On Wednesday 2 December we hosted a webinar that provided an overview of the IHA/UNESCO project on the GHG status of freshwater reservoirs, an introduction to the G-res tool, as well as the opportunity for partcipants to pose questions to the tool's developers.

Mitigation of climate change is one of the most important areas for sustainable development, and measuring the relative contribution of harmful greenhouse gas (GHG) emissions is now an expectation in all sectors.

Although generally considered to be carbon neutral, certain reservoir systems may be an important source or sink of GHG emissions. Due to greater scrutiny from regulators, investors, the scientific community and the public, there is a pressing need to report on the GHG status of freshwater reservoirs.

From the point of view of the hydropower sector, there is an additional need to know the GHG footprint of a reservoir so that the overall emissions from associated hydropower operations can be compared with other forms of electricity generation.

For the last eight years, the International Hydropower Association (IHA) has worked on this matter in collaboration with the International Hydrological Programme of UNESCO. The understanding of how GHG emissions relate to reservoir systems has been increased through the IHA/UNESCO research project on the GHG status of freshwater reservoirs.

This led to the development of the Measurement Guidelines for Freshwater Reservoirs (2011) and the initial GHG Risk Screening Tool (2013). Both the guidelines and the tool dealt with ‘gross emissions’ – emissions that occur once the reservoir is created.

However, it has been recognised by the Intergovernmental Panel on Climate Change (IPCC) that ‘net emissions’ should be considered – measuring the change in GHG emission from the pre-impoundment to the post-impoundment condition. This gives a truer reflection of the actual impact of any reservoir system.

The continuing work of IHA/UNESCO aims to further the understanding of GHG emissions from reservoirs and provide a tool, the ‘G-res tool’, that estimates the actual impact of a reservoir on GHG emissions.

IHA has launched a climate change knowledge network, with the aim to foster discussion and build knowledge on this topic. You can find out more about the new initiative and how to get involved here.