Friday, August 10, 2012

1.5 Million Years of Climate History Revealed After Scientists Solve Mystery of the Deep

ScienceDaily ^ | Aug. 9, 2012 | NA

A new study has successfully reconstructed temperature from the deep sea to reveal how global ice volume has varied over the glacial-interglacial cycles of the past 1.5 million years.

Scientists have announced a major breakthrough in understanding Earth's climate machine by reconstructing highly accurate records of changes in ice volume and deep-ocean temperatures over the last 1.5 million years.

The study, which is reported in the journal Science, offers new insights into a decades-long debate about how the shifts in Earth's orbit relative to the sun have taken Earth into and out of an ice-age climate.
Being able to reconstruct ancient climate change is a critical part of understanding why the climate behaves the way it does. It also helps us to predict how the planet might respond to human-made changes, such as the injection of large quantities of carbon dioxide into the atmosphere, in the future.
Unfortunately, scientists trying to construct an accurate picture of how such changes caused past climatic shifts have been thwarted by the fact that the most readily available marine geological record of ice-ages -- changes in the ratio of oxygen isotopes (Oxygen 18 to Oxygen 16) preserved in tiny calcareous deep sea fossils called foraminifera -- is compromised.
This is because the isotope record shows the combined effects of both deep sea temperature changes, and changes in the amount of ice volume. Separating these has in the past...
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"Any uncertainty about Earth's climate system fuels the sense that we don't really know how the climate is behaving, either in response to natural effects or those which are man-made," Professor Elderfield added. "If we can understand how earlier changes were initiated and what the impacts were, we stand a much better chance of being able to predict and prepare for changes in the future."
(Excerpt) Read more at sciencedaily.com­ ...

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