Can mega-engineering contribute to a greening Earth?
Human activities are usually related with deforestation, destruction of the environment, conversion of forest areas into farmlands or urban areas and air pollution
The paper in Nature Sustainability is here: http://go.nature.com/2n90wgL
This is particularly the case in densely populated and fast developing countries like China. However, here we show that management and conservation activities can lead to a large increase in vegetation cover and carbon stocks, in spite of drought conditions. The observed increase in vegetation growth does not only improve the ecological environment by alleviating degradation, but also the magnitude of increase is found to be large enough to contribute to a greening Earth and store large amounts of carbon. Our study shows that ecological engineering, if applied at a large spatial scale, may be a way to impact on the global carbon cycle and to mitigate climate change.
The human population is increasing rapidly, and the continued growth is expected in the future. It is thus inevitable that marginal lands are being populated and controlled by management. Natural vegetation is globally transformed to a human controlled environment and there is no way to stop the encroachment of settlements. Here, only a suitable management of natural resources can ensure a sustainable development for the long term. The Chinese karst region is a very fragile ecosystem in which population pressure and overuse of natural resources have led to widespread desertification over the past century. The expansion of croplands to sloping hills has accelerated soil erosion leading to a loss of ecosystem services and increasing poverty of the local population. Since the end of the 1990s, the Chinese government has launched the largest conservation projects in human history. These “mega-projects” include afforestation and reforestation activities planting millions of trees and converting farmland on sloping hills into forests. Moreover, large forested areas have been protected and it is no longer allowed to collect firewood.
Using satellite time series, our paper quantifies increases in vegetation cover and carbon stocks. We simulate natural growing conditions (without human influence) with an ecosystem model and compare the results with satellite observations. The results are impressive: under natural conditions, both vegetation cover and carbon stocks would have declined in the past decades (because of drought conditions), however, the satellites observe an increase of about 10% carbon stocks, clearly following the temporal and spatial implementation of project areas. We quantify the increase as +0.05 Pg C per year, which is an impressive number with a clear impact on the global carbon balance. This number shows that ecological engineering can be a serious measure for carbon sequestration offsetting or at least mitigating emissions from fossil fuels and our study gives hope that there is a potential tool to fight climate change.
Tong X, Brandt M, Yue Y, et al. Increased vegetation growth and carbon stock in China karst via ecological engineering. Nature Sustainability, 2018, 1: 44-50.