En undersökning av samband mellan förändringar i fenologi och temperatur 1982-2005 med hjälp av GIMMS datasetet och klimatdata från SMHI

The earth’s climate is undergoing vast and rapid chages due to the increased greenhouse gases in the atmosphere. These changes in the atmosphere are affecting life on earth in many different ways. This degree thesis attempts to quantify the changes in vegetation phenology in Europe during the last 23 years and link these changes to changes in temperature. The phenological parameters that were studied were extracted from the GIMMS dataset using the computer program TIMESAT which calculates phenological parameters from a curve fitted to NDVI values in a satellite timeseries. The parameters calculated from the GIMMS were:Amplitude, Start of season, End of season, Length of season, Large integral, Maximum value and the base value. For each year in the timeseries a value for each of the different parameters was calculated and from these values changes were calculated. These phenolgical changes were then compared to changes in temperature parameters calculated from MESAN climate modell data. The temperature paramaters used were monthly means from January to April, a mean of the months January to April and the number of weeks from the first week of the year until the weekly meantemperature exceeds 5ºC. The analyses were carried out on three different levels: continental ie Europe, regional eg southern Sweden, the British Isles etc and on pixel level. The analyses on the continental and regional levels were visual analyses while the analyses on the pixel level were statistical. The results of this study can neither confirm nor disconfirm the hypothsesis that the changing temperature has influenced vegetation phenology in Europe. However it can be concluded that it in general has become warmer in Europe during the study period, it can also be concluded that the growing season of the vegetation has lengthened and that the green biomass has increased.