6
J.F.R. Gower
It is possible that clever calibration may allow them to successfully continue the
SeaWiFS time series. It is even possible that SeaWiFS may rise from the dead, and
operate for a few more years (G. Feldman, personal communication).
1.5 Sea Surface Temperature (SST)
The Reynolds time series is based on ship and buoy data, using satellite data in
data-sparse areas. This is only partly a “satellite” data time series and is becoming
less so as surface data sources such as Argo, increase in density. Figure 1.5 shows
the Hadley SST data series, in which the long-term warming trend is very clear,
with short-term increases at the 1972 and 1997 El-Nino events, and a recent slight
interruption of the steady warming, which is being made much of by warming skeptics (“cooling since 1998”), but which in fact looks typical of the variability in the
record.
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
1970
1980
1990
2000
2010
Start of year
Global average SST (C)
Fig. 1.5 Time series of global SST provided by the Hadley Centre, UK. Data show a warming
trend of 0.014 ◦ C/year, with increases of about 0.3 ◦ C during the 1972 and 1997 El Ninos, but a
smaller signal from the 1982 event
1.6 Polar Sea Ice Cover
The US National Snow and Ice Data Center (NSIDC) provides an archive of Arctic
ice cover data based on satellite microwave radiometer observations of polar ice. 3
Figure 1.6 shows the anomaly time series deduced for each month by subtracting
a fixed annual cycle. From the late 1970s to about the year 2000, the measured
total ice areas oscillated with the seasons between about 5 and 15 million km 2 . In
Fig. 1.6, a slow drop of about 1 million km 2 is evident over this period, accelerating
3 Available at ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/
J.F.R. Gower
It is possible that clever calibration may allow them to successfully continue the
SeaWiFS time series. It is even possible that SeaWiFS may rise from the dead, and
operate for a few more years (G. Feldman, personal communication).
1.5 Sea Surface Temperature (SST)
The Reynolds time series is based on ship and buoy data, using satellite data in
data-sparse areas. This is only partly a “satellite” data time series and is becoming
less so as surface data sources such as Argo, increase in density. Figure 1.5 shows
the Hadley SST data series, in which the long-term warming trend is very clear,
with short-term increases at the 1972 and 1997 El-Nino events, and a recent slight
interruption of the steady warming, which is being made much of by warming skeptics (“cooling since 1998”), but which in fact looks typical of the variability in the
record.
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
1970
1980
1990
2000
2010
Start of year
Global average SST (C)
Fig. 1.5 Time series of global SST provided by the Hadley Centre, UK. Data show a warming
trend of 0.014 ◦ C/year, with increases of about 0.3 ◦ C during the 1972 and 1997 El Ninos, but a
smaller signal from the 1982 event
1.6 Polar Sea Ice Cover
The US National Snow and Ice Data Center (NSIDC) provides an archive of Arctic
ice cover data based on satellite microwave radiometer observations of polar ice. 3
Figure 1.6 shows the anomaly time series deduced for each month by subtracting
a fixed annual cycle. From the late 1970s to about the year 2000, the measured
total ice areas oscillated with the seasons between about 5 and 15 million km 2 . In
Fig. 1.6, a slow drop of about 1 million km 2 is evident over this period, accelerating
3 Available at ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/