Substandard MSM Reporting on Climate Change in Alaska

Over the last few days, three major newspapers have reported on Alaska's climate. Unsurprisingly, there are problems in each article.

At the Washington Post, Philip Bump discusses how "Anchorage, Alaska never saw a day below zero in 2014" and then states that "Complete annual records from the National Oceanic and Atmospheric Administration begin on Jan. 1, 1954." That's odd, since complete annual records from the NOAA National Weather Service online database for Anchorage appear to begin in 1917, not 1954.

The L.A. Times has a piece on Anchorage's climate, and it shows the graph below of the lowest temperature each year for the city, going back to 1953. How does the L.A. Times show annual data for 1953, if the annual data doesn't begin until 1954? And what data is NOAA-NWS providing for Anchorage that starts in 1917?

Regardless, starting a climate change time series for Anchorage in the mid-1950s is a concern. Let's have a look at the "Lowest temperature recorded by year" for Anchorage using the complete dataset headed back to 1917, rather than just the 1953-2014 period the L.A. Times used.

Some points to note. If you look closely at the L.A. Times' graphic, it is clear they have a lowest temperature for 1953 of what looks to be -13 F, followed by -29 F in 1954 and -27 F in 1955. The temperatures for 1954 and 1955 are correct, but 1953 appears to be very wrong. According to the NOAA-NWS database, the lowest temperature in 1953 was -19 F (on January 24, 1953), not -13 F.

Looking at only the time series starting in the mid-1950s, it appears as though Anchorage's annual minimum temperature has been continually increasing up to the present, and that the suite of annual minimum temperatures around -10 F that the city has seen since the 1980s have been the warmest on record.

Of course, if you use the complete record back to 1917, there were several temperatures at or above the -10 F mark during the 1930s and early 1940s, along with a very rapid "warming" trend from the 1910s to the 1940s. Thus, the increasing trend in annual minimum temperatures that Anchorage has experienced since the 1950s is nothing new. It saw a similar -- actually, much more rapid -- increase in the first half of the 20th century. Unfortunately, this earlier period doesn't appear on the L.A. Times' plot, leaving readers with the impression that the current trend is unprecedented within the historical record, when it is not.

More problems with the Times' article:

"The Last Frontier didn't exactly sweat through Death Valley-style temperatures. Anchorage's 2014 annual average was a chilly 40.6 degrees or so Fahrenheit, said Richard Thoman, climate science and services manager with the weather service in Fairbanks. Still, that was well above last year's annual average temperature of 37 degrees."

Yes, "Anchorage's 2014 annual average was a chilly 40.6 degrees or so Fahrenheit." Actually, it was 40.5 F. Close enough. But 2013's annual average temperature was not 37 F. It was 38.4 F. That is not close enough. For the record, the warmest year in the city was 1926, at 41.0 F. Over the last 30 years, there is no sign of a significant trend in the annual temperature.

On December 31, Andrew Revkin at the New York Times claimed that "much of southern Alaska has been unusually warm, with Anchorage poised to record its warmest year on record"? Anchorage poised to record its warmest year on record? As noted above, 2014 came in at a full half-degree below its warmest year ever, and this would have been obvious by New Year’s Eve.

Revkin's source was an article from KTVA Alaska that claimed "with just days left in the year, Anchorage is expected to set a new record high of 40.4 degrees Fahrenheit for its average temperature. The old record was set more than three decades ago -- 39.7 degrees in 1978."

To set the record straight, here is the screencapture from the NOAA-NWS database.

Ignore 1929, since much of the year is missing. It is clear that 1926 holds the apparent record at 41.0 F, not 2014 at 40.5 F, or 1978 having the previous record at 39.7 F.

Revkin also links to a presentation on the "Climate of Alaska: Past, Present and Future" by the University of Alaska at Fairbanks that shows the following chart of "frost-free season" length for Fairbanks.

Just a quick glance at this plot shows it is well out of date -- the latest year appears to be 2004 -- and that a linear regression over the entire time series is not the best trend fit. It looks like the increasing trend from the early 1900s stopped in the 1970s, which is a problem if you want to link the overall increase to anthropogenic climate change (i.e., most of the anthropogenic greenhouse gas emissions have occurred after 1970).

Different researchers also use varying definitions for the growing season. Those using the "frost-free season" criteria employ terminology such as the length of time between the first and last occurrences of minimum temperatures "below 32 F." Some interpret this "below" to mean "less than or equal to 32 F" whereas others use the strict definition of "less than 32 F." Either way, when I look up the growing season length for Fairbanks from the NOAA-NWS database, my numbers are slightly different than the plot above that the NYT linked to, but close enough that the overall trends are the same.

The orange lines are regressions from 1970 to 2014. They are both highly nonsignificant and effectively flat lines. Thus, we reasonably must conclude that since 1970, there is no evidence that the growing season length has any trend for Fairbanks, and no evidence that anthropogenic climate change is leading to a longer growing season for this region.

Alaska is one of the case studies often trotted out when climate change is discussed in the media. One only hopes that as 2015 progresses, we can collectively agree on the datasets to be using, and to get the full picture of what is really going on in this state out to the public in a more accurate fashion.