Humans Are to Blame for Rapidly Melting Glaciers
Human influence is melting glaciers, including the Artesonraju Glacier in Peru.
John Hyde/Design Pics/Corbis
The effects of global warming are frequently projected decades into the future, but two recent reports -- one from theU.S. Global Change Research Program
and the otherfrom the U.N.
-- put into sharp focus visible consequences of our warming planet. An increase in temperature, extreme weather, loss of ice and rising sea level are just a few of changes we can measure right now. Let's take a look at some of the most concerning trends.BLOG: War Of The Words: Climate Change Or Global Warming?
Glaciers are shrinking worldwide and permafrost is thawing in high-latitude and high-elevation areas, reports this year's Fifth Assessment Report from the Intergovernmental Panel on Climate Change.BLOG: Dire Outlook For Climate Impacts, New Report Says
Only a few extinctions are attributed to climate change, reports the IPCC, but climate change that occurred much more slowly, over millions of years, caused major ecosystem shifts and species extinctions. Land and sea animals are changing their geographic ranges and migratory patterns due to climate change.NEWS: Climate Change: Why Haven't We Done More?
Sea level around the world has increased by about 8 inches since 1880, reports the 2014 National Climate Assessment, which projects a 1 to 4 foot rise by the end of the century.PHOTOS: Craziest Environmental Ideas (That Could Work)
Massimo Brega/The Lighthouse//Vi/Visuals Unlimited/Corbis
Excess CO2 is dissolving in the ocean and decreasing the pH of seawater. The ocean is about 30 percent more acidic than it was in pre-industrial times. More acidity in the oceans makes it harder for animals to form calcium carbonate shells and skeletons and erodes coral reefs.11 Health Threats from Climate Change
The probability of a Sandy-like storm deluging New York, New Jersey and other parts of the East Coast has nearly doubled compared to 1950, according to the American Meteorological Society. Even weaker storms will be more damaging now than they were 10 years ago because of rising sea levels. Superstorm Sandy cost the nation $65 billion, according to the 2014 National Climate Assessment, and 2012's Hurricane Isaac cost $2.3 billion.
The global sea level rises along with the temperature for two major reasons. For one, heat causes water to expand, which causes the existing water to take up more space and encroach on the coast. At the same time, ice at the poles and in glaciers melts and increases the amount of water in the oceans.PHOTOS: Melting Glaciers
Across the United States, heavy downpours are on the rise, especially in the Northeast and Midwest. Increases in extreme precipitation are expected for all U.S. regions, reports the 2014 National Climate Assessment.NEWS: Shrinking Greenland Glacier Smashes Speed Record
Ted Soqui/Ted Soqui Photography/Corbis
The most recent IPCC report states with "very high confidence" that current climate-related extremes like heat waves, droughts, floods, cyclones and wildfires are showing that countries around the world, at all development levels, are significantly unprepared. The American Meteorological Society estimates that approximately 35 percent of the extreme heat in the eastern United States between March and May 2012 resulted from human activities' effects on climate. The AMS warned that deadly heat waves will become four times more likely in the north-central and northeastern United States as the planet continues to warm.NASA: Global Warming Goes On
The steady melt of glacial ice around the world is largely due to man-made factors, such as greenhouse-gas emissions and aerosols, a new study finds.
Humans have caused roughly a quarter of the globe's glacial loss between 1851 and 2010, and about 69 percent of glacial melting between 1991 and 2010, the study suggests.
"In a sense, we got a confirmation that by now, it is really mostly humans that are responsible for the melting glaciers," said lead researcher Ben Marzeion, an associate professor of meteorology and geophysics at the University of Innsbruck in Austria. [Images of Melt: See Earth's Vanishing Ice]
Vanishing glaciers are often associated with global warming, and other studies have estimated past ice loss and made projections of future melt. But until now, researchers were unsure how much glacial loss was tied to human factors.
"So far, it has been unclear how much of the observed mass losses are caused by humans rather than natural climate variations," Regine Hock, a professor of geophysics at the University of Alaska Fairbanks who was not involved in the study, wrote an in email to Live Science.
The researchers used "state-of-the art modeling techniques," in their work, Hock said.
The research team relied on 12 climate models, most of them from the latest reports from the Intergovernmental Panel on Climate Change, an international group of climate-change experts convened by the United Nations. By combining the models, along with data from the Randolph Glacier Inventory (a catalog of nearly 200,000 glaciers), the researchers created a computer model that included only natural contributions to glacier melt, such as volcanic eruptions and solar variability, and another model with both human and natural factors.
Using data from 1851 to 2010, the researchers compared the two models with real measurements of glaciers to determine which one better represented reality. The study did not include glaciers in Antarctica, because not enough data on the region was available during the 159 years covered by the study.
The model with the man-made influences was a better fit, they found.
Human influence is melting glaciers, including the Artesonraju Glacier in Peru.Ben Marzeion
"Glaciers thin and retreat around the world as a result of rising air temperature, but the glaciers don't care whether or not the increase in temperature is due to natural or human causes," Hock said. "Over the last 150 years, most of the mass loss was due to natural climate variability, caused, for example, by volcanic eruptions or changes in solar activity.
"However, during the last 20 years, almost 70 percent of the glacier mass changes were caused by climate change due to humans," she wrote.
Interestingly, the study found that glaciers, which are slow to react to climate change, are still recovering from the end of the Little Ice Age that lasted from the 14th to the 19th centuries. During the Little Ice Age, temperatures were about 1.8 degrees Fahrenheit (1 degree Celsius) colder than they are today.
Warmer temperatures after the Little Ice Age affected the glaciers. "Essentially, what we find is that glaciers would be melting without any human influence," Marzeion told Live Science.
The melt, however, would not be happening as quickly as it is today if it weren't for man-made contributions, such as aerosols from wood or coal fires, he said. Aerosols are particles suspended in the atmosphere that absorb and scatter the sun's radiation.
Even if climate change from both man-made and natural causes stopped today, the glaciers would continue to melt and are projected to raise ocean levels by 2.7 inches (7 centimeters) during this century, Marzeion said.
As global temperatures continue to rise, the glaciers will continue to disappear. The melt may provide more water for irrigation and other needs, but it won't be sustainable because the glaciers may eventually vanish, Marzeion said. In the meantime, people can try to reduce man-made contributions to global warming and adapt to the changing planet, he said.
The study was published online today (Aug. 14) in the journal Science.
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