NI: CONFLUENCE - Disentangling the role of rivers as greenhouse gas conduits

Lead Research Organisation: University of Liverpool
Department Name: Geography and Planning


Rivers emit ~2-3 Pg of carbon as the greenhouse gas carbon dioxide (CO2) to the atmosphere, each year. This is equivalent to 20% of annual anthropogenic CO2 emissions and an important component of the global carbon cycle.

Methane (CH4) emissions from river networks are very poorly understood. CH4 is a potent greenhouse gas, 34 times stronger than CO2 over a 100-year timeframe. Rivers are estimated to emit ~27 Tg of CH4 each year, equivalent to 8% of anthropogenic CH4 emissions. However, these CH4 emissions vary greatly both spatially and over time.

Rivers, acting as conduits for terrestrial greenhouse gases, can thus influence ongoing climate change. Landscape disturbance, either through human activity or climate change, can enhance river carbon emissions adding substantially to an already overloaded atmospheric carbon pool. This may represent a feedback to the global climate system as river carbon emissions can be enhanced by the impact of climate change on the terrestrial carbon cycle. Characterising the magnitude and source of river carbon emissions across globally representative ecosystems is therefore urgently needed for us to understand and predict current and future climate change.

Carbon emissions from rivers are primarily derived from the landscapes they drain. But sources within these landscapes can vary depending on the ecosystem. Carbon sources can include recent atmospheric CO2 fixed into biomass via photosynthesis, carbon that has accumulated in organic soils over millennia such as in Arctic, temperate and tropical peatlands, and even ancient geological carbon derived from erosion and weathering. With such a diverse range of potential carbon sources across ecosystems, it is vital to establish a framework from which to determine whether the source of carbon observed in river networks matches what would be expected from normal landscape function, or if it represents signals of a disturbed carbon cycle. I.e. are older and slower carbon cycles becoming shorter and faster?

Isotopes, especially radiocarbon (14C), are a powerful tool for identifying disturbed carbon cycles. Through a network of leading researchers, this project will bring together novel techniques and study sites to serve as a foundation for in-depth investigations into river carbon emissions around the globe. The project will utilise low-cost sensors for measuring the magnitude of river carbon emissions developed by the international Project Partners. These will be combined with in-depth isotopic investigations using novel techniques developed by the UK investigators. A network of existing study site and measurement infrastructure will be established covering a diverse range of ecosystems. The project will therefore provide a springboard from which to constrain the magnitude and source of river carbon emissions through direct observations at globally representative scales.

Rivers can drain large landscape areas and as such their water chemistry represents an integrated signal of landscape carbon loss. This project will provide the techniques to tease apart these signals and determine if they represent natural or disturbed carbon cycling. The project will build a database of existing observations of these signals. In addition, we will use the interacting, complimentary techniques brought together in this project to carry out a scoping project to provide preliminary observations of the magnitude and source of carbon emissions from a subset of disturbed landscapes.

CONFLUENCE will also include planning for an international meeting of researchers in relevant fields to grow the network of people, techniques and sites beyond the lifetime of this project. CONFLUENCE will be used as a launchpad for consortium funding to use this unprecedented infrastructure to make a step-change in observational capability of freshwater carbon emissions at spatial and temporal scales that individual research groups alone cannot achieve.


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Description Do peatland wildfires change the age of carbon released into rivers?
Amount £42,055 (GBP)
Funding ID 2509.0422 NEIF (National Environmental Isotope Facility) 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 04/2022 
End 05/2024
Description Finding and fixing gas leaks: Using urban waterways to halt the global rise in methane emissions
Amount £1,232,205 (GBP)
Funding ID MR/V025082/1 
Organisation United Kingdom Research and Innovation 
Sector Public
Country United Kingdom
Start 03/2022 
End 02/2026
Description Topic B: The Enigma of the Soil Hydrogen Sink Variability [ELGAR]
Amount £151,975 (GBP)
Funding ID NE/X013405/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 11/2022 
End 11/2024
Title Aquatic carbon isotope composition in natural and restoration pools in blanket peatlands in Scotland and Northern Ireland, 2014-2015 
Description The dataset contains the isotopic composition of aquatic carbon forms obtained from peatland pools across six locations in Scotland and Northern Ireland. Samples were collected from the surface of peatland ponds. Variables include radiocarbon (14C) content, stable carbon (d13C) isotopic content, and associated data used in the data analysis in the published manuscript collected from the study locations in 2014 and 2015. 
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
Impact This is the underlying dataset to another output partly supoorted by this grant: