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)，以及这在全球格局中的重要性。我们将通过在几个关键岛屿和一艘商业船只上测量大气二氧化碳和相关物种来实现这一点，并在模拟研究中使用大气数据来确定吸收(吸收的量)以及是否随着时间的推移而变化。如果我们要迎接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，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占据，这虽然不会加剧全球变暖，但确实会加剧海洋的有害酸化。但是，到底有多少被吸收，在哪些海洋中，以及这种吸收在气候变暖的情况下可能会发生什么变化，目前尚不清楚。最不透明的一个重要区域是南大西洋。通过确定南大西洋和邻近南大洋的二氧化碳吸收情况，该项目将提供新的信息，改进全球二氧化碳循环的模型。我们的工作也将有助于回答南大洋二氧化碳吸收在全球变暖下是否发生变化的问题。如果是这样，其影响是严重的，并将影响未来的国际排放谈判。尽管南大西洋的海水中有二氧化碳的测量(例如，英国南极调查局)，但该地区上空的空气中几乎没有二氧化碳的测量。这是因为有人居住的岛屿属于英国所有，英国没有参与由联合国全球大气观察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，也更能揭示问题。原因是大气混合的速度比海洋快得多，所以任何一个测站的测量都代表着一个覆盖数百甚至数千平方公里的区域，而海水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水吸收时二氧化碳的差异。二氧化碳在整个地球上都有很大的变化，无论是在纬度上还是在季节上，就像温度变化一样。我们的测量将通过连续观察和罐采样相结合的方式进行。赤道附近的阿森松岛和大约50度的福克兰群岛将连续测量二氧化碳。在这些岛屿和其他三个英国岛屿，二氧化碳也将通过罐采样进行测量。此外，还将从容器样品中测量氧气浓度和二氧化碳中的同位素13C。通过测量这些额外的物种，我们可以了解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，我们还将在一艘横跨大西洋的商船上连续测量二氧化碳和氧气，以补充来自固定站点的数据。为了解释我们的测量结果，我们将进行建模研究。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，二氧化碳吸收可能会发生变化，但还需要更多证据。我们的模型研究将解决这些问题，并将更好地了解该地区水中吸收了多少二氧化碳。我们的工作将有助于增进对全球碳预算中最鲜为人知的部分之一--南大洋的了解。更好地理解方程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伟大的全球气象工厂，也是海洋循环系统的关键转折点。

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.