INTERDECADAL CHANGES OF SURFACE-TEMPERATURE SINCE THE LATE-19TH-CENTURY

We present global fields of decadal annual surface temperature anomalies, referred to the period 1951-1980, for each decade from 1881-1890 to 1981-1990 and for 1984-1993. In addition, we show decadal calendar-seasonal anomaly fields for the warm decades 1936-1945 and 1981-1990. The fields are based on sea surface temperature (SST) and land surface air temperature data. The SSTs are corrected for the pre-World War II use of uninsulated sea temperature buckets and incorporate adjusted satellite-based SSTs from 1982 onward. Our results extend those published in the 1990 Intergovernmental Panel on Climate Change Scientific Assessment and its 1992 supplement. We assess the impact of various sources of error in the fields. Despite poor data coverage initially and around the two World Wars the generally cold end of the nineteenth century and start to the twentieth century are confirmed, together with the substantial warming between about 1920 and 1940. Slight cooling of the northern hemisphere took place between the 1950s and the mid-1970s, although slight warming continued south of the equator. Recent warmth has been most marked over the northern continents in winter and spring, but the 1980s were warm almost everywhere apart from Greenland, the northwestern Atlantic and the midlatitude North Pacific. Parts of the middle- to high-latitude southern ocean may also have been cool in the 1980s, but in this area the 1951-1980 climatology is unreliable. The impact of the satellite data is reduced because the record of blended satellite and in situ SST is still too short to yield a climatology from which to calculate representative anomalies reflecting climatic change in the southern ocean. However, we propose a method of using existing satellite data in a step toward this target. The maps are condensed into global and hemispheric decadal surface temperature anomalies. We show the sensitivity of these estimated anomalies to alternative methods of compositing the spatially incomplete fields. Running decadal zonal means and annual global and hemispheric time series are also shown. Finally, we discuss some salient features in terms of observed atmospheric circulation changes and of the results of climate model integrations with increasing atmospheric greenhouse gases.