29 October 2015, Yale Connections, Long-Term Drought Impacts on Trees. Scientists find that droughts harm trees for longer than previously understood. ANDEREGG: “We’ve known for decades that drought has harmful effects on trees. That during drought they grow slower and they have a higher chance of death.” That’s William Anderegg, a biologist at the University of Utah. He says until recently, researchers were not clear about what happened to the trees after a drought ended. So his team looked at the growth of trees after severe drought in more than a thousand forests across North America, Europe, and Asia. They found that even four years after a drought, trees continued to grow more slowly than normal. ANDEREGG: “Trees take up about a quarter of human emissions of CO2 each year, and that’s a very big slowing effect on climate change. So if droughts cause forests to take up less carbon, that could very much speed up the pace and the severity of climate change.” Anderegg says it is too early to know what the long-term implications will be. ANDEREGG: “Some of our best models suggest that forests could be relatively resilient and others suggest they could really die off en masse and lose a lot of their carbon to the atmosphere. And we don’t know which of those is more likely.” But Anderegg says that the future of the world’s forests is still in our hands. ANDEREGG: “I always like to emphasize that a lot of that future does depend on human decisions and what we do about climate change.” Read More here
Tag Archives: Drought
28 August 2015, Climate News Network, Drought becoming the ‘new normal’ for Californians. Human impacts on global warming and water resources are threatening to turn the landscape of the US west into a dustbowl. One way or another, humans are to blame for the catastrophic drought in California that scientists say may be emerging as a “new normal”. Either humans have mismanaged the state’s water, or human-triggered global warming has begun to help turn America’s landscape of wine and roses into a dustbowl, according to two new studies. And the arguments have relevance extending far beyond the US west, as the European Drought Observatory has warned that much of mainland Europe is now caught up in the continent’s worst drought since 2003. The consequences of any drought could also be more enduring than expected. A research team in the US reports in the journal Ecological Applications that trees that survived severe drought in the US southeast 10 years ago are now dying – because of the long-ended drought. Read More here
30 July 2015, Science Daily, Drought’s lasting impact on forests. Forests across the planet take years to rebound from drought, storing far less carbon dioxide than widely assumed in climate models. In the virtual worlds of climate modeling, forests and other vegetation are assumed to bounce back quickly from extreme drought. But that assumption is far off the mark, according to a new study of drought impacts at forest sites worldwide. Living trees took an average of two to four years to recover and resume normal growth rates after droughts ended, researchers report today in the journal Science. “This really matters because in the future droughts are expected to increase in frequency and severity due to climate change,” says lead author William R.L. Anderegg, an assistant professor of biology at the University of Utah. “Some forests could be in a race to recover before the next drought strikes.” Forest trees play a big role in buffering the impact of human-induced climate change by removing massive amounts of carbon dioxide emissions from the atmosphere and incorporating the carbon into woody tissues. The finding that drought stress sets back tree growth for years suggests that Earth’s forests are capable of storing less carbon than climate models have calculated. Read More here
27/7/2015, The Vane, El Niño Probably Won’t Solve California’s Dire Drought: If anyone is eagerly following news of the strengthening El Niño in the Pacific, it’s California. Strong El Niño events have a history of bringing drenching rain to the West Coast during the winter months, and we could see that play out this year. However, don’t get too wrapped-up in the hype—it’s going to take more than one rainy stretch to ease the damage done by the lasting drought. In order to understand what El Niño may or may not do for California, we need to understand El Niño itself, and shockingly (!!!) the national media doesn’t do a great job explaining things that could get them a lot of ratings if they spin it just right (see: polar vortex)….
….The latest update of the drought monitor doesn’t paint a pretty picture across the western United States. Believe it or not, the drought has improved by a hair since September 30—California started the water year with 58% of the state in an exceptional drought, which is the worst of the five categories. As of last Tuesday, only (“only”) 46% of the state is in an exceptional drought. Any progress is progress, I guess.The intensity and duration of this drought is unprecedented in the modern era, and it’s going to take more than a month or two of rain to fix what’s gone so horribly wrong over the past couple of years. The problem with the potential of seeing big bursts of heavy rain is that much of the rain will run off, helping reservoirs and bodies of water no doubt, but causing floods, mud and landslides in the process, not to mention the water being unable to seep into and rejuvenate the soil. This doesn’t even begin to cover the fact that (currently non-existent) snowpack is a huge water resource in the state.Read More here