ScienceDaily (Mar. 16, 2010) -- NASA scientists analyzing 30 years of satellite data have found that the amount of ultraviolet (UV) radiation reaching Earth's surface has increased markedly over the last three decades. Most of the increase has occurred in the mid-and-high latitudes, and there's been little or no increase in tropical regions.

The new analysis shows, for example, that at one line of latitude -- 32.5 degrees -- a line that runs through central Texas in the northern hemisphere and the country of Uruguay in the southern hemisphere, 305 nanometer UV levels have gone up by some 6 percent on average since 1979.

The primary culprit: decreasing levels of stratospheric ozone, a colorless gas that acts as Earth's natural sunscreen by shielding the surface from damaging UV radiation.

The finding reinforces previous observations that show UV levels are stabilizing after countries began signing an international treaty that limited the emissions of ozone-depleting gases in 1987. The study also shows that increased cloudiness in the southern hemisphere over the 30-year period has impacted UV.

WASHINGTON -- When it comes to dinner, Puget Sound's killer whales show no respect for international boundaries.

It's long been known that their favorite meal is Chinook salmon. However, using new genetic tests on the orcas' feces, and fish tissue and scales taken from the waters near where the whales are feasting, scientists say that as much as 90 percent of the Chinook they eat are from Canada's Fraser River.

Though the dietary habits of killer whales may not seem like a big deal, the orcas and various salmon species are protected on both sides of the border. Efforts to revive endangered species that share the same ecosystem can become intertwined.

"It is fascinating the whales specialize in a particular species, and the species they focus on is one of the rarer ones and in some case protected," said Michael Ford, the director of the conservation biology division at the National Marine Fisheries Science Center in Seattle. "Recovery of the whales could be dependent on the recovery of salmon. It is all related."

Ford was among a group of U.S. and Canadian scientists who published the results of their study in the recent edition of the journal Endangered Species Research.

A running mantra through the climate debate is that global warming is global indeed. Now, however, a scientist has found that localized "CO2 domes" could increase urban smog and other air pollution problems.

In a study published in Environmental Science & Technology, Stanford University professor Mark Jacobson estimated that the effect could cause the premature deaths of 50 to 100 people a year in California and 300 to 1,000 for the continental United States. By comparison, anywhere from 50,000 to 100,000 people a year die in air pollution-related deaths.

The finding, he says, could justify a regional or local approach to cutting greenhouse gas emissions.

Nearly all global and national emissions reduction plans operate on the assumption that a ton of CO2 from a coal plant in China or Ohio has the same climate effect as a ton from cars stuck in traffic on the Los Angeles freeway. Instead, he said, the local health effects of those emissions should also be considered.

"For better or worse, there is this local effect of CO2. That does give us scientific basis for controlling CO2 based on its local impact," said Jacobson.

NEW YORK, March 16 (Reuters) - A huge snowpack from a harsh winter will cause extensive flooding this spring in the upper Midwest and in the major corn-growing state of Iowa, the U.S. National Oceanic Atmospheric Administration said on Tuesday.

"We are looking at potentially historic flooding in some parts of the country this spring," NOAA administrator Jane Lubchenco told reporters in a briefing while presenting the government's spring flood risk outlook.

The snowpack in the Midwest is "more extensive than in 2009," with precipitation in December up to four times above average, NOAA said.

"It's a terrible case of deja vu, but this time the flooding will likely be more widespread," Lubchenco said. "As the spring thaw melts the snowpack, saturated and frozen ground in the Midwest will exacerbate the flooding of the flat terrain and feed rising rivers and streams."

Of particular risk is the Red River Valley in Minnesota, with NOAA officials saying it was unusual that the area would face the threat of severe floods for the second year running. [ID:nN15199245]

The Red River runs north, dividing North Dakota and Minnesota, before running through the flat southern plains of the Canadian province of Manitoba.

WASHINGTON -- Many of America's coal-fired power plants lack widely available pollution controls for the highly toxic metal mercury, and mercury emissions recently increased at more than half of the country's 50 largest mercury-emitting power plants, according to a report Wednesday.

The nonpartisan Environmental Integrity Project reported that five of the 10 plants with the highest amount of mercury emitted are in Texas. Plants in Georgia, Missouri, Alabama, Pennsylvania and Michigan also are in the top 10.

The report, which used the most recent data available from the Environmental Protection Agency, found that mercury emissions increased at 27 of the top 50 plants from 2007 to 2008. Overall, power plant emissions of mercury decreased 4.7 percent in that timeframe, but that amount was far less than what would be possible with available emissions controls, the report said.

Coal-fired power plants are the largest source of mercury pollution, generating more than 40 percent of U.S. emissions. Mercury released into the air settles in rivers and lakes, where it moves through the food chain to the fish that people eat.