Ecosystem restoration is a critical nature-based solution to mitigate climate change. However, the carbon sequestration potential of restoration, defined as the maximum achievable carbon storage, has likely been overestimated because previous studies have not adequately accounted for the competition between ecosystem water demands for maximizing carbon sequestration and human water needs. Here we used a comprehensive process-based model combined with extensive land-use data and evaporation recycling accounting for land–atmosphere feedback to estimate the water requirements associated with ecosystem restoration. We found that achieving the carbon sequestration potential of restoration would significantly reduce global water availability per capita by 26%, posing considerable risks to water security in water-stressed and highly populated regions.
If human water use is safeguarded, the achievable carbon sequestration potential would be reduced by a third (from 396 PgC to 270 PgC). Brazil, the United States and Russia have the largest achievable potentials. Future projections accounting for changes in climate, atmospheric CO2 , land use and human population under the shared socioeconomic pathway (SSP) scenarios SSP119, SSP245 and SSP585 suggest an increase in this achievable potential to 274–302 PgC by the end of the century, with China expected to have the largest potential. Our findings provide a nuanced understanding of the trade-offs and synergies between carbon sequestration goals and water security, offering an empirical framework to guide the sustainable implementation of ecosystem restoration strategies.
This study offers a nuanced understanding of the potential for increased carbon storage in terrestrial ecosystems and the corresponding impacts on water resources. Using a process-based model, calibrated and verified using independent datasets, in the current period, we have identified a global potential for increased carbon storage of 396 PgC. Our findings reveal a complex interplay between carbon restoration and water resource consumption, with 74% of areas showing a reduction in water resources with increased carbon storage. Most notably, the results underscore a significant trade-off between carbon restoration and water security worldwide, with a potential decline in global water availability per capita of 26% under full restoration. This insight sets the stage for a detailed exploration of the mechanisms at play and the strategic considerations necessary to implement NCS in a manner that balances both environmental and human needs.
Overall, this study provides traceable estimates of the potential for increased carbon storage and changes in water resources, as well as a reference for ecosystem restoration. Unlike the previous work of Walker et al. ,which used zonal statistical methods, our study lever aged a process-based model integrated with land-use-change data. Compared with the current carbon restoration potential on global land (excluding farmland and urban areas) reported by Walker et al. (352 PgC, 177–712 PgC), our study has narrowed the uncertainty range (396 PgC, 283–526 PgC), thereby improving the reliability of the estimates. Moreover, considering an increasing atmospheric CO2 concentration from the past to the future and its positive effects on the carbon sink, our model also incorporates the atmospheric CO2 fertilization effect from 1851–2100 (Supplementary Methods), thus offering a more holistic view of the carbon restoration potential. We caution, however, about the potential uncertainty of CO2 fertilization of the carbon sink in process-based models , noting that this uncertainty stems from the wide range of responses in observations of vegetation CO2 responses (mainly free-air CO2 enhancement experiments). Compared with other global models, LPJ-GUESS is a mid-range model in terms of the strength of the impact of CO2 fertilization on plant productivity and carbon storage and accounts for the nitrogen cycle feedbacks believed to limit CO2 fertilization strength across temperate and borealforest biomes.
Consistent with regional studies that have reported declines in both stream flow and total terrestrial water storage following vegetation restoration15–17, our global analysis reveals that 74% of areas with enhanced carbon storage simultaneously experienced diminished water resources. Conversely, a minority of 26% of these areas demonstrated the potential for increased water availability . This increased water availability may be contributed to by positive vegetation–soil water feedback, that is, via decreased soil evaporation after ecosystem restoration in areas with high-intensity anthropogenic activities. Moreover, the additional precipitation generated by land–atmosphere feedback after ecosystem restoration could further increase water availability and thus play a critical role in these outcomes, especially in warm and humid regions.
Source:
Nature Water
https://www.nature.com/articles/s44221-024-00323-5 .
Provided by the IKCEST Disaster Risk Reduction Knowledge Service System
Comment list ( 0 )
