As March began, people living the eastern United States were enjoying warmer temperatures, budding flowers, and other signs of the approaching spring season. But on the opposite coast, a series of wintry storms rolled through the already snow-packed Cascades, leaving behind several feet of powder and sparking avalanche warnings throughout the region.

According to NOAA’s 2012 Spring Outlook, odds are that dry conditions and above-average temperatures will persist in much of the South, where drought is still lingering after making headlines in 2011. But last year’s most devastating flood events are unlikely to repeat.

When NOAA’s National Climatic Data Center crunched the numbers for December, January and February—”meteorological” winter for 2011-2012—it stacked up as the fourth warmest of the past 117 winters. Virtually all of the West received less than its average precipitation.

The U.S. had its fourth warmest winter on record. NOAA's Deke Arndt recaps the 2011-2012 winter.

It is virtually certain our world will continue to warm over this century and beyond. The exact amount of warming that will occur in the coming century depends largely on the energy choices that we make now and in the next few decades.

For Europe, the first two calendar months of winter were mild. As if to make up for lost time, however, exceptionally cold weather arrived in late January and remained firmly entrenched for weeks.

Modeling predicts that increasing greenhouse gas emissions will significantly increase thermal stress on Pacific Northwest salmon in coming decades, making the hard job of restoring endangered wild salmon even harder.

Climate scientist Michael MacCracken explores some of the scientific, legal, and ethical implications of "geo-engineering" options that have been proposed by some people to address global climate change.

Claudia Mengelt and Robert Fri talk about strategies for adapting to and reducing global climate change.

Humans currently release about 70 million tons of carbon dioxide every day into the atmosphere and about 20 million tons is being absorbed regularly by the oceans, causing the pH to drop.  Chris Sabine describes current and projected future impacts of this acidification on marine ecology.