This morning a friend in Georgia mentioned that the common consensus among his friends there is that recent summers have been much hotter than in the past, and for that reason they’re inclined to believe claims of rapid human-induced global warming. Aside from the facts that what’s happening in one tiny part of the globe doesn’t reveal what’s happening everywhere else and that warming doesn’t prove human causation, I told him I suspected the anecdotal memories might conflict with hard data. That’s a common occurrence.

So I checked by asking one of the best temperature data sources I know, Dr. John Christy, Principal Research Scientist in Climatology at the University of Alabama, Huntsville, and Alabama State Climatologist. He provided the raw data (below) from which I then quickly constructed this graph:

Five of the last seven and ten of the last eighteen summers have been below the long-term average of 89.9F. (And that’s despite the fact that the long-term average is weighted downward a bit by the comparatively cold mid-1950s through mid-1970s.) The overall trend is a cooling of 0.06F/decade, or 0.735F for the entire 12-1/4 decades.

I suspect the folks who think it’s been much hotter recently than in their memories of the past probably grew up in the 1960s, which were the coldest decade of the 20^th century for North America—and for Georgia, as you can see here. It’s also likely that many grew up in rural areas but now live in urban or suburban areas, which are strongly affected by urban heat island effect. They’re confusing localized heating by urbanization and industrialization for regional or global heating by greenhouse gases.

As we suspected, anecdotal memories often differ significantly from hard data.

Here are Christy’s data:

1895       89.4

1896       90.2

1897       91.0

1898       89.5

1899       91.6

1900       90.7

1901       89.8

1902       92.8

1903       89.7

1904       89.9

1905       90.6

1906       89.8

1907       90.8

1908       90.6

1909       89.9

1910       88.2

1911       91.1

1912       88.6

1913       91.1

1914       92.0

1915       90.9

1916       88.7

1917       90.2

1918       90.8

1919       88.8

1920       89.2

1921       90.6

1922       89.7

1923       88.8

1924       91.9

1925       93.1

1926       90.1

1927       89.3

1928       89.1

1929       89.6

1930       90.7

1931       92.5

1932       90.7

1933       90.6

1934       91.3

1935       90.2

1936       92.0

1937       90.4

1938       89.5

1939       89.8

1940       89.0

1941       90.2

1942       90.1

1943       92.0

1944       90.4

1945       89.8

1946       88.6

1947       88.8

1948       90.1

1949       88.6

1950       89.2

1951       91.8

1952       93.1

1953       89.9

1954       93.8

1955       89.2

1956       90.6

1957       89.4

1958       89.7

1959       90.0

1960       89.8

1961       87.9

1962       90.2

1963       88.9

1964       88.4

1965       87.7

1966       88.1

1967       86.3

1968       90.2

1969       89.6

1970       88.9

1971       88.5

1972       88.5

1973       88.7

1974       87.6

1975       88.0

1976       87.9

1977       91.8

1978       90.1

1979       88.2

1980       92.3

1981       90.7

1982       88.7

1983       90.5

1984       88.6

1985       88.6

1986       92.2

1987       91.2

1988       90.4

1989       88.1

1990       91.6

1991       88.1

1992       87.4

1993       92.2

1994       87.2

1995       89.7

1996       88.8

1997       87.4

1998       92.5

1999       90.4

2000       91.4

2001       88.5

2002       90.3

2003       87.5

2004       88.7

2005       88.4

2006       91.7

2007       91.2

2008       90.4

2009       89.7

2010       92.3

2011       93.7

2012       89.2

2013       86.9

2014       89.7

2015       90.7

2016       92.6

2017       88.4

2018       89.5