As temperatures warm, plants release gases that help form clouds and cool the atmosphere, according to research from IIASA and the University of Helsinki.
The new study, published in Nature Geoscience, identified a negative feedback loop in which higher temperatures lead to an increase in concentrations of natural aerosols that have a cooling effect on the atmosphere.
"Plants, by reacting to changes in temperature, also moderate these changes," says IIASA and University of Helsinki researcher Pauli Paasonen, who led the study.
Scientists had known that some aerosols ? particles that float in the atmosphere ? cool the climate as they reflect sunlight and form cloud droplets, which reflect sunlight efficiently. Aerosol particles come from many sources, including human emissions. But the effect of so-called biogenic aerosol ? particulate matter that originates from plants ? had been less well understood. Plants release gases that, after atmospheric oxidation, tend to stick to aerosol particles, growing them into the larger-sized particles that reflect sunlight and also serve as the basis for cloud droplets. The new study showed that as temperatures warm and plants consequently release more of these gases, the concentrations of particles active in cloud formation increase.
"Everyone knows the scent of the forest," says Ari Asmi, University of Helsinki researcher who also worked on the study. "That scent is made up of these gases." While previous research had predicted the feedback effect, until now nobody had been able to prove its existence except for case studies limited to single sites and short time periods. The new study showed that the effect occurs over the long-term in continental size scales.
The effect of enhanced plant gas emissions on climate is small on a global scale ? only countering approximately 1 percent of climate warming, the study suggested. "This does not save us from climate warming," says Paasonen. However, he says, "Aerosol effects on climate are one of the main uncertainties in climate models. Understanding this mechanism could help us reduce those uncertainties and make the models better."
The study also showed that the effect was much larger on a regional scale, counteracting possibly up to 30% of warming in more rural, forested areas where anthropogenic emissions of aerosols were much lower in comparison to the natural aerosols. That means that especially in places like Finland, Siberia, and Canada this feedback loop may reduce warming substantially.
The researchers collected data at 11 different sites around the world, measuring the concentrations of aerosol particles in the atmosphere, along with the concentrations of plant gases, the temperature, and reanalysis estimates for the height of the boundary layer, which turned out to be a key variable. The boundary layer refers to the layer of air closest to the Earth, in which gases and particles mix effectively. The height of that layer changes with weather. Paasonen says, "One of the reasons that this phenomenon was not discovered earlier was because these estimates for boundary layer height are very difficult to do. Only recently have the reanalysis estimates been improved to where they can be taken as representative of reality."
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International Institute for Applied Systems Analysis: http://www.iiasa.ac.at
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Source: http://www.labspaces.net/127976/Plants_moderate_climate_warming
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Akamai published its quarterly “State of the Internet” report for the last quarter of 2012 today. The report, as usual, looks at global Internet speeds, as well as the state of Internet security, the number if IPv4 numbers in use and other similar metrics. Internet speeds, of course, are the most interesting numbers for users in this report. South Korea has long been in the lead in this category, and that’s not likely to change anytime soon. Interestingly, though, the average Internet speed in South Korea has slowed down a bit lately. At an average speed of 14 Mbps, South Korean Internet users now surf 4.8 percent slower than last quarter and 13 percent slower than a year ago. In the U.S., Akamai found, the average connection now clocks in at 7.4 Mbps. That’s up a respectable 28 percent year-over-year and 2.3?percent since last quarter and enough to rank the U.S. No. 8 on Akamai’s list. Currently, about 19?percent of U.S. Internet connections deliver speeds over 10 Mbps+ connections. It’s encouraging to see that this number increased 90?percent since last year, though growth in this metric seems to have stalled a bit, as the U.S. only registered a low 5.5?percent increase since last quarter. Overall, the 10 countries with the fastest connections saw relatively minor speed increases over the last quarter, ranging from just 0.1?percent in the Netherlands to 7.4?percent in Sweden. Globally, though, the average connection speed grew by 25?percent year-over-year. The only country to see a major dip in speeds since the last quarter was Guatemala (39?percent). As for mobile connectivity, Akamai reports that its partner Ericsson found that mobile data traffic around the world grew 28?percent in the last quarter alone and doubled year-over-year. Android and Apple’s Mobile Safari are almost even here when it comes to connections over cellular networks (35.3?percent vs. 32.6?percent), but taking all connections into account (that is, including Wi-Fi), Apple accounts for 58.7?percent of requests compared to 21.7?percent for Android Webkit. In this quarter’s report, Akamai is also taking a closer look at DDoS attacks. The company says its own customers reported 768 attacks in 2012, a 200?percent year-over-year increase. While this is not necessarily representative of the Internet as a whole, it’s yet another indication that the number of these attacks across the Interent continues to increase.
How do we get our teens to be responsible and pay for their own luxury items. With the cost of car insurance, cell phone, gasoline and entertainment rising, many of the nations teen are being told by their parents that they need to help pay for these expenses.
VC firm Andreessen Horowitz is announcing another major win for its powerhouse of talent?? Ken Coleman, enterprise tech veteran, is joining the firm as a Special Advisor. Coleman is a Silicon Valley pioneer and former chairman/CEO of ITM Software, and a trusted mentor to countless IT companies and entrepreneurs, including the firm's founder Ben Horowitz. Coleman joins fellow special advisors, former Washington D.C. mayor Adrian Fenty and former US Treasury Secretary Larry Summers at the firm.