* Astronomy

Blobrana · L

RE: Climate change

Blobrana · L

Fastest Sea-Level Rise in Two Millennia Linked to Increasing Global Temperatures

The rate of sea level rise along the U.S. Atlantic coast is greater now than at any time in the past 2,000 years--and has shown a consistent link between changes in global mean surface temperature and sea level.
The findings are published this week in the journal Proceedings of the National Academy of Sciences (PNAS).
The research, funded by the National Science Foundation (NSF), was conducted by Andrew Kemp, Yale University; Benjamin Horton, University of Pennsylvania; Jeffrey Donnelly, Woods Hole Oceanographic Institution; Michael Mann, Pennsylvania State University; Martin Vermeer, Aalto University School of Engineering, Finland; and Stefan Rahmstorf, Potsdam Institute for Climate Impact Research, Germany.
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Blobrana · L

Human impacts of rising oceans will extend well beyond coasts

Identifying the human impact of rising sea levels is far more complex than just looking at coastal cities on a map.
Rather, estimates that are based on current, static population data can greatly misrepresent the true extent - and the pronounced variability - of the human toll of climate change, say University of Wisconsin-Madison researchers.
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Blobrana · L

Soils of UK and Europe drying out

The scale of just how dry the start of 2011 has been is evident in some fascinating data from one of Europe's latest Earth observation satellites.
Smos senses the moisture in the top layers of soil, and it is very clear in these maps that the ground across the UK and much of Europe is now gasping for water.
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Blobrana · L

Models bolster case for early human effect on greenhouse-gas levels.

Scientists have come up with new evidence in support of the controversial idea that humanity's influence on climate began not during the industrial revolution, but thousands of years ago. Proposed by palaeoclimatologist William Ruddiman in 2003, the theory says that human influences offset the imminent plunge into another ice age and helped create the relatively stable climate that we are familiar with today. It has been repeatedly panned as implausible by palaeoclimate researchers, but eight years on, Ruddiman and others say that they have the data to support early anthropogenic climate change.
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Blobrana · L

NASA Study Goes to Earth's Core for Climate Insights
The latest evidence of the dominant role humans play in changing Earth's climate comes not from observations of Earth's ocean, atmosphere or land surface, but from deep within its molten core.
Scientists have long known that the length of an Earth day - the time it takes for Earth to make one full rotation - fluctuates around a 24-hour average. Over the course of a year, the length of a day varies by about 1 millisecond, getting longer in the winter and shorter in the summer. These seasonal changes in Earth's length of day are driven by exchanges of energy between the solid Earth and fluid motions of Earth's atmosphere (blowing winds and changes in atmospheric pressure) and its ocean. Scientists can measure these small changes in Earth's rotation using astronomical observations and very precise geodetic techniques.
But the length of an Earth day also fluctuates over much longer timescales, such as interannual (two to 10 years), decadal (approximately 10 years), or those lasting multiple decades or even longer. A dominant longer timescale mode that ranges from 65 to 80 years was observed to change the length of day by approximately 4 milliseconds at the beginning of the 20th century.

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Blobrana · L

NASA Finds Polar Ice Adding More to Rising Seas

The Greenland and Antarctic ice sheets are losing mass at an accelerating pace, according to a new NASA-funded satellite study. The findings of the study -- the longest to date of changes in polar ice sheet mass -- suggest these ice sheets are overtaking ice loss from Earth's mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted.
The nearly 20-year study reveals that in 2006, a year in which comparable results for mass loss in mountain glaciers and ice caps are available from a separate study conducted using other methods, the Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes a year on average. That's enough to raise global sea level by an average of 1.3 millimetres a year.
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Blobrana · L

Scott's Antarctic samples give climate clues

Samples of a marine creature collected during Captain Scott's Antarctic trips are yielding data that may prove valuable in projecting climate change.
The expeditions in the early 1900s brought back many finds including samples of life from the sea floor.
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Blobrana · L

New Discoveries Improve Climate Models

New discoveries on how underwater ridges impact the ocean's circulation system will help improve climate projections.
An underwater ridge can trap the flow of cold, dense water at the bottom of the ocean. Without the ridge, deepwater can flow freely and speed up the ocean circulation pattern, which generally increases the flow of warm surface water.
Warm water on the ocean's surface makes the formation of sea ice difficult. With less ice present to reflect the sun, surface water will absorb more sunlight and continue to warm.
U.S. Geological Survey scientists looked back 3 million years, to the mid-Pliocene warm period, and studied the influence of the North Atlantic Oceans Greenland-Scotland Ridge on surface water temperature.
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Blobrana · L

Caltech Geobiologists Uncover Links between Ancient Climate Change and Mass Extinction

About 450 million years ago, Earth suffered the second-largest mass extinction in its history - the Late Ordovician mass extinction, during which more than 75 percent of marine species died. Exactly what caused this tremendous loss in biodiversity remains a mystery, but now a team led by researchers at the California Institute of Technology (Caltech) has discovered new details supporting the idea that the mass extinction was linked to a cooling climate.