Drought, heat linked to global warming
Monte Morin
Monday, October 15, 2012 - The worst drought in half a century has plagued two-thirds of the US, devastating farms and stoking wildfires that scorched almost 9 million acres this year. Withering heat blanketed the East Coast and Midwest, killing scores of people and making July the hottest month ever recorded in the US. And in the Arctic this summer, polar snow and ice melted away to the smallest size ever observed by man.
Extreme events like drought, heat waves, intense rainfall, flooding and fires have prompted many people to reconsider the connection between the weather and the changing climate. Now, a handful of scientists are among them. In a break with the mainstream scientific consensus, a few prominent climate scientists now argue that there have been enough episodes of drought and intense heat in the last 10 years to establish a statistical pattern of extreme weather due to global warming. Around the world, “the incidence of drought is consistent with what the climate models are predicting,” said John Seinfeld, an atmospheric researcher at Caltech. “It certainly doesn’t appear to be out of line to conclude that this last summer could be statistically attributed to global warming.” In the US, the summer ranked as the third-hottest in the nation’s history. Among laypeople, the perception that extreme weather is getting worse — and that it’s linked to climate change — is increasingly taking hold.
Nearly 75% of Americans now say global warming is affecting the weather in the US, according to a poll released this week by scientists at Yale University. The poll found that about 60% of Americans reported experiencing an extreme heat wave or drought this year, while an equal percentage said weather had worsened over the last several years. A companion poll reported earlier this year that 8 in 10 Americans had personally experienced at least one extreme weather event in the last year, and more than one-third said they had suffered as a result.
Climate scientists overwhelmingly agree that the planet is getting hotter and that mankind’s use of fossil fuels is largely responsible. When fossil fuels are burned, carbon dioxide is produced and traps heat within the atmosphere. The more that’s added, the hotter it gets. It’s not the only greenhouse gas, but it’s the one many scientists focus on because it stays in the atmosphere for hundreds or thousands of years.
The average global temperature has risen by 1.6 degrees Fahrenheit over the last century, a period that gave rise to mass-produced automobiles and commercial aviation, among other developments. Altogether, modernization has led to an 800% increase in global fossil fuel consumption since 1900, with a corresponding jump in emissions of heat-trapping greenhouse gases.
As the temperature rises, evaporation increases and draws more water from soil. Experts predict that moist areas of the planet will become wetter, while dry areas will become drier. Looking ahead, some climate scientists are predicting more extreme weather events in North America and Europe this winter — and those following — thanks to the record amount of Arctic ice melting over the summer. Last month, researchers announced that Arctic sea ice had dwindled to the smallest size ever observed by man. At about 1 million square miles, the ice mass was less than half the size it was at its smallest point 30 years ago, when satellites and submarines first began taking detailed measurements. The loss of Arctic ice has several effects. Ice reflects heat and solar energy back into space. With less ice cover, that heat energy is instead absorbed by the ocean, which warms and melts more ice.
The heating of polar seawater has also reduced the temperature difference between the Arctic and Earth’s middle latitudes. That slows down the jet stream, the river of air that flows from west to east high above Earth’s surface. The jet stream, in turn, controls the formation and movement of storm systems. The result is that weather conditions in an area persist for longer periods, according to a study published this year in Geophysical Research Letters.
— Courtesy: Los Angeles Times
Extreme events like drought, heat waves, intense rainfall, flooding and fires have prompted many people to reconsider the connection between the weather and the changing climate. Now, a handful of scientists are among them. In a break with the mainstream scientific consensus, a few prominent climate scientists now argue that there have been enough episodes of drought and intense heat in the last 10 years to establish a statistical pattern of extreme weather due to global warming. Around the world, “the incidence of drought is consistent with what the climate models are predicting,” said John Seinfeld, an atmospheric researcher at Caltech. “It certainly doesn’t appear to be out of line to conclude that this last summer could be statistically attributed to global warming.” In the US, the summer ranked as the third-hottest in the nation’s history. Among laypeople, the perception that extreme weather is getting worse — and that it’s linked to climate change — is increasingly taking hold.
Nearly 75% of Americans now say global warming is affecting the weather in the US, according to a poll released this week by scientists at Yale University. The poll found that about 60% of Americans reported experiencing an extreme heat wave or drought this year, while an equal percentage said weather had worsened over the last several years. A companion poll reported earlier this year that 8 in 10 Americans had personally experienced at least one extreme weather event in the last year, and more than one-third said they had suffered as a result.
Climate scientists overwhelmingly agree that the planet is getting hotter and that mankind’s use of fossil fuels is largely responsible. When fossil fuels are burned, carbon dioxide is produced and traps heat within the atmosphere. The more that’s added, the hotter it gets. It’s not the only greenhouse gas, but it’s the one many scientists focus on because it stays in the atmosphere for hundreds or thousands of years.
The average global temperature has risen by 1.6 degrees Fahrenheit over the last century, a period that gave rise to mass-produced automobiles and commercial aviation, among other developments. Altogether, modernization has led to an 800% increase in global fossil fuel consumption since 1900, with a corresponding jump in emissions of heat-trapping greenhouse gases.
As the temperature rises, evaporation increases and draws more water from soil. Experts predict that moist areas of the planet will become wetter, while dry areas will become drier. Looking ahead, some climate scientists are predicting more extreme weather events in North America and Europe this winter — and those following — thanks to the record amount of Arctic ice melting over the summer. Last month, researchers announced that Arctic sea ice had dwindled to the smallest size ever observed by man. At about 1 million square miles, the ice mass was less than half the size it was at its smallest point 30 years ago, when satellites and submarines first began taking detailed measurements. The loss of Arctic ice has several effects. Ice reflects heat and solar energy back into space. With less ice cover, that heat energy is instead absorbed by the ocean, which warms and melts more ice.
The heating of polar seawater has also reduced the temperature difference between the Arctic and Earth’s middle latitudes. That slows down the jet stream, the river of air that flows from west to east high above Earth’s surface. The jet stream, in turn, controls the formation and movement of storm systems. The result is that weather conditions in an area persist for longer periods, according to a study published this year in Geophysical Research Letters.
— Courtesy: Los Angeles Times
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