Monday, 12 January 2009: 11:45 AM
Land use change and temperature trends
Room 129B (Phoenix Convention Center)
Recently, changes in land use/land cover were quantified for areas near U.S. Cooperative Observation stations. In particular, stations with land cover changes during the decade of 1980s were identified and the temperature tendencies before and after the land cover change were compared. From this analysis, temperature trends after the land cover changes were found to be overwhelmingly positive while those before the land cover changes were a near equal mix of positive and negative. Although it has been suggested that this difference in the distribution of trends may indicate a causal association between temperature trends and land cover, given the nature of multi-decadal temperature variations during the 1971 to 2000 period, more positive trends would be expected in general during the 1990s than during the 1970s. To determine whether land cover changes have led to any preference for positive changes, a “null” test of the distribution of trends is required. To that end, the distribution of trends for stations with no land cover changes are compared to the same distribution for those stations that had intervening land cover changes in the 1980s. In addition, the composition of station trends from the two classes of stations are compared to the distribution of trends calculated from the NCAR/NCEP reanalysis whose temperatures have been purported to be immune to changes in land cover.