So we'll assume that the global surface
air temperature trend since 1984 has been one of 0.20 °C per decade warming.
Not exact matches
With documented warmer
air temperatures in eastern Canada
since the 1970s, there has been a
trend of earlier ice melting and less ice in general, explained Lavery.
The former is likely to overestimate the true global surface
air temperature trend (
since the oceans do not warm as fast as the land), while the latter may underestimate the true
trend,
since the
air temperature over the ocean is predicted to rise at a slightly higher rate than the ocean
temperature.
Even if you restrict the definition of «hiatus» to
air temperatures, there are few datasets that actually demonstrate a
trend of 0
since circa 2000.
Glaciers and ice caps in Arctic Canada are continuing to lose mass at a rate that has been increasing
since 1987, reflecting a
trend towards warmer summer
air temperatures and longer melt seasons.
The former is likely to overestimate the true global surface
air temperature trend (
since the oceans do not warm as fast as the land), while the latter may underestimate the true
trend,
since the
air temperature over the ocean is predicted to rise at a slightly higher rate than the ocean
temperature.
There has been no material
trend in surface
air temperature during the last 10 years when taken in isolation, but 13 of the 14 warmest years on record have occurred
since 1995.
The Western Antarctic Peninsula's surface
air temperatures have been cooling rapidly
since 1999 («a cooling
trend of − 0.47 °C / decade during 1999 — 2014» [Oliva et al., 2017]-RRB-.
The global SST show mostly similar
trends to those of the land - surface
air temperature until 1976, but the
trend since 1976 is markedly less (Table 2.1).
The difference in
trend between global SST and global land
air temperature since 1976 does not appear to be significant, but the
trend in NMAT (despite any residual data problems) does appear to be less than that in the land
air temperature since 1976.
However, ~ 80 % of the total warming involved occurred after 1979, and as noted earlier
since 1979 the
trend in HadCRUT4v4 matches that in the (adjusted) ERA - interim dataset, which estimates purely surface
air temperature, not a blend with SST, and has complete coverage.
This provides an upper bound for the surface
temperature since the upper
air is supposed to have larger
trends than the surface (e.g. see Klotzbach et al (2011).
Greenland surface
air temperature trends, including at the Summit site, have not shown persistent warming
since 1930 in contrast to global average surface
temperature (23).
Using computer climate models, climatologists have established that the recent
trend of an increasing global average
air temperature, especially
since the mid-20 th century, is unprecedented and unnatural.
Of course there is uncertainty in the
trends (both from fitting the OLS line, + / -0.6 ºC, and structurally,
since RSS has slightly different numbers), and there is no expectation that TLT and surface
air temperature should have identical
trends (overall, TLT should be increasing a little faster than SAT — but this is also subject to noise over relatively short periods).
One would think that the two sources of data would yield quite similar
trends and have important similarities
since they attempt to measure
air temperatures so close to each other.