Archive for the ‘ Global warming ’ Category

Air-Conditioned Greenhouse Uses Alternative Energy

Air-Conditioned Greenhouse Uses Alternative EnergyScienceDaily (Feb. 8, 2011) — Neiker-Tecnalia (The Basque Institute for Agricultural Research and Development) has created an air-conditioned greenhouse using alternative energies that enable the reduction of energy costs, improvements in energy efficiency and an increase in crop yields. The novel system has a biomass boiler and thermodynamic solar panels, which reach an optimum temperature for the crop without using fuels derived from petroleum oil or gas.

Neiker-Tecnalia has installed a biomass boiler (using wood and other organic waste as fuel), together with thermodynamic panels, with the goal of air-conditioning greenhouses destined for intensive crop cultivation. With this method they have managed to reduce costs and improve crop yields, in such a way that seasonal products can be harvested throughout the year. This project seeks an alternative to the usual diesel or heating oil boilers, which emit significant amounts of CO2 to the atmosphere and are very costly for the farmer, given the high price of petroleum oil-derived fuels.

400 kW power

The project was undertaken at a greenhouse in NEIKER-Tecnalia located in Derio, in the Basque province of Bizkaia and near Bilbao. A biomass boiler which produces 400 kW power and is, to date, the largest in Spain using air-conditioning in greenhouses was installed. With the boiler there are 40 thermodynamic panels, employed for the first time in intensive greenhouse cultivation. The combination of both energies act to heat the water which circulates in tubes located a few centimetres above the floor and below the substrate of the crop, the aim being to heat the roots.

The tubes, distributed throughout the whole surface of the greenhouse, transport water at an average temperature of 80 degrees centigrade. Thus optimum air-conditioning for greenhouses is achieved, with the result that the plants grow as in the natural production period. Achieving less expenditure in consumption and having seasonal crops all year round considerably reduces the price of the final product and, thus, enabling competition in the market with products coming from other zones.

The thermodynamic panels used generate energy thanks to the difference in temperature between a cold gas that circulates through a closed circuit and the ambient air temperature. They outstand for their low energy cost, as they are able to function in situations without sunlight and, thereby, produce energy both by day and by night. Moreover, it drastically reduces emissions of CO2 to the atmosphere. They are capable of heating water to 45 degrees centigrade and their cost per kilowatt consumed is 60 % less than the one generated by conventional diesel or heating oil boilers.

The biomass boiler used by Neiker-Tecnalia works with organic waste, such as almond nut shells, olive oil stones, tree pruning cuttings, the waste obtained from clearing forests, granulated pellets of sawdust, sawdust itself, wood shavings or any other leftover from the timber industry. The expenditure in fuel for the biomass boiler is 55 cents for kilowatt consumed, well below the 92 cents of a euro needed for boilers fed by petroleum oil-derived fuels or by natural gas or propane.

Source: ScienceDaily

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Polar Bears Still on Thin Ice, but Cutting Greenhouse Gases Now Can Avert Extinction, Experts Say

Polar Bears Still on Thin IceScienceDaily (Dec. 15, 2010) — Polar bears were added to the threatened species list nearly three years ago as their icy habitat showed steady, precipitous decline because of a warming climate. But it appears the Arctic icons aren’t necessarily doomed after all.

Scientists from several institutions, including the U.S. Geological Survey and the University of Washington, have found that if humans reduce greenhouse gas emissions significantly in the next decade or two, enough Arctic ice is likely to remain intact during late summer and early autumn for polar bears to survive.

“What we projected in 2007 was based solely on the business-as-usual greenhouse gas scenario,” said Steven Amstrup, an emeritus researcher with the U.S. Geological Survey and the senior scientist with the Montana-based conservation organization Polar Bears International. “That was a pretty dire outlook, but it didn’t consider the possibility of greenhouse gas mitigation.”

That study projected that only about one-third of the world’s 22,000 polar bears might be left by mid-century if the dramatic Arctic ice decline continued, and that eventually they could disappear completely. The work led to the 2008 listing of polar bears as a threatened species.

The new research, published in the Dec. 16 issue of Nature, is based in part on modeling proposed by Cecilia Bitz, a UW associate professor of atmospheric sciences. It indicates there is no “tipping point” that would result in unstoppable loss of summer sea ice when greenhouse gas-driven warming rose above a certain threshold.

“Our research offers a very promising, hopeful message, but it’s also an incentive for mitigating greenhouse emissions,” Bitz said.

Amstrup is the lead author of the Nature paper. Besides Bitz, co-authors are Eric DeWeaver of the National Science Foundation, David Douglas and George Durner of the USGS Alaska Science Center, Bruce Marcot of the U.S. Forest Service in Oregon and David Bailey of the National Center for Atmospheric Research in Colorado.

Because the scientists were looking specifically to see if there is a tipping point beyond which seasonal Arctic ice could not recover, they used a general circulation model with a sea-ice component particularly sensitive to rising temperatures, with major parts of it designed by Bitz.

“We didn’t necessarily need to compare with other models since we were using one that is extremely sensitive in the Arctic, which allowed us to make a more conservative statement about the potential to slow the loss of sea ice,” she said.

Previous work by Bitz and others showed that unchecked temperature increases, along with natural environmental volatility, could result in the loss of vast areas of Arctic ice in less than a decade. It also showed that with continued business-as-usual greenhouse gas emissions the ice did not recover after such rapid ice losses, and it largely disappeared altogether in following decades.

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Ozone Hole Affects Upper-Atmosphere Temperature and Circulation

ScienceDaily (Dec. 4, 2010) — Observations have shown differences in altitude and brightness between polar mesospheric clouds (clouds made of ice crystals in the upper mesosphere) in the Northern Hemisphere and those in the Southern Hemisphere.

Various mechanisms have been suggested to explain the differences; a new study shows that the ozone hole in the stratosphere above Antarctica could be playing a key role in the temperature and circulation patterns in the mesosphere (an atmospheric layer that begins 50 kilometers above Earth’s surface, just above the stratosphere), leading to differences in polar mesospheric clouds.

Using climate model simulations, Smith et al. show that the ozone hole causes a decrease in temperature in the lower stratosphere that persists into the summer. These temperature changes are accompanied by wind changes that modify the upward propagation of small-scale waves, which in turn alter the atmospheric circulation in the mesosphere in the Southern Hemisphere.

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Rising Sea Levels: Environmental Impact

This is an article  on the effects of rising sea levels. In this article, I discuss the ways in which rising tides can decimate local ecosystems and the environment.

Rising sea level

Rising sea level

One of the most discussed effects of global warming is the increased rate of sea level rise. The rise is due primarily to higher temperatures, which effect sea levels in two ways. First, if temperatures rise, water gets hotter, causing it to expand. Second, the heat melts ice sheets, caps, and glaciers, causing meltwater to flow into the oceans. In a previous article, I discussed the impact of sea level rise on humans; in this article, I will discuss the impact on the environment.

Land Loss

Coastal wetlands are key ecosystems in the biosphere. They support a combination of oceanic species and land species- everything from seagulls to striped bass. They form a “transition zone”, where salt and freshwater fish species like the trout can pass from rivers and streams to the sea. However, rising sea levels are threatening these key habitats. As ocean levels rise, erosion occurs on the shore. As wetlands depend on solid ground for cattails and other aquatic plants to grow, the removal of earth can be devastating. Researchers suggest that by 2080 almost 33% of wetlands will be converted into open water.

Water Salinity

Most aquatic animal and plant species are highly sensitive to salinity levels in their water. As sea levels rise, they flood low-lying freshwater marshes and lakes, making them partially saline. This can kill and damage many native species. The Florida Everglades, for example, are in danger of become salty due to the encroachment of the Atlantic ocean. This would devastate the rich plant and animal life of the Everglades.

Storms

Rising sea levels increase the intensity of storms and floods throughout the world. In high-risk areas like Southeast Asia and Australia, floods could decimate much of the inland plant and animal population. Most ground and burrowing animals, for example, could drown in their dens. Australian researchers have modeled the effects of floods in the future and have discovered that, with the current rate of sea level rise, a storm that now floods 32 square kilometers will flood 71 square kilometers by 2050.

So even though sea levels rise only a few millimeters per year, they can have disastrous effects on world ecosystems. It shows just how sensitive nature is- the smallest change can make a world of difference.

More Information

http://www.smh.com.au/news/environment/effects-of-sealevel-rise-only-just-beginning/2007/10/02/1191091115328.html

http://www.epa.gov/climatechange/effects/coastal/index.html

http://environment.about.com/od/greenhouseeffect/a/rising_sea_leve.htm