Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print North Atlantic warming tied to natural variability; but global warming may be at play elsewhere

North Atlantic warming tied to natural variability; but global warming may be at play elsewhere

January 04, 2008

DURHAM, N.C. - A Duke University-led analysis of available records shows that while the North Atlantic Ocean's surface waters warmed in the 50 years between 1950 and 2000, the change was not uniform. In fact, the subpolar regions cooled at the same time that subtropical and tropical waters warmed.

This striking pattern can be explained largely by the influence of a natural and cyclical wind circulation pattern called the North Atlantic Oscillation (NAO), wrote authors of a study published Thursday, Jan. 3, in Science Express, the online edition of the journal Science.




Winds that power the NAO are driven by atmospheric pressure differences between areas around Iceland and the Azores. "The winds have a tremendous impact on the underlying ocean," said Susan Lozier, a professor of physical oceanography at Duke's Nicholas School of the Environment and Earth Sciences who is the study's first author.

Other studies cited in the Science Express report suggest human-caused global warming may be affecting recent ocean heating trends. But Lozier and her coauthors found their data can't support that view for the North Atlantic. "It is premature to conclusively attribute these regional patterns of heat gain to greenhouse warming," they wrote.

"The take-home message is that the NAO produces strong natural variability," said Lozier in an interview. "The simplistic view of global warming is that everything forward in time will warm uniformly. But this very strong natural variability is superimposed on human-caused warming. So researchers will need to unravel that natural variability to get at the part humans are responsible for."

In research supported by the National Science Foundation in the United States and the Natural Environment Research Council in the United Kingdom, her international team analyzed 50 years of North Atlantic temperature records collected at the National Oceanic Data Center in Washington, D.C.

To piece together the mechanisms involved in the observed changes, their analysis employed an ocean circulation model that predicts how winds, evaporation, precipitation and the exchange of heat with the atmosphere influences the North Atlantic's heat content over time. They also compared those computer predictions to real observations "to test the model's skill," the authors wrote.

Her group's analysis showed that water in the sub-polar ocean -- roughly between 45 degrees North latitude and the Arctic Circle -- became cooler as the water directly exchanged heat with the air above it.

By contrast, NOA-driven winds served to "pile up" sun-warmed waters in parts of the subtropical and tropical North Atlantic south of 45 degrees, Lozier said. That retained and distributed heat at the surface while pushing underlying cooler water further down.

The group's computer model predicted warmer sea surfaces in the tropics and subtropics and colder readings within the sub-polar zone whenever the NAO is in an elevated state of activity. Such a high NAO has been the case during the years 1980 to 2000, the scientists reported.

"We suggest that the large-scale, decadal changes...associated with the NAO are primarily responsible for the ocean heat content changes in the North Atlantic over the past 50 years," the authors concluded.

However, the researchers also noted that this study should not be viewed in isolation. Given reported heat content gains in other oceans basins, and rising air temperatures, the authors surmised that other parts of the world's ocean systems may have taken up the excess heat produced by global warming.

"But in the North Atlantic, any anthropogenic (human-caused) warming would presently be masked by such strong natural variability," they wrote.

Duke University



Related Global Warming Current Events and Global Warming News Articles Global Warming Current Events and Global Warming News RSS Global Warming Current Events and Global Warming News RSS
Climate variability impacts the deep sea
Deep-sea ecosystems occupying 60% of the Earth's surface could be vulnerable to the effects of global warming warn scientists writing in the Proceedings of the National Academy of Sciences.

Interactions with aerosols boost warming potential of some gases
For decades, climate scientists have worked to identify and measure key substances -- notably greenhouse gases and aerosol particles -- that affect Earth's climate.

Volcanoes played pivotal role in ancient ice age, mass extinction
Researchers here have discovered the pivotal role that volcanoes played in a deadly ice age 450 million years ago. Perhaps ironically, these volcanoes first caused global warming -- by releasing massive amounts of carbon dioxide into the atmosphere. When they stopped erupting, Earth's climate was thrown off balance, and the ice age began.

Glacial melting may release pollutants in the environment
Those pristine-looking Alpine glaciers now melting as global warming sets in may explain the mysterious increase in persistent organic pollutants in sediment from certain lakes since the 1990s, despite decreased use of those compounds in pesticides, electric equipment, paints and other products.

Seismic Noise Unearths Lost Hurricanes
Seismologists have found a new way to piece together the history of hurricanes in the North Atlantic - by looking back through records of the planet's seismic noise. It's an entirely new way to tap into the rich trove of seismic records, and the strategy might help establish a link between global warming and the frequency or intensity of hurricanes.

As Greenland melts
Not that long ago - the blink of a geologic eye - global temperatures were so warm that ice on Greenland could have been hard to come by. Today, the largest island in the world is covered with ice 1.6 miles thick. Even so, Greenland has become a hot spot for climate scientists.

Television Has Less Effect on Education about Climate Change than Other Forms of Media
Worried about climate change and want to learn more? You probably aren't watching television then. A new study by George Mason University Communication Professor Xiaoquan Zhao suggests that watching television has no significant impact on viewers' knowledge about the issue of climate change. Reading newspapers and using the web, however, seem to contribute to people's knowledge about this issue.

Arctic land and seas account for up to 25 percent of world's carbon sink
In a new study in the journal Ecological Monographs, ecologists estimate that Arctic lands and oceans are responsible for up to 25 percent of the global net sink of atmospheric carbon dioxide.

Growth versus global warming
Houses on stilts, small scale energy generation and recycling our dishwater are just some of the measures that are being proposed to prepare our cities for the effects of global warming.

Key new ingredient in climate model refines global predictions
For the first time, climate scientists from across the country have successfully incorporated the nitrogen cycle into global simulations for climate change, questioning previous assumptions regarding carbon feedback and potentially helping to refine model forecasts about global warming.
More Global Warming Current Events and Global Warming News Articles
Unstoppable Global Warming: Every 1,500 Years, Updated and Expanded Edition

Unstoppable Global Warming: Every 1,500 Years, Updated and Expanded Edition
by S. Fred Singer (Author), Dennis T. Avery (Author)

In this New York Times bestseller, authors Singer and Avery present the compelling concept that global temperatures have been rising mostly or entirely because of a natural cycle. Using historic data from two millennia of recorded history combined with natural physical records, the authors argue that the 1,500 year solar-driven cycle that has always controlled the earth's climate remains the driving force in the current warming trend.

Climate Confusion: How Global Warming Hysteria Leads to Bad Science, Pandering Politicians and Misguided Policies That Hurt the Poor

Climate Confusion: How Global Warming Hysteria Leads to Bad Science, Pandering Politicians and Misguided Policies That Hurt the Poor
by Roy W. Spencer (Author)

The current frenzy over global warming has galvanized the public and cost taxpayers billons of dollars in federal expenditures for climate research. It has spawned Hollywood blockbusters and inspired major political movements. It has given a higher calling to celebrities and built a lucrative industry for scores of eager scientists. In short, ending climate change has become a national crusade.

And yet, despite this dominant and sprawling campaign, the facts behind global warming remain as confounding as ever.

In Climate Confusion, distinguished climatologist Dr. Roy Spencer observes that our obsession with global warming has only clouded the issue. Forsaking blindingly technical statistics and doomsday scenarios, Dr. Spencer explains in simple terms how the climate system...

Global Warming: The Complete Briefing

Global Warming: The Complete Briefing
by John Houghton (Author)

John Houghton's market-leading textbook is now in full color and includes the latest IPCC findings, making it the definitive guide to climate change. Written for students across a wide range of disciplines, its simple, logical flow of ideas gives an invaluable grounding in the science and impacts of climate change and highlights the need for action on global warming. Is there evidence for climate changing due to human activities? How do we account for recent extremes of weather and climate? Can global electricity provision and transport ever be carbon free? Written by a leading figure at the forefront of action to confront humanity's most serious environmental problem, this undergraduate textbook comprehensively explores these and other issues, allowing students to think through the...

The Deniers: The World Renowned Scientists Who Stood Up Against Global Warming Hysteria, Political Persecution, and Fraud**And those who are too fearful to do so

The Deniers: The World Renowned Scientists Who Stood Up Against Global Warming Hysteria, Political Persecution, and Fraud**And those who are too fearful to do so
by Lawrence Solomon (Author)



The Real Global Warming Disaster: Is the Obsession with "Climate Change" Turning Out to Be the Most Costly Scientific Blunder in History?

The Real Global Warming Disaster: Is the Obsession with "Climate Change" Turning Out to Be the Most Costly Scientific Blunder in History?
by Christopher Booker (Author)

Booker focuses his attention on the mother of all environmental scares: global warming. This original book considers one of the most extraordinary scientific and political stories of our time: how in the 1980s a handful of scientists came to believe that mankind faced catastrophe from runaway global warming, and how today this has persuaded politicians to land us with what promises to be the biggest bill in history. Christopher Booker interweaves the science of global warming with that of its growing political consequences, showing how just when the politicians are threatening to change our Western way of life beyond recognition, the scientific evidence behind the global warming theory is being challenged like never before. The book exposes the myth that the global warming theory is...

Heaven and Earth: Global Warming, the Missing Science

Heaven and Earth: Global Warming, the Missing Science
by Ian Plimer (Author)

Climate, sea level, and ice sheets have always changed, and the changes observed today are less than those of the past. Climate changes are cyclical and are driven by the Earth's position in the galaxy, the sun, wobbles in the Earth's orbit, ocean currents, and plate tectonics. In previous times, atmospheric carbon dioxide was far higher than at present but did not drive climate change. No runaway greenhouse effect or acid oceans occurred during times of excessively high carbon dioxide. During past glaciations, carbon dioxide was higher than it is today. The non-scientific popular political view is that humans change climate. Do we have reason for concern about possible human-induced climate change?

This book's 504 pages and over 2,300 references to peer-reviewed scientific...

Global Warming: A Scientific and Biblical Expose' of Climate Change

Global Warming: A Scientific and Biblical Expose' of Climate Change
Starring: Larry Vardiman, Calvin Beisner, Al Gore, Jason Lisle, Michael J. Oard
Directed By: Jason Beaupied,Ben Wilt Javier Pena



The Politically Incorrect Guide to Global Warming (and Environmentalism)

The Politically Incorrect Guide to Global Warming (and Environmentalism)
by Christopher C. Horner (Author)

This latest installment in the P.I.G. series provides a provocative, entertaining, and well-documented expose of some of the most shamelessly politicized pseudo-science we are likely to see in our relatively cool lifetimes.

Global Warming: Understanding the Forecast

Global Warming: Understanding the Forecast
by David Archer (Author)

Global Warming: Understanding the Forecast is a comprehensive introduction to all aspects of global warming. Written in an accessible style, this important book examines the processes of climate change and climate stability, from the distant past to the distant future.

Examining the greenhouse effect, the carbon cycle, and what the future may hold for global climate, this text draws on a wide range of disciplines, and summarizes not only scientific evidence, but also economic and policy issues, related to global warming. A companion web site at (http://understandingtheforecast.org) provides access to interactive computer models of the physics and chemistry behind the global warming forecast, which can be used to support suggested student projects included at the end of each...

Down-to-Earth Guide To Global Warming

Down-to-Earth Guide To Global Warming
by Laurie David and Cambria Gordon (Author)

Irreverent and entertaining, DOWN TO EARTH is filled with fact about global warming and its disastrous consequences, loads of photos and illustrations, as well as suggestions for how kids can help combat global warming in their homes, schools, and communities. Engagingly designed, DOWN TO EARTH will educate and empower, leaving readers with the knowledge they need to understand this problem and a sense of hope to inspire them into action.

© 2009 BrightSurf.com