Waste heat from major cities is contributing to warmer winters, according to a new study. (Photo: Petr Magera via Creative Commons at Flickr)

Everyday energy consumption in urban areas could be significant enough to cause winter temperatures to rise.

According to a new study funded by the US National Oceanic and Atmospheric Administration (NOAA), waste heat released in major cities in the Northern Hemisphere in the northern-most parts of North America and Eurasia.

“The world’s most populated metropolitan areas, which also have the highest rates of energy consumption, are along the east and west coasts of the North American and Eurasian continents, underneath the most prominent atmospheric circulation troughs and ridges,” said Ming Cai, from Florida State University and an author of the study. “The concentrated and intensive release of waste energy in these areas causes a noticeable interruption to normal atmospheric circulation systems, leading to remote surface temperature changes far away from the regions where the waste heat is generated.”

According to the study published Nature Climate Change, the total amount of energy consumed throughout the world in 2006 was 16 terawatts, 16 trillion watts with 6.7 terawatts of that amount consumed within the 86 metropolitan areas considered in the study.

“The burning of fossil fuel not only emits greenhouse gases but also directly effects temperatures because of heat that escapes from sources like buildings and cars,” said Aixue Hu of the National Center for Atmospheric Research in Boulder, Colorado, another of the study’s authors.

The excess energy and resulting warmer winter temperatures could also help explain the discrepancies between actual observed warming over the last half-century, compared to the amount of warming that computer models have been able to account for.

US National Weather Service illustration of two atmospheric systems known as jet streams traveling northeast across the United States. (NOAA)

Waste heat from urban areas is different from energy found naturally in atmosphere, such as what’s produced by our Sun-warmed planet.  That atmospheric energy is normally distributed from one region to another by various circulation systems, like the Jet Stream.

Humans consume energy produced by fossil fuel sources, oil and coal, that have stayed hidden and unused for millions of years.  Although the amount of energy produced and used by humans represents only a small portion of what’s actually transported throughout the atmosphere by nature, the researchers say that it is highly concentrated in urban areas.

“What we found is that energy use from multiple urban areas collectively can warm the atmosphere remotely, thousands of miles away from the energy consumption regions,” said study co-author Guang Zhang, from Scripps Institution of Oceanography. “This is accomplished through atmospheric circulation change.”

The influence of heat generated in urban areas can widen the jet stream and strengthen atmospheric flows in regions located at mid-latitudes, areas which lie between the tropics and the polar regions of the world.

Researchers point out this warming effect generated by urban heat is not necessarily even and uniform throughout the world.  They say changes in major atmospheric systems, that can cool parts of Europe by up to 1 degree C mostly during the fall, can offset this heating effect. That’s why the impact of the urban winter heat on global temperatures is slight, raising the temperature by an average of about .1 degree C worldwide.

The study does not address whether the effects of urban heating can actually disrupt atmospheric weather patterns or if it plays any role in hastening global warming.

This graphic shows the extent of Arctic sea ice on Aug. 26, 2012, the day the sea ice dipped to its smallest extent in more than three decades of satellite measurements, according to scientists from NASA and the National Snow and Ice Data Center. (Image: NASA)

The Arctic sea ice cover has melted to its lowest extent since satellite observations of it began more than three decades ago, breaking a previous record low set in 2007.

NASA and scientists at the University of Colorado, Boulder report the Arctic sea ice extent  -  the amount of ice covering the sea surface – fell to 4.10 million square kilometers in Aug. 26, 2012.  And, with more days left in the summer melting cycle, they anticipate even more of a loss before the freeze cycle begins at the end of September.

“By itself it’s just a number, and occasionally records are going to get set. But in the context of what’s happened in the last several years and throughout the satellite record, it’s an indication that the Arctic sea ice cover is fundamentally changing,” said Walt Meier, a scientist at the National Snow and Ice Data Center (NSIDC) at the University of Colorado.

Sea ice in the Arctic goes through a regular yearly cycle of growing and melting. While it doesn’t raise sea level, says Meier, it does have an effect on the climate systems through how much energy gets absorbed from the sun.

Since the Arctic sea ice observational record began in 1979,  the trend of ice melt went from slow and steady to more significant as time went on.

Over the last 10 years, according to Meier, this trend quickly began to escalate, with record-breaking years of sea ice melt along the way. The significant drop in the amount of Arctic sea ice, says Meier, “is a kind of an exclamation point on the long term trend.”

Scattered ice floes seen from the bridge of the USCGC Healy on August 20, 2012 northwest of Barrow, Alaska. Arctic sea ice fell to its lowest daily extent in the satellite record on Sunday, August 26, 2012. (Photo: U.S. Coast Guard)

NSIDC officials say the previous record low, set back in 2007, happened because of a near-perfect summer weather for melting ice.

“The Arctic used to be dominated by multiyear ice, or ice that stayed around for several years,” Meier said. “Now it’s becoming more of a seasonal ice cover and large areas are now prone to melting out in summer.”

Because of this, he said, what’s occurring now is an overall thinning of the multiyear ice cover, as well as a decrease in the seasonal ice cover.

That thinning continues throughout the entire year because the ice in the wintertime is also thinner than it used to be, reflecting what Meier calls “another big change in the Arctic sea ice system.”

Meier worries about changes to the Arctic, and consequently Earth’s weather systems, should this trend of escalated sea ice melt continue.

The sea ice is very reflective, it’s white and reflects most of the sun’s energy, says Meier. Because there is continuous daylight during the Arctic summer, most of that solar energy is reflected back into space; it doesn’t warm things and helps keep the Arctic cool. Meier calls this process not only the Arctic’s “air conditioner,” but also the entire Earth’s “air conditioner” as well.

“As we lose that sea ice in the summertime,” says Meier, “it gets replaced by the ocean which is very dark relative to the sunlight. It absorbs most of that energy, reflects very little of it, and that energy then heats up the ocean, which heats up the atmosphere and makes the entire Arctic warmer than it normally would be without sea ice.”

Animals which have long resided in the Arctic, such as the polar bear, could be in danger if the current trend of Arctic sea ice melt continues (Photo: Yukon White Light on Flickr/Creative Commons)

This causes greater warming, taking what has been the globe’s air conditioner and kind of “draining out the coolant,” says Meier.  As a result, the ability and efficiency of that process to help cool the Earth is reduced as more and more sea ice is lost in the summertime.

There has been a sort of climate balance on Earth between cold in the polar areas and warmth in the equatorial regions. The contrast between the polar cold and the equatorial warmth, according to Meier, sets up weather patterns like the jet-stream, ocean currents, storm tracks and where, when and how much it rains.

Changes in either climate system  throw off this balance and disrupt weather patterns. There’s not enough data right now to say for sure what the exact impacts these weather changes will bring, but Meier  suspects areas that are dependent on predictable weather patterns – such as agriculture and other things needed to help sustain life on Earth – may be affected.  It’s possible, he says, that droughts may become harsher or that more flooding will occur.

Accelerated melting could also impact animals,  such as polar bears, who make their homes on the Arctic ice. Meier says some of these polar animals will find new habitats to live in, but others will be forced to either adapt to the changing climate conditions or face extinction.

Walt Meier joins us this weekend on the radio edition of Science World.  Check out the right column for scheduled air-times or listen now to the interview below.

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Study expedition crossing Drake Passage in the Southern Ocean (Photo: British Antarctic Survey (BAS))

Scientists have discovered  how carbon dioxide is drawn from the atmosphere and stored  deep in the ocean.

According to a new study published in Nature Geoscience, instead of CO² being evenly absorbed deep into the water over wide areas of the Southern Ocean, it is pulled down and locked away from the atmosphere through localized pathways  created by a combination of winds, currents and  whirlpools that are 1,000 kilometers wide.

The world’s oceans help ease climate change by absorbing carbon dioxide in a process called carbon sequestration.  The Southern Ocean is considered to be one the most important carbon sinks in the world, absorbing around 40 percent of the annual global CO² emissions.

“The Southern Ocean is a large window by which the atmosphere connects to the interior of the ocean below. Until now we didn’t know exactly the physical processes of how carbon ends up being stored deep in the ocean,” says the paper’s lead author, Dr. Jean-Baptiste Sallée from British Antarctic Survey. “It’s the combination of winds, currents and eddies that create these carbon-capturing pathways drawing waters down into the deep ocean from the ocean surface.”

Because of the Southern Ocean’s size and remoteness, researchers have only just begun to explore the mechanisms of the ocean with the help of small robotic probes called Argo floats.

The robotic probes are just over a meter in length and can dive  about two kilometers.  Eighty of these floats were set out in the Southern Ocean back in 2002  to collect information on the ocean’s temperature and salinity. Ten years of observations from these probes allowed  scientists to study this remote area of the world for the  first time.

Australian oceanographer and Southern Ocean specialist Steve Rintoul explains how the ocean absorbs CO2.
(Video: Commonwealth Scientific and Industrial Research Organisation)

The researchers were also able to gather further information, such as water temperature, salinity and pressure, by using an instrument called the CTD profiler, a cluster of sensors which records measurements as it is lowered deep into the ocean to depths of more than seven kilometers.

“Now that we have an improved understanding of the mechanisms for carbon draw-down we are better placed to understand the effects of changing climate and future carbon absorption by the ocean,” says  Sallée.”

Black coral and barrel sponge on coral reef in Saint Lucia (Photo: Chuck Savall/Marine Photobank)

More than 2,600 scientists are calling on governments worldwide to take steps to protect valuable coral reef ecosystems.

They’ve endorsed a statement  written by scientists brought together by the Center for Ocean Solutions at California’s Stanford University.

The statement was released this week to kick off the 12th International Coral Reef Symposium  being held in Cairns, Australia.

“Rising sea levels, more intense storms, changes in ocean chemistry due to air and water pollution – all these stress coral reefs,” said Steve Palumbi, an expert on corals with the Center for Ocean Solutions and the chief organizer in developing the consensus statement. “At least 25 percent of the world’s coral reefs have been degraded.  Because of the global origin of climate change, the only way to tackle this is through a worldwide effort.”

The  statement calls on governments to take action through global initiatives to reduce emissions of carbon dioxide and other greenhouse gases, and to increase local protection of coral reefs throughout the world.

A rare moment during the process of coral bleaching.  When corals are stressed by various changes in their conditions they blow out the symbiotic algae that live in their tissues, causing them to turn completely white(Photo: Ryan Goehrung/Marine Photobank)

The scientists referred to the world’s coral reefs as important ecosystems which, despite being ecologically, economically and culturally valuable, are in decline everywhere due to human-based factors such as pollution, sedimentation, overfishing and climate change, all of which, they say, are expected to rise in severity.

The statement lists changes  scientists have already been observed over the last century:

• Approximately 25-30% of the world’s coral reefs are already severely degraded by local impacts from land and by over-harvesting.
• The surface of the world’s tropical oceans has warmed by 0.8°C, resulting in unprecedented coral bleaching and mortality events.
• The acidity of the ocean’s surface has increased due to increased atmospheric CO2.
• Sea-level has risen on average by 18cm.

Unless action is taken now,  future impacts on coral reefs could include:

• Most corals will face water temperatures above their current tolerance.
• Most reefs will experience higher acidification, impairing calcification of corals and reef growth.
• Rising sea levels will be accompanied by disruption of human communities, increased sedimentation impacts and increased levels of wave damage.
• Together, this combination of climate-related stressors represents an unprecedented challenge for the future of coral reefs and to the services they provide to people.

The International Coral Reef Symposium, which runs through July 13, is held once every four years. Organizers say  this year’s symposium will draw more than 2,000 scientists from 80 countries. They’re expected to present cutting-edge science and to share the latest advances in coral reef conservation.