Cost of fighting warming ‘modest,’ says UN panel (from @AP)
Over the past 30 years, we’ve made tremendous scientific gains in understanding how marine ecosystems work while monitoring the impacts of fishing and other extractive activities on the health of our oceans. What’s more, the application of new science, along with critical reforms of key laws…
Climate impacts ‘overwhelming’ - UN @ BBC
IPCC report: Climate change a threat to security, food and humankind: Warming is leading to more volatile weather patterns that are already reducing crop yields, the IPCC has warned @ Guardian
A Changing Climate Creates Pervasive Risks but Opportunities Exist for Effective Responses - IPCC Report @ UNEP
After canoeing through the Colorado River delta in 1922, naturalist Aldo Leopold described it as a landscape of a “hundred green lagoons.” Nearly a century later, canoes are no longer an option, and a more fitting description of the area would include the words “brown” and “parched.”
Due to increasing demand for Colorado River water by the United States and Mexico, the final stretch of the Lower Colorado has virtually disappeared. It has been decades since the Colorado flowed all the way through Mexico to the Gulf of California. Major spring floods are a rarity, and the lower reaches of the river only flow after rainstorms or when agricultural runoff drains into the dried riverbed.
The effects on the delta ecosystem have been profound. Willow and cottonwood forests that used to thrive along the Colorado’s banks and in its wetlands now struggle to survive, while a drought-adapted invasive shrub called salt cedar (tamarisk) dominates. Populations of birds and other animals have dwindled. According to ecologists, only 10 percent of the Colorado’s original wetlands remain, with just 3 percent of cottonwood and willow forests surviving.
On March 23, 2014, researchers and water managers plan to bring some water—and, hopefully, some life—back to the Lower Colorado River. The floodgates at a diversion dam near the U.S.-Mexico border will be opened, sending a pulse of water rushing toward the delta once again. The “pulse flow” from Morelos Dam is intended to simulate spring floods of the past. After the water subsides, ecologists expect to see a wave of green emerge, as the fresh water flushes away salts and helps cottonwood and willow seeds germinate.
Morelos, the southernmost dam on the river, straddles the border near Los Algodones, Sonora (Mexico), and Yuma, Arizona (U.S.). Storage dams upriver released water earlier this year, and the Morelos dam is the last barrier before the delta. The Operational Land Imager (OLI) on the Landsat 8 satellite captured this image of the area around Morelos Dam on March 8, 2014. Normally, all of the remaining river water at this point gets diverted into a canal, which is used to irrigate farms in northern Mexico. A small amount of water does seep around, causing a small flow in the river immediately south of the dam.
Before dams were built, approximately 18,500 million cubic meters (15 million acre-feet) of water flowed down the Colorado River to the Pacific Ocean each year. This year’s pulse flow—the product of an historic agreement called Minute 319—a total of 130 million cubic meters (105,000 acre-feet) of water will be released over an eight-week period. While small in comparison to the natural floods of the past, scientists think it will be enough to trigger some dramatic changes downstream.
Edward Glenn, an environmental scientist from the University of Arizona, is among a group of scientists who first argued that relatively modest pulse floods could have a major impact on downstream ecosystems. Glenn and colleaguesanalyzed decades of Landsat imagery and found that the willows and cottonwoods responded surprisingly well to sporadic floods that occurred in the 1990s during wet El Niño years.
Glenn plans to use Landsat 8 and other satellite imagery to monitor changes this time as well. “What we’re trying to do here is a really big deal,” he said. “Nobody has done an international restoration project using a pulse flow on such a large scale before.”
- Flessa, K. et al (2013, December 10) Flooding the Colorado River Delta: A Landscape-Scale Experiment. EOS, 94 (50), 485-496. Accessed March 20, 2014.
- International Boundary and Water Commission Minute 319 Environmental Flow. Accessed March 20, 2014.
- Leopold, A. A Sand County Almanac: The Green Lagoons. Accessed March 20, 2014.
- Nagler, P. et al (2005, October 25) Regeneration of Native Trees in the Presence of Invasive Saltcedar in the Colorado River Delta, Mexico. Conservation Biology, 19 (6), 1842-1852 Accessed March 20, 2014.
- New Scientist (2014, March 12) Huge water pulse to bring Colorado river back from dead. Accessed March 20, 2014.
- National Geographic News archive for Minute 319. Accessed March 20, 2014.
- NPR (2011, July 14) Why the Colorado River Stopped Flowing. Accessed March 20, 2014.
- Science Insider (2014, March 18) U.S. and Mexico Unleash a Flood to Restore Colorado River Delta. Accessed March 20, 2014.
- The Nature Conservancy Colorado River: Explaining the Delta Pulse Flow. Accessed March 20, 2014.
NASA Earth Observatory image by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey.Caption by Adam Voiland, with information from Karl Flessa (University of Arizona), Edward Glenn (University of Arizona), Eloise Kendy (The Nature Conservancy).Instrument(s): Landsat 8 - OLI
The sea has protected Venice since the fifth century, when people moved to the fish-shaped islands of Rialto for safety from mainland invaders. Over the next thirteen centuries, the seafaring city-state grew in power and strength. The art, architecture, and history amassed in the small “floating city” of Venice has earned it a place on the UNESCO list of World Heritage Sites.
But the tide has turned, and the sea that once protected Venice now threatens it. Nestled in the Venetian Lagoon, the 118 low-lying islands of modern-day Venice are separated from the Adriatic Sea by a 45-kilometer (28-mile) chain of barrier islands. The Adriatic connects to the lagoon via three inlets—the Lido, Malamocco, and Chioggia.
The sea now imperils Venice because of three conflated issues: groundwater pumping and offshore gas drilling have caused the city to subside; sea level has been rising; and natural tidal protections like mudflats and marshes have been disrupted over the past century. River courses have been made rigid, inlets have been widened, and the lagoon has been dredged to create shipping channels; adjustments to make boating and shipping safer have helped make the land more vulnerable.
The city now regularly experiences Acqua Alta, or high water, when the tide inundates the streets and squares, menaces the historic architecture, and forces citizens to don galoshes. In 1900, such events occurred ten times per year. NowAcqua Alta, happens more than 60 times per year.
In November 1966, two days of heavy rain coincided with high tides, a static low-pressure system, and a severe Siroccowind that drove 2 meters (six feet) of water into Venice. The flood destroyed millions of dollars of artwork, wrecked businesses, and left thousands of people homeless. The event prompted many people to think that the city was doomed unless some sort of intervention was made.
After decades of debate, construction began in 2003 on a major engineering project called MOSE. The project acronym stands for MOdulo Sperimentale Elettromeccanico (Experimental Electromechanical Module) and alludes to the parting of the Red Sea by Moses. The concept behind MOSE is to temporarily separate the Venetian Lagoon from the Adriatic Sea when unusually high tides occur. This is done through a series of 78 gates that seal the lagoon’s three inlets.
Each gate is approximately 30 meters high (98 feet), 20 meters wide (65 feet), 5 meters thick (16 feet), and weighs 300 tons. During normal tides, each of the massive gates lie on a concrete foundation on the seabed, with one end hinged to steel and concrete pilings. When high tide exceeds 87 centimeters (34 inches) above mean sea level, compressed air is pumped into the gates until they slowly pivot upwards. Raising the gates takes about one hour. In a high-tide event, the gates will likely remain in place for four to five hours until the waters subside; then they will be filled with water and lowered back to their seabed berths.
The natural-color Landsat images above show some of the MOSE engineering efforts that are visible above the water line near the Lido Inlet. The top image was acquired on June 20, 2000, by the Enhanced Thematic Mapper+ on Landsat 7. The second image, from the Operational Land Imager on Landsat 8, was collected on September 4, 2013. Turn on the image comparison tool to make the changes easier to see. (Note that Landsat 8 has a greater dynamic range than Landsat 7, so the Landsat 8 image is crisper the Landsat 7 image.)
In 2013, a curved breakwater stands just south of the inlet’s south jetty. On the lagoon side of the Lido Inlet, a new manmade island appears; it houses the buildings and plants that operate the gates, which are underwater in two arrays on either side of the island. On the north side of the inlet, a manmade harbor for small vessels includes a small lock system that allows boats to pass from the lagoon to the sea when the gates are raised.
Since the beginning of MOSE construction, five million cubic meters of sediment have been excavated from areas adjacent to the lagoon’s three inlets. The $8.8 billion dollar project has encountered some scientific, environmental, and political objections about disrupting the natural water exchange between the lagoon and Adriatic.
The Lido Inlet gates were successfully tested on October 12, 2013, and operators aim to have the MOSE system fully functional by 2016.
References and Related Reading
- An Engineer’s Excuse to Travel (2013, February 21) The MOSE Project. Accessed March 20, 2014.
- Comerlati, A., et al (2003, December 9) Can CO2 Help Save Venice from the Sea? Eos, Transactions, American Geophysical Union 84 (49) 546–553.
- Engineering.com (2013, October 28) Can High Tech Flood Gates Save Venice? Accessed March 20, 2014.
- European Space Agency (2014, March 7) Earth Watching: Venice, Italy. Accessed March 19, 2014.
- Nosengo, N., (2003, August 7) Save Our City! Nature 424, 608–609.
- The Telegraph (2013, October 13) ‘Moses project’ to secure future of Venice. Accessed March 19, 2014.
- Water-technology.net MOSE Project, Venice, Venetian Lagoon, Italy. Accessed March 20, 2014.
NASA Earth Observatory images by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey.Caption by Laura Rocchio.
5 Climate Policy Priorities That Should Top President Obama’s To-Do List
A quick review of the past year reveals that President Obama has made important strides toward accomplishing most of our second-term priorities. His historic Climate Action Plan, announced in June, should achieve many of these goals if it is fully implemented and enforced.
Despite this progress, we need more swift action to slow climate change and prevent further damage from fossil-fuel pollution …
LONDON — For years, Europe has tried to set the global standard for climate-change regulation, creating tough rules…
Inequality may be very harmfull for economic growth. Extreme rich people cant spent their money no matter wath they try. Poor people have to spend every penny. Only the politician can do something about it. E.G. raising the minimum wage twice as much as inflation.