In 2011, global sea levels fell below the long-term trend of sea level rise, but as La Niña waned late in the year, global ocean levels began rising rapidly.
NOAA scientists have documented a new impact of the increasingly thin blanket of Arctic sea ice: gases escaping from the thinner ice in spring are affecting air chemistry, reducing ground-level ozone, and likely increasing mercury contamination.
Temperatures in the eastern tropical Pacific Ocean swing back and forth like an irregular pendulum. The cool phase—which the Pacific has been in for the past two winters—is called La Niña. According to NOAA’s April 2012 ENSO Diagnostics Discussion, La Niña is fading and will likely be over by the end of April.
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.
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.
The Arctic of recent years—warmer, greener, less icy—is likely to be the new normal for the Far North. One sign of the ongoing transformation of the Arctic is the spread of shrubs across the tundra.
Seasonal precipitation patterns across the globe showed large differences from average in 2011, with several areas receiving heavy rains during more than one season of the La Niña-influenced year.
A year-long La Niña contributed to dramatic variability in seasonal temperature patterns in 2011.
In the 2011 Arctic Report Card, scientists report that the bright white surface of the Greenland Ice Sheet has grown less reflective. The darker surface absorbs more sunlight, accelerating melting.