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- ItemPotential of land-based climate change mitigation strategies on abandoned cropland(Springer Nature, 2023-02-16) Gvein, Maren H.; Hu, Xiangping; Næss, Jan S.; Watanabe, Marcos D. B.; Cavalett, Otávio; Malbranque, Maxime; Kindermann, Georg; Cherubini, FrancescoNatural revegetation, afforestation, and lignocellulosic crops for bioenergy, possibly coupled with a developing technology like carbon capture and storage, are the most common land-based climate change mitigation options. However, they can compete for land and threaten food security or nature conservation. Using abandoned cropland for their deployment can minimize these risks, but associated potentials are unclear. Here, we compare alternative land-based mitigation options by integrating historical and future (up to 2050) abandoned cropland with site-specific biomass yields and life-cycle emissions. Considering natural revegetation in biodiversity priority areas and different measures in the remaining land can achieve a mitigation potential of 0.8–4.0 GtCO2-equivalents yr−1 (2–11% of 2021 global CO2 emissions). Afforestation generally provides larger climate benefits than bioenergy, but bioenergy with carbon capture and storage delivers the highest mitigation in most locations. Overall, these results offer refined estimates of mitigation potentials from abandoned cropland and highlight opportunities for context-specific mitigation measures.
- ItemEcological resilience of restored peatlands to climate change(Springer Nature, 2022-09-13) Loisel, Julie; Gallego-Sala, AngelaDegradation of peatlands through land-use change and drainage is currently responsible for 5-10% of global annual anthropogenic carbon dioxide emissions. Therefore, restoring disturbed and degraded peatlands is an emerging priority in efforts to mitigate climate change. While restoration can revive multiple ecosystem functions, including carbon storage, the resilience of restored peatlands to climate change and other disturbances remains poorly understood. Here, we review the recent literature on the response of degraded and restored peatlands to fire, drought and flood. We find that degraded sites can generally be restored in a way that allows for net carbon sequestration. However, biodiversity, hydrological regime, and peat soil structure are not always fully restored, even after a decade of restoration efforts, potentially weakening ecosystem resilience to future disturbances. As the recovery of degraded peatlands is fundamental to achieving net-zero goals and biodiversity targets, sound science and monitoring efforts are needed to further inform restoration investments and priorities.
- ItemNatural forest growth and human induced ecosystem disturbance influence water yield in forests(Springer Nature, 2022-06-27) Yu, Zhen; Chen, Xiuzhi; Zhou, Guoyi; Agathokleous, Evgenios; Li, Lin; Liu, Zhiyong; Wu, Jianping; Zhou, Ping; Xue, Meimei; Chen, Yuchan; Yan, Wenting; Shi, Tingting; Zhao, XiangTogether natural growth, afforestation and forest disturbance, such as felling, contribute to the dynamic nature of forests. Thus to enhance forest management, water resource management and carbon sequestration, the net effect of forest changes on water yield must be better understood. Here, we conduct a global meta-analysis of 496 watersheds over 25 years to investigate the impact of forest complexity and overall changes on water yields. We classify watersheds based on the type of human disturbance, including felling and thinning, afforestation, and absence of external disturbances. We find that the runoff coefficient (ratio of annual water yield in watershed outlet to precipitation) is more sensitive to external disturbances in forests with lower ecosystem complexity compared to forests with higher complexity. In addition, we found forest natural growth may increase runoff and lead to an increased runoff coefficient decades later. Our findings highlight the importance of nature-based forest restoration, especially in regions vulnerable to water shortage.
- ItemTemporary nature-based carbon removal can lower peak warming in a well-below 2 °C scenario(Springer Nature, 2022-03-17) Matthews, H. Damon; Zickfield, Kirsten; Dickau, Mitchell; MacIsaac, Alexander J.; Mathesius, Sabine; Nzotungicimpaye, Claude-Michel; Luers, AmyMeeting the Paris Agreement’s climate objectives will require the world to achieve net-zero CO2 emissions around or before mid-century. Nature-based climate solutions, which aim to preserve and enhance carbon storage in terrestrial or aquatic ecosystems, could be a potential contributor to net-zero emissions targets. However, there is a risk that successfully stored land carbon could be subsequently lost back to the atmosphere as a result of disturbances such as wildfire or deforestation. Here we quantify the climate effect of nature-based climate solutions in a scenario where land-based carbon storage is enhanced over the next several decades, and then returned to the atmosphere during the second half of this century. We show that temporary carbon sequestration has the potential to decrease the peak temperature increase, but only if implemented alongside an ambitious mitigation scenario where fossil fuel CO2 emissions were also decreased to net-zero. We also show that non-CO2 effects such as surface albedo decreases associated with reforestation could counter almost half of the climate effect of carbon sequestration. Our results suggest that there is climate benefit associated with temporary nature-based carbon storage, but only if implemented as a complement (and not an alternative) to ambitious fossil fuel CO2 emissions reductions.
- ItemNature-based solutions in mountain catchments reduce impact of anthropogenic climate change on drought streamflow(Springer Nature, 2022-03-09) Holden, Petra B.; Rebelo, Alanna J.; Wolski, Piotr; Odoulami, Romaric C.; Lawal, Kamoru A.; Kimutai, Joyce; Nkemelang, Tiro; New, Mark G.Quantifying how well Nature-based Solutions can offset anthropogenic climate change impacts is important for adaptation planning, but has rarely been done. Here we show that a widely-applied Nature-based Solution in South Africa – invasive alien tree clearing – reduces the impact of anthropogenic climate change on drought streamflow. Using a multi-model joint-attribution of climate and landscape-vegetation states during the 2015–2017 Cape Town “Day Zero” drought, we find that anthropogenic climate change reduced streamflow by 12–29% relative to a counterfactual world with anthropogenic emissions removed. This impact on streamflow was larger than corresponding reductions in rainfall (7–15%) and reference evapotranspiration (1.7–2%). Clearing invasive alien trees could have ameliorated streamflow reductions by 3–16% points for moderate invasions levels. Preventing further invasive alien tree spread avoided potential additional reductions of 10–27% points. Total clearing could not have offset the anthropogenic climate change impact completely. Invasive alien tree clearing is an important form of catchment restoration for managing changing hydroclimatic risk, but will need to be combined with other adaptation options as climate change accelerates.