Physics Today Daily Edition
Los Angeles Times: The US Environmental Protection Agency is proposing to reduce the federal standard for ground-level ozone. The EPA is required by the Clean Air Act to review the standard every five years. California, which has 16 areas that don’t meet the current ozone limit, will be particularly hard pressed if it is lowered. "We're going to need to have zero or near-zero emissions across the entire economy,” said Sam Atwood, a spokesman for the South Coast Air Quality Management District. Although industry representatives and Republican members of Congress insist that lowering the environmental limit will damage the economy, Janice Nolen, assistant vice president of national policy at the American Lung Association, claims just the opposite: “Since the 1970s, we've reduced major air pollutants by 70% and the economy has more than doubled."
New Scientist: According to a recent paper published in Precambrian Research, both the average rate of continental collisions and the average speed with which the continents change latitude have doubled over the past 2 billion years. Kent Condie of the New Mexico Institute of Mining and Technology and colleagues based their findings on two sets of data: the timing and locations of mountain-range formation and average plate velocities based on magnetic data from volcanic rocks. The researchers think the acceleration may be due to the amount of water in Earth’s mantle, which has recently been found to be much vaster than previously thought. As a result, the mantle may becoming runnier, which could speed up the rock flow. However, the work is considered controversial because it contradicts a previous study that says plate motion has been slowing for the past 1.2 billion years due to the cooling of Earth’s core and mantle.