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New research suggests that the correct answer is (a), twice as long as previously believed.  Back in 1872-1876 the HMS Challenger sailed 69,000 miles across the Atlantic, Indian and Pacific Oceans, taking temperature measurements at several depths at each of 300 sites.  Today’s researchers from the University of California, San Diego, compared Challenger’s temperature readings with data from the Argo project, which uses 3,500 floats to measure the temperature and salinity of the oceans every 10 days.  The team found a 1.1 degree Fahrenheit (0.59-degree Celsius) increase in the surface temperature of the oceans over the last 135 years.  Comparison of subsurface temperature differences between Challenger and Argo had to be corrected for several errors in the Challenger data.  For example, the vessel’s scientists didn’t measure the depth of their thermometers directly, but had to rely on the length of the lines lowering the thermometers into the water.  They had no way to ensure that the lines were vertical, so the actual depth was a little less than the length of the line, and because temperatures at shallower depths are usually warmer than temperatures at deeper depths, the Challenger readings were therefore a little warmer than they should have been.  After correcting for this error and others, the research team found that global ocean temperatures increased by an average of 0.59 degrees F (0.33 degrees C) in the upper ocean down to about 2,300 feet (700 meters).  This temperature change is twice that observed over the past 50 years, which suggests that the oceans have been warming for many decades.

GR

NOAA scientists have reported that March 2012 was the warmest on record for the contiguous United States, dating back to 1895 (click here to see an interesting animation displaying the record temperatures).  The average temperature for the month was 51.1 °F, 8.6 °F above the 20th century March average.  Only 1 other month, January 2006, has experienced a larger departure from its average.  According to preliminary data, March saw over 15,000 warm temperature records broken across the contiguous United States, and every state experienced at least one record warm daily temperature.  There were also 21 instances when the overnight lows were as warm or warmer than the previous record highs for those particular locations.  March 2012 was the warmest on record for 25 states, while ranking in the top 10 for an additional 15 states.  The same persistent pattern resulted in cooler-than-average conditions in the Pacific Northwest.  The Pacific Northwest and Southern Plains were much wetter than average while the interior West, Northeast and Florida were drier than average, although the nationally-averaged precipitation total was slightly above average.  According to NOAA’s Storm Prediction Center, there were 223 preliminary tornado reports during March 2012, as compared to the typical average of 80.  The March 2-3 outbreak across the Ohio Valley and Southeast caused 40 fatalities and an estimated $1.5 billion in damage.

The aggregated January-March average temperature for the contiguous United States (42.0 °F) was also a record, 6.0 °F above the long-term average.  January-March 2012 was the warmest on record for the 25 states east of the Rockies and ranked in the top 10 warmest for an additional 16 states.  No state in the contiguous United States experienced three-month temperatures below average.  Nationally-averaged precipitation for the three-month period was slightly below average, with wetter than average conditions prevailing across the Pacific Northwest and Southern Plains and drier than average conditions in the Intermountain West, Ohio Valley and the east coast.

The nationally-averaged temperature for the six-month period defined as the cold season (October 2011-March 2012) was 3.8 °F above average, the second-warmest on record for the contiguous United States.  The previous 12-month period (April 2011-March 2012) was the warmest on record at 55.4 °F, 2.6 °F above the 20th century average.

Gary Monitz