Maps: Europe Thermal Growing Season Length

by
IMPACT2C project

Thermal Growing Season Length

Key messages:

  • Thermal growing season length is projected to increase almost everywhere under a +2°C global warming
  • The findings must be interpreted carefully and in conjunction with temperature- and water-related changes
  • Positive impacts related to a +2°C global warming are likely limited to very specific regions in North Europe, including Scandinavia

Why is the content of this map important?

Thermal growing season describes the length of time in a calendar year when temperatures are consistently warm enough for agricultural activity. Growing season length increases dramatically almost everywhere over Europe at +2°C global warming. However, due to excessive heat and drying during the growing season in southern Europe, the potential benefits are likely limited to  northern Europe and Scandinavia.

Which sectors are affected by this result?

Growing seasons are obviously most important for agriculture. But it also links strongly to water resources as other industries and municipalities compete for limited resources in water-stressed or water-limited environments.

What is shown on the maps?

The current map shows the typical North-South growing season length gradient under present day conditions. On the +2°C period map, the northward extension of the thermal growing season is clearly evident. The difference map shows increases almost everywhere, though they are likely only meaningful in specific regions. Areas where increases in growing season might have the most impact are northern Europe (Germany, Poland) and southern Scandinavia (Sweden, Denmark, Norway). These areas already have arable land and stand to experience increases of a month or longer. The risks due to increases in damaging dry spells and heat waves are also lower for these regions than the in southern Europe. However, these risks increase as warming continues past +2°C so any benefit may be short-lived.

Details and further information:

Thermal growing season length is defined as the number of days between the first five day period with average temperatures above 5°C to the first five day period with temperatures below 5°C. It is important to consider thermal growing season length along with other indicators as it alone does not consider the damaging effects of excessive heat and dryness. Also, since the index is based solely on temperature, readers should consider the geography. A large increase in growing season length over mountainous terrain (e.g., the central mountains of Norway) may not be particularly meaningful.