The South Atlantic / Southern Ocean carbon sink: Is it significant, and is it changing over time?

该项目旨在确定南大西洋和邻近的南大洋吸收了多少二氧化碳（CO2），以及这在全球图景中的重要性。我们将在几个主要岛屿和一艘商业船上测量大气中的二氧化碳和相关物种，并在建模研究中使用大气数据来确定吸收量（吸收量）以及它是否随时间而变化，从而实现这一目标。如果我们要应对理解温室气体导致的全球变暖的挑战，了解海洋对二氧化碳的吸收是至关重要的。这是因为，在我们燃烧化石燃料产生的二氧化碳中，只有大约一半留在大气中，导致全球变暖。其余的大部分被全球海洋吸收，这虽然不会导致全球变暖，但确实会导致有害的海洋酸化。但究竟有多少被吸收，哪些海洋被吸收，以及在气候变暖的情况下这种吸收会如何变化，目前还不清楚。最不清晰的一个重要地区是南大西洋。通过确定南大西洋和邻近的南大洋的二氧化碳吸收量，该项目将提供新的信息，以改进全球二氧化碳循环模型。我们的工作也将有助于回答南大洋的二氧化碳吸收是否在全球变暖的情况下发生变化的问题。如果是这样，其影响将是严重的，并将影响未来的国际排放谈判。虽然在南大西洋的海水中测量了二氧化碳（例如英国南极调查局），但实际上没有测量该地区上空空气中的二氧化碳。这是因为有人居住的岛屿是英国所有的，而英国没有参与由联合国全球大气监测计划协调的监测大气二氧化碳的国际努力。从大气中测量二氧化碳可能比从海洋中测量更重要，也更能说明问题。原因是大气的混合速度比海洋快得多，因此，任何一个给定站点的测量结果都代表了覆盖数百甚至数千平方公里的区域，而对海水的测量只有几平方公里。我们的测量将评估空气吹过海洋和二氧化碳被海水吸收时二氧化碳含量的差异。就像温度变化一样，二氧化碳在地球上因纬度和季节的不同而变化很大。我们的测量将通过连续观察和筒状取样的混合方式进行。在赤道附近的阿森松岛和50年代左右的福克兰群岛将持续测量二氧化碳。二氧化碳也将在这些岛屿和其他三个英国岛屿上通过筒形取样进行测量。此外，将从罐样中测量O2浓度和CO2中的同位素13C。测量这些额外的物种可以告诉我们非光合作用的二氧化碳，包括化石燃料排放和海洋吸收。最后，我们还将在一艘穿越大西洋的商船上连续测量二氧化碳和氧气，以补充固定站点的数据。为了解释我们的测量结果，我们将进行模型研究。目前，基于海水测量的模型似乎与基于稀疏大气数据的模型给出了不同的答案。随着海洋变暖，二氧化碳的吸收可能会发生变化，但还需要更多的证据。我们的模拟研究将解决这些问题，并将更好地了解该地区的水中吸收了多少二氧化碳。我们的工作将有助于提高对全球碳预算中最不为人所知的部分之一——南大洋的认识。更好地了解这个方程式的大气方面也将对海洋学家非常有帮助，因为南大西洋和邻近的南大洋是一个巨大的全球天气工厂，也是海洋环流系统的一个关键转折点。

This project is designed to determine how much carbon dioxide (CO2) is absorbed by the South Atlantic and neighbouring Southern Ocean, and how important this is in the global picture. We will achieve this by measurement of atmospheric CO2 and related species at several key islands, and on a commercial ship, and by use of the atmospheric data in modelling studies to determine the uptake (amount absorbed) and whether it is changing over time. Understanding the uptake of CO2 by the oceans is essential, if we are to meet the challenge of understanding global warming by greenhouse gases. This is because, of the CO2 we produce by burning fossil fuels, only about half stays in the atmosphere and contributes to global warming. Most of the remainder is taken up by the global oceans, which, while not contributing to global warming, does contribute to the harmful acidification of the oceans. But exactly how much is taken up, in which oceans, and how this uptake might change in a warming climate is unclear. One important region with the least clarity is the South Atlantic Ocean. By determining CO2 uptake of the South Atlantic and neighbouring Southern Ocean, this project will provide new information that will improve models of the global CO2 cycle. Our work will also contribute to answering the question if Southern Ocean CO2 uptake is changing under global warming. If it is, the implications are serious, and will affect future international emissions negotiations. Although CO2 is measured in seawater in the South Atlantic (for example by British Antarctic Survey), there are virtually no measurements of CO2 in the air above the region. This is because the inhabited islands are UK-owned, and the UK does not participate in international efforts to monitor atmospheric CO2, which are coordinated by the UN's Global Atmosphere Watch programme. Measuring CO2 from the atmosphere is perhaps more important, and more revealing, than measuring from the ocean. The reason is that the atmosphere mixes much faster than the ocean, and so measurements from any given station are representative of a region covering hundreds or even thousands of square kilometres, compared to only a few square kilometres for ocean water measurements. Our measurements will assess the differences in CO2 as air blows across the ocean and CO2 is absorbed by the water. CO2 varies greatly across the planet, both by latitude and by season, just as temperature varies. Our measurements will be carried out by a mixture of continuous observations and canister sampling. Continuous measurement of CO2 will be made at Ascension Island, near the equator, and at Falkland Islands, around 50S. CO2 will also be measured by canister sampling at these and three other UK islands. In addition, O2 concentrations and the isotope 13C in CO2 will be measured from the canister samples. Measuring these additional species tells us about the non-photosynthetic CO2, both fossil-fuel emissions and ocean uptake. Finally, we will also measure CO2 and O2 continuously onboard a commercial ship travelling across the Atlantic, to complement the data from the fixed stations. To interpret our measurements, we will carry out modelling studies. Presently, models based on ocean-water measurement seem to give different answers from the models based on the sparse atmospheric data. It is possible that CO2 uptake may change as the oceans warm, but much more evidence is needed. Our modelling studies will address these problems and will provide a much better understanding of how much CO2 is being taken up into the water in the region. Our work will help improve knowledge of one of the most poorly understood parts of the global carbon budget, the Southern Ocean. Better understanding of the atmospheric side of the equation will also be very helpful to oceanographers, because the South Atlantic and neighbouring Southern Ocean are a great global weather factory, and a key turning point of the ocean circulation system.