Whether to buy green or to act green is a common conundrum for the environmentally-friendly consumer. Should you buy a newer, more efficient appliance? Or would it be better to buy a used one? Or does it make the most sense to keep what you have? Which is more environmentally responsible?

International Bat Night is happening this weekend, an event that hopes to inspire people across Europe to understand more about how bats live and why they are so important to conserve. A series of presentations, exhibitions and bat walks are happening in more than 30 countries, including the UK – check out the bat walk at Harcourt Arboretum in Oxford this Thursday. To join in the celebrations, we have delved into the ARKive collection to come up with some truly batty facts to get you in the mood for International Bat Night and to hopefully inspire you to take part in an event near you!

The Arctic is a polar region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Denmark (Greenland), Norway, the United States (Alaska), Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost. The blanket of sea ice floating on the Arctic Ocean melted to its lowest extent ever recorded since satellites began measuring it in 1979, according to the University of Colorado Boulder’s National Snow and Ice Data Center (NSID). On Aug. 26, the Arctic sea ice extent fell to 1.58 million square miles, or 4.10 million square kilometers. The number is 27,000 square miles, or 70,000 square kilometers below the record low daily sea ice extent set Sept. 18, 2007. Since the summer Arctic sea ice minimum normally does not occur until the melt season ends in mid- to late September, the CU-Boulder research team expects the sea ice extent to continue to dwindle for the next two or three weeks, said Walt Meier, an NSID scientist.

The droughts that have parched big regions of the country are killing forests. In the arid Southwest, the body count is especially high. Besides trying to keep wildfires from burning up these desiccated forests, there’s not much anyone can do. In fact, scientists are only now figuring out how drought affects trees. Park Williams studies trees at the Los Alamos National Laboratory in New Mexico, but not the way most scientists do. “We’re interested in trees that die,” he says — spefiically, death by heat and drought. Sure, lack of water kills trees, but which ones die first, how long does it take, how long can they go without water? “That’s a part we don’t understand very well as ecologists,” says Craig Allen, an ecologist with the U.S. Geological Survey. “We don’t know what it takes to kill trees.”

Mutation is simply defined as “random changes in genetic material”. Without mutations and there would be very little change in species or evolution. Humans inherit more than three times as many mutations from their fathers as from their mothers, and mutation rates increase with the father’s age but not the mother’s, researchers have recently found in the largest study of human genetic mutations to date. The study, based on the DNA of around 85,000 Icelanders, also calculates the rate of human mutation at high resolution, providing estimates of when human ancestors diverged from nonhuman primates. It is one of two papers published this week by the journal Nature Genetics as well as one published at Nature that shed dramatic new light on human evolution.

For millions of years, sea stars have been among the most recognized oceanic organisms. People around the world have recognized their beauty and importance since ancient times. Finding one washed up on the shore or during a snorkeling expedition is even more exciting and chances are we will be seeing one species, the yellow brittle sea star, Ophiothela mirabilis, more often as it has made it’s way to the Atlantic Ocean. However, this colorful, six-armed species of sea star is not be welcomed to these waters. In a study published in Coral Reefs, the Journal of the International Society for Reef Studies, Ophiothela mirabilis, which was once restricted to Pacific waters, has been found at Brazilian and Caribbean ports in the Atlantic Ocean. Not only is this species non-native to the Atlantic Ocean, but it is considered invasive because of its ability to reproduce asexually.

The world’s first community-owned tidal turbine will be made and deployed in Scotland, after a fabrication contract between Scottish firms Steel Engineering and Nova Innovation was announced by First Minister Alex Salmond. During a visit that formed part of the Scottish Government’s Summer Cabinet programme in Renfrew, the First Minister confirmed that the two companies had reached agreement to manufacture a tidal turbine that will be connected to the grid and provide electricity to people in one of the most remote parts of Scotland.

Four years after overturning a major Environmental Protection Agency air pollution rule as inconsistent with the Clean Air Act, this week the D.C. Circuit Court of Appeals vacated the program that EPA had tailored to take its place, ruling that the replacement rule “exceeds the agency’s statutory authority” and imposes “impossible” burdens upon covered states. As a result, hundreds of power plants in 28 states are once again subject to the very rule the same court rejected in 2008. The regulations in question implement the Clean Air Act’s “good neighbor” provisions, which prohibit states from significantly contributing to unsafe levels of air pollution, or interfering with Clean Air Act compliance, in downwind states. In 2005, EPA finalized the Clean Air Interstate Rule, establishing an emissions trading program for Eastern and Midwestern power plants aimed at reducing interstate air pollution transport.

Rice is a cereal grain, it is the most important staple food for a large part of the world’s human population, especially in Asia and the West Indies. It is the grain with the second-highest worldwide production, after maize (corn), according to data for 2010. Since a large portion of maize crops are grown for purposes other than human consumption, rice is the most important grain with regard to human nutrition and caloric intake, providing more than one fifth of the calories consumed worldwide by the human species Scientists have now pinpointed a gene that enables rice plants to produce around 20% more grain by increasing uptake of phosphorus, an important, but limited, plant nutrient. The discovery unlocks the potential to improve the food security of rice farmers with the lowest value phosphorus-deficient land allowing them to grow more rice to add to global production, and earn more.

There is a general desire to be healthy and happy in life. Succeeding at these tasks is quite daunting. Middle-aged adults help their hearts with regular leisure-time physical activities according to one new study. The midlife well being of both men and women seems to depend on having a wide circle of friends whom they see regularly according to another study. Both are simple concepts and readily apparent but now supported by these studies.