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.

Turns out obesity isn’t just a health issue;  all of that overeating could seriously cut into the future world food supply.

According to a new study from Great Britain, if the current worldwide obesity epidemic continues unabated, maintaining enough food to feed the world could actually become a much more serious challenge.

Right now, the world’s population is over seven billion, and growing.  The more people there are, the more food and resources are needed.

According to the London School of Hygiene & Tropical Medicine,  the weight of the human population should be taken into consideration – in addition to the number of people in the world -  when determining future food security and environmental sustainability.

Using data from various studies, researchers determined the world’s adult population weighs 287 million metric tons, or 287 billion kilograms.

Separately, we each weigh an average of 62 kilograms, but that average varies from country to country.

Researchers estimate 15 million of that 287 metric tons is due to those who are overweight, while 3.5 million metric tons are due to obesity.

North Americans have the highest body mass of any continent, according to the study, with an average body mass of 80.7kg.

While North America has only about six percent of the world’s population, it contributes 34 percent of the world’s biomass.

Asians, on the other hand, whose average weight is 58 kilograms, make up around 61 percent of the world’s population, but they’re only responsible for roughly 13 percent of the world’s biomass.

Among nations,  the United States came in as the “heaviest” country, while Eritrea was the “lightest”.

The researchers also looked at how those who are overweight and obese impact the total weight and averages.

Keep in mind that there is a difference between being overweight and obese.

You’re considered to be overweight when you weigh more than the weight that is appropriate for your height and bone structure or have a Body Mass Index (BMI) of 25 or greater.

If you have BMI of 30 or more, medical experts consider you to be obese.

Experts say that up to half of all food that is eaten is burned up by various physical activities.  But as your weight rises, your energy requirements increase as well, because it takes more energy to move a heavy body.

Even when at rest, those who have a bigger body mass burn more energy.

So, the bigger you are, the more energy you’ll need; the more energy you need means you must eat more; the more food eaten by a growing world population could  then, in turn, impact affect food supplies and future food security.

Soybeans being harvested (Photo: Jake was here via Wikimedia Commons)

The domino effect of a heavier populace can also affect environmental sustainability.  Because in order to feed, cool or warm and transport a heavier population, more natural resources, such as fossil-fuels, will be needed and consumed.

Sarah Walpole, a practicing medical doctor who co-authored the study,  worries people from developing nations, who tend to be thinner than those in developed countries, will be most at risk of food insecurity.

“If our global consumption for food or our demand for food are increasing, it going to be those poor populations that feel the impact most,” she says.

One of the areas researchers want to study next is the impact the global child population has on the world’s total human biomass.

Dr. Walpole joins us on this week’s radio edition of “Science World.”  Check out the right column for scheduled air-times or listen to the interview with Dr. Walpole below.

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Other stories we cover on the “Science World” radio program this week include:

• Kenyan conservationists preserve endangered sea turtles
• Ocean levels rising faster on US coasts than elsewhere in the world
• 2009 swine flu deaths were much higher than first reported
• Crisis mapping helps first-responders do their jobs in times of disaster
• Gastric Bypass Surgery, Alcohol Not a Good Mix for Some