Permanent grassland soils can act as a sink for carbon and may therefore positively contribute to climate change mitigation and adaptation. We compared young (5–15 years since latest grassland renewal) with old (>20 years since latest grassland renewal) permanent grassland soils in terms of carbon stock, carbon sequestration, drought tolerance and flood resistance. The research was carried out on marine clay soil at 10 dairy farms with young and old permanent grassland. As hypothesized, the carbon stock was larger in old grassland (62 Mg C ha−1) topsoil (0–10 cm) than in young grassland topsoil (51 Mg C ha−1). The carbon sequestration rate was greater in young (on average 3.0 Mg C ha−1 year−1) compared with old grassland (1.6 Mg C ha−1 year−1) and determined by initial carbon stock. Regarding potential drought tolerance, we found larger soil moisture and soil organic matter (SOM) contents in old compared with young grassland topsoils. As hypothesized, the old grassland soils were more resistant to heavy rainfall as measured by water infiltration rate and macroporosity (at 20 cm depth) in comparison with the young grassland soils. In contrast to our hypothesis we did not find a difference in rooting between young and old permanent grassland, probably due to large variability in root biomass and root tip density. We conclude that old grasslands at dairy farms on clay soil can contribute more to the ecosystem services climate change mitigation and climate change adaptation than young grasslands. This study shows that under real farm conditions on a clay topsoil, carbon stock increases with grassland age and even after 30 years carbon saturation has not been reached. Further study is warranted to determine by how much extending grassland age can contribute to climate change mitigation and adaptation.
MULTIFILE
Contrary to most sectors, to date the tourism and aviation industries have not managed to level off greenhouse gas emissions. Moreover, effective mitigation through technological innovation or structural and behavioural change cannot be expected shortly. Airlines and tourism companies appear to use carbon offsetting as a last resort. However, offsetting is generally acknowledged as a second-best solution for mitigating emissions, after reducing energy use. This paper seeks to determine the mitigation potential of voluntary carbon offsetting by comparing public and industry awareness of climate change and aviation emissions, and attitudes to various mitigation measures with relevant online communication by 64 offset providers. Methods were a literature review and online content analyses. Overall, the gaps that were identified between awareness, attitude and actual behaviour are not bridged by provider communication. From this perspective, the mitigation potential of voluntary carbon offsetting for achieving reductions of tourism transport emissions is estimated as low. The same conclusion is reached by comparing carbon dioxide volumes of flight offsets with actual air travel emissions. Current sales of flight offsets compensate less than 1% of all aviation emissions.
MULTIFILE
There is a clear demand for a collaborative knowledge-sharing on climate adaptation and mitigation. The aim of most climate adaptation platforms is (inter)national knowledge exchange and raising awareness about climate adaptation in urban areas and promote solutions such as Nature-based solutions (NBS) and floating infrastructure. However their multiple benefits are often unknown to the wider public. During seminars (February 2020) in Indonesia climate adaptation measures where mapped and the relevance of the climate adaption platforms such as ClimateScan was evaluated by the means of workshops and a survey. The platform ClimateScan holds now over 5000 locations in 5 main categories of climate adaptation (water, nature, agriculture, energy and people). The conclusions from the workshops in Semarang and Surabaya show high relevance scores for NBS: permeable pavement and swales; for infiltration of stormwater to groundwater; for mitigation of high temperatures with heat stress measures; and flood barriers to mitigate flooding. There were low scores for floating urbanization because this is not a culturally accepted practice in contradiction to other parts of the world. Indonesian floating infrastructure as a floating library, restaurant and airport terminal where mapped during workshops bringing the total of international floating structure locations to 150. The workshops have raised awareness among participants and contributed to capacity building by empowering the participants to map and review climate adaptation measures. A high majority see the value of climate adaptation platforms and will use it in the future.
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