Bad news about forests
A new scientific study seems to indicate that the ability of forests to absorb carbon dioxide is decreasing, according to this report.
” “We are currently getting a 50 per cent discount on the climatic impact of our fossil fuel emissions,” the climate scientist John Miller, of the University of Colorado, wrote in the journal Nature - meaning half of what we put out is sucked up by the oceans and ecosystems on land.
“Unfortunately we have no guarantee the 50 per cent 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 evidence from around the world that winter is starting later and spring earlier. In northern latitudes, spring and autumn temperatures have risen by 1.1 degrees and 0.8 degrees 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.
However, new data suggests this is too simplistic. The team analysed data from more than 30 monitoring stations 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 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, the date got earlier. “The information we had from satellite data, that the greening was increasing, looked like a positive sign. There was hope this would help us to mitigate emissions,” said Anders Lindroth at Lund University in Sweden, who was part of the research team.”