Bastviken et al. (2025) Future methane emissions from lakes and reservoirs

Identification

• Journal: Nature Water
• Year: 2025
• Date: 2025-11-04
• Authors: David Bastviken, Matthew S. Johnson
• DOI: 10.1038/s44221-025-00532-6

Research Groups

• Department of Thematic Studies–Environmental Change, Linköping University, Linköping, Sweden
• Earth Science Division, NASA Ames Research Center, Moffett Field, CA, USA

Short Summary

This study presents data-driven, globally gridded modeling to project future methane emissions from lakes and reservoirs under various IPCC climate change scenarios. It predicts a 24–91% increase in total lake and reservoir CH4 emissions by 2080–2099, primarily driven by changes in temperature and seasonality, with area and nutrient load also contributing significantly to reservoir emissions.

Objective

• To quantify future open-water methane (CH4) fluxes from lakes and reservoirs globally under different IPCC Shared Socioeconomic Pathway (SSP) climate change scenarios (SSP1-2.6 to SSP5-8.5), identifying the dominant environmental drivers and their geospatial distribution.

Study Configuration

• Spatial Scale: Global, gridded at 0.25° × 0.25° resolution, covering boreal–arctic, temperate, and tropical–subtropical ecoclimatic regions.
• Temporal Scale: Baseline period (2000–2019) and future 20-year periods (2020–2039, 2040–2059, 2060–2079, 2080–2099).

Methodology and Data

• Models used:
  • Data-driven, globally gridded model, an extension of a previous static model for contemporary CH4 emissions.
  • IPCC Shared Socioeconomic Pathway (SSP) climate change scenarios: SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5.
  • Aggregated ensemble of 20 climate models for temperature predictions (CMIP6).
• Data sources:
  • Peer-reviewed in situ CH4 flux observations from 606 individual lakes and 161 reservoirs.
  • Satellite microwave observations for ice-cover phenology.
  • Remote-sensing-derived geospatial area distributions of lakes and reservoirs (>0.1 km² from Messager et al. 2016; <0.1 km² estimated from BWALD data).
  • Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) for annually averaged soil temperature and 2-metre air temperature.
  • Projected future river phosphorus (P) export (as a proxy for nutrient load) under different SSP scenarios.

Main Results

• Total lake and reservoir CH4 emissions are projected to increase by 24–91% (14–53 Tg CH4 yr⁻¹) from present-day levels by 2080–2099, depending on the climate scenario (SSP1-2.6 to SSP5-8.5).
• Under the warmest scenario (SSP5-8.5), combined emissions increase by 80–91% to 107–112 Tg CH4 yr⁻¹, representing almost a doubling of current emissions and an ~10% increase of total global contemporary CH4 emissions.
• Effects of changed temperature and seasonality (ice-free period length) dominated these increases.
• Changes in water surface area and nutrient load also contributed substantially, particularly to reservoir emissions. For example, planned reservoir area increases had similar effects to temperature increases in lower SSP scenarios.
• Reservoir emissions increased proportionally more than lake emissions (124% versus 81% increase in SSP5-8.5), contributing 26% of the total combined absolute emissions increase.
• While relative increases were greater at high latitudes (boreal–arctic), tropical and subtropical regions contributed large absolute flux changes due to high year-round emissions and the exponential response to increasing temperatures.
• The total propagated uncertainty (coefficient of variation, CV) was 60.7% for lakes and 48.7% for reservoirs, but was substantially reduced to ~20% after regional optimization of the temperature sensitivity factor (θ) using monthly mean fluxes.

Contributions

• This study is the first global, geospatial assessment to integrate multiple influencing factors (temperature sensitivity, ice-cover phenology, diel patterns, water column storage and turnover, methane oxidation, ecoclimatic regions, updated small lake area, and established projections of climate, lake area, and nutrient regimes) to predict future CH4 emissions from both lake and reservoir water surfaces.
• It uniquely distinguishes the relative contributions of different environmental drivers to future CH4 fluxes.
• Provides a robust, data-driven, and conservative estimate of future inland water CH4 emissions, highlighting the critical role of climate change mitigation in avoiding substantial increases in these natural emissions.

Funding

• European Research Council (ERC H2020 grant number 725546 METLAKE)
• Swedish Research Councils VR (grant numbers 2016-04829 and 2022-03841)
• Formas (grant number 2018-01794)
• Linköping University
• NASA’s Interdisciplinary Research in Earth Science (IDS) Program
• NASA Terrestrial Ecology and Tropospheric Composition Programs

Citation

@article{Bastviken2025Future,
  author = {Bastviken, David and Johnson, Matthew S.},
  title = {Future methane emissions from lakes and reservoirs},
  journal = {Nature Water},
  year = {2025},
  doi = {10.1038/s44221-025-00532-6},
  url = {https://doi.org/10.1038/s44221-025-00532-6}
}