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TOPIC: Ancient climate
Blobrana


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RE: Ancient climate
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Ice Core Reveals How Quickly Climate Can Change
Weather patterns can permanently shift in as little as a year, according to the records preserved in an ice core from Greenland.

Roughly 14,700 years ago the weather patterns that bring snow to Greenland shifted from one year to the nexta pattern of abrupt change that was repeated 12,900 years ago and 11,700 years ago when the earths climate became the one enjoyed todayaccording to records preserved in an ice core taken from the northern island. These speedy changestransitions from warming to cooling and back againin the absence of changes in greenhouse gas could presage abrupt, catastrophic climate change in our future.

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Blobrana


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Billions of years ago, a weaker sun should have made the Earth a chilly place - so why was it balmy instead?
The sun that shone on the early Earth was around 25 per cent dimmer than today, so atmospheric temperatures should have been colder by around 25 °C. But ancient rocks show that liquid water existed, proving that temperatures must have been above freezing.
This can be explained if greenhouse gases acted as an insulator - but modelling has showed that carbon dioxide in the atmosphere would need to have had an implausibly high partial pressure of over 50 millibars to trap the heat.
Now Philip von Paris of the German Aerospace Centre in Berlin and colleagues have built a model that they say better simulates the types, pressures and layering of atmospheric gases at that time.

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Blobrana


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Jurassic period
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Scientists from the Open University in the United Kingdom are studying climate change throughout Earth's history. Their results indicate how dangerous modern global climate change might be for the future of life on Earth. In a new study published in the journal Geology, the researchers examined layers of sedimentary rocks from the ocean floor in order to unravel the story of climate change during the early Jurassic period.

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Blobrana


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The Cretaceous
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The Cretaceous (145 million to 65 million years ago) was one long heat wave. Average annual temperatures at the equator topped 38 degrees Celsius and even polar temperatures hovered near a temperate 10 degrees Celsius. Exactly how the planet got so warm is something that scientists have struggled to explain. Now, researchers say they may have the answer: A slight reduction in cloud cover that allowed more sunlight to reach Earth could have been the necessary nudge needed to push the planet into a "supergreenhouse" world.

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Blobrana


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A researcher at Northern Arizona University (NAU) has a cow dung collection dating back to thousands of years, that might reveal past climate patterns.
The researcher is Jim Mead, director of NAU's Laboratory of Quaternary Palaeontology, who is an expert on researching dung for clues about ancient life.
The collection includes dung from modern animals to prehistoric ground sloths and 40,000-year-old mammoths.

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Blobrana


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 Insects will feast and leafy plants will suffer if temperatures warm and atmospheric carbon dioxide increases, according to a team of researchers who studied evidence of insect feeding on fossil leaves from before, during and after the Palaeocene-Eocene Thermal Maximum (PETM).
The PETM occurred 55.8 million years ago and was an abrupt global warming event linked to a temporary increase in carbon dioxide in the atmosphere. This event is comparable in size and rate to the current climate changes brought on by human activity.

"Our study suggests that increased insect herbivory is likely to be a net, long-term effect of anthropogenic carbon dioxide increase and warming temperature" - Researchers in a report yesterday (Feb.11) in the online Proceedings of the National Academy of Sciences.

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Blobrana


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Using the genetic equivalent of an ancient thermometer, a team of scientists has determined that the Earth endured a massive cooling period between 500 million and 3.5 billion years ago.
Reporting today (Feb. 7) in the journal Nature, researchers from the University of Florida, the Foundation for Applied Molecular Evolution and the biotechnology company DNA2.0 describe how they reconstructed proteins from ancient bacteria to measure the Earths temperature over the ages.

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Blobrana


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Little Ice Ages
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Aerosols from tropical volcanoes likely caused the "Little Ice Ages" that kept the Northern Hemisphere cool for 600 years until 1850, a study by the University of Colorado found.
Nothing seems to be helping the ice caps of Baffin Island, west of Greenland, though, say the researchers who found the ice caps are smaller now than at any time in at least 1,600 years. They've shrunk by more than half in the last half-century.

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Blobrana


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Scientists aboard the Southern Surveyor, a research vessel, have retrieved live and fossilised deep-ocean corals from a depth of 1,650 meters near the Tasman Fracture Zone, south-east of Tasmania, which might reveal ancient climate secrets.
The samples were collected by scientists from the US and CSIROs (Commonwealth Scientific and Research Organisation) Wealth from Oceans National Research Flagship.

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Blobrana


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After enduring months on the coldest, driest and windiest continent on Earth, researchers today closed out the inaugural season on an unprecedented, multi-year effort to retrieve the most detailed record of greenhouse gases in Earth's atmosphere over the last 100,000 years.
Working as part of the National Science Foundation's West Antarctic Ice Sheet Divide (WAIS Divide) Ice Core Project, a team of scientists, engineers, technicians and students from multiple U.S. institutions have recovered a 580-meter (1,900-foot) ice core--the first section of what is hoped to be a 3,465-meter (11,360-foot) column of ice detailing 100,000 years of Earth's climate history, including a precise year-by-year record of the last 40,000 years.

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