[Reader-list] Impact of Global Warming

[Ananth S]

Trees absorbing less CO2 as world warms, study finds

· Shorter winters weaken forest 'carbon sinks'
· Data analysis reverses scientists' expectations

     * James Randerson, science correspondent
     * The Guardian,
     * Thursday January 3 2008

http://www.guardian.co.uk/environment/2008/jan/03/ 
climatechange.carbonemissions

The ability of forests to soak up man-made carbon dioxide is  
weakening, according to an analysis of two decades of data from more  
than 30 sites in the frozen north.

The finding published today is crucial, because it means that more of  
the CO2 we release will end up affecting the climate in the  
atmosphere rather than being safely locked away in trees or soil.

The results may partly explain recent studies suggesting that the  
amount of CO2 in the atmosphere is increasing faster than expected.  
If higher temperatures mean less carbon is soaked up by plants and  
microbes, global warming will accelerate.

The Intergovernmental Panel on Climate Change, which shared the Nobel  
peace prize with Al Gore, has concluded that humanity has eight years  
left to prevent the worst effects of global warming.

Carbon uptake by land and sea is crucial to predictions about future  
warming. "We are currently getting a 50% discount on the climatic  
impact of our fossil fuel emissions," the climate scientist John  
Miller of the University of Colorado wrote in a commentary on the  
research in the journal Nature - meaning that half of what we put out  
is sucked up by the oceans and ecosystems on land.

"Unfortunately, we have no guarantee that the 50% discount will  
continue, and if it disappears we will feel the full climatic brunt  
of our unrelenting emission of CO2 from fossil fuels."

The surprise rethink concerns abundant evidence from around the world  
that winter is starting later and spring earlier. In northern  
attitudes, spring and autumn temperatures have risen by 1.1C and 0.8C  
respectively in the past two decades. That means a longer growing  
season for plants, which scientists thought should be a good thing  
for slowing warming. This increased growth is even visible from  
space, with satellite measurements indicating a greening of the land.  
As plants take up more CO2, that should put a break on CO2 increases.

However, the new data suggests that is too simplistic. The team  
analysed data from more than 30 monitoring stations spread across  
northern regions including Siberia, Alaska, Canada and Europe. The  
data, which goes back to 1980, charts the levels of CO2 in the local  
atmosphere. This is a product of both uptake by plants during  
photosynthesis and release of CO2 by plants and microbes during  
respiration.

The team focused particularly on the date in autumn at which the  
forests switched from being a net sink for carbon into a net source.  
Instead of moving later in the year as they had expected, this date  
actually got earlier - in some places by a few days, but in others by  
a few weeks.

"The information that we had from satellite data, that the greening  
was increasing, looked like a positive sign. There was hope that this  
would help us to mitigate emissions," said Anders Lindroth at Lund  
University in Sweden, who was part of the research team. "But even if  
we have a greening, it doesn't mean that we have a positive effect on  
the carbon balance ... it's bad news."

"This means potentially a bigger warming effect," said Timo Vesala at  
the University of Helsinki, who led the study.

The precise effect the trend will have on future warming is hard to  
predict, said Colin Prentice of the University of Bristol. "Over a  
longer period of decades, models predict changes in vegetation  
structure, including tundra regions becoming forested, and the  
forests tend to take up far more carbon than the tundra. So I would  
be sceptical about reading any particular future implication into  
these findings."

The research could partly explain results by the Global Carbon  
Project, which confirmed that the rise in CO2 levels in the  
atmosphere is accelerating. Between 1970 and 2000 the concentration  
rose by about 1.5 parts per million (ppm), but since 2000 the annual  
rise leapt to an average of 1.9ppm - 35% higher than expected. Part  
of the rise is due to increased CO2 production by China, but the team  
said weakening carbon sinks were also to blame.



Burning biofuels may be worse than coal and oil, say experts

· Scientists point to cost in biodiversity and farmland
· Razing tropical forests 'will increase carbon'

     * Alok Jha, science correspondent
     * The Guardian,
     * Friday January 4 2008

http://www.guardian.co.uk/science/2008/jan/04/sciencenews.biofuels

Using biofuels made from corn, sugar cane and soy could have a  
greater environmental impact than burning fossil fuels, according to  
experts. Although the fuels themselves emit fewer greenhouse gases,  
they all have higher costs in terms of biodiversity loss and  
destruction of farmland.

The problems of climate change and the rising cost of oil have led to  
a race to develop environmentally-friendly biofuels, such as palm oil  
or ethanol derived from corn and sugar cane. The EU has proposed that  
10% of all fuel used in transport should come from biofuels by 2020  
and the emerging global market is expected to be worth billions of  
dollars a year.

But the new fuels have attracted controversy. "Regardless of how  
effective sugar cane is for producing ethanol, its benefits quickly  
diminish if carbon-rich tropical forests are being razed to make the  
sugar cane fields, thereby causing vast greenhouse-gas emission  
increases," Jörn Scharlemann and William Laurance, of the Smithsonian  
Tropical Research Institute in Panama, write in Science today.

"Such comparisons become even more lopsided if the full environmental  
benefits of tropical forests - for example, for biodiversity  
conservation, hydrological functioning, and soil protection - are  
included."

Efforts to work out which crops are most environmentally friendly  
have, until now, focused only on the amount of greenhouse gases a  
fuel emits when it is burned. Scharlemann and Laurance highlighted a  
more comprehensive method, developed by Rainer Zah of the Empa  
Research Institute in Switzerland, that can take total environmental  
impacts - such as loss of forests and farmland and effects on  
biodiversity - into account.

In a study of 26 biofuels the Swiss method showed that 21 fuels  
reduced greenhouse-gas emissions by more than 30% compared with  
gasoline when burned. But almost half of the biofuels, a total of 12,  
had greater total environmental impacts than fossil fuels. These  
included economically-significant fuels such as US corn ethanol,  
Brazilian sugar cane ethanol and soy diesel, and Malaysian palm-oil  
diesel. Biofuels that fared best were those produced from waste  
products such as recycled cooking oil, as well as ethanol from grass  
or wood.

Scharlemann and Laurance also pointed to "perverse" government  
initiatives that had resulted in unintended environmental impacts. In  
the US, for example, farmers have been offered incentives to shift  
from growing soy to growing corn for biofuels. "This is helping to  
drive up global soy prices, which in turn amplifies economic  
incentives to destroy Amazonian forests and Brazilian tropical  
savannas for soy production."

They added: "The findings highlight the enormous differences in costs  
and benefits among different biofuels. There is a clear need to  
consider more than just energy and greenhouse gas emissions when  
evaluating different biofuels and to pursue new biofuel crops and  
technologies."

Andy Tait, campaign manager at Greenpeace, said: "We're already  
bought into mandatory targets for the use of biofuels with very  
little thought of what the environmental impacts will be. This study  
further confirms that there are serious risks associated with first  
generation biofuels, particularly from corn, soya and palm oil."

He said that the biofuel technology had been oversold by industry and  
politicians. "It's clear that what government and industry are trying  
to do is find a neat, drop-in solution that allows people to continue  
business as usual.

"If you're looking at the emissions from the transport sector, the  
first thing you need to look at is fuel efficiency and massively  
increasing it. That needs to come before you even get to the point of  
discussing which biofuels might be good or bad."