Biomass: Weighing Carbon Stored in Forests
- 1st Apr 2025
- Author: Sean Sweeney
Professor Shaun Quegan, from the University of Sheffield and the National Centre for Earth Observation (NCEO), first developed and proposed the concept for the Biomass mission in 2005. 20 years later, that proposal is finally going to become a reality as ESA's forest mission gets ready to launch! The Biomass satellite will use radar to measure global forest carbon stocks and height, helping track carbon cycle changes and improve our understanding of climate change.
How do you Weigh Forests from Space?
But what is biomass you might ask?!
It’s basically the amount of living stuff – mostly wood – that exists in those forests. This tells us how much carbon they hold, which is vital for tracking climate change.
The Biomass satellite is the first satellite to have a P-band synthetic aperture radar (SAR) onboard. This radar uses long wavelength radio waves (around 70cm) allowing it to penetrate through tree cover to measure the amount of carbon stored in the trunk, branches and stems of trees. These are the three areas where most of a tree’s carbon is stored.
The images below show how different 'bands' of radar can be used to probe the different parts of trees, from focusing on the foliage and leaves, to specifically looking at the trunk and thick branches.
The specific band of radio waves is able to penetrate the forest canopies to reach the tree trunks and branches hidden below. The P-band SAR is able to map the forest biomass by transmitting radio wave pulses and receiving their echoes. The data can then be used to create high-resolution images and work out the structure and density of the forest.
We need to figure out how much carbon dioxide our forests are absorbing so that we can figure out how much we need to reduce our impact and develop technologies to further remove carbon dioxide that humans are contributing to the planet.
Why is this Important for us?
So why do we want to do this? Well, the biomass mission aims to answer a complex question. How much living organic matter (biomass) is in forests worldwide? This is crucial to know because forests play a vital role in Earth's carbon cycle.
The Earth's carbon cycle is what regulates our climate and supports ecosystems, which is vital because it is essential for life as we know it. We also need to know how much carbon is being absorbed by forests so we can make better decisions on tackling climate change.
One of the ways we do this is through international agreements and programmes that aim to protect our environment and tackle climate change. Missions like Biomass give concrete scientific evidence to support these agreements and programmes, particularly ones that are focused on climate change.
One of these programmes, run by the United Nations, is called REDD + (Reducing Emissions from Deforestation and Forest Degradation) which aims to reduce emissions that are caused by deforestation and forest degradation.
Existing methods of accurately measuring Earth’s biomass have major challenges and limitations. For example, traditional ground-based methods can be expensive and accessing these remote forest environments on the ground, such as tropical rainforests, can be very hard for scientists.
This can lead to incomplete and potentially inaccurate data. Professor Quegan has made it clear that data from these tropical rainforests are critical for understanding how they regulate and provide stability to our climate: "The Biomass mission is set to fundamentally change our understanding of the Earth’s carbon balance and, as a result, climate change."
Climate change is here to stay, and we cannot ignore it. Through different international and individual efforts, we can make a positive difference.
More about the Mission
The Biomass mission is set to launch in April 2025 from Kourou, French Guiana, on board the Vega-C single body rocket which stretches nearly 35m high. In 2016, ESA and Airbus Defence and Space UK signed a £229 million Euro contract to build the satellite. The satellite was built by Airbus in Stevenage, UK before being transported to Kourou. Biomass is planned to be a five-year mission, during which time it will generate global maps of forest biomass and height.
The ESA Biomass mission has the potential to change our lives for the better through improved understanding of forest structure and how they work, enhanced monitoring of deforestation and forest degradation. It will reduce uncertainties in climate projections which will enable us to better predict future climate change, its impact on us and how humanity can collectively act to avoid any negative impacts it may have on us. Professor Shaun Quegan’s vision for the Biomass mission is that it will provide essential data for climate science, enable better monitoring of forest carbon stocks and contribute to more effective climate change policies.
Full references / credits:
(Banner) Earth's forests. Credit: Public domain
(1) Mission badge for the biomass mission. Credit: ESA
(Image gallery) How different radar bands let us see different parts of trees and biomass. Credit: National Space Centre
(2a) Professor Shaun Quegan, lead of the Biomass scientific team. Credit: ESA
(2b) How the Biomass mission works. Credit: ESA
(3) The Biomass satellite will study the worlds forests in 3 dimensions using a P-band tomographic radar. Credit: ESA
