* Astronomy

Blobrana · L

RE: Climate change

Blobrana · L

Ancient leaves help researchers understand future climate

Potential climate change caused by rising levels of carbon dioxide might be better understood by examining fossil plant remains from millions of years ago, according to biogeochemists. The types of carbon within the leaves can serve as a window into past temperatures and environmental conditions.
Carbon naturally occurs in two non-radioactive isotopes -- different forms of the same element -- carbon 12 and carbon 13. Plants absorb carbon from the atmosphere as carbon dioxide. The ratio of carbon 12 to carbon 13 within a plant mirrors the ratio in the atmosphere, which varies with changes in the carbon cycle -- the cycling of the element carbon through plants and animals, the ocean, the atmosphere and Earth's crust.
Clues about how the environment responded to global warming events millions of years ago can be found in carbon isotope ratios from ancient fossil leaves, sediments and pollen. However, environmental conditions also impact leaf carbon isotope ratios, a complexity that Diefendorf and Kevin Mueller, graduate student in ecology, Penn State, set out to resolve with their study.
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Blobrana · L

"Missing" Heat May Affect Future Climate Change

Current observational tools cannot account for roughly half of the heat that is believed to have built up on Earth in recent years, according to a "Perspectives" article in this week's issue of the journal Science.
Scientists at the National Centre for Atmospheric Research (NCAR) in Boulder, Colo., warn that satellite sensors, ocean floats, and other instruments are inadequate to track this "missing" heat, which may be building up in the deep oceans or elsewhere in the climate system.
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Blobrana · L

Quiet sun puts Europe on ice

Brace yourself for more winters like the last one, northern Europe. Freezing conditions could become more likely: winter temperatures may even plummet to depths last seen at the end of the 17th century, a time known as the Little Ice Age. That's the message from a new study that identifies a compelling link between solar activity and winter temperatures in northern Europe.
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Blobrana · L

Climate change human link evidence 'stronger'

A review from the UK Met Office says it is becoming clearer that human activities are causing climate change.
It says the evidence is stronger now than when the Intergovernmental Panel on Climate Change carried out its last assessment in 2007.
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Blobrana · L

A quiet sun won't save us from global warming

Even if there's a "grand minimum" in the sun's output over the next century, it won't be enough to counter rising temperatures caused by humans
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Blobrana · L

More Tropical Cyclones in Past Could Play Role in Warmer Future

More frequent tropical cyclones in Earth's ancient past contributed to persistent El Niño-like conditions, according to a team of climate scientists led by Yale University. Their findings, which appear in the Feb. 25 issue of the journal Nature, could have implications for the planet's future as global temperatures continue to rise due to climate change.
The team used both cyclone and climate models to study the frequency and distribution of tropical cyclones (also known as hurricanes or typhoons) during the Pliocene epoch, a period three to five million years ago when temperatures were up to four degrees Celsius warmer than today.
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Blobrana · L

NASA has launched a new web page to help people better understand the causes and effects of Earth's changing climate.

Will 2010 be the warmest year on record? How do the recent U.S. "Snowmageddon" winter storms and record low temperatures in Europe fit into the bigger picture of long-term global warming? NASA has launched a new web page to help people better understand the causes and effects of Earth's changing climate.
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Blobrana · L

2009: Second Warmest Year on Record; End of Warmest Decade

2009 was tied for the second warmest year in the modern record, a new NASA analysis of global surface temperature shows. The analysis, conducted by the Goddard Institute for Space Studies (GISS) in New York City, also shows that in the Southern Hemisphere, 2009 was the warmest year since modern records began in 1880.
Although 2008 was the coolest year of the decade -- due to strong cooling of the tropical Pacific Ocean -- 2009 saw a return to near-record global temperatures. The past year was only a fraction of a degree cooler than 2005, the warmest year on record, and tied with a cluster of other years -- 1998, 2002, 2003, 2006 and 2007 -- as the second warmest year since record keeping began.
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Blobrana · L

Why hasn't Earth warmed as much as expected?

Earth has warmed much less than expected during the industrial era based on current best estimates of Earth's "climate sensitivity" -- the amount of global temperature increase expected in response to a given rise in atmospheric concentrations of carbon dioxide.
In a study published online on Jan. 19 in the Journal of Climate, Stephen Schwartz of Brookhaven National Laboratory, Robert Charlson of the University of Washington and colleagues examine the reasons for this discrepancy.
According to current best estimates of climate sensitivity, the amount of carbon dioxide and other heat-trapping gases added to Earth's atmosphere since humanity began burning fossil fuels on a significant scale during the industrial period would be expected to result in a mean global temperature rise of 3.8 degrees Fahrenheit. That is well more than the 1.4 degrees F. increase that has been observed for this time span.
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