Climate change brings longer spring and autumn to US

Expanding growing season has enabled the forests to store an additional 26 million tonnes of carbon dioxide, say researchers

 
By Elga Morrison
Last Updated: Monday 17 August 2015

Using a combination of satellite imagery, tower-mounted instruments and on-the-ground observations, the team found that forests throughout eastern US are showing signs of spring growth earlier

Global warming, depletion of ozone layer, rise in sea level, species going extinct— till now these have been the dreaded trends associated with climate change. But if a new study is to be believed, all that is associated with climate change is not bad.

The study carried out by researchers from across the world shows that warming leads to increased growing season in forests. Experts from Macquarie University in Sydney, Harvard University in the US, University of Cambridge in the UK, and Ohio State University, Columbus, have found that over the last two decades, forests in the eastern part of the United States of America, are experiencing earlier springs and late autumns more than ever before. This is helping the forests store more carbon dioxide.

Lead author Trevor Keenan from department of biological sciences in Macquarie University explains that his team found that despite the increased respiration due to warming, the duration of increased green foliage cover is stronger, thereby leading to a net response of increased carbon uptake. He adds that warming generally causes increased decomposition and drought, both of which lead to larger net releases of CO2 into the atmosphere.

Using a combination of satellite imagery, tower-mounted instruments and on-the-ground observations, the team found that forests throughout eastern US are showing signs of spring growth earlier.

Satellites were used to track when forests across the region began to turn green in spring, and when leaves began to dry in the fall. Ground observations made every three to seven days at the Harvard Forest in Petersham and a long-term research site in New Hampshire provided direct information about the state of the buds, leaves and branches. The carbon balance of forest ecosystem at three different scales were studies using eddy covariance system that analyses the atmosphere using ultrasonic and infrared gas analysers, during which carbon exchange is estimated based on the changes created by these carbon emissions in different atmospheric layers.

“The expanded growing season has enabled forests to store as much as 26 million tonnes more CO2 than before,” the team reported in June 1 issue of Nature Climate Change.

When questioned whether the carbon uptake is occurring on a significant level so as to reduce the global warming levels, Keenan said, “Increased carbon uptake can slow the rate of climate warming, which is significant even if it does not stop it. So yes, global warming is still a major concern, but the observed response is serving to slow it down somewhat.”


Research: Net carbon uptake has increased through warming-induced changes in temperate forest phenology

Interactive: Summer weather continues to get hotter in every U.S. region since 1970

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  • The study presumes "Global

    The study presumes "Global warming, depletion of ozone layer, rise in sea level, species going extinctÔÇö till now these have been the dreaded trends associated with climate change. But if a new study is to be believed, all that is associated with climate change is not bad." and using a small period data predicts a big thing.

    First-off-all ozone depletion is not part of climate change and also, now this problem is almost resolved with the change of ozone depleting substances by non-ozone depleting substances. Some of the substances used here are greenhouse gases but this is nothing to do with ozone depletion. Also, UV component in the solar spectrum is insignificant but yet if increased by a little affect the life forms on the Earth. The observed data showed no increase in UV at the ground level.

    Very recently Obama Administration got carried out National Climate Assessment-2014 as a prelude to introduce a EPA order to reduce 30% of carbon dioxide release from thermal power plants -- India's National Action Plan on Climate Chane also had a similar component but not direct reduction but indirect reduction through use of solar energy --.

    Scientists responded to this report. It was presented at www.scribd.com/doc/224538945/NAC-Rebuttal. Also voice of Russia observed "US National Climate Assessment misguided".

    The rebuttal observed "With the Earth's vast ocean and atmosphere never in complete equilibrium, our climate will always be changing on time scales from weeks to months to decades to centuries and beyond. According to IPCC there is "high agreement" among leading experts that long-term trends in weather disasters are not attributable to fossil fuels. Hurricanes have not increased in the US in frequency, intensity, or normalized damage since at least 1900. Currently US is enjoying a period of over eight years without category 3 or stronger Hurricanes making landfall. Government data also indicate no association between use of fossil fuels and tornado activity -- The frequency of occurrence of hurricanes showed a normal distribution pattern with the peak around 10 September. IPCC also states there is "low confidence" in any climate-related trends for floods magnitude or frequency on a global scale." Also, the sea level rise along the east coast is different from the West coast -- rising and falling.

    Conclusions based on a very short period observations in a weather system with rhythmic pattern is meaningless. So also, the reason of a change associated with non-weather attributing to climate change like our present Environment minister on desertification has no meaning and help only to arrive at misleading conclusions.

    Dr. S. Jeevananda Reddy


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