CO2 emissions per unit of energy consumed--already are higher than those predicted by the IPCC because of rapid economic development, says lead author Pielke. In Asia, for instance, the demands of more energy-intensive economies are being met with conventional fossil-fuel technologies, a process expected to continue there for decades and eventually move into Africa.

Atmospheric CO2 levels are currently about 390 parts per million. A commonly cited goal is to stabilize concentrations at roughly 500 parts per million or less.

Because technical innovation is ongoing, the IPCC authors assume that most of the needed reductions will occur automatically. According to calculations by the authors, the IPCC assumes that 57 to 96 percent of the total carbon removed from the energy supply will occur automatically through such routine technological progress.

--www.scienceagogo.com

Eco-Logic
Laser used to get thunder clouds sparking

Using a powerful ground-based laser, European scientists were able to induce electrical activity in thunderclouds, a precursor to stimulating lightning strikes on demand. It is reported that the experiment was conducted at the top of South Baldy Peak, in New Mexico, where the laser pulses created electricity conducting plasma filaments in the clouds. The filaments were too short-lived to create air-to-ground lightning but the researchers believe that triggering actual lightning strikes is not far away. "This was an important first step toward triggering lightning strikes with laser beams," says Jerome Kasparian of the University of Lyon in France. "It was the first time we generated lighting precursors in a thundercloud." The next step of generating full-blown lightning strikes may come, he adds, after the team reprogramme their lasers to use more sophisticated pulse sequences that will make longer-lived filaments.

Shorebird numbers crash in Australia

One of the world's great wildlife spectacles is under way across Australia: as many as two million migratory shorebirds of 36 species are gathering around Broome before an amazing 10,000-kilometre annual flight to their northern hemisphere breeding grounds. But an alarming new study has revealed that both these migrants and Australia's one million resident shorebirds have suffered a massive collapse in numbers over the past 25 years. A large scale aerial survey study covering the eastern third of the continent by researchers at the University of New South Wales has identified that migratory shorebirds populations there plunged by 73 percent between 1983 and 2006, while Australia's 15 species of resident shorebirds - such as avocets and stilts - have declined by 81 percent. It is the first long-term analysis of shorebird populations and health at an almost a continental scale and reveals a disturbing trend of serious long-term decline.

Lizards rapidly evolve after introduction to island

Italian wall lizards introduced to a tiny island off the coast of Croatia are evolving in ways that would normally take millions of years to play out, new research shows. In just a few decades the five-inch-long lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say. In 1971, scientists transplanted five adult pairs of the reptiles from their original island home in Pod Kopiste to the tiny neighbouring island of Pod Mrcaru, both in the south Adriatic Sea. Genetic testing on the Pod Mrcaru lizards confirmed that the modern population of more than 5,000 Italian wall lizards are all descendants of the original ten lizards left behind in the 1970s.

Komodo dragon's bite is "weaker than a house cat's"

The world's largest living lizard, the fearsome Komodo dragon, has a bite weaker than a house cat's, researchers say. Though known for killing prey much larger than itself, the Komodo relies on its razor-sharp teeth, strong neck muscles, and "space frame" skull to subdue its prey, according to a new study. Using computer models, researchers from Australia's University of New South Wales analysed a Komodo specimen from the Australian Museum in Sydney. Measuring the forces and composition of the lizard's skull, the researchers found that its jaw is not designed for crushing. "The bite is really quite incredibly weak for such a big lizard-less than you'd expect from the average house cat," said Stephen Wroe, author of the study. If a Komodo actually tried to crush prey with its jaws, like crocodiles do, "it would break its own skull," he said.

Captive tigers harbour rare "purebred" genes

Nearly half of tested captive tigers are "purebred" members of an endangered subspecies, raising the possibility they could bolster conservation efforts, a new genetic analysis suggests. Similar screening of some of the thousands of tigers with unknown heritage held on farms and by private owners would considerably increase the number of animals useful for captive breeding programmes, the scientists say. The news comes at a dire time for wild tigers. As few as 3,000 individuals remain where more than 100,000 roamed just a century ago. Three of the eight subspecies have become extinct, and a fourth, the South China tiger, persists only in zoos. The number of captive tigers, on the other hand, has boomed. Zoos, farms, circuses, and private owners hold an estimated 15,000 to 20,000 tigers. Only a small fraction of these are part of breeding programs oriented toward conservation.