Please elucidate how GISS is constructed (see climateaudit.org for example).
And while we're doing that, let's also see if we can figure out why spring is earlier and fall is later over the past 130 years or so -- just in case we're concerned GISS might be wildly in error or something like that.
Global Warming Rushes Timing of Spring
(I'm a little curious where that 8 hours earlier spring green-up since 1982 is from)