Courtesy Mark RyanWhat a difference a year can make. The water levels of the Mississippi River this year are at their lowest on record, yet just last year, in the spring of 2011, extreme flooding of Ol’ Muddy was a source of deep concern for those living along its eroding banks.
NASA’s Earth Observatory page shows the striking difference in the river’s appearance near Memphis using two Landsat satellite images taken a year apart. One photograph shows the river in August of 2011 just after the river returned to its pre-flood levels. But if you compare it to a more recent image, its obvious that water levels have gone the opposite direction from flooding. The site conveniently allows you to combine the two views into a single image with a scroll bar you can manipulate back and forth over to see “then and now” differences (just click on the "View Image Comparison" button below the photos).
The lower levels of 2012 have allowed the US Army Corp of Engineers to patch and reinforce some of the levees built along the river to hold back flood waters, but tons of sediment from last year’s floods have reshaped river traffic corridors, reducing barge holding capacities and adding additional shipping costs.
An opinion piece in the Sunday, August 12, 2012 New York Times by three scientists (listed at the end) deserves repeating. Here are some excerpts:
Until recently, many scientists spoke of climate change mainly as a “threat,” sometime in the future. But it is increasingly clear that we already live in the era of human-induced climate change, with a growing frequency of weather and climate extremes like heat waves, droughts, floods and fires.
In terms of severity and geographic extent, the 2000-4 drought in the West exceeded such legendary events as the Dust Bowl of the 1930s. More seriously still, long-term climate records from tree-ring chronologies show that this drought was the most severe event of its kind in the western United States in the past 800 years.
Most frightening is that this extreme event could become the new normal: climate models point to a warmer planet, largely because of greenhouse gas emissions. Planetary warming, in turn, is expected to create drier conditions across western North America, because of the way global-wind and atmospheric-pressure patterns shift in response.
The current drought plaguing the country is worryingly consistent with these expectations. Although we do not attribute any single event to global warming, the severity of both the turn-of-the-century drought and the current one is consistent with simulations accounting for warming from increased greenhouse gases.
And yet that may be only the beginning, a fact that should force us to confront the likelihood of new and painful challenges. A megadrought would present a major risk to water resources in the American West, which are distributed through a complex series of local, state and regional water-sharing agreements and laws. Virtually every drop of water flowing in the American West is legally claimed, sometimes by several users, and the demand is expected to increase as the population grows.
There is still time to prevent the worst; the risk of a multidecade megadrought in the American West can be reduced if we reduce fossil-fuel emissions. But there can be little doubt that what was once thought to be a future threat is suddenly, catastrophically upon us.
(Christopher R. Schwalm is a research assistant professor of earth sciences at Northern Arizona University. Christopher A. Williams is an assistant professor of geography at Clark University. Kevin Schaefer is a research scientist at the National Snow and Ice Data Center)
Courtesy Mark Svoboda, National Drought Mitigation Center.
Courtesy Tomas CastelazoIt was just a few weeks ago we posted incredible pictures and video of devastating floods ripping through Duluth. Now, on a national scale, the weather story is drought. But how bad is it really?
Depends on where you live, but much of the Midwest is falling into drought conditions. It's bad, but not as wide spread as the peak of U.S. drought conditions from 1934. USA Today has an interesting toggle map that allows you compare today's conditions with that record drought.
Even earlier this summer, heavy rains in the Twin Cities had lockmasters along the Mississippi River shutting their gates to control fast-flowing river water. Now downstream, the Mississippi is approaching record-level lows. In some areas around Memphis, the river level has fallen 55 feet from highs set last summer. This CNN website report has interesting satellite images of the newly slimmed Mississippi compared to last year's look.
What do you think of this crazy weather? Share your thoughts here with other Buzz readers.
Twin Cities TV meteorologists can only dream about reporting on this. It's pretty amazing footage of a fire tornado forming in Brazil in an area experiencing wild fires.
Courtesy Mark GobleScientists know that the Amazon rainforest can help to slow down climate change. The trees not only take in carbon dioxide and release oxygen, but they also are made of carbon. All living things are made of carbon, and when these things die that carbon is released.
There was an unusually severe drought in 2005, which gave scientists a preview of the Amazon's future climate. Scientists think the rainforest will see hotter and more intense dry seasons with climate change. When Oliver Phillips a professor at the University of Leeds, looked at the effects of the drought, he found that it caused carbon losses in the rainforest. This is bad for us, because we rely on the Amazon to take in carbon dioxide, not release it!
In most years the Amazon absorbs almost 2 billion tons of carbon dioxide. In 2005, the trees did not absorb that much carbon dioxide, but the forest lost more than 3 billion tons. The losses were caused by all the trees that died in the drought. The impact of the drought, 5 billion extra tons of carbon dioxide is more than the annual emissions of Europe and Japan put together.
Courtesy RmhermenVacation season is upon us and if you're planning to go to Yellowstone National Park, prepare to wait a little bit longer to see Old Faithful erupt. Due to several years of drought, the iconic geyser has been erupting at longer intervals in recent years. Read more about it here to find out excactly how much longer the waiting time is between eruptions.
And that could speed up global warming with 'incalculable consequences', says alarming new research. Studies by the blue-chip Woods Hole Research Centre, carried out in Amazonia, have concluded that the forest cannot withstand more than two consecutive years of drought without breaking down. And that process, which would be irreversible, could begin as early as next year.
For those who'd like some perspective, the Amazon rainforest represents half the rainforests in the world. It encompasses 1.2 billion acres, or 1.875 million square miles. That's 3.25% of the planets land mass. That’s a huge chunk of land. So if this report is accurate, it’s far from being insignificant.
The Amazon now appears to be entering its second successive year of drought, raising the possibility that it could start dying next year. The immense forest contains 90 billion tons of carbon, enough in itself to increase the rate of global warming by 50 per cent.
Read more from The Independent (U.K.), July 23, 2006
Two months ago I spent a week canoeing, portaging, and camping in the Boundary Waters Canoe Area. I visited many lakes, including Seagull Lake at the end of the Gunflint Trail. Today, the landscape of some of the lakes I visited is changing dramatically as fires move through the area. The Cavity Lake Fire is presently spanning about 22,000 acres. It is hard for me to imagine that some of the serene forests I awed at and some of the campsites I relaxed at are now merely ashes.
The wildfires in northern Minnesota got me thinking about the science behind forest fires. Forest fires (also called wildfires) are a natural occurrence. Lightning is the most common natural cause of the fires. Human carelessness and arson are unnatural causes. Droughts in the summer and high winds in the fall make areas more susceptible to forest fires.
The Cavity Lake Fire is a result of lightning. The drought conditions have created a dry wooded environment. Anyone who has a fireplace knows that the driest wood burns the best.
Also, this fire is moving through an area full of debris left over from a blowdown from a storm in 1999. There is unfortunately plenty of fuel to keep this fire going.
Most of the damage from this fire may not be apparent until it's over. The after effects of forest fires can be even more harmful than the fires themselves. Erosion, introduction of invasive species, landslides, and changes in water quality are a few of these negative outcomes.
While wildfires sound like a horrible catastrophe, they can actually be beneficial for an ecosystem. Periodic fires can help the overall health of the forest. They are important for nutrient cycling, improving habitats, and maintaining biodiversity.
It can actually be more harmful to prevent wildfires than to let them happen naturally. Suppression can lead to more dangerous and hotter fires, because the time without fires allows more time for debris to accumulate.
I am interested in revisiting Seagull Lake to see how the fire has altered the ecosystem I remember. From the photos, I can see it beginning to change.