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Planeta Tierra Desbalanceado

Earth unbalanced
Life on griddle Earth

By LOUIS BERGERON

Lately, global warming seems like it’s everywhere, and that’s not just geographically speaking. It’s in the press, on the radio and all over the television, too. There was a time when the best way to escape the heat was to go see a movie, but with Al Gore’s film, An Inconvenient Truth, making the rounds, even a theater provides no respite.

Is there no escaping it? Probably not. It is, after all, global and its reach will be felt across the planet. According to news reports of a draft analysis by the world’s leading climate scientists, the Intergovernmental Panel on Climate Change, by 2080 up to 7 million more homes will be threatened by coastal flooding, up to 600 million more people will go hungry and up to 3.2 billion will be hurt by lack of water. Diseases borne by insects, rodents and foul waters will spread. And more of us will die from intense heat waves and declining air quality.

It’s not a pretty picture. But the United States is so large and environmentally diverse, the impact of warming will vary from one region to another. Could there be parts of the country where health will be just mildly affected? Might things even improve for some?

Coastal concerns

Pity the Pacific Islanders, whose balmy atolls are being slowly inundated by a sea already swelling from thermal expansion. Most of the United States is higher in elevation than landmasses founded on coral reefs, though, so if the sea level rise isn’t too extreme, the worst effects might be confined to deltas, estuaries and other lowlands, like New Orleans’ Ninth Ward.

But that’s a big if. The IPCC’s 2007 report predicts up to an 11.5 F rise in temperature over the course of this century and a sea level rise of up to 2 feet. But that estimate of sea level rise leaves out the full effects of ice melting in Antarctica and Greenland. Recent studies in Science show the ice sheet covering Greenland is melting two to three times as fast as was thought just five years ago. The ice sheet probably won’t disappear by 2100, but it appears to be melting on a scale of centuries rather than millennia. By the time the last ice crystal has liquified, that sheet alone will have added about 20 feet to sea level, affecting major coastal cities like New York.

Still, most folks can shuffle out of the way of a sea pursuing them at less than a half-inch a year. It’s the indirect effects that’ll get them. Like hurricanes. Warm water powers hurricanes, and warmer waters will spawn stronger ones. According to climate scientist and policy analyst Stephen Schneider, PhD, the Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies and a senior fellow at the Woods Institute for the Environment, weather records show that the last 30 years have seen a substantial increase in Category 5 hurricanes, of which Katrina in 2005 was an example. Sustained winds over 150 mph and storm surges over 30 feet high will be hard to dodge along most any coastline.

Katrina can’t necessarily be laid at the feet of global warming, but Schneider notes, given that global temperatures have risen 1.2 F in the last 150 years, it’s likely that the increase in strong hurricanes over the past few decades is at least partially due to global warming.

And some of the most damaging health effects don’t kick in until the storm dies down. That’s when retreating floodwaters wash raw sewage and other contaminants out into the sea. When a lack of potable water triggers outbreaks of diarrhea and other intestinal ills. When mold and fungus begin to flourish in the sea-soaked walls of houses and move into people’s lungs, exacerbating asthma and other respiratory diseases.

Similar to the increase in severe hurricanes is a predicted increase in violent rainstorms, which will unleash more intense runoff episodes, ferrying contaminants from soil to sea. Coastal burgs that once vied for titles like “Surf City, USA” may find themselves christened with new nicknames. Like it or not, some town’s probably going to win the uncoveted title of “E. coli capital of America.”

The rise in sea surface temperature will provide a thriving environment for dinoflagellates, one-celled organisms that cause toxic red tides, thus poisoning marine life and sickening humans who eat or inhale them, says environmental health physician Jonathan Patz, MD, at the University of Wisconsin-Madison. Cholera, too, might avail itself of the welcoming warmer waters. Gulf Coast sushi? No thanks.

Okay, so the coasts might be in for a rough time. Perhaps it’s best to move inland: the rural realm of red barns, the lonesome high plains and the cozy woodland. But, will the old homestead provide a haven from the heat?

Down (and out?) on the farm

One effect of global warming already manifest is a longer growing season. Coupled with warmer days and nights, the result is that on average, corn reaches the elephant’s eye a little earlier each year.

“Usually the simulations come out that warming — up to a couple of degrees — is likely to increase the potential for food production overall in North America,” says Chris Field, PhD, professor of biological sciences and director of the Carnegie Institution’s global ecology department. “Expected crop yields tend to go up a little bit in the northern parts and down a little bit in the southern parts.”

Mosquitoes will lay eggs more times over a longer growing season, says William Reisen, PhD, research entomologist at the Center for Vector-borne Disease Research at UC-Davis. Eggs will mature and hatch faster. Any viruses such as West Nile or encephalitis ingested by mosquitoes will move from their guts to their saliva more quickly. The result will be more mosquitoes, more of which are infectious at once.

Flowering plants typically produce more pollen in warmer weather, including that bane of the allergy sufferer, ragweed. Some studies have suggested that as temperature climbs, ragweed might crank out as much as 50 percent more pollen.

Warming is already making rainfall patterns more erratic. “Within the last century, we’ve seen a 20 percent increase in heavy rain events, and we’re going to see more droughts and more floods,” says Kristie Ebi, PhD, an independent consultant on climate and health issues and contributor to several IPCC reports.

In agricultural areas, more flooding is likely to produce more problems like the spinach scare of 2006, when spinach grown in California’s Salinas Valley was shipped around the United States with E. coli hitchhikers in its leaves. Feces from wild pigs and nearby cattle was eventually pegged as the culprit.

The droughts will bring a different set of problems. Drying soils will create more particulates available to be scooped up by the wind, adding to the growing ranks of the asthmatics. “Particulate matter is the biggest health hazard from air pollution,” says atmospheric scientist Mark Jacobson, PhD, associate professor of civil and environmental engineering. Most of the particulates that kill people are from combustion, but soil dust adds to the damage and can act as a nucleus for condensation of combustion gases, causing even more harm.

Urban angst?

If anything, the heat is likely to be worse in a city than in the surrounding countryside, says Reisen. “Cities are forming their own little environments and acting as heat sinks,” he says, noting that in Los Angeles, the average yearly temperature rose almost 3.5 F between 1951 and 2001. That change didn’t show up in rural areas in the region.

Even with ample air conditioning, the number of deaths from intense heat waves will likely continue to rise. It’s all part of the more extreme behavior of the weather already noted along the coast and out in the countryside.

And cities are just as vulnerable as rural areas to sewage system overflows, mosquito population increases and the diseases they spread. Urban areas are full of receptacles for water, such as potholes and discarded beverage cans. But most mosquitoes bite largely around dusk, and some at dawn, which could limit our exposure, for, as Ebi says, “In the mornings and evenings we tend to be indoors with the TV we love to watch — not outside with the mosquitoes.”

According to environmental health physician Patz, the smog that’s generated from the combination of sunlight and volatile organic compounds will be especially severe in cities.

Particulates will be an even worse problem in the cities than in the countryside, as engines burning fossil fuels produce plenty of particulates.

So, if city life is souring, it must be time to take off and head to that traditional refuge of those fleeing the trappings and travails of civilization, the mountains.

Head for the hills

The pristine peaks of America’s mountains tower above the plains below, but they’re still rooted in the same firmament as the rest of the country. And many of the troubles that beset other regions will come crawling up the slopes. In some cases literally, such as Lyme disease-bearing ticks moving to higher elevations, following the warming trend.

Extreme weather and warmer temperatures will reduce snowfall in winter, as well as turn what snowpack there is into mel*censored*er earlier each spring. The loss of snowfields as natural reservoirs will hurt the reliability of water supplies down in the farm fields, affecting crops, the workers who tend them and the consumers who eat them. It will also deprive the plants and animals in higher elevations of the water they need, aggravating ecosystem destruction as the less drought-tolerant creatures move off in search of water, and plants that can’t survive in a drier climate simply die.

The full effects of these drastic shifts can’t even be predicted yet, but Schneider says that virtually all the studies say that warming beyond a few degrees seems to have few if any silver linings. For one thing, a lack of water and the warmer dry seasons will promote an increase in wildfires, with more particulates thrown up into the atmosphere and sucked into people’s lungs.

Though the mountains might not have to contend with the heat of the concrete urban islands or the extra-strength hurricanes of the coast, they don’t seem scheduled to remain pristine and healthful at century’s end.

Escape to Alaska

Removed from much of the travails of the lower 48 states, not to mention the shrinking islands of Hawaii, might the 49th state fare any better? The lower elevations will, of course, be inundated by melting ice, and areas that were permafrost will likely become close to impassably muddy as the frost melts. Mosquito populations could explode.

But the average elevation of Alaska is 1,900 feet, so some areas will be high enough to stay above the mel*censored*er. Still Alaska will have to reckon with what might be the worst sort of runoff. A study in the December 2006 issue of Journal of Virology (G. Zhang et al.) cited evidence that some Arctic ice hosts viruses, bacteria and fungi that could become active as the ice thaws. If that’s correct, then influenza viruses, dormant for perhaps as long as 140,000 years, could surge out of the glacial mel*censored*er and reassert their dominance over our comparatively large and fragile bodies, with little immuno-experience to deal with them.

Nowhere to run, nowhere to hide

With an increasingly hot and generally inhospitable environment closing in on us wherever we live or go, our internal emotional temperature will likely also climb, as the stress builds up within. “Post-traumatic stress is a pretty significant mental health problem that extreme climate variability and stronger storms could really increase,” says Patz.

Just how well our health-care system will cope with the added strain of more people with emotional issues on top of the added allergic reactions, respiratory illnesses and episodic diarrheal diseases that will accompany global warming is anyone’s guess. And let’s not overlook the expected increase in encephalitis, possibly malaria and the various tick- and rodent-borne diseases.

The old saw that if you have your health, you have everything will still be true, but it’s likely to be a lot tougher to attain as the mercury rises.

Comments? Contact Stanford Medicine at
medicinemag-owner@lists.Stanford.edu


Courtesy of Stanford Medicine Magazine

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