Extensive reforestation can help curb global warming
The Paris Agreement has set the ambitious goal of limiting global temperature rise to 1.5C above pre-industrial levels. Achieving this requires both a reduction in CO2 emissions and active efforts to remove existing CO2 from the atmosphere. The study led by LMU scientists Yiannis Moustakis and Julia Pongratz demonstrates that large-scale afforestation and reforestation (AR) could significantly contribute to these efforts by reducing peak and long-term temperatures.
Afforestation and reforestation are currently the most widely adopted strategies for carbon removal. "Overall, the international community has already announced ambitious AR goals of up to 490 million hectares by 2060, and this figure is likely to increase even further as more countries present their long-term plans. We wanted to find out how strongly these measures can influence the climate," says Moustakis.
Simulations of over 1,200 scenarios
Using advanced models that integrate climate policies with energy, economic, and land-use factors, the researchers explored over 1,200 scenarios. These scenarios, coupled with biodiversity and restoration priority maps, helped develop an ambitious AR strategy while considering technical and economic challenges.
Their proposed scenario projects 595 million hectares of forested land by 2060 and 935 million hectares by 2100. "We tried to develop a scenario that is rather in the range of country pledges globally, extend it to the end of the century, and constrain its spatial and temporal features by technoeconomic considerations, while minimizing the impact on biodiversity," emphasizes Moustakis.
Analyzing this scenario with the Earth System Model from the Max Planck Institute for Meteorology, the researchers studied its effects in a climate overshoot scenario, where global temperatures temporarily rise above the 1.5C target before declining later in the century. "As delays in drastic climate action persist, such scenarios are becoming increasingly probable," explains Moustakis.
AR could lower peak temperatures by 0.08C by mid-century and reduce end-of-century temperatures by 0.2C. Moreover, AR measures could shorten the period in which global temperatures exceed the 1.5C threshold by 13 years, with noticeable impacts as early as 2052.
While AR affects the physical properties of the Earth's surface, such as albedo and water evaporation, the study confirms that the benefits of CO2 absorption outweigh any potential warming caused by these changes. "These results show that global AR can in fact make an important contribution to mitigating climate change, when applied at the large scale," says Moustakis. "But it is not a panacea and must be viewed in a more comprehensive framework that takes socioeconomic trade-offs equally into account. Planting a forest could create jobs, revenue, and promote ecosystem services, but it could also deprive people's livelihood, exacerbate poverty, financially or physically displace people, and disturb local food networks."
Research Report:Temperature overshoot responses to ambitious forestation in an Earth System Model
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