The Diurnal Temperature Range, or DTR, is a fancy title for a daily temperature range (the daily maximum temperature minus the daily minimum temperature -- usually a late afternoon temperature peak minus a just before dawn temperature low).
A DTR decline is claimed to be a "fingerprint" of manmade global warming.
(A) Surface temperature measurement data did show a DTR decline from 1900 (very rough data) to 1988.
(B) But … BEST (Berkeley Earth Surface Temperature) data, first released to the public in October, 2011, showed a DTR increase after 1988, not a decline, contradicting the global climate physics model.
( C) Detailed analyses of the contiguous United States, Soviet Union, and China supported (A): Most warming in the past 40 years was from higher minimum (usually nighttime) temperatures during a 24-hour day, while maximum (usually daytime) temperatures reflected little or no warming.
As usual, nothing is certain about global warming !
But if global warming land surface measurements reflect mainly higher nighttime lows (not as cold before dawn), then I'd say that's a reason to celebrate global warming !
Give me more global warming !
Note:
The physics model for greenhouse gas warming assumes much more impact at night, when carbon dioxide (CO2) is believed to slow infrared heat rising from the cooling Earth and escaping into space.
Earth is heated during the day by the sun -- CO2 has no effect on that heating, because CO2 is invisible to sunlight .
If our planet did not cool at night, we would soon be boiling.