READY TO RUMBLE? The Eyjafjallajokull volcano in Iceland is calming down a bit,  as geologists report seeing more "sputtering and bubbling" of lava and less ash production, potentially offering Europe a breather from a frustrating week of flight delays. The remaining ash cloud is elongated and thin, and while it still reaches as far as eastern Canada and central Russia, airlines in Europe are already taking back to the skies, and many weary travelers are hoping the worst is behind them. Unfortunately, however, the worst may be yet to come: The only other known eruptions of Eyjafjallajokull — in 920, 1612 and 1821 — were soon followed by an outburst from its larger neighbor, Katla, which last erupted in 1918 and tends to do so about every 80 years, making it slightly overdue. While Eyjafjallajokull has wreaked unprecedented havoc with European travel, it could still just be the opening act for a Katla eruption, which would be 10 times stronger and would spew larger, taller ash plumes. Katla showed no signs of activity Tuesday, but scientists caution it could erupt with little warning, and point out they still can't even be sure that Eyjafjallajokull is finished. "If something stops for five minutes, it doesn't mean it's shutting down," one volcano expert tells USA Today. "There's three things we never know in volcano science: when, how big and for how long." (Sources: Associated Press, Washington PostUSA Today)

OIL RIG EXPLOSION: A deep-water oil rig in the Gulf of Mexico exploded and caught fire around 10 p.m. Tuesday, while 126 workers were aboard the platform located 52 miles southeast of Venice, La. No deaths were reported, but eight people are in critical condition, and at least 11 workers are still missing. "A substantial majority of the 126 member crew is safe, but some crew members remain unaccounted for at this time," says a statement today from the company that owns the drilling platform, Transocean Ltd., which owns 140 offshore rigs and bills itself as the "world's largest offshore drilling contractor." Four helicopters, four U.S. Coast Guard boats and a plane were searching for the workers Wednesday morning, and officials believe they may have evacuated following the explosion. "We're hoping everyone's in a life raft," says Coast Guard Senior Chief Petty Officer Mike O'Berry. Meanwhile, Coast Guard fire boats are battling the ongoing inferno at the oil platform, known as Deepwater Horizon (pictured). "It's burning pretty good and there's no estimate on when the fire will be put out," O'Berry says. (Sources: New Orleans Times-Picayune, CNNAP)

CZAR TALK: A congressional climate bill is "doable" this year, according to White House climate adviser (aka "climate czar") Carol Browner, who discussed the long-delayed legislation during an energy forum Tuesday in Washington, D.C., hosted by the National Journal. Browner said lawmakers increasingly understand the importance of domestically developing clean-energy technology, pointing to a compromise climate bill that Sens. Lindsey Graham, R-S.C., John Kerry, D-Mass., and Joseph Lieberman, I-Conn., are set to introduce on Monday. That bill aims to cut U.S. greenhouse gas emissions to 17 percent of 2005 levels by 2020, but dodges the murky waters of cap-and-trade, a concept that has drawn widespread criticism in Congress. Browner said Tuesday that the Obama administration supports the Graham-Kerry-Lieberman bill, and is flexible on how it achieves emissions cuts. "If they want to use different tools for one sector or another, then that's fine," she said. Browner notably didn't rule out so-called "carbon tariffs," which would tax goods from countries that don't impose their own emissions controls. While President Obama has spoken against that idea, and it would likely damage ties with China and India, many U.S. senators from states with large manufacturing industries are demanding it be included in any climate bill before they'll support it. (Sources: The Hill, AP)

BIRD BRAINS: Crows have already proven themselves quite capable of wielding sticks and paper clips to suit their needs, often surprising scientists. But on top of being avian MacGyvers, a new study from New Zealand shows crows can multitask, too. Crows on the South Pacific island of New Caledonia are the only birds known to use tools in the wild, and University of Auckland researchers traveled there to capture and temporarily hold seven wild ones, just long enough to test their wits. Food was presented out of reach, and a long tool was placed nearby that could be used to extract it; the long tool was also out of reach, however, and required a short tool to obtain it, which was tied to a string dangling from the crows' perch. The crows were taught each task individually first, but researchers were astonished at how easily they then combined the three together — all but two birds nailed it on their first try (and those two finally got it on their third and fourth attempts). "Finding that the crows could solve the problem even when they had to innovate two behaviors was incredibly surprising," the study's lead author says. (Source: BBC News)

HAPPY [skipwords]EARTH DAY[/skipwords] EVE: Thursday marks the 40th anniversary of Earth Day, an annual holiday that helped kick off America's modern environmental movement when it was first held on April 22, 1970. The milestone comes at a time of heightened tensions over environmental issues — mainly related to climate change and efforts to control it, from "Climategate" and "Glaciergate" to recent polls that show fewer Americans are concerned about global warming than they were two years ago. But interest in Earth Day's ruby anniversary remains "pretty robust," according to Denis Haynes, who served as national coordinator for the first Earth Day and is its international chairman this year. He points out to USA Today's Wendy Koch that 192 nations will participate in one way or another, reflecting "mounting concern" that broad, coordinated action is needed to solve the planet's problems. President Obama sounded a similar theme when he released an Earth Day video last week, urging Americans to take part by explaining that "it can be as simple as riding the bus or subway to work, making your home more energy-efficient, or organizing your neighbors to clean up a nearby park." A climate rally will be held on the National Mall in [skipwords]Washington, D.C.,[/skipwords] featuring speeches from scientists and activists, as well as a performance from Sting. For all things Earth Day 2010 — including an animated history of Earth Day, a list of must-see Earth Day entertainment, seven Earth Day songs and a list of 40 eco-ideas for Earth Day — make sure to check out MNN's Earth Day central. (Sources: USA Today, Earth Day Network,

Russell McLendon

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Photo (Eyjafjallajokull volcano's ash cloud): News Pictures/

Photo (Deepwater Horizon drilling platform): Transocean Ltd./AP

Photo (Carol Browner): James A. Finley/AP

Photo (crow): 03ahmed/Flickr

Russell McLendon ( @russmclendon ) writes about humans and other wildlife.