El Niño,
the cyclic warming of the tropical Pacific, brought wet weather to the southeastern U.S. at the same time that a strong negative phase in a pressure cycle called the North Atlantic Oscillation pushed frigid air from the arctic down the East Coast and across northwest Europe.
Thus their meta - analyses totally obscured
the cyclic warming and cooling that accompanied those migrations during the 20th century.
This 0.16 deg C per decade is
a cyclic warming rate, as there was the same warming rate from 1910 to 1940.