Changes to climatic variables across the world are evidenced from a large range of sources, including climate station logging by humans. Future predictions for climate change are variable and complex; however, there is broad agreement for the direction of impacts for many areas. We at American Truffle Company are often asked the question ‘how will the predicated changes in climate impact current Périgord truffle (Tuber melanosporum) production?’
For the answer, we look to France and Spain where the majority of Périgord are produced. We know that in recent history, the climate of these two countries has observably changed and predictions for further change are discussed below.
T. melanosporum is a temperature and precipitation sensitive species. The known temperature range of this species is displayed in Table 1.
Table 1. Climatic data compiled from sites that are producing Tuber melanosporum fruiting bodies. The data incorporates sites in Africa, Asia, Australia, Europe, North America and South America.
|Annual temperature (°C)||9.8||16.4||12.9|
|Summer temperature (°C)||15.8||25.0||20.6|
|Winter temperature (°C)||0.5||10.4||5.8|
|Annual sunshine hours||1704||2888||2226|
|Annual rainfall (mm)||288||1788||777|
|Summer rainfall (mm)||39||324||193|
|Winter rainfall (mm)||26||894||127|
If we look at the data for the two of the biggest truffle producing regions in both Spain and France, we can see that their temperature profiles fall well within the averages displayed in Table 1 (see Table 2).
Table 2. Climatic averages and predicted future change for two truffle producing regions.
|Summer temperature||22.5°C (72.5°F)||21°C (69.8°F)|
|Winter temperature||4°C (39.2°F)||6°C (42.8°F)|
|Summer temp predictions||0.35°C increase per decade||0.7°C increase per decade|
|Winter temp predictions||0.2°C increase per decade||0.4°C increase per decade|
|Years until climate is unsuitable||114 years||35.7 years|
However, within just 35.7 years for Spain, the climate will fall outside of the known parameters for truffle fruiting. Although the time until these regions may be unsuitable is measured in decades, its important to note that these are averaged figures and that they mask variability and extreme climatic events, such as drought periods. Therefore it is likely that impact on production could materialize sooner.
This brief analysis also treats suitable summer and winter temperatures, individually. But this is an overly simplistic view and of more importance may be accumulated temperature; as such the summer and winter temperatures must be viewed in tandem. In this case, both regions in Spain and France may fall out-side of known productive parameters far sooner than the above predictions.
The climate question is complex. However, we are teasing apart the data and hope to publish a full analysis later this year. Finally, one thing is clear; Truffle producing regions in Europe are going to face significant challenges over the coming decades. With these challenges, production is likely to decline in some existing orchards. Here in the US, our assessment for new truffle orchard locations already factor in predictions from climate change models. If we want to maintain annual supply, we need to explore new areas and increase cultivation in new territories, be they in Europe or beyond.
For further information on climate models, see: www.climatechangepost.com.
Thomas P. (2013) An analysis of the climatic parameters needed for Tuber melanosporum cultivation incorporating data from six continents. Mycosphere. 2014;5(1):137–142.