A twenty year record of greenhouse gases in the Eastern Mediterranean atmosphere

Nikos Gialesakis; Nikos Kalivitis; Giorgos Kouvarakis; Michel Ramonet; Morgan Lopez; Camille Yver Kwok; Clement Narbaud; Nikos Daskalakis; Marios Mermigkas; Nikolaos Mihalopoulos; Maria Kanakidou

doi:10.1016/j.scitotenv.2022.161003

A twenty year record of greenhouse gases in the Eastern Mediterranean atmosphere

Sci Total Environ. 2023 Mar 15:864:161003. doi: 10.1016/j.scitotenv.2022.161003. Epub 2022 Dec 17.

Affiliations

¹ Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, 70013 Heraklion, Greece.
² Laboratoire des Sciences du Climat et de l'Environnement (LSCE), IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France.
³ Laboratory for Modeling and Observation of the Earth System (LAMOS), Institute of Environmental Physics (IUP), University of Bremen, Bremen, Germany.
⁴ Department of Physics, Aristotle University of Thessaloniki, Greece.
⁵ Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, 70013 Heraklion, Greece; Institute for Environmental Research and Sustainable Development (IERSD), National Observatory of Athens, Penteli, Greece.
⁶ Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, 70013 Heraklion, Greece; Laboratory for Modeling and Observation of the Earth System (LAMOS), Institute of Environmental Physics (IUP), University of Bremen, Bremen, Germany; Center of Studies on Air quality and Climate Change (CSTACC), ICE-HT/FORTH, Patras, Greece. Electronic address: mariak@uoc.gr.

PMID: 36539090
DOI: 10.1016/j.scitotenv.2022.161003

Abstract

Twenty years of CO₂, CH₄ and CO greenhouse gas atmospheric concentration measurements at Finokalia station on Crete in the Eastern Mediterranean region are presented. This dataset is the longest in the Eastern Mediterranean, based on bi-weekly grab sampling since 2002 and continuous observations since June 2014. CO₂ concentrations increase by 2.4 ppm·y^-1 since 2002, in agreement with the general north hemisphere trend as derived by worldwide NOAA observations. CH₄ showed a mean increasing trend of 7.5 ppb·y^-1 since 2002, a rate that has accelerated since 2018 (12.4 ppb·y^-1). In contrast, CO has decreased by 1.6 ppb·y^-1 since 2002, which resulted from a strong decrease until 2017 (2.5 ppb·y^-1), followed by a small increase in the last 3 years (0.2 ppb·y^-1). Both CO₂ and CH₄ present maxima during winter and minima during summer, in general agreement with the observations at the ICOS stations in Europe. CO also presents the highest values in winter and the lowest values in summer during June, while a secondary maximum is seen in August, which can be attributed to open fires that often occur in the area during this period. The mean summertime diurnal cycles of CH₄ and CO agree with a 24-h mean OH radical concentration of the order of 0.3-1 × 10⁷ molecules·cm^-3 over the region, in general agreement with the only existing in-situ observations at Finokalia for 2001.

Keywords: Carbon dioxide; Carbon monoxide; Eastern Mediterranean atmosphere; Greenhouse gases; Methane; Trends.