North Atlantic signalled Ice Age thaw 1,000 years before it happened, reveals new research

The Atlantic Ocean at mid-depths may have given out early warning signals – 1,000 years in advance – that the last Ice Age was going to end, scientists report today in the journal Paleoceanography.

Scientists had previously known that at the end of the last Ice Age, around 14,700 years ago, major changes occurred to the Atlantic Ocean in a period known as the Bolling-Allerod interval. During this period, as glaciers melted and the Earth warmed, the currents of the Atlantic Ocean at its deepest levels changed direction.

The researchers have analysed the chemistry of 24 ancient coral fossils from the North Atlantic Ocean to learn more about the circulation of its waters during the last Ice Age. They found that the corals recorded a high variability in the currents of the Atlantic Ocean at mid-depths, around 2km below the surface, up to 1,000 years prior to the Bolling-Allerod interval. The team suggests that these changes may have been an early warning signal that the world was poised to switch from its glacial state to the warmer world we know today, and that the changes happened first at mid-depths.

The study was carried out by researchers from Imperial College London in conjunction with academics from the Scottish Marine Institute, the University of Bristol and Caltech Division of Geology and Planetary Sciences.

Dr David Wilson, from the Department of Earth Science and Engineering at Imperial College London, said: “The world’s oceans have always been an important barometer when it comes to changes in our planet. Excitingly, the coral fossils we’ve studied are showing us that the North Atlantic Ocean at mid-depths was undergoing changes up to 1,000 years earlier than we had expected. The tantalising prospect is that this high variability may have been a signal that the last Ice Age was about to end.”

The fossil corals analysed by the team come from a species called Desmophyllum dianthus, which are often around 5cm in diameter and look like budding flowers. They typically only live for 100 years, giving the team a rare insight into what was happening to the ocean’s currents during this relatively brief time. Thousands of years ago they grew on the New England Seamounts, which are a chain of undersea mountains approximately 1000km off the east coast of the US, located at mid-depths 2km beneath the surface. This underwater area is important for understanding the North Atlantic’s currents.

While some of the corals analysed by the team come from historical collections, most have been collected by researchers from previous expeditions in 2003 and 2005 to the New England Seamounts. The researchers used deep sea robotic submergence vehicles called Hercules and Alvin to collect the ancient coral fossils.

These ancient coral fossils accumulated rare earth elements from seawater, including neodymium, which leached from rocks on land into the Atlantic Ocean and circulated in its currents, eventually ending up in the coral skeletons. Neodymium isotopes in different regions of the world have specific signatures, created by radioactive decay over billions of years. The scientists studied the chemistry of the coral fossils to determine where the neodymium isotopes had come from, giving them a glimpse into the circulation of the Atlantic Ocean at the end of the Ice Age.

Since the world’s oceans are connected by currents, the next step will see the team integrating the evidence they gathered from the North Atlantic Ocean into a picture of global changes in the mid-depths of oceans around the world. In particular, the team is interested in exploring how the Southern Ocean around Antarctica changed around the same time by analysing neodymium isotopes in a collection of Southern Ocean corals.

Critical minerals ignite geopolitical storm

The clean energy economy of the future hinges on a lot of things, chief among them the availability of the scores of rare earth elements and other elements used to make everything from photovoltaic panels and cellphone displays to the permanent magnets in cutting edge new wind generators. And right out of the gate trouble is brewing over projected growth in demand for these minerals and the security of their supplies.

Last year, for instance, China restricted the export of neodymium, which is used in wind energy generators. The move was ostensibly to direct the supplies to toward a massive wind generation project within China. The effect, however, is to create a two-tiered price for neodymium: one inside China and another, higher price, for the rest of the world, explained economics professor Roderick Eggert of the Colorado School of Mines. The result could be that China not only will control the neodymium supply, but the manufacture of neodymium technology as well.

The geopolitical implications of critical minerals have started bringing together scientists, economists and policy makers who are trying to cut a path through the growing thicket of challenges. In that spirit, on Monday, 10 October, 2011, Eggert and other professors will be presenting their research alongside senior staff from the U.S. House of Representatives and Senate, the Executive Office of the President of the U.S., the U.S. Geological Survey, in a session at the meeting of The Geological Society of America in Minneapolis.

Among the basics that need to be grasped to understand the current state of affairs is how rare these minerals and elements really are. Some are plentiful, but only found in rare places or are difficult to extract. Indium, for instance, is a byproduct of zinc mining and extraction. It is not economically viable to extract unless zinc is being sought in the same ore, Eggert explained, Others are just plain scarce, like rhenium and tellurium, which only exist in very small amounts in the Earth’s crust.

There are basically two responses to this sort of situation: use less of these minerals or improve the extraction of them from other ores in other parts of the world. The latter would seem to be where most people are heading.

“China’s efforts to restrict exports of mineral commodities garnered the attention of Congress and highlighted the need for the United States to assess the state of the Nation’s mineral policies and examine opportunities to produce rare earths and other strategic and critical minerals domestically,” reads the session abstract of Kathleen Benedetto of the Subcommittee on Energy and Mineral Resources, Committee on Natural Resources, U.S. House of Representatives. “Nine bills have been introduced in the House and Senate to address supply disruptions of rare earths and other important mineral commodities.”

Benedetto will be explaining the meaning and status of those bills, and what it will take to get them signed into law.

“Deposits of rare earth elements and other critical minerals occur throughout the Nation,” reads the abstract for another prominent session presenter: Marcia McNutt, director of the U.S. Geological Survey. She will be putting the current events in the larger historical perspective of mineral resource management, which has been the USGS’s job for more than 130 years. “The definition of ‘a critical mineral or material’ is extremely time dependent, as advances in materials science yield new products and the adoption of new technologies result in shifts in both supply and demand.”

The White House Office of Science and Technology Policy (OSTP) has answered the call as well. An abstract by OSTP Assistant Director Cyrus Wadia provides a five-point strategy to begin addressing the matter. The first point is to mitigating long term risks associated with the use of critical materials. The second, diversify supplies of raw materials. Third, to promote a domestic supply chain for areas of strategic importance like clean energy. Fourth, inform decision makers; and fifth, prepare the workforce of the next generation.

Rare earth elements in US not so rare

Approximately 13 million metric tons of rare earth elements (REE) exist within known deposits in the United States, according to the first-ever nationwide estimate of these elements by the U.S. Geological Survey.

This estimate of domestic rare earth deposits is part of a larger report that includes a review of global sources for REE, information on known deposits that might provide domestic sources of REE in the future, and geologic information crucial for studies of the availability of REE to U.S. industry.

The report describes significant deposits of REE in 14 states, with the largest known REE deposits at Mountain Pass, Calif.; Bokan Mountain, Alaska; and the Bear Lodge Mountains, Wyo. The Mountain Pass mine produced REE until it closed in 2002. Additional states with known REE deposits include Colorado, Florida, Georgia, Idaho, Illinois, Missouri, Nebraska, New Mexico, New York, North Carolina, and South Carolina.

“This is the first detailed assessment of rare earth elements for the entire nation, describing deposits throughout the United States,” commented USGS Director Marcia McNutt, Ph.D. “It will be very important, both to policy-makers and industry, and it reinforces the value of our efforts to maintain accurate, independent information on our nation’s natural resources. Although many of these deposits have yet to be proven, at recent domestic consumption rates of about 10,000 metric tons annually, the US deposits have the potential to meet our needs for years to come.”

REE are a group of 16 metallic elements with similar properties and structures that are essential in the manufacture of a diverse and expanding array of high-technology applications. Despite their name, they are relatively common within the earth’s crust, but because of their geochemical properties, they are not often found in economically exploitable concentrations.

Hard-rock deposits yield the most economically exploitable concentrations of REE. USGS researchers also analyzed two other types of REE deposits: placer and phosphorite deposits. Placer deposits are alluvial formations of sandy sediments, which often contain concentrations of heavy, dense minerals, some containing REE. Phosphorite deposits, which mostly occur in the southeastern U.S., contain large amounts of phosphate-bearing minerals. These phosphates can yield yttrium and lanthanum, which are also REE.

Ninety-six percent of REE produced globally now comes from China. New REE mines are being developed in Australia, and projects exploring the feasibility of economically developing additional REE deposits are under way in the United States, Australia, and Canada; successful completion of these projects could help meet increasing demand for REE, the report said.

REE are important ingredients in high-strength magnets, metal alloys for batteries and light-weight structures, and phosphors. These are essential components for many current and emerging alternative energy technologies, such as electric vehicles, photo-voltaic cells, energy-efficient lighting, and wind power. REEs are also critical for a number of key defense applications.

This report is part of a larger, Department of Defense-funded study of how the United States, and the Department of Defense in particular, use REE, as well as the status and security of domestic and global supply chains. In addition, the USGS National Minerals Information Center maintains statistics on global mineral production, trade, and resources that include rare earth elements.