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Climatologists find familiar fluctuations in Pacific's past - test. “During past ice ages the tropical Pacific Ocean behaved rather as it does today in an El Niño event, bringing downpours to some places and drought to others.” Thus began a 2002 article Nature magazine (12 Jul 2002) For example, it could explain the low atmospheric levels of greenhouse gases, such as carbon dioxide, methane and nitrous oxide, during the last ice age. It is not clear whether this was a cause or a consequence of the difference in global climate, but such decreases would have lowered global temperatures still further,...

It might sound preposterous, like astrology, to suggest that galactic events help determine when North America is or isn't buried under immense sheets of ice taller than skyscrapers. But new research suggests the coming and going of major ice ages might result partly from our solar system's passage through immense, snakelike clouds of exploding stars in the Milky Way galaxy. Resembling the curved contrails of a whirling Fourth of July pinwheel, the Milky Way's spiral arms are clouds of stars rich in supernovas, or exploding stars. Supernovas emit showers of charged particles called cosmic rays. Theorists have proposed that when...

MADISON - If you are curious about Earth's periodic mass extinction events such as the sudden demise of the dinosaurs 65 million years ago, you might consider crashing asteroids and sky-darkening super volcanoes as culprits. But a new study, published online today (June 15, 2008) in the journal Nature, suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world's periodic mass extinctions during the past 500[sc1] million years. "The expansions and contractions of those environments have pretty...