A large number of ZEW survey participants took the opportunity to voluntarily donate part of their expense allowance to the city of Mannheim for urban reforestation initiatives in preparation for the 2023 German National Garden Show (BUGA). A total of 2,809.40 euros was passed on to the “Bundesgartenschau Mannheim 2023 gGmbH”. The money was used to plant four Caucasian wingnuts in the eastern part of the newly emerging Käfertal park bowl in May 2021. Looking at the survey results, it can be seen that the willingness of participants to donate trees is significantly greater than the willingness to voluntarily offset CO2 by retiring certificates from emissions trading.

The tree donation campaign has proved to be particularly beneficial.
In May 2021, four Caucasian wing nuts were planted in the eastern part of the newly emerging Käfertal park bowl.

Michael Schnellbach, managing director of the 2023 German National Garden Show, is delighted with the support of the ZEW respondents: “The Käfertal park bowl is an important part of the ‘Spinelli’ exhibition area and the entire North-East green corridor, which stretches from Luisenpark to the Vogelstang lakes. As a link between the new residential quarter in the south of Käfertal and the Spinelli climate park, numerous play, exercise and sports areas are being created that will be freely accessible to all Mannheim citizens from 2023. The approximately 500 trees that will be planted in the park bowl and the climate park will serve as structural elements and provide shade onsite while naturally contributing to increasing biodiversity. The fact that so many participants in the ZEW survey decided to donate trees highlights the importance that local green projects have in the public perception.”

The high willingness of the participants, however, was a surprising discovery for ZEW researchers. The tree donation campaign proved to be particularly effective compared to previous projects in which participants could engage in climate protection in other ways. “The willingness of participants to donate trees is significantly higher than supporting voluntary CO2 offsetting, for example by purchasing certificates that are then retired from the European emissions trading scheme,” notes ZEW environmental economist Lara Bartels.
With regard to voluntary climate protection measures, the results are surprising for two reasons: on the one hand, emissions trading is the leading instrument of European climate policy, whereas afforestation projects currently only play a supporting role on the path to climate neutrality. Natural CO2 absorbers such as forests or bogs are primarily intended to compensate for emissions that cannot be avoided or can only be avoided at very high cost. On the other hand, the ability of new forests to compensate for CO2 emissions is associated with many uncertainties, such as water supply, soil quality and the expected durability of the tree population.
For the researchers, the observed behaviour can be explained by the fact that trust in afforestation projects is higher than in emissions trading. “Of course, it is important to promote afforestation projects for many reasons, especially against the background of their many positive local effects such as the reduction of air pollutants, the protection against soil erosion and the increase of biodiversity,” Professor Martin Kesternich, deputy head of the ZEW Research Department “Environmental and Resource Economics, Environmental Management” comments on the survey results. “For climate protection, however, we should focus our attention on strengthening trust in emissions trading.” Project partner and ZEW Research Associate Professor Andreas Löschel from the University of Münster adds: “Both in the German Climate Change Act and in the European Climate & Energy Package, the contribution of natural ecosystems to climate protection plays an important role. This study is the first to provide evidence for the great support this approach has among the population.”



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