Is the Climate Killing Our Trees?

Aerial_Shasta forestsA new collaborative study suggests that warming temperatures are taking a toll on trees in old-growth forests across the western US.

The study concluded that the near doubling in the mortality rate over several decades transcends forest types, elevation, tree size and species. The study will by published in Science this week.

Phil van Mantgem, who co-led the research team at USGS, said the spike in dying trees could lead to habitat destruction for forest wildlife. And while living trees absorb greenhouse gases, dying trees actually release carbon dioxide into the atmosphere, furthering the effects of global warming.

Usually, van Mantgem said, a small number of trees in a forest die each year and are replaced by new growth. However he’s observed that trees are dying so quickly that new growth is having trouble keeping up. He said one of the causes could be the West’s rising average temperature. While it rose only 1 degree (F) during the past few decades, he said it’s been enough to reduce the snowpack and melt the snow earlier, causing longer periods of dry weather and distressing forests.

Warm weather might also nurture insects and diseases that attack trees. Some reports have already tied destructive bark-beetle outbreaks to higher temperatures.

Nate Stephenson, another research team co-leader with the USGS, said the deaths, over time, could reduce the age of the western forests. “Tree death rates are like interest on a bank account – the effects compound over time,” Stephenson said. Stephenson worries that the increasing rate could lead to a bigger and more abrupt change in forests, similar to sudden and extensive die-backs observed in the southwest, Colorado and British Columbia.

Scientists from the U.S. Forest Service, and six universities collaborated on the study. Van Mantgem appeared on KQED’s Forum program today, along with host Dave Iverson, Climate Watch Sr. Editor Craig Miller and Inez Fung, author of a new study on seasons shifting from rising temperatures. Van Mantgem then popped up on NPR’s Science Friday. New York Times correspondent Andrew Revkin, author of the widely followed Dot Earth blog, also appeared and responded to recent polling on attitudes toward climate change.

  • http://beam.to/outatbobs/ Bob Sakall

    Good show today on Forum. It’s to bad people have their heads in the sand hoping things aren’t true or will get better on their own. People tend to also believe in myths which guide them which is totally wrong. They don’t want to see or believe the change. Even if you present the change in photos and video they will look at it and say, it can’t happen here. Well, it’s happening here. Another problem I see is the loss of wild life because of mans development. A forest can’t live without wild life. If you look at a persons home in the mountain that fenced off their yard and has a dog, nothing grows in that yard because the dog keeps birds from distributing seeds. If people want to live in the forest they should trim trees like a fire has come through. This would make them fire safe but still have a forest there. Covering the ground is very important to keep the ground cool and water in the soil.

  • Todd Armstrong

    I can not argue with the argument written above. It’s right on.

    Everyone seems to have a short term memory with regard to climate. It’s understandable given the long term and complex nature of the phenomenon. All it takes is a cold winter to get people off the mark.

    This is nothing compared to the short term issues associated with the economy. Housing prices, loan defaults, an inability to get credit and job losses. Climate change will never beat the economy.

    Fortunately, climate issue resolution can have a very positive return on several fronts. Cheap gas will always be a major issue and one that can not be over come unless we tax or people understand the harm of not having energy independence.

    We have a positive business case with renewable energy but it has to be delivered without calculator or spreadsheet. We need to get to a point where we can say it’s 1.5 more expensive to go fossil fuel (say coal) vs. a highly insulated solar power driven home.

    Then we can start talking about polution – “what about posterity? your kids, your grand kids? The best science minds in the world have demonstrated the dangers of CO2 pollution.”

    Then we can (develop) and introduce the Henry Ford argument – “the sun is the greatest source of energy; I hope we don’t have to wait for fossil fuels to run out until we switch to solar.”

    The point here is we need to make a series of arguments sequentially that can’t be matched by going traditional fuel sources. After all, theoretically, it is much more efficient to harness the sun’s energy directly than to access it through the strata laid down millions of years ago.

    I believe this is possible.

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