European greenhouse gas emissions drop, but carbon absorption weakens

European greenhouse gas emissions drop, but carbon absorption weakens
by Erica Marchand
Paris, France (SPX) Sep 05, 2024

A recent study reveals that Europe's net greenhouse gas emissions have decreased by roughly 25% since the 1990s. While this reduction is encouraging, the research also indicates a decline in the capacity of land and vegetation to absorb and store atmospheric carbon.

Published in the journal 'Global Biochemical Cycles', the study involved scientists creating an up-to-date carbon budget for Europe. The research spanned three decades, focusing on carbon dioxide, methane, and nitrous oxide, the three primary greenhouse gases.

This study was supported by ESA and the Horizon Europe project EYE CLIMA and forms part of ESA's Regional Carbon Cycle Assessment and Processes Phase 2 (RECCAP-2) project. By combining satellite data and atmospheric models, researchers quantified the exchange of these gases between land and atmosphere. Emissions from fossil fuel burning, industrial activities, waste management, and agriculture were also estimated, adhering to Intergovernmental Panel on Climate Change guidelines.

The researchers estimated that in the 2010s, annual net greenhouse gas emissions in Europe had the equivalent warming potential of 3.9 billion tonnes of carbon dioxide. The majority of these emissions - 85% - were linked to fossil fuel combustion.

Comparing the 2010s to the previous two decades, the study found a significant reduction in emissions, approximately 1.2 billion tonnes of carbon dioxide equivalents per year. Ronny Lauerwald from Paris-Saclay University stated, "The decline of emissions is mainly due to a reduction in the energy required to drive economic growth and the decline of carbon dioxide emissions in the energy mix, with more renewable energies being used while many coal-fuelled power plants have closed."

Additionally, the study revealed that during the 2010s, land acted as a net carbon sink, removing about 0.9 billion tonnes of carbon dioxide equivalents annually from the atmosphere. However, this ability of land and vegetation to sequester carbon has weakened since the 2000s. Dr. Lauerwald explained, "The weakening of the land carbon sink is caused by an accelerated increase in the emission of carbon dioxide from the biosphere, which is not counterbalanced by a concomitant increase in carbon dioxide uptake by vegetation, as in the decades before."

The study emphasizes the importance of enhancing carbon monitoring frameworks to accurately capture changes driven by land-use practices and natural disturbances. Most of Europe's carbon sinks were identified in the northern regions, though a decline in carbon sink strength was noted in Scandinavia, attributed to intensified forest management and disturbances like wind damage and bark beetle infestations.

Agricultural activities, particularly livestock and fertilizer use, were highlighted as major sources of methane and nitrous oxide emissions, especially in Belgium, the Netherlands, and southern UK. Although methane and nitrous oxide emissions generally decreased, the carbon dioxide budget showed significant annual variability, influenced by natural factors like extreme weather events.

Ana Bastos from the Max-Planck-Institute for Biogeochemistry noted, "Climate variability, and especially extreme events, influence much of the fluctuations in the European carbon sink. We have seen that major heat and drought events, like in summer 2003, 2018 and 2019, have even switched carbon sinks into temporary sources due to fires, drought-induced tree mortality and pest outbreaks."

Philippe Ciais from the Laboratory for Climate and Environmental Sciences added, "By comparing our estimates with those of UNFCCC reports, our study provides a key contribution to the evaluation of national reporting of greenhouse gas and carbon emissions on a continental scale."

The research represents a continued collaboration between ESA and the Global Carbon Project on global and regional greenhouse gas budgets and carbon exchange science. Clement Albergel from ESA's Climate and Long-Term Action Division highlighted, "In addition to work on carbon budgets, this successful collaboration has advanced the science around forest carbon exchange while also developing cutting-edge methods that exploit satellite observations to improve consistency with national greenhouse gas reports submitted to the UNFCCC, and demonstrates progress on climate mitigation action."

ESA is launching a new three-year project, Climate Space RECCAP-2, to further reduce uncertainties around carbon dioxide and methane emissions and removals across key regions, including Europe, Siberia, the Amazon, and the Arctic, in efforts to better address global warming.

Research Report:Carbon and Greenhouse Gas Budgets of Europe: Trends, Interannual and Spatial Variability, and Their Drivers