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1. Tropical cyclones cumulatively control regional carbon fluxes in Everglades mangrove wetlands (Florida, USA)

   https://doi.org/10.1038/s41598-021-92899-1  

   Zhao, Xiaochen; Rivera-Monroy, Victor H.; Farfán, Luis M.; Briceño, Henry; Castañeda-Moya, Edward; Travieso, Rafael; Gaiser, Evelyn E. (December 2021, Scientific Reports)

   null (Ed.)

   Abstract Mangroves are the most blue-carbon rich coastal wetlands contributing to the reduction of atmospheric CO 2 through photosynthesis (sequestration) and high soil organic carbon (C) storage. Globally, mangroves are increasingly impacted by human and natural disturbances under climate warming, including pervasive pulsing tropical cyclones. However, there is limited information assessing cyclone’s functional role in regulating wetlands carbon cycling from annual to decadal scales. Here we show how cyclones with a wide range of integrated kinetic energy (IKE) impact C fluxes in the Everglades, a neotropical region with high cyclone landing frequency. Using long-term mangrove Net Primary Productivity (Litterfall, NPP L ) data (2001–2018), we estimated cyclone-induced litterfall particulate organic C (litter-POC) export from mangroves to estuarine waters. Our analysis revealed that this lateral litter-POC flux (71–205 g C m −2  year −1 )—currently unaccounted in global C budgets—is similar to C burial rates (69–157 g C m −2  year −1 ) and dissolved inorganic carbon (DIC, 61–229 g C m −2  year −1 ) export. We proposed a statistical model (PULITER) between IKE-based pulse index and NPP L to determine cyclone’s impact on mangrove role as C sink or source. Including the cyclone’s functional role in regulating mangrove C fluxes is critical to developing local and regional climate change mitigation plans. 

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2. Responding to rising waters and temperatures: greenhouse gas flux from a high-latitude coastal wetland

   https://doi.org/10.1088/1748-9326/adff98  

   Kelsey, Katharine C; Leffler, A Joshua; Petit_Bon, Matteo; Barr, Briana N; Beard, Karen H (September 2025, Environmental Research Letters)

   Abstract Climate change is exposing coastal landscapes to more flooding, in addition to rapidly rising temperatures. These changes are critical in the Arctic where the effects of sea level rise are exacerbated by the loss of sea ice protecting coasts, subsidence as permafrost thaws, and a projected increase in storms. Such changes will likely alter the land-atmosphere gas exchange of high-latitude coastal ecosystems, but the effects of flooding with warming remain unexplored. In this work we use a field experiment to examine the interacting effects of increased tidal flooding and warming on land-atmosphere CO₂and CH₄exchange in the coastal Yukon–Kuskokwim Delta, a large sub-Arctic wetland and tundra complex in western Alaska. We inundated dammed plots to simulate two levels of future flooding: low-intensity flooding represented by one day of flooding per summer-month (June, July and August), and high-intensity flooding represented by three-consecutive days of flooding per summer-month, crossed with a warming treatment of 1.4 °C. We found that both flooding and warming influenced greenhouse gas (GHG) exchange. Low-intensity flooding reduced net CO₂uptake by 20% (0.78µmol m⁻²s⁻¹) regardless of temperature, and marginally increased CH₄emissions 0.83 nmol m⁻²s⁻¹(33%) under ambient temperature, while decreasing CH₄emissions by −1.96 nmol m⁻²s⁻¹(40%) under warming. In contrast, high-intensity flooding restored net CO₂uptake to control levels due to enhanced primary productivity under both temperature treatments. High-intensity flooding decreased CH₄emissions under ambient temperature by 0.76 nmol m⁻²s⁻¹(30%), but greatly increased emissions under warming by 4.68 nmol m⁻²s⁻¹(265%), presumably driven by increased plant-mediated CH₄transport. These findings reveal that GHG exchange responds rapidly and non-linearly to intensifying flooding, and highlight the importance of short-term flooding dynamics and warming in shaping future carbon cycling in this Arctic coastal wetland. 

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3. Carbon fluxes in two temperate ponds are mediated by stratification and primary producers

   https://doi.org/10.1002/lno.70273  

   Holgerson, Meredith A; Ray, Nicholas E; Gannon, Kathryn A; Heathcote, Adam J (January 2026, Limnology and Oceanography)

   Abstract Ponds influence global carbon (C) cycling due to high rates of organic C (OC) burial and carbon dioxide (CO₂) and methane (CH₄) emissions. Here, we quantified OC burial rates and CO₂and CH₄concentrations and fluxes in two ponds that were similar in size and gross primary production, but differed in depth and dominant primary producers. The deeper (3.9 m) Texas Hollow Pond was phytoplankton dominated with stronger and longer (143 d) stratification compared to the shallower (2.7 m) macrophyte‐dominated Mud Pond (85 d). Both ponds exhibited high CO₂and CH₄emissions and high OC burial, yet C pathways differed. Strong stratification in Texas Hollow Pond led to anoxic bottom waters, benthic CO₂and CH₄accumulation, and limited OC decomposition, whereas Mud Pond remained oxygenated with similar gas concentrations across the water column. Texas Hollow Pond had 2.6 times higher CO₂emissions than Mud Pond, perhaps related to greater wetland C inputs in Texas Hollow. Despite similar diffusive CH₄emissions between ponds, the weakly stratified Mud Pond had twice as much CH₄ebullition, likely due to warmer waters and macrophyte‐derived OC fueling methanogenesis. In summary, slight differences in depth and light attenuation can regulate stratification, plant communities, oxygen availability, and C processing in ponds. Given that ponds are hotspots for C cycling and are sensitive to climate‐driven changes in stratification, understanding the mechanisms behind C processing is critical for local management and predicting global C budgets. 

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4. Resolving the Carbon‐Climate Feedback Potential of Wetland CO ₂ and CH ₄ Fluxes in Alaska

   https://doi.org/10.1029/2022GB007524  

   Ma, Shuang; Bloom, A Anthony; Watts, Jennifer D; Quetin, Gregory R; Donatella, Zona; Euskirchen, Eugénie S; Norton, Alexander J; Yin, Yi; Levine, Paul A; Braghiere, Renato K; et al (September 2023, Global Biogeochemical Cycles)

   Abstract Boreal‐Arctic regions are key stores of organic carbon (C) and play a major role in the greenhouse gas balance of high‐latitude ecosystems. The carbon‐climate (C‐climate) feedback potential of northern high‐latitude ecosystems remains poorly understood due to uncertainty in temperature and precipitation controls on carbon dioxide (CO₂) uptake and the decomposition of soil C into CO₂and methane (CH₄) fluxes. While CH₄fluxes account for a smaller component of the C balance, the climatic impact of CH₄outweighs CO₂(28–34 times larger global warming potential on a 100‐year scale), highlighting the need to jointly resolve the climatic sensitivities of both CO₂and CH₄. Here, we jointly constrain a terrestrial biosphere model with in situ CO₂and CH₄flux observations at seven eddy covariance sites using a data‐model integration approach to resolve the integrated environmental controls on land‐atmosphere CO₂and CH₄exchanges in Alaska. Based on the combined CO₂and CH₄flux responses to climate variables, we find that 1970‐present climate trends will induce positive C‐climate feedback at all tundra sites, and negative C‐climate feedback at the boreal and shrub fen sites. The positive C‐climate feedback at the tundra sites is predominantly driven by increased CH₄emissions while the negative C‐climate feedback at the boreal site is predominantly driven by increased CO₂uptake (80% from decreased heterotrophic respiration, and 20% from increased photosynthesis). Our study demonstrates the need for joint observational constraints on CO₂and CH₄biogeochemical processes—and their associated climatic sensitivities—for resolving the sign and magnitude of high‐latitude ecosystem C‐climate feedback in the coming decades. 

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5. Persistent net release of carbon dioxide and methane from an Alaskan lowland boreal peatland complex

   https://doi.org/10.1111/gcb.17139  

   Euskirchen, Eugénie S.; Edgar, Colin W.; Kane, Evan S.; Waldrop, Mark P.; Neumann, Rebecca B.; Manies, Kristen L.; Douglas, Thomas A.; Dieleman, Catherine; Jones, Miriam C.; Turetsky, Merritt R. (January 2024, Global Change Biology)

   Abstract Permafrost degradation in peatlands is altering vegetation and soil properties and impacting net carbon storage. We studied four adjacent sites in Alaska with varied permafrost regimes, including a black spruce forest on a peat plateau with permafrost, two collapse scar bogs of different ages formed following thermokarst, and a rich fen without permafrost. Measurements included year‐round eddy covariance estimates of net carbon dioxide (CO₂), mid‐April to October methane (CH₄) emissions, and environmental variables. From 2011 to 2022, annual rainfall was above the historical average, snow water equivalent increased, and snow‐season duration shortened due to later snow return. Seasonally thawed active layer depths also increased. During this period, all ecosystems acted as slight annual sources of CO₂(13–59 g C m⁻² year⁻¹) and stronger sources of CH₄(11–14 g CH₄ m⁻²from ~April to October). The interannual variability of net ecosystem exchange was high, approximately ±100 g C m⁻² year⁻¹, or twice what has been previously reported across other boreal sites. Net CO₂release was positively related to increased summer rainfall and winter snow water equivalent and later snow return. Controls over CH₄emissions were related to increased soil moisture and inundation status. The dominant emitter of carbon was the rich fen, which, in addition to being a source of CO₂, was also the largest CH₄emitter. These results suggest that the future carbon‐source strength of boreal lowlands in Interior Alaska may be determined by the area occupied by minerotrophic fens, which are expected to become more abundant as permafrost thaw increases hydrologic connectivity. Since our measurements occur within close proximity of each other (≤1 km²), this study also has implications for the spatial scale and data used in benchmarking carbon cycle models and emphasizes the necessity of long‐term measurements to identify carbon cycle process changes in a warming climate. 

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