Earth Watch Report – Saturday August 25th, 2012
August 25, 2012 by desertrose
Climate Change
Drastic desertification: Researchers study Dead Sea climate past, finding dramatic results
Over the past 10,000 years, climate changes in the Dead Sea region have led to surprisingly swift desertification within mere decades. This is what researchers from the University of Bonn and their Israeli colleagues found when analyzing pollen in sediments and fluctuations in sea levels, calling the findings ‘dramatic.’ They are presented in the current issue of the international geosciences journal Quaternary Science Reviews, whose print version is published on 23 August.
The Dead Sea, a salt sea without an outlet, lies over 400 meters below sea level. Tourists like its high salt content because it increases their buoyancy. “For scientists, however, the Dead Sea is a popular archive that provides a diachronic view of its climate past,” says Prof. Dr. Thomas Litt from the Steinmann-Institute for Geology, Mineralogy and Paleontology at the University of Bonn. Using drilling cores from riparian lake sediments, paleontologists and meteorologists from the University of Bonn deduced the climate conditions of the past 10,000 years. This became possible because the Dead Sea level has sunk drastically over the past years, mostly because of increasing water withdrawals lowering the water supply. Oldest pollen analysis In collaboration with the GeoForschungsZentrum Potsdam (German Research Centre for Geosciences) and Israel’s Geological Service, the researchers took a 21 m long sediment sample in the oasis Ein Gedi at the west bank of the Dead Sea. They then matched the fossil pollen to indicator plants for different levels of precipitation and temperature. Radiocarbon-dating was used to determine the age of the layers. “This allowed us to reconstruct the climate of the entire postglacial era,” Prof. Litt reports. “This is the oldest pollen analysis that has been done on the Dead Sea to date.” In total, there were three different formations of vegetation around this salt sea. In moist phases, a lush, sclerophyll vegetation thrived as can be found today around the Mediterranean Sea. When the climate turned drier, steppe vegetation took over. Drier episodes yet were characterized by desert plants. The researchers found some rapid changes between moist and dry phases.
Transforming pollen data into climate information The pollen data allows inferring what kinds of plants were growing at the corresponding times. Meteorologists from the University of Bonn took this paleontological data and converted it into climate information. Using statistical methods, they matched plant species with statistical parameters regarding temperature and precipitation that determine whether a certain plant can occur. “This allows us to make statements on the probable climate that prevailed during a certain period of time within the catchment area of the Dead Sea,” reports Prof. Dr. Andreas Hense from the University of Bonn’s Meteorological Institute. The resilience of the resulting climate information was tested using the data on Dead Sea level fluctuations collected by their Israeli colleagues around Prof. Dr. Mordechai Stein from the Geological Services in Jerusalem. “The two independent data records corresponded very closely,” explains Prof. Litt. “In the moist phases that were determined based on pollen analysis, our Israeli colleagues found that water levels were indeed rising in the Dead Sea, while they fell during dry episodes.” This is plausible since the water level of a terminal lake without an outlet is exclusively determined by precipitation and evaporation. Droughts led to the biblical exodus According to the Bonn researchers’ data, there were distinct dry phases particularly during the pottery Neolithic (about 7,500 to 6,500 years ago), as well as at the transition from the late Bronze Age to the early Iron Age (about 3,200 years ago). “Humans were also strongly affected by these climate changes,” Prof. Litt summarizes the effects. The dry phases might have resulted in the Canaanites’ urban culture collapsing while nomads invaded their area. “At least, this is what the Old Testament refers to as the exodus of the Israelites to the Promised Land.” Dramatic results In addition, this look back allows developing scenarios for potential future trends. “Our results are dramatic; they indicate how vulnerable the Dead Sea ecosystems are,” says Prof. Litt. “They clearly show how surprisingly fast lush Mediterranean sclerophyll vegetation can morph into steppe or even desert vegetation within a few decades if it becomes drier.” Back then, the consequences in terms of agriculture and feeding the population were most likely devastating. The researchers want to probe even further back into the climate past of the region around the Dead Sea by drilling even deeper. More information: Holocene climate variability in the Levant from the Dead Sea pollen record, Quaternary Science Reviews 49 (August 2012), dx.doi.org/10.1016/j.quascirev.2012.06.012 Journal reference: Quaternary Science Reviews search and more info website Provided by University of Bonn search and more info website
Arctic cap on course for record melt: US scientists
by Shaun Tandon
Ice melts next to the village of Ny-Aalesundin Norway in 2009. The Arctic ice cap is melting at a startlingly rapid rate and may shrink to its smallest-ever level within weeks as the planet’s temperatures rise, US scientists said Tuesday. The Arctic ice cap is melting at a startlingly rapid rate and may shrink to its smallest-ever level within weeks as the planet’s temperatures rise, US scientists said Tuesday.
Researchers at the University of Colorado at Boulder said that the summer ice in the Arctic was already nearing its lowest level recorded, even though the summer melt season is not yet over. “The numbers are coming in and we are looking at them with a sense of amazement,” said Mark Serreze, director of the National Snow and Ice Data Center at the university. “If the melt were to just suddenly stop today, we would be at the third lowest in the satellite record. We’ve still got another two weeks of melt to go, so I think we’re very likely to set a new record,” he told AFP. The previous record was set in 2007 when the ice cap shrunk to 4.25 million square kilometers (1.64 million square miles), stunning scientists who had not forecast such a drastic melt so soon. The Colorado-based center said that one potential factor could be an Arctic cyclone earlier this month. However, Serreze played down the effects of the cyclone and said that this year’s melt was all the more remarkable because of the lack of special weather factors seen in 2007. Serreze said that the extensive melt was in line with the effects of global warming, with the ice being hit by a double whammy of rising temperatures in the atmosphere and warmer oceans. “The ice now is so thin in the spring just because of the general pattern of warming that large parts of the pack ice just can’t survive the summer melt season anymore,” he said. Russia’s Roshydromet environmental agency also reported earlier this month that the Arctic melt was reaching record levels. Several studies have predicted that the cap in the summer could melt completely in coming decades. The thaw in the Arctic is rapidly transforming the geopolitics of the region, with the long forbidding ocean looking more attractive to the shipping and energy industries.
Five nations surround the Arctic Ocean — Russia, which has about half of the coastline, along with Canada, Denmark, Norway and the United States — but the route could see a growing number of commercial players. The first ship from China — the Xuelong, or Snow Dragon — recently sailed from the Pacific to the Atlantic via the Arctic Ocean, cutting the distance by more than 40 percent. Egill Thor Nielsson, an Icelandic scientist who participated in the expedition, said last week in Reykjavik that he expected China to be increasingly interested in the route as it was relatively easy to sail. But the rapid melt affects local people’s lifestyles and scientists warn of serious consequences for the rest of the planet. The Arctic ice cap serves a vital function by reflecting light and hence keeping the earth cool. Serreze said it was possible that the rapid melt was a factor in severe storms witnessed in recent years in the United States and elsewhere as it changed the nature of the planet’s temperature gradients. The planet has charted a slew of record temperatures in recent years. In the continental United States, July was the hottest ever recorded with temperatures 3.3 degrees Fahrenheit (1.8 Celsius) higher than the average in the 20th century, according to the National Oceanic and Atmospheric Administration. Most scientists believe that carbon emissions from industry cause global warming. Efforts to control the gases have encountered resistance in a number of countries, with some lawmakers in the United States questioning the science.
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Rising Seas
U.Va. institute assists Virginians with sea-level rise
By Preston Pezzaro
Virginia’s largest city may get up to 45,000 acres smaller over the next century, due to an anticipated 2.3 to 5.2 feet of relative sea-level rise expected in Virginia Beach – a rise that would also impact the entire Hampton Roads region and the Eastern Shore. Recognizing the challenges this will pose, the University of Virginia’s Institute for Environmental Negotiation is assisting citizens and decision-makers in long-range planning. Under director Frank Dukes, associate director Tanya Denckla Cobb and graduate associate Melissa Keywood – all from U.Va.’s School of Architecture – the institute is working to develop awareness of, and strategies to face, rising sea levels. Beginning in March 2011, the institute established partnerships with the Hampton Roads Planning District Commission, Wetlands Watch and the city of Virginia Beach to host four listening sessions for Hampton Roads and Eastern Shore citizens to share their experiences of sea-level rise and ideas for confronting it. Following these gatherings, the institute has been working with its partners to synthesize its findings and develop recommendations for action. Later this week, it will release a report on a May 9 session in Virginia Beach, at which the institute facilitated a meeting of a diverse group of 15 regional stakeholders. There, the project partners sorted through 56 potential policies and chose the five most important, and relevant, policy categories for Virginia Beach, discussing in detail the costs and benefits of each category. These included preparing educational materials, tools and online programs; the use of transfer or purchase of development rights; reasonable restrictions and rolling easements; special tax districts for improvements; and updating the zoning code to prepare buildings in vulnerable areas. “I feel strongly that planners need to play a pivotal role in helping communities prepare for these difficult challenges. However, this is not an issue we can address with traditional planning tools, like zoning, alone,” said Keywood, who developed the coastal listening sessions (for which she earned the National Oceanic and Atmospheric Administration’s Walter B. Jones Award for Excellence in Coastal and Ocean Management in June). Nearly 200 citizens and elected officials turned out June 13 for a Coastal Flooding Workshop in Melfa on Virginia’s Eastern Shore. Denckla Cobb, the project coordinator, said the turnout was “record-breaking,” and remarked on participants’ enthusiasm and desire for local government to boost its involvement in education and outreach regarding rising sea levels – a sentiment also heard in Virginia Beach. A vast majority of the Melfa participants said they had noticed changes in wetlands and beaches, she said. “They know that rising sea levels are having real impacts, such as causing more frequent flooding during storm events. It’s also clear that people want more information, not just about what’s happening and why, but also about specific ways communities can prepare for sea-level rise.” “It was clear that people were very interested in catalyzing action to implement new policies to address this concern,” said Keywood, a graduate of the Architecture School’s master’s program in urban and environmental planning. According to a survey taken in Virginia Beach, people considered themselves fairly knowledgeable about sea-level rise and its potential consequences, ranging from wildlife habitat concerns to potential road blockages. “Participants in our workshops are very in tune with their local environments and are acutely aware of the changes they’ve observed over time in regards to habitat loss, shoreline erosion, business loss and others,” Keywood said. Nevertheless, Denckla Cobb saw that many were less aware of strategies and tools they could implement on an individual or local level – reinforcing the need for the institute to play a role in facilitating the development of practical solutions. Sea-level rise is a “multifaceted issue for which there are not a lot of practical, usable tools, unless political will changes,” she said, adding, “There is a difference between knowing what is needed and getting it done.” In addition to the efforts of the institute, Virginia Sea Grant has funded graduate student fieldwork in Hampton Roads as part of architecture professor Timothy Beatley’s “Climate Change and Coastal Planning” course. Its final report focuses on adaptation and accommodation as ways to mitigate sea-level rise, specifically through strategies of land use and growth management, resilience and knowledge dissemination. Since 1980, the Institute for Environmental Negotiation has worked throughout Virginia to mediate natural and man-made environmental issues, such as re-mediating coal mines, revitalizing tobacco farms and mitigating sea-level changes. For more on its Community Resilience in Coastal Virginia initiative, including the new focus group reports, visit its website. Provided by University of Virginia search and more info website
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