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WASHINGTON, June 6 (Xinhua) -- The tropics and much of the Northern Hemisphere are likely to experience an irreversible rise in summer temperatures within the next 20 to 60 years if atmospheric greenhouse gas concentrations continue to increase, according to a new climate study by Stanford University scientists. The results will be published later this month in the journal Climatic Change.In the study, the Stanford team concluded that many tropical regions in Africa, Asia and South America could see "the permanent emergence of unprecedented summer heat" in the next two decades. Middle latitudes of Europe, China and North America -- including the United States -- are likely to undergo extreme summer temperature shifts within 60 years, the researchers found."According to our projections, large areas of the globe are likely to warm up so quickly that, by the middle of this century, even the coolest summers will be hotter than the hottest summers of the past 50 years," said the study's lead author, Noah Diffenbaugh, an assistant professor of environmental Earth system science and fellow at the Woods Institute for the Environment at Stanford. The study is co-authored by Stanford research assistant Martin Scherer."When scientists talk about global warming causing more heat waves, people often ask if that means that the hottest temperatures will become 'the new normal,'" Diffenbaugh said. " That got us thinking -- at what point can we expect the coolest seasonal temperatures to always be hotter than the historically highest temperatures for that season?"To determine the seasonal impact of global warming in coming decades, Diffenbaugh and Scherer analyzed more than 50 climate model experiments -- including computer simulations of the 21st century when global greenhouse gas concentrations are expected to increase, and simulations of the 20th century that accurately " predicted" the Earth's climate during the last 50 years. The analysis revealed that many parts of the planet could experience a permanent spike in seasonal temperatures within 60 years."We also analyzed historical data from weather stations around the world to see if the projected emergence of unprecedented heat had already begun," Diffenbaugh said. "It turns out that when we look back in time using temperature records, we find that this extreme heat emergence is occurring now, and that climate models represent the historical patterns remarkably well."According to both the climate model analysis and the historical weather data, the tropics are heating up the fastest. "We find that the most immediate increase in extreme seasonal heat occurs in the tropics, with up to 70 percent of seasons in the early 21st century (2010-2039) exceeding the late-20th century maximum," the authors wrote.Tropical regions may see the most dramatic changes first, but wide swaths of North America, China and Mediterranean Europe are also likely to enter into a new heat regime by 2070, according to the study.This dramatic shift in seasonal temperatures could have severe consequences for human health, agricultural production and ecosystem productivity, Diffenbaugh said. As an example, he pointed to record heat waves in Europe in 2003 that killed 40,000 people. He also cited studies showing that projected increases in summer temperatures in the Midwestern United States could reduce the harvest of staples, such as corn and soybeans, by more than 30 percent.

BEIJING, Sept. 23 (Xinhua) -- A defunct U.S. satellite is expected to crash down to Earth Friday, with nobody knowing where or when exactly it will hit. This was avoidable, a Chinese expert said Thursday.Pang Zhihao, a researcher from the Chinese Research Institute of Space Technology, told Xinhua that the crash could have been avoided had the satellite been put into a higher orbit, or manipulated to drop in the South Pacific when it had abundant fuel. It would pose no threat to Earth if these measures had been taken.NASA's tumbling, 5,900 kg Upper Atmosphere Research Satellite, or UARS, is the first of such man-made space vehicles that have been launched into outer space according to the agency's Mission to Planet Earth. The mission was launched in the 1990s.The mission is designed to provide data for better understanding Earth's upper atmosphere and the effects of natural and human interactions on the atmosphere.The satellite was deactivated in 2005 as it ran out of fuel and was left orbiting Earth like a big piece of space junk.There are other cases of defunct satellites. The European Space Agency said earlier its observation satellite ERS-2 has run out of fuel and is deorbiting. It would therefore also crash sooner or later.Pang said all countries which are operating space vehicles should take care of their own spacecrafts so that they won't pose any danger.The expert also said that the public need not worry too much.Pang said most spacecrafts will be incinerated upon re-entering Earth's atmosphere, and the debris will mostly likely fall into the ocean or hit an uninhabited area. In addition, a debris tracker is able to give a comparatively accurate prediction where the craft will fall about two hours before it hits Earth, giving residents, if there are any, time to evacuate.He added that there are several ways to minimize the threat of decommissioned spacecrafts, like putting them into higher orbits and crashing them into designated waters.Scientific progress would possibly bring about more ways of dealing with tumbling satellites. Scientists have already been trying to build spacecrafts with degradable materials so that they can self-destruct when re-entering Earth's atmosphere.

BEIJING, July 27 (Xinhuanet) -- Amazon.com’s e-book reader Kindle 3G with special offers is now the company’s top-selling e-book device, according to media reports on Wednesday.Amazon revealed in its quarterly earnings report that the ad-supported version costs 139 U.S. dollars,  50 dollars cheaper than the comparable Kindle 3G, and costs the same as a Kindle with Wi-Fi connectivity. Many believe Kindle is the most popular dedicated e-book device on the market today.The advertisements will appear only in screensavers (which appear when the reader is in an idle state) and at the bottom of the home screen, so they don’t interrupt readers.“Since AT&T agreed to sponsor screensavers, Kindle 3G with Special Offers is now our bestselling Kindle device,” Amazon’s press release said.Having zoomed past the earlier Sony Reader, and kicked off a wave of competition including the Barnes & Noble Nook and the Kobo E-Reader, Kindle is believed the most popular dedicated e-book device on the market today.

HAVANA, Aug. 15 (Xinhua) -- Cuba's Ministry of Public Health launched an intensive sanitation campaign Monday against the Aedes Aegypti mosquito, which can spread dengue fever.The operation, which is running through Sept. 15, will cover the most vulnerable cities in the country, including the capital Havana and the eastern city Guantanamo.Deputy Health Minister Luis Estruch stressed the importance of the prevention campaign and urged all families to check their houses for mosquitoes each week.Maria Guadalupe Guzman, director of the Pan-American and World Health Organization Cooperation Center for the Study of Dengue and Its Vector at the Pedro Kouri Institute of Tropical Medicine, said the epidemiological situation in the country is stable. However, she warned that an epidemic outbreak is still possible in the island state, given the high temperatures and heavy rains in the eastern areas, and drought in the west.Cuba, along with Chile and Uruguay, are the only Latin American countries where dengue is not endemic.In 1981, the country suffered its worst dengue outbreak in history, which left 158 dead.

SUVA, Sept. 21 (Xinhua) -- The Secretariat of the Pacific Community (SPC) stressed on Wednesday that sustainable use and management of forests and tree resources will remain its important focus for the foreseeable future.Sairusi Bulai, a forestry team coordinator of SPC's Land Resources Division (LRD) told a regional workshop currently underway in Fiji's western tourist city of Nadi that "our main issue was and continues to be the lack of adequate resources to enable countries to effectively implement sustainable forest management.""Therefore, we are very fortunate that we have this opportunity to discuss findings and recommendations of the mission, which the UN-REDD Program has undertaken in the Pacific earlier this year," he added.REDD+ is a new international mechanism to compensate developing countries for reducing their rate of deforestation and forest degradation and increasing their carbon stocks.Developing countries participate on a voluntary basis. They provide technical and financial assistance to enable eligible countries to meet the requirements for future participation. Once a country begins participating, it receives compensation for its verified reduction in carbon emission from forest activities.The UN-REDD Program is a collaborative partnership of the United Nations Development Program (UNDP), the United Nations Environment Program (UNEP) and the Food and Agriculture Organization (FAO) to support countries in the preparation of this mechanism.Bulai encouraged participants to take advantage of the excellent opportunity to discuss REDD+ experiences in the region and to link up with the experts in attendance.REDD+ gives an excellent opportunity to create better awareness and understanding amongst all stakeholders, including resource owners, so that informed decisions are made to avoid exploitation, he said.Bulai, meanwhile, stressed on the critical importance of multi- sectoral as well as multi-stakeholder based approaches to forest management to effectively reduce deforestation and forest degradation.