Southern Cross researchers cited in global climate change report

Published 17 August 2021
Dr Luke Jeffrey

Southern Cross University research into the role of trees in greenhouse gas emissions has appeared in a landmark climate change report commissioned by the United Nations.

The long-awaited Intergovernmental Panel on Climate Change (IPCC) Assessment Report 6 (AR6) provides the most up to date scientific knowledge on climate change, referencing the University’s ground-breaking research on tree-mediated methane emissions.

Led by Southern Cross University wetland biogeochemist Dr Luke Jeffrey, the research cited in the IPCC report investigates how wetland tree-stems contribute to methane emissions.

“Wetlands capture vast amounts of carbon from the atmosphere but are also Earth’s largest natural source of methane. Methane is a greenhouse gas but far more potent than carbon dioxide and it’s about 35 times more powerful at warming our planet,” Dr Jeffrey explains. 

“Our research provides evidence that tree-stem methane emissions may be an important and unaccounted-for component of local, regional, and global carbon budgets.”

Prior to the release of the IPCC-cited study led by Dr Jeffrey in 2019, ‘Are methane emissions from mangrove stems a cryptic carbon loss pathway? Insights from a catastrophic forest mortality’, no data on tree-stem fluxes from estuarine species existed.

“This is a relatively new field of research. Ten years ago, no one really knew that trees could emit methane. This was just something that science had previously overlooked. This IPCC report is the first time that trees have been identified as a knowledge gap and with three trillion trees on Earth - something that is potentially important at the global scale,” Dr Jeffrey said. 

Methane is a potent greenhouse gas about 45 times stronger at warming our planet's atmosphere than carbon dioxide. Most naturally occurring methane is produced within Earth's wetlands. Methane is created when organic carbon from vegetation and soils are slowly decomposed by microbes in these saturated environments. Our preliminary data suggests that in wetland forests the below-ground methane is transported upwards by the roots and the bark of trees and then outwards through their stems. But while measuring methane gas emissions our team recently discovered that the bark of melaleuca was home to a unique microbial community that make an easy living out of consuming the potent greenhouse gas. So we now know that bark-dwelling microbes have the capacity to regulate the methane emissions from trees and therefore may play an important mitigation role in the global methane cycle and in climate change. With this newfound knowledge and data can land managers decision makers and future climate change mitigation strategies be better advised in ways to maximize carbon sequestration in forests and avoid potential and unwanted methane emissions

Since the 2019 study, Southern Cross University has continued to lead new research into ‘treethane’ emissions. Earlier this year, Dr Jeffrey and collaborators from Monash University and University of Melbourne revealed an unlikely microscopic ally in the battle to reduce the amount of methane gas in the atmosphere.

Unique methane-eating microbial communities were identified living in the bark of a common but globally distributed Australian tree species, the Paperbark. These microbes were shown to consume about one third of total methane emissions.

“The trees are providing a habitat for these unique microbial communities that mitigate a lot of the methane coming from the soil below. This was a world-first as well, discovering that methane munching microbes, known as ‘methanotrophs’ are living in the bark of these trees and perhaps they might live in other trees and ecosystems globally too,” Dr Jeffrey said.

This field of research received $364,850 in funding from the Australian Research Council (ARC), to pursue a collaborative project titled ‘Tree-mediated methane fluxes: A new frontier in the global carbon cycle’, led by Southern Cross University’s Professor Damien Maher. 

“With this project we hope to reduce uncertainty in the global methane budget. Understanding the processes involved in the production, destruction, and accumulation of methane in the atmosphere is critical to understand the trajectory of climate change. Trees may play an important, but as yet unknown role in the global methane cycle – with this project we aim to shed light on this mystery” Professor Maher said.

The objective of the IPCC Assessment Report is to ‘inform policymakers what scientists know about climate change’. Providing an important resource for society, domestic policymaking and global climate negotiations. 

Deputy Vice Chancellor Research Professor Mary Spongberg said that Southern Cross University’s world-leading research surrounding trees and their role in the methane cycle will help future management and modelling and IPCC reports moving forward.

“Dr Jeffrey recently graduated from his doctoral studies at Southern Cross, winning the Chancellor’s Medal. The inclusion of his research in the IPCC report highlights the global impact and innovation of the research being undertaken here at Southern Cross University,” Professor Spongberg said.

While the IPCC report highlights the stark scientific evidence of our climate change trajectory, Dr Jeffrey is hopeful that the research will not only help to reduce uncertainties surrounding the global methane budget and future IPCC reports, but will  also assist to inform environmental solutions to mitigate climate change such as the Trillion Trees project.

“Our research may help guide the most effective places to plant trees in order to achieve the Trillion Trees by 2030 goal of sequestering carbon dioxide, as well as the most suitable species to minimise any potential methane emissions,” Dr Jeffrey said.

Published on Monday 9 August, the Intergovernmental Panel on Climate Change (IPCC) is United Nations’ body for assessing the science related to climate change. The full report can be read here.

Media contact: Media and content team content@scu.edu.au