Carbon enrichment project maps impact of CO2 increases by 2050
The results of a fascinating carbon enrichment project have been revealed in the Rheingau area of Germany, where vineyards are being tested with levels of CO2 which are 20% higher than the current global average – and mimic where global atmospheric concentration will be by the middle of the century.
Dubbed FACE (Free Air Carbon Dioxide Enrichment), the project provides a portrait of carbon saturated vineyards. The results show an entire ecosystem under strain. With additional levels of CO2 being emitted between the vines via sensor technology, researchers report an acceleration of photosynthesis which then leads to increased production of biomass across the vines. The result is hyper productive shoots and leaves which pull resources away from berry formation and put significant strain on water resources. Meanwhile, the prevalence of insect life begins to accelerate under these conditions as populations swell from increased access to food. Increased berry sizes are also another entry on this list of challenges. This is particularly the case for already dense Riesling grapes, where close-knit berries are under significantly more threat from mildew and disease.
“CO2 is a fertiliser,” explained project lead Prof Manfred Stoll (pictured), head of the department for general and organic viticulture at Geisenheim University, where FACE has its home. “You get more of everything, including bigger roots which are able to bring up more water.” That seems like a good thing, at first. But over time, “the ratio of what is happening above and below ground changes. The balance between crop yields and biomass disappears”.
Germany, like many places, is facing climate whiplash. Periods of oppressive drought and humidity in regions such as Rheingau are impacting its cool climate reputation. Meanwhile bloated cloud formations from increased CO2 significantly contributed to the unprecedented flooding of 2021, when the Ahr river burst its banks and claimed the lives of over 100 people.
However, there are ways to offset the effects of a CO2 enriched future. This is now a top priority for the Geisenheim project, which is operating in tandem with the University of Bordeaux, the Australian Wine Institute (AWI) and Adelaide University.
This includes the development of drought resistant rootstocks and fungus resistant PIWI varieties such as Calardis Blanc. Also, there is the use of photovoltaic semi-transparent panels which are able to convert sunlight into electricity while doubling up as shade cover. A return to the terraced vineyards of old is additionally gaining momentum within the region.
Focused on biodiversity and vine health, Geisenheim professor Ilona Leyer explained how terraced embankments create advantageous biodiversity corridors and remove the threat of vineyards being swept away with flooding and erosion. Safety is also a major concern. Working on vertical slopes at an incline of up to 70% are still very much fatal: at least one life is usually lost in the region every year.
“Dry and hot feels like the new normal with exposed vineyards,” adds Theresa Breuer, who manages the family estate at Georg Breuer. “But working with nature is never free of challenges… We are the generation that has to try everything in order to find out what’s going to work for the future. Our needs constantly are changing.”
For the full report on the FACE project, see the upcoming edition of Harpers, available online and in print from 1 August.
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