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Deep under the sea, a sand grain sized fossil nestles among a billion of its closest dead kins. Known as foraminifera, these complex little shells of calcium carbonate can tell you the sea level, temperature, and ocean conditions of Earth millions of years ago - that is, if you know what to look for.
Miriam Katz, assistant professor of earth and environmental sciences at Rensselaer Polytechnic Institute (RPI) has spent the past two decades studying these ancient, deep-sea fossils to reconstruct the climates up to 250 million years ago.


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Volcanic eruptions were responsible for a deadly ice age 450 million years ago, as well as - in an ironic twist - a period of global warming that preceded it, a new study finds.
The finding underscores the importance of carbon in Earth's climate today, said study researcher Matthew Saltzman of Ohio State University.
The ancient ice age featured glaciers that covered the South Pole on top of the supercontinent of Gondwana (which would eventually break apart to form the present-day continents of the southern hemisphere). Two-thirds of all species perished in the frigid climate.

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Deep under the sea, a fossil the size of a sand grain is nestled among a billion of its closest dead relatives. Known as foraminifera, these complex little shells of calcium carbonate can tell you the sea level, temperature, and ocean conditions of Earth millions of years ago. That is, if you know what to look for.
Assistant Professor of Earth and Environmental Sciences at Rensselaer Polytechnic Institute Miriam Katz has spent the past two decades studying these ancient, deep-sea fossils to reconstruct the climates of Earth up to 250 million years ago. Through ice ages and greenhouse climates, Katz has been able to piece together oxygen, carbon, and faunal data to paint a portrait of how, when, and why our climate has changed so drastically over geologic history. In addition, her investigations into the deep past of Earth have important implications for understanding and tracking the potential drastic repercussions of modern, human-induced climate change.

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Sand dunes reveal unexpected dryness during heavy monsoon
The windswept deserts of northern China might seem an odd destination for studying the heavy monsoon rains that routinely drench the more tropical regions of Southeast Asia.
But the sandy dunefields that mark the desert margin between greener pastures to the south and the Gobi Desert to the north are a rich source of information about past climates in Asia, says University of Wisconsin-Madison geographer Joseph Mason. Wetter periods allow vegetation to take root on and stabilize sand dunes. During dry spells, plants die off and the dunes are more active, constantly shifting as sand is blown away and replenished.

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Scientists Confirms No Summer Nearly 2,000 Years Ago
Austrian scientists found that 13,000 years to 19,000 years ago, there was no "real" summer on the Earth. At that time, the average temperature in summer was low and sharply volatile.
Kerstin Huber, a scientist of the Institute for Limnology, Austrian Academy of Sciences, pointed out in his latest academic report that, according to the analysis of the remnants of algae and pollen in the sediment of the Lange Lake, Carinthia, Austria, there was no summer in this area at that time, and the range of fluctuation reached nearly 8 degrees Celsius.
The report said, after the end of Ice age about 20,000 years ago, the temperatures on the Earth became warming. About 17,000 years ago, the Earth experienced a drastic cold spell which lasted nearly 2,500 years. Till 14,500 years ago, the temperatures increased again.

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Harbingers of increased Atlantic hurricane activity identified
Reconstructions of past hurricane activity in the Atlantic Ocean indicate that the most active hurricane period in the past was during the "Medieval Climate Anomaly" about a thousand years ago when climate conditions created a "perfect storm" of La Niņa-like conditions combined with warm tropical Atlantic waters.

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Carbon Dioxide Not to Blame In Ice Age Mystery
Scientists have peered back in time with a new analytical technique to see atmospheric concentrations of carbon dioxide more than 2 million years into the past. The findings indicate that a long-term decline in the levels of that greenhouse gas isn't to blame for a geologically recent shift in the frequency of ice ages, scientists say.
The record of ice ages in North America stretches back 2.4 million years. Until about 1.2 million years ago, ice ages in the Northern Hemisphere occurred about every 40,000 years, says Jerry F. McManus, a palaeoclimatologist at Lamont-Doherty Earth Observatory in Palisades, N.Y. But for the past 500,000 years or so, ice ages have occurred, on average, only once every 100,000 years, he notes.
Several explanations for this shift have been proposed, but one of the most popular ones - a long-term decline in carbon dioxide levels - isn't to blame, McManus and his colleagues suggest in the June 19 Science.

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Extent of ancient ice age
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University of Leicester geologists demonstrate extent of ancient ice age
Geologists at the University of Leicester have shown that an ancient Ice Age, once regarded as a brief 'blip', in fact lasted for 30 million years.
Their research suggests that during this ancient Ice Age, global warming was curbed through the burial of organic carbon that eventually lead to the formation of oil - including the 'hot shales' of north Africa and Arabia which constitute the world's most productive oil source rock.
This ice age has been named 'the Early Palaeozoic Icehouse' by Dr Alex Page and his colleagues in a paper published as part of a collaborative Deep Time Climate project between the University of Leicester and British Geological Survey.
The Ice Age occurred in the Ordovician and Silurian Periods of geological time (part of the Early Palaeozoic Era), an interval that witnessed a major diversification of early marine animals including trilobites and primitive fish as well as the emergence of the first land plants.
The Early Palaeozoic climate had long been considered characterised by essentially greenhouse conditions with elevated atmospheric CO2 and warm temperatures extending to high latitudes, and only brief snaps of frigid climate. However, during his doctoral studies in the internationally renowned Palaeobiology Research Group of the University of Leicester, Department of Geology, Alex Page and his colleagues Jan Zalasiewicz and Mark Williams demonstrated how the ice age was probably of much longer duration.
The team demonstrated that the Late Ordovician and Early Silurian Epochs were characterised by widespread ice formation, with changes in the extent of continental glaciation resulting in rapid sea-level changes around the globe.
They compared evidence of sea-level change from the rock record of ancient coastlines with evidence of sediments being deposited by glacial mel****ers or ice-rafting at high latitudes, and with chemical indicators of temperature in the strata.
The team showed that although the Early Palaeozoic Icehouse was of similar extent and duration to the modern ice age, the workings of the carbon cycle appeared markedly different to that of the present day. Unlike the modern oceans, the oceans of the Early Palaeozoic were often oxygen-starved 'dead zones' leading to the burial of plankton-derived carbon in the sea floor sediments. The strata produced in this way include the 'hot shales' of north Africa and Arabia which constitute the world's most productive oil source rock. In fact, the burial of organic carbon derived from fossil plankton may have served to draw down CO2 from the atmosphere to promote cooling during the Early Palaeozoic Icehouse.

"These fossil fuel- rich deposits formed during relatively warmer episodes during the Early Palaeozoic Icehouse when the partial melting of ice sheets brought about rapid sea-level rise. This melt-water may have bought a massive influx of nutrients into the surface waters, allowing animals and algae to thrive and bloom in the plankton, but also altered ocean circulation, creating oxygen-poor deep waters which facilitated the preservation of fragile, carbonaceous planktonic fossils. The deglacial outwash formed a less dense, low-salinity 'lid' on the oceans preventing atmospheric oxygen penetrating to the seafloor. The absence of oxygen under such conditions served to shut down decay accounting for the preservation of these fossils" - Alex Page.

Page added that the burial of oil shales in deglacial anoxia "may have been a negative feedback mechanism that prevented runaway warming, meaning that in the Early Palaeozoic Icehouse at least, processes eventually leading to oil formation may have been the solution to the greenhouse effect."

Alex Page's research will be presented at the Doctoral Inaugural Lectures being held at the University of Leicester. on June 17.  They have also published their findings.

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A new explanation for the cause of changes in the chemical makeup of the oceans through recent Earth history is put forward in a paper published in Nature.
Scientists from the Universities of Southampton and Bristol suggest that adjustments in ocean chemistry through recent geological time are driven by variations in the intensity of chemical breakdown of continental rocks by rain and ground water. These changes are, in turn, controlled by the profound changes in the Earth's climate, and in particular the Ice Ages, that have occurred over the past 2-3 million years.
The elements that give seawater its distinctive saltiness are mostly supplied in dissolved form by rivers. Rivers, in turn, receive these elements from runoff that has reacted with and partially dissolved rocks, a process known as chemical weathering. Another major source of dissolved material to seawater is submarine "black smoker" hydrothermal systems. Movement of seawater through young, hot rocks at the mid-ocean ridges causes leaching of some elements from sea-floor basalts, as well as the precipitation out of solution of some constituents of seawater. Thus, these hydrothermal systems are both a source of dissolved material to the oceans and also a means by which some others are lost. The other major output of dissolved material from the oceans is to marine sediments, which are principally made up of the shells of dead marine organisms. Imbalances in these inputs and outputs cause changes in the chemical make-up of the oceans through time.

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Fossilised corals from tropical Tahiti show that the behaviour of ice sheets is much more volatile and dynamic than previously thought, a team led by Oxford University scientists has found.
Analysis of the corals suggests that ice sheets can change rapidly over just hundreds of years - events associated with sea level rises of several metres over the same period. It also shows that a natural warming mechanism thought to be responsible for ending ice ages does not fit the timing of the end of the penultimate ice age, around 137,000 years ago.
A report of the research appears online in the journal Science on April 23.

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