Saturday, October 30, 2010

Climate Change Tipping Points for Populations, Not Just Species: Survival, Reproduction of Thousands of Arctic and Alpine Plants Measured

ScienceDaily (Oct. 21, 2010) — As Earth's climate warms, species are expected to shift their geographical ranges away from the equator or to higher elevations.

While scientists have documented such shifts for many plants and animals, the ranges of others seem stable.
When species respond in different ways to the same amount of warming, it becomes more difficult for ecologists to predict future biological effects of climate change -- and to plan for these effects.
In a study published in the journal Nature, University of Wyoming ecologist Daniel Doak and Duke University ecologist William Morris report on a long-term study of arctic and alpine plants.
The results show why some species may be slow to shift their geographic ranges in the face of climate change, and why we might expect to see sudden shifts as warming continues.
"This study illustrates the critical need for long-term research to address our most pressing ecological challenges," says Saran Twombly, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research.
"Without the temporal and spatial scales employed here, we have little hope of understanding the complex ways in which organisms will respond to climate change."
The plant species targeted by Morris and Doak range from populations in the high mountains of Colorado and New Mexico to species growing along the arctic coastline in far northern Alaska.
These regions include habitats that have undergone substantial climate change, leading to the expectation, says Doak, that -- especially at the southern edge of their range -- populations of the plants should be collapsing.
However, after studying the growth and survival of tens of thousands of individual plants over six years, the researchers show a more complex pattern of responses.
At the southern edge of their ranges, the plants indeed show negative effects of warmer conditions, with lower survival.
"But in most years," says Doak, "these effects are balanced by plants in the south growing more rapidly, so that populations there are no less stable than those in the north."
The opposing trends mean that under current conditions, even across the huge range of conditions Morris and Doak studied, populations of these plants are doing equally well across 30 degrees of latitude -- one-third the distance from the equator to the north pole.
However, the researchers' results don't indicate that these plants, or other species, will be unaffected by warming conditions.
By looking at the performance of individual plants in particularly hot and cold years, they found that the compensatory effects across moderately cold to moderately warm years (lower survival balanced by more rapid growth) will not hold up with increased warming.
Instead, in the warmest years at all study sites, both survival and growth of the plants fell.
"Up to a point," says Doak, "we may see little effect of warming for many organisms. But past a climatic tipping point, the balance of opposing effects of warming will likely cease, leading to subsequent rapid declines in populations."
While this tipping point will be different for each species, responses of natural populations to gradual shifts in climate will not necessarily in turn be gradual.
"We shouldn't interpret a lack of ecological response to past warming to mean that little or no effects are likely in the future," says Doak.
The researchers' work also points to a methodology with which to better understand and predict how climate effects on one species will combine to create overall population-wide effects.
"A key part of this approach is the need for long-term studies so we can observe and use the rare years with extreme climates to anticipate what the average future climate will bring," Doak says.

Trees' ability to soak up CO2 has limits

By Carl Holm for ABC Science Online
ABC News Online, Tue Oct 26, 2010
The ability of forests to absorb carbon dioxide from the atmosphere has been overrated, according to a new study by US and Australian scientists.
In a paper appearing this week in the Proceedings of the National Academy of Sciences, Dr Richard Norby of the Oak Ridge National Laboratory, Tennessee, and colleagues argue that an essential element, nitrogen, had previously not been adequately factored into the equation.
One of the co-authors of the paper, Dr Belinda Medlyn of the Department of Biological Sciences at Macquarie University in Sydney, says the current study is a continuation of earlier research investigating Liquidambar styraciflua trees that were exposed to carbon dioxide (CO2) concentrations about 25 per cent higher than current levels.
"The CO2 concentration at the moment is about 390 parts per million (ppm) and the concentration in the study at Oak Ridge was about 550 ppm," said Dr Medlyn.
"It depends on whether we manage to get our CO2 emissions under control, but 550 ppm will probably be reached somewhere in the second half of this century."
The trees' response to this higher CO2 environment was measured over a five year period. Initially they grew faster, and Dr Medlyn says modelling of the first five years of the experiment gave some quite optimistic results.
"In the first five years they didn't find any reduction in the CO2 response," she said.
"So basically what happened was the trees had a higher productivity level as soon as the CO2 was switched on, and they maintained that for the first five years."

Deep roots

After extending the study for a further five years, the latest modelling tempers the optimistic predictions from the 2005 analysis.
Dr Medlyn says the study into how the trees would respond to increased concentrations of CO2 confirmed their hypothesis that there would be a point at which nutrient availability, specifically nitrogen availability, would limit the CO2 uptake of plants.
"The exciting thing about these results is that after another five years we found that the CO2 response is not actually maintained. What that's telling us is that plants have the capacity to go looking for extra nutrition in the soil and that's what's happened here," she said.
"They put down deeper roots, they found extra nutrition in the soil and that's kept them going for a while, and certainly longer than we thought they would be able to. But after ten years they've finally run out of nitrogen.
"The implication of that for the broader landscapes is that particularly in nutrient poor soils, the rising CO2 concentration in the atmosphere is probably not going to be as beneficial to plants as we've been hoping."
Dr Medlyn argues that the models that were used in the Intergovernmental Panel on Climate Change (IPCC) 4th assessment report to predict land-based CO2 sequestration did not include nitrogen feedbacks on the CO2 response, and therefore these predictions are too optimistic.
She says currently plants soak up about 25 per cent of human CO2 emissions. Previously, models had assumed that this was because plants are responding to rising CO2, and that they would continue to respond, taking up ever more CO2 out of the atmosphere.
"So the models are being revised at the moment to try and incorporate these nitrogen feedbacks," she said.
"Where they are incorporated, we generally find that the predicted carbon sink in the land over the next century really goes down a fair bit."

Thursday, October 28, 2010

One-fifth of world's back-boned animals face extinction, study warns

One species of vertebrate is added to the endangered list each week, IUCN report warns at biodiversity summit  
• One in five plant species faces extinction 
• In pictures: New species in the Amazon   
Jonathan Watts in Nagoya 
Tuesday 26 October 2010

One species is added to the endangered list every week as the risk of extinction spreads to almost one-fifth of the world's vertebrates, according to a landmark study released today.

The Evolution Lost report, published in the journal Science by more than 100 of the world's leading zoologists and botanists, found that populations of mammal, bird, reptile, amphibian and fish species had declined by an average of 30% in the past 40 years.

Multiple factors have contributed to the demise, including logging, agricultural land conversion, over-exploitation, population growth, pollution and the impact of invasive alien species.

The worst die-off has occurred in south-east Asia, where hunting, dam building and the conversion of forest to palm oil plantations and paddy fields has been most dramatic. But Australia and the Andes have also suffered significant losses.

Land mammal populations are estimated to have declined by one-quarter, marine fish by one-fifth and freshwater fish by almost two-thirds, noted the study, which analyses the states of 25,000 back-boned animals on the International Union for Conservation of Nature (IUCN)"red list" of threatened species.

"The backbone of biodiversity is being eroded," said veteran American ecologist and writer Prof Edward O Wilson. "One small step up the red list is one giant leap forward towards extinction. This is just a small window on the global losses currently taking place."

The report has been released during a crucial United Nations biodiversity conference in Nagoya that aims to draw up a new global action plan to halt the demise of plant and animal life on Earth.

While current conservation strategies have failed to reverse the decline in wildlife and ecosystems, the authors of the report say the situation would be far worse without the establishment of nature reserves, breeding programmes and protection plans.

Such measures have helped 64 species recover, including the several that were eradicated in the wild but then reintroduced, such as the California condor and black-footed ferret in the United States and Przewalski's horse in Mongolia.

The study estimates that an extra 20% of species, such as the black stilt, a wading bird endemic to New Zealand, would have moved higher into the threatened categories without conservation measures. The white rhino and humpback whale have also moved out of the "intensive care ward" thanks to prolonged protection measures.

But the pressures on wildlife are outweighing the support provided by conservation efforts. None of the UN's 2010 targets to maintain species and habitats have been achieved.

Julia Marton-Lefèvre, director general of the IUCN, called on the negotiators at Nagoya to raise their efforts to save biodiversity. "This is clear evidence of why we absolutely must emerge from Nagoya with a strategic plan of action to direct our efforts for biodiversity in the coming decade," she said. "Conservation does work, but it needs our support and it needs it fast."

Many species are in a perilous position. The family of life most at risk may be the oldest seed plants. Two-thirds of cycads are in a critical condition due to illegal harvesting and trade. If current trends continue, the authors say the plants will go the way of the dinosaurs.

separate study coordinated by the Royal Botanic Gardens at Kew suggested that just over one-fifth of plant species are threatened – mostly in the tropics – due to man-made habitat loss. But the extent of the risk remains unclear.

At the release of a first Asia-wide study of plants, Ma Keping, one of China's leading botanists, said many of the region's 100,000 plus species of higher plants were under pressure from rapid economic development, population growth, pollution and poverty.

Scientists cautioned against focusing exclusively on flagship endangered animals when the wider and closer risk was the demise of once common species, such as bees and fish, that are crucial to the food chain.

"Future extinctions risks are projected to be high, but the biodiversity crisis is much more than extinctions," said Henrique Miguel Pereira, who analysed several recent global environment assessments for Diversitas, the UN Environment Programme and other groups. "Much of what will happen to biodiversity in 21st century is not global extinctions, but major changes in the abundance of species and the composition of communities".

The co-author of his paper, Paul Leadley of University Paris-Sud, France, said the trends demanded radical change. "There is no question that business-as-usual development pathways will lead to catastrophic biodiversity loss. Even optimistic scenarios for this century consistently predict extinctions and shrinking populations of many species."

A UN-sponsored study called The Economics of Ecosystems and Biodiversity calculated the cost of losing nature at $2-5 trillion per year, predominantly in poorer parts of the world.

Wednesday, October 13, 2010

Consumption outstrips Earth's production

Adam Morton 
The Age,October 14, 2010

HUMANS are churning through the Earth's resources at 1.5 times the rate that nature can replace them - and the over-consumption rate is worsening.
The Living Planet Report, by environment group WWF, estimates that the Earth has enough productive land and sea for each person to use 1.8 hectares to draw the resources they need. In 2007, the average person used 2.7 hectares.
Scientists call this a state of ''ecological overshoot'' - extracting resources at a faster rate than the natural world can replace them.
The average Australian had an ecological footprint of 6.8 hectares, making Australia the eighth most destructive country on a per capita basis. Only the residents of United Arab Emirates, Qatar, Denmark, Belgium, the US, Estonia and Canada consumed more.
The report says it is possible to over-consume - for example, to log more wood from a forest than re-grows each year, or harvest more fish from an ocean than can be replenished - but only for so long.
''The analogy I like to use is that if this is a bank we are not living off the interest that the Earth is providing us, we are drawing down on the principal,'' says WWF Australia chief executive Dermot O'Gorman.
''That is undermining not just the environmental sustainability of this planet, but the economic and emotional sustainability of the planet in the short-term.''
The largest chunk of the global ecological footprint is greenhouse gas emissions, which have increased 35 per cent since the firstLiving Planet Report in 1998.
The 2010 report says local exhaustion of natural resources was already happening in some places, citing Newfoundland's collapse of cod stocks.
It says although people can shift to new areas when a natural resource is spent, current consumption rates mean those resources will eventually also run out.
On current projections for population growth, consumption and climate change, the world will be using the equivalent of two planets' renewable resources a year by 2030.
Produced with the Zoological Society of London and the Global Footprint Network, the report includes three main indicators to monitor the state of the planet.
The Living Planet Index, which tracks nearly 8000 populations of more than 2500 animal species, found a decline in biodiversity of nearly 30 per cent between 1970 and 2007. Biodiversity loss was most severe in the tropics and in poorer countries.
The Water Footprint of Production index found 71 countries were experiencing water stress.

Saturday, October 9, 2010

New coal plant a $750m mistake, says Flannery

Melissa Fyfe 
Sunday Age, October 10, 2010
SCIENTIST and former Australian of the Year Tim Flannery has called on Premier John Brumby to stop Victoria's proposed brown coal power station, saying he will have ''zero credibility'' on climate change if he allows the project to go ahead.
Dr Flannery's call comes as public opposition mounts against the proposal to build a 600-megawatt plant in the Latrobe Valley.
As of last week, the Environment Protection Authority had received more than 4000 submissions on the project, most of them objections. The authority said it had never received so many submissions for a project under assessment.
Dr Flannery told The Sunday Age the future of coal was uncertain and the plant would be a $750 million waste of money. He said if the power station was approved, voters would not trust Mr Brumby's recently announced target to reduce emissions by 20 per cent by 2020.
''We've already seen the Howard government fall over on the climate change issue, we've seen Kevin Rudd lose his prime ministership over it and we've seen Malcolm Turnbull deposed,'' Dr Flannery said.
''This is not an issue that politicians can dodge. Premier Brumby will have zero credibility in the environmental area without dealing with this issue before the election. If he doesn't, every environmentalist and voter will look sceptically at his target.
''You can build as much solar as you want, but if you build new brown coal power plants you will not reach your target,'' Dr Flannery said. ''This is a grossly polluting plant and it will be around for 50 years.''
The proposal is being put forward by Dual Gas, a subsidiary of Melbourne company HRL, which is teamed with the state-owned China National Electric Equipment Corporation. Dual Gas says its new gasification technology will mean the plant is a third less polluting than Victoria's existing brown coal generators.
But environmentalists say it is still too polluting and Victoria should not be building any more brown coal power stations. The government recently announced a pollution limit on new power stations - 0.8 tonnes of carbon dioxide per megawatt hour of electricity.
Dual Gas resubmitted its application to the EPA after it was told it would not meet the new limit.
The company now says the plant's average intensity is between 0.73 and 0.78 tonnes per megawatt hour, although Environment Victoria says Dual Gas has failed to include the emissions associated with the energy use of the coal-fired power station itself.
The average emissions intensity of power plants in the OECD is 0.45 tonnes.
Environment Victoria wants Mr Brumby to withdraw the $50 million of taxpayer funds he has committed to the project - which failed to meet its original construction deadlines - and hold a public consultation process, as he committed to in Parliament, on whether 0.8 tonnes of carbon dioxide is an appropriate limit.
Mr Brumby's spokeswoman Fiona Macrae said the EPA process was independent.
''The government is confident of meeting its target to cut emissions by at least 20 per cent by 2020, irrespective of whether the EPA approves the HRL project,'' she said.

Thursday, October 7, 2010

Weather and feedbacks lead to third-lowest Arctic Sea Ice extent

National Snow and Ice Data Centre

October 4, 2010

An eventful summer sea ice melt season has ended in the Arctic. Ice extent reached its low for the year, the third lowest in the satellite record, on 19 September. Both the Northwest Passage and the Northern Sea Route were open for a period during September.

Overview of conditions

Average ice extent for September 2010 was 4.90 million square kilometers (1.89 million square miles), 2.14 million square kilometers (830,000 square miles) below the 1979 to 2000 average, but 600,000 square kilometers (230,00 square miles) above the average for September 2007, the lowest monthly extent in the satellite record. Ice extent was below the 1979 to 2000 average everywhere except in the East Greenland Sea near Svalbard.

The U.S. National Ice Center declared both the Northwest Passage and the Northern Sea Route open for a period during September. Stephen Howell of Environment Canada reported a record early melt-out and low extent in the western Parry Channel region of the Northwest Passage, based on analyses of the Canadian Ice Service. Two sailing expeditions, one Norwegian and one Russian, successfully navigated both passages and are nearing their goal of circumnavigating the Arctic.

Conditions in context

After the minimum extent of 4.60 million square kilometers (1.78 million square kilometers) on September 19, 2010, a rapid freeze-up has begun. On October 1, the 5-day average ice extent was 5.44 million square kilometers (2.10 million square miles).

September 2010 compared to past years

Ice extent for September 2010 was the third lowest in the satellite record for the month, behind 2007 (lowest) and 2008 (second lowest). The linear rate of decline of September ice extent over the period 1979 to 2010 is now 81,400 square kilometers (31,400 square miles) per year, or 11.5% per decade relative to the 1979 to 2000 average. Sea ice extent at the end of the melt season is shaped by conditions in the atmosphere and ocean, as well as the condition of the ice cover itself.