By Rod Hill on 2010-07-21
Portland temperature average is one degree below normal through the first 20 days of July. With warmer days expected this weekend, odds favor a near normal month both for temperature and precipitation. Interesting to note that our cool weather comes during a year that is the warmest on record globally when both sea and land temperatures are measured. Below is a report from NOAA:
Last month’s combined global land and ocean surface temperature made it the warmest June on record and the warmest on record averaged for any April-June and January-June periods, according to NOAA. Worldwide average land surface temperature was the warmest on record for June and the April-June period, and the second warmest on record for the year-to-date (January-June) period, behind 2007.
Arctic sea ice continued its annual decline, typically reaching a September minimum. Similar to May 2010, the Arctic sea ice continued to decline at a record rapid rate—the fastest measured for June (more than 50 percent greater than average). The previous record for the fastest decline rate in June was set in 1999. According to the National Snow and Ice Data Center (NSIDC), June 2010 Arctic sea ice extent was 10.9 million square kilometers (10.6 percent or 1.29 million square kilometers below the 1979–2000 average), resulting in the lowest June sea ice extent since records began in 1979—the previous June record low was set in 2006. This was also the 19th consecutive June with below-average Arctic sea ice extent. It was reported that sea ice was below average everywhere with the exception of the East Greenland Sea, where sea ice extent was near average. June Arctic sea ice extent has decreased at an average rate of 3.5 percent per decade. Of note, the Arctic dipole (DA) anomaly—an atmospheric pressure pattern—was present during June 2010 (similar to 2007—which had record low September sea ice extent).
As the Arctic sea ice extent contracts (during the Northern Hemisphere warm season), the Antarctic sea ice extent expands (during the Southern Hemisphere cold season). During June 2010, the Southern Hemisphere sea ice extent reached its largest extent on record for June, 8.3 percent above the 1979–2000 average. This is the eighth consecutive June with above-average Southern Hemisphere sea ice extent. Southern Hemisphere sea ice extent for June has increased at an average rate of 1.4 percent per decade.
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There continues to be debate over temperature records, but the bottom line is that record numbers are being put into the books. Little debate can be offered about Arctic sea ice decreasing year after year. Of course, it is interesting to note the increase of southern hemispheric ice.
Rod Hill
Coldest In 24 Years!