Archives for November 14, 2007

The delay in autumnal leaf coloration and leaf fall in trees is caused by rising levels of carbon dioxide (CO2) in the atmosphere and not by increased global temperatures, suggests a new study by researchers at the University of Southampton.

In recent years, woodland autumnal colour changes have been occurring later in the season whilst re-greening in spring has been occurring earlier. During the last 30 years across Europe, autumnal senescence – the process of plant aging where leaves discolour and then fall – has been delayed by 1.3 – 1.8 days a decade. To date, this has been explained by global warming, with increasing temperatures causing longer growing seasons.

However, while a strong correlation has been observed between increased global temperatures and earlier spring re-greening and bud break, the correlation between autumn leaf colour change and fall and temperature trends in 14 European countries is weak.

Over the 30 years that progressive delays in autumnal senescence have been observed, atmospheric CO2 has risen by 13.5 per cent. Experimental studies show that increased atmospheric CO2 affects plant physiology and function, influencing a myriad of processes.

The Southampton researchers undertook two large forest ecosystem experiments in which poplar (Populus) trees in separate plots were exposed to either ambient or elevated levels of CO2 from planting to maturity. The elevated concentration was at 550 parts per million, proposed as representative of concentrations that may occur in 2050. Changes in the tree canopy were measured by remote sensing.

The trees exposed to elevated CO2 retained their leaves for longer and also experienced a smaller decline in end of season chlorophyll content, resulting in a greener autumn canopy relative to that in ambient CO2.

Professor Gail Taylor, of the University’s School of Biological Sciences, explains:
‘The research data provide compelling evidence in terms of both the leaf and canopy that autumnal senescence in such forest ecosystems will be delayed as the atmospheric concentration of CO2 continues to rise, independent of increased temperatures.

‘Photosynthesis and canopy greenness are maintained for longer in elevated CO2. This is because a CO2 rich atmosphere allows the tree to generate carbon rich compounds that are known to prolong the life of leaves. These compounds may have a positive effect for carbon balance and stress tolerance but may also have a negative effect on the control of dormancy.

‘When trees keep their leaves for longer, they continue to photosynthesise but trees also need to set bud and if they don’t do that, it makes them susceptible to frost and other weather events. A key question now is whether we should be selecting trees which are better adapted to coping with increasing levels of CO2, perhaps considering different varieties and species to plant, rather than using locally sourced seed, as is current practice,’ she continues.

The study also provides the first insight into changes in the genetic make-up of Populus that can account for this shift to delayed senescence. Using cDNA microarrays, the researchers looked at approximately 20,000 genes and have identified a suite of genes that are switched on during delayed senescence in elevated CO2.

News Release from the University of Southampton:

New research suggests delay in autumn colour is caused by increased atmospheric CO2 not global warming

One analysis by CRA International estimates the Lieberman-Warner bill will cost $4 to $6 trillion over 40 years. The American Council for Capital Formation has concluded that the legislation’s emissions-swapping scheme would lead to “higher energy prices, lost jobs and reduced [gross domestic product].” During testimony before a House committee, Peter Orszag, director of the Congressional Budget Office (CBO), stated that such swapping programs known as “cap-and-trade” would create “windfall” profits – profits that have even been denounced by presidential candidate John Edwards. The CBO has also cautioned that “price increases would disproportionately affect people at the lower end of the income scale.” It is baffling that congressional Democrats, who never cease to spout their populist rhetoric, are ignoring such a clarion call for ensuring economic stability among low and middle-income families. Former Federal Reserve Chairman Alan Greenspan in his new book, “The Age of Turbulence,” described how these programs have unintended effects when he wrote that “[c]ap-and-trade systems or carbon taxes are likely to be popular only until real people lose real jobs as their consequence. There is no effective way to meaningfully reduce emissions without negatively impacting a large part of an economy,” he argued. Democrats in Congress would do well to listen to Mr. Greenspan’s cogent views. The rhetoric surrounding the issue of greenhouse gases has been fraught with emotion rather than reason.

Senate Climate Bill Will Cost Trillions for No Benefit, Says The Washington Times Editorial:

Globaloney

Small island states meeting in the Maldives in the Indian Ocean this week are working on a resolution saying that climate change is a threat to human rights.

Reuters: Is climate change “human rights abuse”?

Nov. 12 (Bloomberg) — American officials are planning to back a new United Nations document that says governments and businesses will have to spend billions of dollars a year to reduce global warming and adapt to its effects.

UN Panel’s Global Warming Report May Win U.S. Support (Update1)

The ocean’s plankton can suck up far more airborne carbon dioxide (CO2) than previously realised, although the marine ecoystem may suffer damage if this happens, a new study into global warming says.

The sea has soaked up nearly half of the CO2 that has been emitted by fossil fuels since the start of the Industrial Revolution.

Global warming: Oceans could absorb far more CO2, says study

Reading about the recent global warming rally at Kincaid Park, I wondered if the participants would be relieved if man’s activities were proved not responsible for Alaska’s warming weather. An intriguing question.

Despite predictions, sky is not falling

The IPCC’s Assessment Report will tell policy-makers what to expect from man-made climate change. It is the result of rigorous and painstaking labour: more than can be said for the other Nobel Prize winner. The difference between Gore’s claims and IPCC research is instructive.

Ignore Al Gore – but not his Nobel friends
By Bjorn Lomborg

We should always begin our scientific pronouncements with this statement: “At our present level of ignorance, we think we know…,” John Christy.

Read John Christy’s viewpoint article on the BBC News Website:

No consensus on IPCC’s level of ignorance

Read an alternative view from Martin Parry on the BBC News website:

The IPCC: As good as it gets