Land Development and Role of Evapotranspiration in Climate Change

Analyses of underground temperatures have been used to obtain ground surface temperature (GST) histories. At individual sites, changes in the GST over time are synchronous with development which altered the evapotranspiration. At different, closely spaced sites, measured differences in GST between sites depend on the relative amounts of evaporation and transpiration at each site. These observations prove that a significant portion of the climate change observed on land is caused by changes in the amounts of evapotranspiration at each location. The magnitudes of GST changes vary from 0.6 to 2.6 C, for developments occurring from 8 to 52 years ago. In the temperate zone of Canada, these differences occur primarily in the summer. Our development, including urbanization and development of agricultural land, has produced a significant warming. It is best defined from underground temperature data.