“U.S. temperatures unchanged since 2005”: A follow-up. My column last week titled “NOAA: U.S. temperatures unchanged since 2005” attracted a large number of readers and a number of skeptical comments.

“U.S. temperatures unchanged since 2005”: A follow-up

My column last week titled “NOAA: U.S. temperatures unchanged since 2005” attracted a large number of readers and a number of skeptical comments. A letter to the editor from Mark Rosenthal offered an alternative interpretation of NOAA’s data as did several commenters on the Independent’s Facebook page.

At the risk of wearing out my welcome on this subject, here is additional background information about NOAA’s Climate Reference Network and how its data contrasts with other NOAA data.

As a start, note that NOAA spent tens of millions of dollars to construct the Climate Reference Network — or CRN — in 2005. NOAA intended to gather temperature data that did not require the “adjustments” it has been making to historical temperature data and the controversy that surrounds them. In so doing, it acknowledged that there is uncertainty in its historical data.

As my critics have suggested, there are several ways to analyze NOAA’s CRN temperatures collected from 2005 onward. Rosenthal computes the average CRN temperature over the 14-year interval, noting that it’s higher than the single-year 2005 average. A Facebook commenter computed a linear regression: a sloping, “best fit” straight line through the data. Both methods indicate increasing temperatures by incorporating the distinct upward spikes in temperature in 2012 and again in 2015–16.

I chose instead to compare what NOAA calls the average temperature “anomaly” (the difference from NOAA’s National Temperature Index, or NTI) for the beginning and ending years, 2005 and 2018. NOAA uses the NTI as a reference to eliminate seasonal variations that otherwise would mask underlying trends. NOAA presents its 14 years of monthly CRN data as the difference or “anomaly” between the CRN measurement and the NTI for that month. Since the same NTI is used for all 14 years, the anomaly graph makes comparing monthly temperature trends over the 14 years much easier to analyze.

In 2005, the average anomaly was +0.78 degrees F, and in 2018 it was +0.94 degrees F. That method shows a slight rise of about +0.1 degree F per decade. Note, however, that the month-by-month trend starting in 2016 is distinctly downward. In fact, NOAA’s CRN anomaly data averages minus 0.05 degrees F for the most recent 12 months, September 2018 through August 2019.

None of us knows whether future CRN data will continue downward, stay about the same, or trend back up.

But the point of my article, the one that caught so much attention and flak, is that CRN data shows that temperatures today over broad swaths of the country are about what they were in 2005.

So what about the temperature history graphs that show ever-rising temperatures that NOAA itself puts out?

I made the point in last week’s column that these graphs show temperatures after NOAA has “adjusted” them to account for known problems in its data collection: urban heat islands, varying time of day readings, etc. As I stated, these adjustments are both estimates and controversial.

A thorough technical analysis of how NOAA and NASA “adjust” historical raw temperature measurements is covered here. The bottom line is contained in NOAA’s own graph. Raw, unadjusted temperature data show a clear cooling trend since 1934, the hottest year on record in the U.S.

Read more: http://suindependent.com/u-s-temperatures-unchanged-since-2005-follow/