The use of GCM scenario output to model effects of future climatic change on the thermal climate of marginal maritime uplands

This paper maps the likely changes in growing season strength in Northern England which would be associated with a variety of temperature change scenarios. Estimates of future temperature change, obtained through application of regression analysis and analytical theory, are converted into attendant changes in "thermal potential" (measured by annual accumulated temperatures above 6°C). The scenarios include warm and cold analogues, uni-directional airflow scenarios, arbitrary warming scenarios and two GCM simulations: UKHI (United Kingdom Meteorological Office High Resolution GCM Equilibrium Experiment) and GISS (Goddard Institute for Space Studies). Considerable changes in the thermal potential of Northern England result, especially at high altitudes, and there is great inter-scenario variation. The amount of cultivable land, defined as areas with an annual temperature accumulation of 1000 d°C and above, varies from 74.6% in the control model to over 99% in the two GCM scenarios (2 × CO2). This is to be expected in maritime upland areas such as the Pennines, where growing season strength is extremely sensitive to small changes in mean temperature. Problems in the interpretation of the results are discussed and outlines for future work are given.