Word: waterous
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Unsurprisingly, the outcome doesn't look good. In a new study published April 13 in the Proceedings of the National Academy of Sciences (PNAS), scientists at UA found that water-deprived piñon pines raised in temperatures about 7° Fahrenheit (4° Celsius) above current averages died 28% faster than pines raised in today's climate. It's the first study to isolate the specific impact of temperature on tree mortality during drought - and it indicates that in a warmer world trees are likely to be significantly more vulnerable to the threat of drought than they are today...
...PNAS study, led by Henry Adams, a doctoral student at UA's ecology and evolutionary biology department, also confirms that hotter temperatures actually suffocate trees in dry times. Piñon pines respond to drought by closing the pores in their needle-like leaves to stop water loss. That keeps them from going thirsty, but it also prevents them from breathing in the carbon dioxide they need to live - and eventually, the drought-stressed trees simply suffocate. (See pictures of activists defending backcountry forests from logging...
...higher levels of atmospheric CO2 that would likely be seen in a warmer future won't make much of a difference either - if the pine needles' pores are closed to prevent water loss, CO2 simply won't get in. Even more worrisome, the PNAS study doesn't take into account possible changes in precipitation patterns in a warmer future, which many climate models say could be drier, exacerbating the impacts of higher temperatures. "We can envision the landscape getting hammered over and over again," says Breshears...
...latest in a number of recent studies that paint a grim fate for the world's forests if warming isn't slowed. A major Science study published in January found widespread increase in tree mortality rates in the western U.S., thanks in part to regional warming trends and growing water scarcity. Another study published last month, also in Science, found that even the seemingly limitless Amazon rainforest could be highly vulnerable to drought. And since living trees suck up CO2 from the atmosphere, massive tree mortality due to warming could produce a feedback effect, further intensifying climate change...
...Thai Lunar New Year is usually a time when guns line the streets of Bangkok. Water guns, that is, manned by revelers who spray passersby to summon plenty of rain for the coming year's harvest. But today, as this Thai New Year began, the usual neon-hued water guns were supplanted by submachine guns held by soldiers who were trying to disperse the agitated antigovernment protesters who have blockaded part of central Bangkok for days...