Gute Nachrichten aus dem Nordatlantik. Der Ozeanbereich hat in den letzten 10 Jahren doppelt soviel CO2 aus der Atmosphäre weggepuffert wie noch im Jahrzehnt zuvor. Das berichtete die University of Miami Rosenstiel School of Marine & Atmospheric Science am 2. Februar 2016:
Study Shows North Atlantic Ocean CO2 Storage Doubled Over Last Decade
A University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science-led study shows that the North Atlantic absorbed 100 percent more man-made carbon dioxide over the last decade, compared to the previous decade. The findings show the impact that the burning of fossil fuels have had on the world’s oceans in just 10 years.
To determine the total uptake and storage of carbon dioxide in the North Atlantic over the last several decades, researchers analyzed data collected from the same locations, but 10 years apart, to identify changes caused by man-made CO2. The data were collected during two National Science Foundation-funded international ship-based studies, CLIVAR (Climate Variability CO2 Repeat Hydrography) and GO-SHIP (Global Ocean Ship-Based Hydrographic Investigations Program). “This study shows the large impact all of us are having on the environment and that our use of fossil fuels isn’t only causing the climate to change, but also affects the oceans by decreasing the pH,” said Ryan Woosley, a researcher in the UM Rosenstiel School, Department of Ocean Sciences.
The oceans help to slow the growth of human produced CO2 in the atmosphere by absorbing and storing about a quarter of the total carbon dioxide emissions. The North Atlantic is an area of high uptake and storage due to large-scale ocean circulations. The uptake of CO2 has many impacts on ocean-dwelling organisms by decreasing the pH. The findings have important implications for marine organisms, such as corals and mollusks, which require a certain pH level in the surrounding water to build their calcium carbonate-based shells and exoskeletons.
The researchers hope to return in another 10 years to determine if the increase in carbon uptake continues, or if, as many fear, it will decrease as a result of slowing thermohaline circulation. The study, titled “Rapid Anthropogenic Changes in CO2 and pH in the Atlantic Ocean: 2003-2014” was published in the journal Global Biogeochemical Cycles. The study’s authors include: Woosley and Frank J. Millero of the UM Rosenstiel School; and Rik Wanninkhof of NOAA’s Atlantic Oceanographic and Meteorological Laboratory. The study was funded by the National Science Foundation through grant #OCE0752972. The study can be accessed at http://onlinelibrary.wiley.com/doi/10.1002/2015GB005248/pdf
Aber auch der tropische Atlantik absorbiert CO2. Severino Ibanhez und Kollegen berichteten im April 2016 in den Geophysical Research Letters über eine bisher übersehene bedeutende CO2-Senke im Mündungsbereich des Amazonas:
The overlooked tropical oceanic CO2 sink
The intense rainfall in the tropical Atlantic spatially overlaps with the spread of the Amazon plume. Based on remote-sensed sea surface salinity and rainfall, we removed the contribution of rainfall to the apparent Amazon plume area, thus refining the quantification of its extension (0.84 ± 0.06 × 106 km2 to 0.89 ± 0.06 × 106 km2). Despite the previous overestimation of the Amazon plume area due to the influence of rainfall (>16%), our calculated annual CO2 flux based on rainfall-corrected sea surface CO2 fugacity confirms that the Amazon River plume is an atmospheric CO2 sink of global importance (−7.61 ± 1.01 to −7.85 ± 1.02 Tg C yr−1). Yet we show that current sea-air CO2 flux assessments for the tropical Atlantic could be overestimated in about 10% by neglecting the CO2 sink associated to the Amazon plume. Thus, including the Amazon plume, the sea-air CO2 exchange for the tropical Atlantic is estimated to be 81.1 ± 1.1 to 81.5 ± 1.1 Tg C yr−1.