Biodiversity for kids during the June holidays!
from Celebrating Singapore's BioDiversity!
Join as a day participant in the Sea Anemone Workshop (15-21 Jun) from wild shores of singapore
Spotted Dove that lost its tail feathers
from Bird Ecology Study Group
Is Indonesia losing its most valuable assets?
from mongabay.com by Rhett Butler
Preserve heritage and nature by turning railway lands into eco-tourism spot
Letter from Lee Seow Ser Today Online 17 May 11;
On a recent Saturday, a handful of enthusiastic nature and heritage lovers like myself participated in a guided walk along the tracks of the rustic Bukit Timah Railway Station. This was followed by an insightful sharing session - "The Green Corridor" forum - organised by the National Library Board and Nature Society of Singapore (NSS).
In a proposal titled "The Green Corridor - A Proposal to Keep the Railway Lands as a Continuous Green Corridor" submitted by NSS last year to the authorities, representations were made to preserve the railway lands which brim with historical value and biodiversity in flora and fauna, after the Tanjong Pagar Railway Station ceases to operate on July 1.
In land-scarce Singapore, there is perennial pressure for commercial development to unlock the economic value of land parcels. Many people, myself included, yearn not for yet another mall tenanted to franchise outlets but a link to roots, authenticity and space.
With creative and sensible urban planning, the two goals are not necessarily mutually exclusive. In fact, a balanced co-existence is feasible and may even generate eco-tourism, enhancing Singapore's standing as a model urban garden city. For example, there could be funicular rides - like the popular Alishan tramways in Taiwan - powered by clean energy sources. Artistic enclaves could be nurtured in the surrounding environs for sketching, painting, sculpture or pottery.
Let hikers and cyclists ramble along the vertical corridor from south to north, and stretches of tracks can be adapted for use as a wheelchair-friendly system of trolleys. The National Parks Board's island-wide park connector systems would get a boost, as would the Community-in-Bloom gardening projects in the heartland and private estates nearby.
The Green Corridor is economically viable if points of interests are integrated in an eco-friendly manner to attract local and overseas visitors to enjoy the old cast-iron railway bridges; the black-and-white colonial bungalows in the Portsdown area; or a locomotive museum showcasing yesteryear's mechanical switchboard technology of rail tracks, to name but a few possible attractions.
I was disturbed that public tenders have apparently been called for the removal of rail tracks in some parts. Policy-makers should deliberate carefully and consult interest groups and individuals, particularly where the decision will greatly impact the collective memory of citizens.
Significance of 'Green Corridor'
Heritage should be understood and protected in making redevelopment plans
Jon Cooper The Adam Park Project Project Manager Today Online 19 May 11;
I READ with interest the enlightening letter "A green corridor down memory lane" by Mr Lee Seow Ser (May 17) on the fight to save the heritage and nature along the abandoned railway lines in Singapore .
I would like to add another round to the arsenal of good reasons for the protection of the "Green Corridor". The stretch of line at the west end of Bukit Timah Road which includes the Bukit Timah railway station and girder bridge is perhaps the most iconic and best preserved section of the World War II battlefield in the area.
The railway line, embankments, rail bridge and station marked the furthest point of advance of the only British counter-attack during the seven-day fight for Singapore.
The officers and men of three British battalions (also known as Tomforce) under Lieutenant-Colonel Lionel Thomas advanced up Bukit Timah road on the Japanese dug around Bukit Timah village on Feb 11, 1942, in an attempt to arrest the Japanese advance on the city.
The Loyals Battalion (18th Reconnaissance Corps) in the centre, astride the main road, made it as far as the railway station and were forced to take shelter along the railway embankment around the girder bridge. Elements of the force did manage to get into the village and onto Bukit Tinggi but most of the men hunkered down along the railway and braved the Japanese bombardment.
Finally, after a morning of fierce fighting, The Loyals, along with their compatriots in the 4th Norfolks and the 1/5th Sherwood Foresters, were ordered back down the road and into new positions within General Arthur Percival's last line of defence along Farrer and Adam Road. Gen Percival's one and only counter-attack of the campaign had floundered along the line of the railway.
Recent archaeological surveys on the battlefield at Adam Park (http://www.gla.ac.uk/departments/battlefieldarchaeology/centreprojects/singaporewwiiproject/) just off Adam Road have ably demonstrated that, where sites have remained relatively untouched by modern development, such as the old black and white estates and the railway lands, World War II heritage may well be remarkably preserved just a few centimetres under the surface.
It is, therefore, essential that before any further decisions are made in the redevelopment of the "Green Corridor", full historical significance of the construction is understood and Singapore's industrial and military heritage is duly protected and shared with the people.
Sharon See Today Online 17 May 11;
SINGAPORE - Green buildings are picking up momentum in Singapore, with the Building and Construction Authority (BCA) giving out a record number of BCA Green Mark awards to 164 winners this year, up from 102 last year.
Incentive schemes have been introduced encourage developers to go beyond the mandatory basic Green Mark standard for new buildings, such as additional floor area, which could translate to higher profit, said BCA chief executive office John Keung. "As a result, nowadays, you see a lot more Platinum projects, a lot more Gold Plus projects being developed," he said.
Other incentives include reimbursements for engaging environmental experts, who can help in achieving an energy-efficient design for buildings.
The BCA Green Mark scheme was introduced in 2005 to recognise energy- and water-efficient buildings, and organisations that voluntarily go the extra mile are awarded the Green Mark Gold, Gold Plus and Platinum awards.
Among them is private developer City Developments Limited (CDL), which has clinched more than 50 Green Mark Gold awards or better - 16 of them Green Mark Platinum awards, the highest recognition.
For its track record, the developer earned itself the inaugural BCA Green Mark Platinum Champion Award from BCA this year.
The BCA Green Mark Champion Award went to the Housing and Development Board (HDB) for completing 14 projects that attained at least Green Mark Gold status, five of which were rated Platinum. It is the first public sector agency to receive the award, which was given to CDL in 2008.
Some of HDB's award-winning green projects include Treelodge@Punggol, Waterway Terraces and SkyTerrace@Dawson.
With this year's winners, there are more than 750 Green Mark building projects here, amounting to 11 per cent of the total gross floor area.
The government is aiming to "green" at least 80 per cent of buildings by 2030.
The Star 17 May 11;
MIRI: The collaboration among Asean countries has resulted in a greatly reduced impact of transboundary smoke haze over the last few years.
Member countries’ compliance with the agreement on transboundary haze pollution, signed in 2002, and the regular meetings of Asean ministerial steering committee on haze, had contributed to a better understanding to address the issue.
“I have been in this ministry for three years. You notice that we have been lucky that we didn’t experience what we had experienced in 1997 to 1998, which was a very bad haze,” Natural Resources and Environment Minister Datuk Seri Douglas Uggah Embas told reporters here yesterday.
He said the collaborations that began with the sharing of strategies to combat illegal burning had also been enhanced to include joint efforts in installation of weather and air monitoring systems.
To date, Malaysia, Indonesia and Singapore are spearheading the efforts to install air monitoring stations in the Riau and Jambi provinces in Indonesia.
“We are looking forward to having more areas of collaborations (in the future),” he said, adding that Brunei had already indicated an interests to be involved in the collaboration.
He said the a sum of RM1mil had been spent to build five tube wells as a measure to maintain the water level in peat soil areas in Miri.
He said peat soil had been known to be highly combustible in dry conditions and the risks were apparent especially in the current dry weather.
In addition, he said, 13 check dams were also constructed at a cost of between RM5,000 and RM10,000 each as another measure to maintain the water level in peat soil areas as well as to provide water source for combating peat fire.
A watch tower had also been completed at a cost of under RM400,000 to be used for monitoring peat soil areas, he said. — Bernama
Experts film previously unknown group on hidden cameras – but loss of habitat and threat from poachers cloud newfound hope
Jonathan Watts The Guardian 17 May 11;
Deep in the jungle, armed forest rangers trek through the palms on a mission to confirm some rare good news: the discovery of a wild tiger population in an area of Thap Lan national park previously written off by wildlife experts.
Working with foreign conservationists, the rangers have been gathering evidence from camera traps over the past two years that suggests this single national park in Thailand may have more tigers than China.
Thap Lan, with its spectacular forests of saw-bladed plan palms, is an oasis of biodiversity amid expanding human development. Elephants, clouded leopards, spotted linsang, boar and deer thrive below the canopy, which is filled with the song of myna, lapwings, laughing thrushes and other exotic birds.
Locals have long insisted that tigers also prowl in this area. Camera traps, triggered by heat and movement, have been left strapped to trees for a month. Some have been destroyed by wild elephants or infested by nesting ants, but the memory cards inside have yielded a trove of images of bears, leopards, itinerant monks, as well as tigers and – worryingly – armed poachers.
More than half the park has still to be checked, but rangers have already confirmed eight tigers. This is not yet enough to be classified as a sustainable population, but park managers are optimistic more animals will be found. "I'm very happy as this is beyond expectations," said Thap Lan's superintendent, Taywin Meesat. "There are areas deeper inside where we haven't placed camera traps yet. Given the results so far, there could be 20 to 50 tigers here."
The conservation group that provided much of the training and equipment for the operation said the results showed a gap in understanding and the need to invest more in research and protection.
Tim Redford of Freedland, a Bangkok-based group that helps rangers in south-east Asia, said: "This place was supposed to be devoid of tigers. But we did a course here and were surprised to find signs of tigers. The more we looked, the more we found. That led me to believe the forest must have tigers throughout and there is a big gap in our knowledge of where they live."
He called for further studies across countries where other small populations may have been missed.
The difficulty of measuring tiger numbers was evident when India increased its estimate by 10% compared with a survey in 2008.
The discovery comes amid a fresh global push to reverse a precipitous decline in the numbers of wild tigers, down 97% compared with a century ago. At the St Petersburg tiger summit last year, participants, including the World Bank, NGOs and range states, pledged $329m (£200m) to help double the predators' numbers in the wild from the current level of about 3,200.
But the new hope in Thap Lan is mixed with old fears. Thailand is thought to be home to between 250 and 300 wild tigers, but they are vulnerable. The biggest threat is a loss of habitat. Although nominally protected, Thailand's national parks are being encroached upon by human development, particularly monoculture plantations, roads and second homes for Bangkok's rich.
Many locals also subsidise their incomes by poaching and illegally logging aloe and tropical hardwood. Park managers and police are worried that poachers and illegal traders would target the tigers once news gets out about their numbers in the area.
Rangers mount night patrols and public education campaigns to halt these activities. It can be dangerous work. A Thap Lan ranger was killed in a gun battle with poachers three years ago. In Cambodia, forest protectors have been murdered in hand grenade attacks.
The stakes are high. According to conservationists and police, poachers are paid 7,000 to 15,000 baht – £150 to £300 – per kg for a tiger carcass.
Middlemen then sell the animals on for about 10 times that amount, mostly to customers in China and Vietnam, where the animal's bones and penis are used in tonics and aphrodisiacs. Yet penalties for wildlife offences remain absurdly low, with fines ranging from 500 to 40,000 baht.
Thailand has much to protect. The country is home to some of the most biodiverse tropical forests in south-east Asia. Just two hours from Bangkok, the Guardian's car almost ran over a King Cobra, which expressed its indignation by rearing up angrily and flickering its tongue.
Despite this ecological wealth, wildlife crime was a low priority for law enforcement authorities for many years. But there are signs that attitudes may be changing. Thai customs officials have made several high-profile arrests in the past two years, including that of a woman who attempted to smuggle a live baby tiger cub through Bangkok airport in a case full of stuffed animal toys.
A sting operation last week apprehended a United Arab Emirates citizen whose belongings concealed two leopards, two panthers, an Asiatic black bear and two macaque monkeys.
More impressive still was an undercover operation by the Thai police this year that exposed a large tiger-trading syndicate. Its ringleader, a woman known as "J", remains at large, partly because her husband is a police officer, but investigators said they were closing in.
"I believe she may have been selling 100 tigers per year for 10 years," said Colonel Kittipong Khawsamang, deputy head of the wildlife crime division as he leafed through police photographs of tiger carcasses kept on ice.
"We know she is a big trader and have been collecting evidence, but we don't yet have enough for a prosecution."
Khawsamang said recent raids have shown Thailand has become a hub of the tiger trade, due to its location between other range nations in south-east Asia and China, the main market.
The business is also supplied by Thailand's many tiger farms, some of which claim to operate as zoos while covertly breeding animals for sale. The most notorious is the Sri Racha zoo near Pattaya, which police have raided on several occasions, confiscating hundreds of animals.
Tourists still flock to watch the farm-bred tigers jump through flaming hoops, suckle at pigs and walk around on their hind legs to the music of the Can-Can and laughter from the audience.
Police and conservationists believe "zoos" encourage poaching both as a source of breeding stock and by sustaining the market for tiger products.
General Misakawan Buara, commander of Thailand's natural resources and environmental crime division, said: "The problem is, we can only check permits and the inventory, but we can't check which tigers and going in and out because we are police, not animal experts. We need more DNA checks, implanted chips or a tagging system so we can verify the origins of tigers."That – like training and equipping rangers – is not cheap. But little of the money pledged at St Petersberg summit is evident yet at the grass roots, where the budgets for rangers and wildlife police are unchanged "Tiger conservation at the top and the bottom are two different worlds.
The people who are high paid researchers and biologists jet-set around the world," said Freeland's Redford.
"The rangers are paid almost nothing. They get $50 to $200 a month to go out and face armed poachers. We need to give them every support we can if we expect to keep tigers into the future.
"There is not a shortage of money, we just have to get it focused in the right places."
Tiger number
There are believed to be about 3,200 tigers left in the wild and more than 13,000 in captivity – half of which are in China.
Assessing populations in the wild is notoriously difficult, given the remoteness of the habitat and the animals' tendency to avoid human contact. It is believed numbers have fallen by 97% over the past century and the trend remains downwards, but several revisions have taken place in recent years.
• In March, India unveiled a new census that put the total number of wild tigers in the country close to 1,550 – 10% up on 2008.
• In Indonesia, camera traps have recently caught images of 12 Sumatran tigers, including a mother playing with cubs. The WWF estimates there are only 400 Sumatran tigers left in the wild. A recent study conducted by Wildlife Conservation Sociey said the population could be much larger than previously believed.
• About 350 adult Siberian or Amur tigers – physically, the largest subspecies – are left in the wild, with 95% inhabiting the far east of Russia.
• Thailand is thought to be home to 250 to 300 wild tigers, though camera traps have revealed that Thaplan National Park has more of the animals than previously believed.
• Bangladesh has between 400-450 wild tigers, mostly in the Sunderbans mangrove forests which overlap with India. Last year, they killed 44 people.
Jonathan Watts
New Straits Times 16 May 11;
MUADZAM SHAH: The state Department of Wildlife and National Parks' (Perhilitan) officers rescued 41 endangered clouded monitor lizards from a house in Bukit Serok here on Sunday.
Acting on a tip-off, an enforcement team found the reptiles in a shed near the house.
The lizards were believed to be destined for cooking pots in exotic meat restaurants overseas.
A 49-year-old man was also arrested during the raid.
It was learnt that the department had raided the shed on numerous occasions, but failed to arrest the man who was responsible for catching the lizards.
Sources in the department said the suspect was a middleman.
State Perhilitan director Khairiah Mohd Shariff said the lizards were believed to have been caught at a nearby oil palm plantation.
She said the lizards, which are on the endangered list, were considered a delicacy.
This was Perhilitan's second success in the fight against poachers of endangered animals in the last 24 hours.
On Saturday, a team led by enforcement officer Abu Zahrim Ismail, arrested a 39-year-old Orang Asli village headman in his house in Kampung Air Molek about 1am for allegedly poaching endangered animals and keeping their meat in a refrigerator.
Khairiah said the enforcement officers found chunks of leopard, bear and deer meat as well as slaughtered mousedeers in the village headman's house.
Antara 16 May 11;
Bengkulu, Sumatra (ANTARA News) - Turtle poaching and illegal trading are still rampant on Enggano island North Bengkulu District, Bengkulu Province, Sumatra Island, a local resident said
"Last week, a 100-kg leatherback sea turtle was poached and its meat was sold, while its shell was thrown away into the sea," Zulvan Zaviery, a resident of Enggano, said here Monday.
Turtle poaching activities on Enggano Island was a big concern because the animal was used not only for traditional ceremonies but for commercial purposes as well, he said.
In fact, turtle meat was not a must in a traditional ceremony menu, he said, adding, however, poaching continued.
Head of the Enggano Island Nature Resource Conservation Agency (BKSDA) Rendra Regen Rais said turtle poaching on the country`s outer most island was very rampant.
The population of turtle on the island has dropped drastically due to massive poaching activities for commercial purposes, according to him.
Enggano Island beach is the habitat of several turtles which lay eggs there. Besides poaching, lizards and wild boars also eat turtle eggs.
According to data of BKSDA, there are five species of endangered turtle in Bengkulu waters, namely leatherback turtle, green turtle, hawksbill turtle, Loggerhead Turtle (Caretta caretta), and ridley turtle (Lepidochelys olivacea).
(F001/A/HAJM)
(ANTARA)
Editor: Ella Syafputri
Antara 16 May 11;
Solo, Central Java (ANTARA News) - The government has temporarily stopped allowing foreign investors to develop new oil palm plantations so as to give opportunities to local businessmen, Forestry Minister Zulkifli Hasan said.
"There is indeed a policy to reduce the number of foreign investors in the oil palm plantation sector to give more opportunities to local businesses," he said here on Monday at a business gathering on developing people`s potentials and opportunities in economic development efforts held during the meeting of the national council on economy and entrepreneurship of the executive board of Muhammadiyah Islamic organization.
The minister said there are now two million hectares of oil palm plantations which are held by foreign investors such as those from Malaysia and others.
In view of the policy he called on national businessmen including those from Muhammadiyah who wish to participate in the business to take the opportunity, adding that there was still plenty of land for the purpose.
He said there were now around 45 million hectares of critical forest land in the country and 30 million hectares of them may be developed into oil palm, rubber or sugar cane plantations.
He said "concession holders who do not develop their land and ignore it would have their permits revoked."
With regard to reforesting the land he said his ministry continued conducting its reforestation program.
In 2010 he said the ministry had developed 600,000 hectares of people-based forestation projects and this year 700,000 hectares in various parts in the country.
This program is mostly implemented in Java island in cooperation with villagers, he said.
He said his office also provides Rp50 million for developing nurseries for each group involved in the program.
The forestry ministry has so far provided Rp2.5 trillion to help maintain the people-based forests and Rp3 trillion to help develop people-based forests, he said. (*)
Editor: Aditia Maruli
Stanford University EurekAlert 16 May 11;
The majority of seaports around the world are unprepared for the potentially damaging impacts of climate change in the coming century, according to a new Stanford University study.
In a survey posed to port authorities around the world, the Stanford team found that most officials are unsure how best to protect their facilities from rising sea levels and more frequent Katrina-magnitude storms, which scientists say could be a consequence of global warming. Results from the survey are published in the journal Climatic Change.
"Part of the problem is that science says that by 2100, we'll experience anywhere from 1.5 to 6 feet of sea level rise," said the study's lead author, Austin Becker, a graduate student at Stanford. "That's a huge range."
Port authorities, like many government agencies and private companies, have to make tough financial decisions when it comes to funding infrastructure, he said. They need accurate information from scientists about what to expect, so that they can plan accordingly. Building a structure to withstand a 6-foot sea level rise would cost much more than trying to accommodate a 1.5-foot rise, said Becker, a doctoral candidate in the Emmett Interdisciplinary Program in Environment and Resources at Stanford.
In 2009, Becker distributed 160 surveys to members of the International Association of Ports and Harbors and the American Association of Port Authorities – the first worldwide survey of port authorities to address climate change adaptation. A total of 93 agencies representing major seaports on every continent, except Antarctica, responded. The majority of respondents ranked sea level rise and increased storm events associated with climate change high on their list of concerns. However, only 6 percent said that they intend to build hurricane barriers within the next 10 years, and fewer than 18 percent had plans to build dikes or other storm protection structures.
"As we saw with Katrina in 2005, storm and flood damage can devastate a regional economy for years after an event and have national impacts," said Becker. Katrina, a Category 5 hurricane, caused an estimated $1.7 billion of damage to Louisiana ports. This month, the region is bracing for flood damage once again, as the National Weather Service is predicting that the Mississippi River could crest in New Orleans on May 23.
And with scientists forecasting a doubling of Category 4 and 5 hurricanes in the Atlantic Ocean by 2100, it seems all the more imperative to start thinking about adapting port infrastructures now, he said.
Threat of violent storms
Sea level rise and more frequent violent storms resulting from climate change threaten to take a tremendous toll on all types of infrastructure – especially along the coasts, said study co-author Martin Fischer, professor of civil and environmental engineering and director of the Center for Integrated Facility Engineering at Stanford.
Fischer, Becker and a group of Stanford engineers are developing computer models to help port authorities and other government agencies make more informed decisions about adapting to climate change as they plan for the next generation of infrastructure. The group meets weekly at a seminar that focuses on engineering and policy for a sustainable future. "Look around at any seaport today and you will see structures that were built 100 years ago," said Fischer. "And the buildings that we are building today will be around when sea level rise begins to reshape the coast."
The problem on a global scale, he said, is that ports may start scrambling all at once to adapt their structures to changing environmental conditions. "It could potentially exceed our capacity for construction worldwide," he added.
Fischer and his colleagues have developed a model that demonstrates how a rapid, simultaneous push to fortify the world's seaports could drive up demand for construction materials and equipment. The model, called Sebastian, uses a Google Earth platform to simulate the costs and time required for building dikes around 200 of the world's most active seaports. Sebastian knows the shape of the ocean floor at each location and tailors the structure to each site to produce an estimate of the materials, labor and equipment that would be needed to fortify the port against sea level rise.
"Sebastian allows us to run different scenarios based on different levels of sea rise, and see how the ports are affected," said Fischer. Using criteria in the Army Corps of Engineers manual, the model calculates the resources needed for each variation of the structure. It's a way to calculate big-picture, worldwide demand, Fischer said, but it also gives managers more reliable information about how much survivability they are buying when they invest in different types of protective structures.
Lack of oversight
Another difficult challenge in preparing for climate change at seaports is that no single agency or individual has sole authority over any given port, according to Becker. Some ports are privately owned, some are public and some are a mixture of both. And a broad range of entities – from transportation companies to insurance companies to the Environmental Protection Agency – have some stake in how they are managed. The arrangement greatly complicates ports' efforts to budget and plan for the future, according to the study.
But plan they must, said Fischer.
"By the end of the century, quite a few ports will be in trouble, even if you are using the most conservative estimates for sea level rise," he said. "And if you use the estimates at the top of the range, all of them will be in trouble."
###
Other co-authors of the study are Satoshi Inoue of the National Graduate Institute for Policy Studies in Tokyo and Ben Schwegler, a consulting professor of civil and environmental engineering at Stanford and chief scientist at Walt Disney Imagineering.
The research was funded by a planning grant from the Sustainable Built Environment Initiative at the Woods Institute for the Environment at Stanford. Additional funding was provided by a McGee grant from the Stanford School of Earth Sciences.
This article is by Donna Hesterman, a science-writer intern at the Woods Institute for the Environment at Stanford.
Natalie Wolchover, Life's Little Mysteries LiveScience.com Yahoo News 16 May 11;
For the first time, scientists have found convincing evidence that the gargantuan hole carved in the ozone layer by man-made chemicals is steadily shrinking. That mean a policy enacted 22 years ago called the Montreal Protocol is working: The 1989 ban on the use of chlorofluorocarbons (CFCs) — toxic chemicals used in air conditioners and solvents that eat away at ozone molecules — has helped the Earth to regain some of its lost protective ozone.
The "ozone hole" is not really a hole, but rather a region above Antarctica where the ozone layer — the 15-mile-thick blanket of O3 molecules that acts as our planet's natural sunscreen — is very, very thin.
That the ozone above Antarctica is thickening again is universally good news for life on Earth. The ozone layer absorbs as much as 99 percent of the sun's dangerous high-frequency ultraviolet light, making Earth habitable. [Read: Is Ozone Good or Bad?]
Atmospheric scientists previously observed that levels of ozone-depleting CFCs were falling in the stratosphere (the level of atmosphere between 5 and 30 miles up in the sky) above Antarctica. Because that's where the ozone hole is, they suspected that the drop in CFCs might correspond to a thickening of ozone, but until now, couldn't prove it. The average ozone levels were observed to fluctuate dramatically from one spring to the next, so that little could be said about the hole's average size.
Now a team of environmental scientists led by Murry Salby at Macquarie University in Sydney, Australia, have identified the cause of the annual fluctuations in ozone. By removing the fluctuations from the data, they produced a baseline of systematic change in Antarctic ozone levels. As detailed in the new issue of the journal Geophysical Research Letters, the team's calculations reveal that the ozone hole is 15 percent smaller than it was at its maximum in the 1990s.
Salby told the site Nature.com that the swings in ozone levels from spring to spring result from a weather pattern known as dynamical forcing. During winters when this effect is pronounced, more cold air gets trapped in the stratosphere above the South Pole, and as a result, more ice crystals form in the atmosphere. When the sun hits these in spring, they serve as platforms upon which chlorine can chemically react with ozone, breaking it apart. Consequentially, "[if] you know what the stratospheric forcing is during the winter, you can predict rather accurately the ozone level for the following spring," Salby said.
Underlying the yearly variations, however, is a consistent, downward-sloping trend in the size of the ozone hole.
"I think this is the first convincing observationally-derived evidence of the ozone rebound," Adrian McDonald, an atmospheric scientist at the University of Canterbury in Christchurch, New Zealand, told the press. "It's the first where the statistical significance is high enough, and you can see the pattern well enough, that you feel comfortable in believing it."
Posts
visitors since Nov 07