By Joseph D’Aleo, CCM
…has the temperature of New York City increased in the past 50 years? Figure 1 below is excerpted from their note, about which they observed.
Note the adjustment was a significant one (a cooling exceeding 6 degrees from the mid 1950s to the mid 1990s.) Then inexplicably the adjustment diminished to less than 2 degrees …The result is what was a flat trend for the past 50 years became one with an accelerated warming in the past 20 years. It is not clear what changes in the metropolitan area occurred in the last 20 years to warrant a major adjustment to the adjustment. The park has remained the same and there has not been a population decline but a spurt in the city’s population in the 1990s.
Well, NCDC has a shiny new very cool tool for plotting data for regions, states and some city locations by month(s), seasons, years. They describe it this way.
Data for the Contiguous U.S., statewide, climate divisions, climate regions, and agricultural belts come from the U.S. Climate Divisional Database, which have data from 1895 to the present.
Information is also available at the city level for the following 60 cities. The 27 cities highlighted in blue below are Automated Surface Observing System (ASOS) stations which are part of the U.S. Historical Climatology Network (USHCN) (temperature data for the USHCN stations were converted to version 2.5 in October 2012). The other 33 cities use Global Historical Climatology Network (GHCN) data. These cities have data from varying beginning periods of record to the present.
New York’s Central Park was one of the blue cities (new USHCN v2.5). So I plotted it for July since that was one of the months in the original comparison.
The surprise (when I plotted the source data myself rather than use NCDC’s tool) was how flat it was in the dust bowl heat of the 1930s. I know that on the NWS NYC web site, they have archived raw monthly means back well into the 1800s. So I downloaded that and compared.
It was dramatically cooler in the NCDC v2.5 than the original data. This plot shows the differences between the original recorded temperature data at Central Park and the final adjusted data that NCDC presents to the public:
As is clearly evident, adjustments made the dust bowl period cooler, while post 1995 had no adjustments applied. This results in a temperature trend that is steeper because the past is cooler than the present. The only problem is that it isn’t what the data actually recorded then.
I think maybe we need to coin a new term for NOAA NCDC – ‘dust bowl deniers’. Yes it appears there is man made warming underway but the men are in Asheville, North Carolina at NOAA’s National Climatic Data Center.
Addendum by Anthony:
Cooling the past increases the trend. We’ve seen this effect happen several times before, yet there seems to be no justification for it. Probably this most dramatic example is what we see in this NOAA GISS plot comparison:
I’ve also written before about this tampering with data from the past. Such tampering with new adjustments like USHCN V2.5 allow claims of “warmest ever” to be made when the past gets cooled: