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Environment
By Pang Soo Mooi
Asian cities face greatest environmental risks - Bloomberg
Asian cities face the greatest risk from environmental issues including air pollution and natural disasters , according to a report released by a research firm . Of the 100 most vulnerable cities , 99 are in Asia . Of those , 37 are in China and 43 are in India , the world ' s first and third biggest emitters of greenhouse gases respectively .
Globally , 1.5 billion people live in 414 cities that are at high risk from pollution , water shortages , extreme heat , natural hazards and the physical impacts of climate change . Jakarta , the capital of Indonesia , topped the list of combined risks based on all nine factors analysed . India is home to 13 of the 20 riskiest cities in the world , a result of its extreme levels of air and water pollution . China ' s flood-prone Guangzhou and Dongguan topped the list of cities facing threats from natural hazards , followed by Japan ' s Osaka and Tokyo for being vulnerable to earthquakes and typhoons .
Trees need wind to reproduce – Popular Science
Trees may seem sedentary , but movement is a big part of their lives . To reproduce , many trees rely on wind to move their pollen and seeds around , says Matthew Kling , a post-doctoral researcher in plant biogeography at the University of California , Berkeley .
A study reported in the journal Proceedings of the National Academy of Sciences , examines how wind patterns affect the exchange of DNA between populations of trees . Their findings suggest that factors such as wind strength and direction can help mould the genetic makeup of forested landscapes .
As the climate heats up , some plants won ’ t thrive as well in their current environments , and will need to be in historically cooler locations to stay within a comfortable temperature range . But plenty of questions remain around precisely how the plants will get there . One of the biggest areas of uncertainty in plant movement is related to wind because wind dispersal can be tricky to measure at large scales .
Kling and his co-author David Ackerly , a professor of integrative biology at UC Berkeley , used 72 previously published scientific papers to gather genetic data on nearly 2,000 populations of trees belonging to nearly 100 different tree species around the globe . The researchers took this genetic data and compared it to a “ windscape ” model they developed , which pulls from three decades of hourly wind data .
The wind model provides a prediction for the way we would expect dispersal of seeds and pollen to take place across large geographic scales and long time periods . “ The genetic data provides a measured estimate , totally independent of the wind data , of the way that the seeds and pollen have dispersed across large landscapes in the past ,” says Kling . The authors then compared the predictions made by the windscape model to the observed genetic patterns , allowing them to test whether the wind was actually driving them .
“ We found evidence that migration of seeds and pollen tends to happen preferentially in the direction of the prevailing wind ,” says Kling . In other words , the seeds and pollen are carried downwind more often than they ’ re carried upwind . They also found that populations located downwind — in the direction the wind is blowing — were typically more genetically diverse overall . In addition , they found that distinct tree populations connected by stronger winds were more similar to one another than populations connected by weaker winds , suggesting that migration is happening between those populations .
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