Tabular iceberg. The production of tabular icebergs is a major mechanism of mass loss from the Antarctic Ice Sheet. Icebergs are calved during both rapid ice-shelf collapse and as part of the normal transfer of mass through the ice sheet to the surrounding ocean. Credit: Julian Dowdeswell.
Study 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. The only way we can work out what the likely effects of the changes we are making to the climate will be is by finding analogues in the geological past. That depends on having an accurate picture of the past behaviour of the climate system." - —Harry Elderfield Scientists have announced a major breakthrough in understanding the 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 , offers new insights into a decades-long debate about how the shifts in the Earth's orbit relative to the sun have taken the 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 man-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.
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