The AGU meeting, held in a building large enough to store a few oil tankers, is the largest gathering of people who study geophysics in the world. Sifting through the thousands of topics was a bit like sipping water from a fire hose, but the organizers set up a few press conferences to help funnel the 120 media members toward breaking news. New studies by California researchers show that the gasoline additive MTBE, an ingredient of oxyfuel already banned in Alaska and Maine, taints more than one in eight wells in urban areas where it's still used. California plans to phase MTBE out of fuels in three years, and results given at AGU may convince officials in other states to get rid of the additive earlier. Often seen over Alaska in August, noctilucent clouds were first reported in the 1870s, about the time of the Industrial Revolution.
Some scientists believe the clouds are related to man-made greenhouse gases.
In the past, these scientists predicted that if global warming persisted long enough, the clouds would be seen at more southerly latitudes. The eruption of Mt. Pinatubo in 1991 cooled Earth's temperature for two years, but some areas of the world experienced warmer winters the first year after the eruptions. Mt. Pinatubo in the Philippines spewed sulfur into the atmosphere that spread around the planet for three weeks. Scientists expected these sulfur particles to reflect sunlight and make the planet cooler, but the next winter was warmer than normal in North America, western Europe and Eastern Siberia. Researchers now think the aerosols spewed by Mt. Pinatubo caused a large temperature contrast between the Arctic and the tropics, and that difference drove a stronger circulation in Earth's weather systems that caused some areas to be warmer.