• Energy Research

This is the 2024-1 release of the ICOS final quality ecosystem data product that includes eddy covariance fluxes, meteorological observations, ancillary and biometric data and full metadata at 73 labelled ICOS stations in the ecosystem domain. The archives contain more detailed description of the different data files contained in the archives. Measurements have been collected using the following instructions: ICOS Ecosystem Instructions for Air Meteorological Measurements (TA, RH, PA, WS, WD), https://doi.org/10.18160/NHEG-4KWW ICOS Ecosystem Instructions for Turbulent Flux Measurements of CO2, Energy and Momentum, https://doi.org/10.18160/QWV4-639G

We analysed the effect of the 2018 European drought on greenhouse gas (GHG) exchange of five North European mire ecosystems. The low precipitation and high summer temperatures in Fennoscandia led to a lowered water table in the majority of these mires. This lowered both carbon dioxide (CO 2 ) uptake and methane (CH 4 ) emission during 2018, turning three out of the five mires from CO 2 sinks to sources. The calculated radiative forcing showed that the drought-induced changes in GHG fluxes first resulted in a cooling effect lasting 15–50 years, due to the lowered CH 4 emission, which was followed by warming due to the lower CO 2 uptake. This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale’.

The Nordic region was subjected to severe drought in 2018 with a particularly long-lasting and large soil water deficit in Denmark, Southern Sweden and Estonia. Here, we analyse the impact of the drought on carbon and water fluxes in 11 forest ecosystems of different composition: spruce, pine, mixed and deciduous. We assess the impact of drought on fluxes by estimating the difference (anomaly) between year 2018 and a reference year without drought. Unexpectedly, the evaporation was only slightly reduced during 2018 compared to the reference year at two sites while it increased or was nearly unchanged at all other sites. This occurred under a 40 to 60% reduction in mean surface conductance and the concurrent increase in evaporative demand due to the warm and dry weather. The anomaly in the net ecosystem productivity (NEP) was 93% explained by a multilinear regression with the anomaly in heterotrophic respiration and the relative precipitation deficit as independent variables. Most of the variation (77%) was explained by the heterotrophic component. Six out of 11 forests reduced their annual NEP with more than 50 g C m −2 yr −1 during 2018 as compared to the reference year. The NEP anomaly ranged between −389 and +74 g C m −2 yr −1 with a median value of −59 g C m −2 yr −1 . This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale’.

This is the 2023-2 INTERIM release of the ICOS final quality ecosystem data product that includes eddy covariance fluxes, meteorological observations, ancillary and biometric data and full metadata at 39 labelled ICOS stations in the ecosystem domain. The archives contain more detailed description of the different data files contained in the archives. Please note that the 2023 measurements included in this interim release don't cover the full year, but do essentially cover the growing season. Measurements have been collected using the following instructions: ICOS Ecosystem Instructions for Air Meteorological Measurements (TA, RH, PA, WS, WD), https://doi.org/10.18160/NHEG-4KWW ICOS Ecosystem Instructions for Turbulent Flux Measurements of CO2, Energy and Momentum, https://doi.org/10.18160/QWV4-639G

To understand what drives the concentration of CO2 in the atmosphere, it is crucial to understand the complexity of the underlying CO2 fluxes, and this first volume of FLUXES provides this information. FLUXES is a new publication designed to inform the interested audience of key scientific aspects of the European greenhouse gas budget. FLUXES will be published every summer to support the European Union in their preparation for the upcoming UNFCCC Conference of Parties and to guide European climate action in general. Greenhouse gas fluxes vary from year to year, that’s natural. However, Europe and the world are currently facing multiple hazards (heatwaves, droughts, fires, floods...) that are driven by climate change and – among many other damages – are altering greenhouse gas fluxes. These feedbacks put particularly natural CO2 sinks at risk but it requires monitoring of over long times to clearly identify and understand them. FLUXES, the European Greenhouse Gas Bulletin aims to transfer most recent scientific findings in order to distinguish occasional phenomena from long-term trends. It will focus on observations as the basis of a scientific value chain towards climate services and policy support.