Assessments of current and future suitability of heat conditions for apple growing in Norway

Abstract

The commercial apple production in Norway is limited to the small regions along the fjord areas in the southwest part of the country and around lakes or near the sea in the southeast part with favorable climate. Due to the rapid rate of climate change over the recent decades, it is expected that suitable heat conditions for apple growing will expand to the areas that previously were too cold. This study analyses the heat suitability of past, present and future climate for six commercial apple varieties in Norway (Discovery, Gravenstein, Summerred, Aroma, Rubinstep, and Elstar). The methodology for identifying favorable heat conditions is developed using meteorological and phenological observations from the Ullensvang orchards and applied on a high-resolution gridded datasets of temperature observations and climate projections. The assessment indicates that with increasing temperatures, heat conditions suitable for cultivation all six apple varieties are expanding. The surfaces with favorable heat conditions for less heat-demanding varieties increased threefold over the last 60 years. In the period 2011-2020, heat suitable climate for cultivating at least one of the considered apple varieties is found at 15% of the analyzed territory, while 2.5% was suitable for growing all six varieties. In the future, the favorable areas will advance from south and southeast northwards and inland in the eastern region, along the west and northwestern coastline towards higher latitudes, and along continental parts of fjords. The fastest expansion of heat suitable conditions is expected for less heat-demanding varieties. The findings of this study show an increasing potential for apple production in Norway that are relevant for strategical planning of climate change adaptation measures within the sector. Weather related risks, such as the risk from damaging low temperatures, drought and extreme precipitation were not considered.

Assessments of current and future suitability of heat conditions for apple growing in Norway