Sea Ice and Westerly winds during the Holocene in coastal Antarctica, to better constrain oceanic CO2 uptake

南大洋不到全球海洋面积的十分之一，但它目前吸收了43%的人为二氧化碳和75%的热量。至关重要的是，南大洋调节大气二氧化碳浓度的能力取决于南半球西风的强度和位置。这些风驱动富含碳的深水上升，再加上海冰覆盖，决定了可用于海-气交换的海洋表面积。预计在21世纪，由于人为强迫，西风的强度将增加，而海冰预计将减少。表层海洋上更强的风和海冰覆盖的减少相结合，将加强从深海涌出的富含碳的水。因此，南大洋可能会从二氧化碳汇转变为二氧化碳源，潜在地将二氧化碳释放到大气中，并通过增强的辐射强迫加速全球变暖。然而，我们对西风对二氧化碳释放的作用的理解受到短期观测记录的限制，气候模型预测的西风变化的幅度存在很大的不确定性。为了更好地限制未来对二氧化碳排放和气候变化的预测，我们迫切需要对南大洋的大气二氧化碳、西风和海冰进行长期记录。冰芯是唯一可以重建仪器时期之后所有三个参数的古气候档案。这项提议的目的是提供几十年至千年时间尺度上西风、海冰和大气二氧化碳浓度的高分辨率记录。为此，我们将在南极洲沿海钻探一个新的冰芯，由印度地球科学部国家极地和海洋研究中心(NCPOR)资助，挪威极地研究所和英国驻德里大使馆提供额外支持。我们将进行最先进的分析，使用新开发的基于海洋硅藻的西风替代品。二氧化碳稳定同位素组成的先进测量将在新建立的英国残留空气提取和气体分析系统(英国稀有气体)实验室进行，并建立在英国在该领域日益增长的专业知识的基础上。这对英国科学家来说是一个令人兴奋的机会，可以与挪威和印度的领先极地研究机构合作。这一三国伙伴关系(印度/挪威/英国)大大增加了科学、社会和政治影响。弄清季节到千年尺度上二氧化碳变异性的驱动因素，对于预测未来大气二氧化碳浓度的变化至关重要。如果南大洋从二氧化碳汇，从大气中去除人为二氧化碳，转变为二氧化碳源，从深海释放二氧化碳，这是全球关注的问题。因此，我们预计这个项目将产生很高的科学、政治和社会经济影响。这些社会经济影响将对一些国家造成比其他国家更严重的冲击。印度广阔的海岸线和快速增长的人口，其中许多人生活在低洼的沿海盆地，这使得它特别容易受到未来海平面上升的影响。印度是世界上第五个最容易受到气候变化影响的国家，面临着减少温室气体排放的压力。因此，与印度合作伙伴的这一新合作为NERC和英国科学家在官方发展援助国家支持和促进气候科学提供了令人信服的潜力。与印度地球科学部直接合作，并通过与德里英国高级专员公署气候变化和环境问题高级顾问的持续合作提供便利。

The Southern Ocean represents less than one-tenth of the area of the global ocean, yet it currently absorbs 43% of the total anthropogenic CO2 and 75% of the heat. Critically, the Southern Ocean's capacity to modulate the atmospheric CO2 concentration is governed by the strength and position of the Southern Hemisphere westerly winds. These winds drive upwelling of carbon-rich deep water, which together with sea ice coverage, determines the ocean surface area available for air-sea gas exchange. Westerly winds are predicted to increase in strength during the 21st century, as a result of anthropogenic forcing, while sea ice is predicted to decrease. The combination of stronger winds over the surface ocean and reduced sea ice cover will enhance upwelling of carbon-rich water from the deep ocean. Thus, the Southern Ocean may switch from a CO2 sink to a CO2 source, potentially releasing CO2 into the atmosphere and accelerating global warming through enhanced radiative forcing.However, our understanding of the role of westerly winds on CO2 release is limited by the short observational records with large uncertainties in the magnitude of projected westerly wind changes in climate models. In order to better constrain future predictions of CO2 emissions and climate change, we urgently require long records of atmospheric CO2, westerly winds and sea ice in the Southern Ocean. Ice cores are the only paleoclimate archive that can reconstruct all three parameters beyond the instrumental period. The aim of this proposal is to provide high resolution records of westerly winds, sea ice and atmospheric CO2 concentrations over multi-decadal to millennial timescales. We will do this by drilling a new ice core in coastal Antarctica, match funded by the National Centre for Polar and Oceanographic Research (NCPOR), Indian Ministry of Earth Science, with additional support secured from the Norwegian Polar Institute and the UK embassy in Delhi. We will conduct state-of-the-art analysis, using newly developed proxies for westerly winds based on marine diatoms. Advanced measurement of the stable isotopic composition of CO2 will take place in the newly established UK Relic Air Extraction and Gas Analysis System (UK RArE-GAS) laboratories and build on the UK's growing expertise in this field.This is an exciting opportunity for UK scientists to collaborate with leading polar research institutes in Norway and India. This tri-national partnership (India/Norway/UK) considerably increases the scientific, societal, and political impact. Disentangling the drivers of CO2 variability over seasonal to millennial scales is essential in predicting future changes in atmospheric CO2 concentrations. If the Southern Ocean switches from a CO2 sink, removing anthropogenic CO2 from the atmosphere, to a CO2 source, releasing CO2 from the deep ocean, is of global concern. Thus, we anticipate this project will have high scientific, political, and social-economic impacts.These social-economic impacts will hit some countries harder than others. India's large coastline and rapidly increasing population, many of whom live in low-lying coastal basins, make it particularly susceptible to future sea level rise. India is the fifth most vulnerable country in the world to the impacts of climate change and is under pressure to reduce its greenhouse gas emissions. Thus, this new collaboration with partners in India provides compelling potential for NERC and UK scientists to support and promote climate science in an ODA country. Working directly with the Indian Ministry of Earth Sciences and facilitated by ongoing collaborations with senior advisor for climate change and environment at the British High Commission in Delhi.