Transient tracer-based Investigation of Circulation and Thermal Ocean Change (TICTOC)

燃烧石油和天然气等化石燃料产生的二氧化碳正在大气中积聚，导致地球变暖。迄今为止，海洋吸收了地球上90%以上的热量。然而，这种加热也导致海洋膨胀，导致海平面上升，从而增加了沿海地区人民和工业的风险和脆弱性。了解未来海平面将变化多少，使我们能够相应地规划我们需要安装的防御措施，以保护沿海社区的基础设施和生计。然而，海洋变暖在地理上并不均匀，因为洋流在全球范围内移动热量。这导致了海洋温度和海平面的对比变化（影响沿海社区和资产）。到本世纪末，一些地区的海平面可能会大幅上升，最高可达1米，而另一些地区的海平面上升幅度则小得多（甚至更低）。这个科学项目将利用科考船和海洋计算机模型所做的观察来了解海洋从大气中吸收热量的位置，以及洋流如何运输和重新分配这些热量。为了研究洋流，我们需要一种“示踪剂”——一种像化学染料一样被放置在洋流中并随洋流移动的东西。虽然并非有意为之，但自20世纪50年代以来，已有三种示踪剂被添加到大气中，并逐渐被海洋吸收，并被洋流重新分配。它们是放射性碳（由20世纪中期的核弹试验产生）、氯氟烃（历史上用于冰箱和气雾剂罐，并导致臭氧洞的扩大）和最近的六氟化硫（以前发现于网球中，但现在主要用于电气工业作为绝缘体）。这些示踪剂在不同的时间以不同的脉冲形式进入海洋，形成了一个我们现在可以观察到的偶然实验。我们将使用高精度设备在大西洋和南大洋测量这些示踪剂，并与国际伙伴合作，追踪它们在全球的命运。我们将利用这些观测来估计热量在整个海洋中被吸收和重新分配的速度，并评估和改进气候模式对区域海平面上升的预测。

Carbon dioxide produced by burning fossil fuels such as oil and gas is building up in the atmosphere and causing the planet to warm. The oceans have absorbed more than 90% of the heat trapped on the planet to date. However, this heating also causes the ocean to expand, leading to rising sea level and consequently to an increased risk to and vulnerability of people and industries located near the coast. Understanding how much sea level will change into the future allows us to plan accordingly the defences we need to install in order to safeguard the infrastructure and livelihoods of our coastal communities. Warming of the ocean is not geographically uniform however, as ocean currents move heat around the globe. This leads to contrasting changes in ocean temperature and sea level (affecting coastal communities and assets). By the end of the century, some regions may experience very large sea level rises of up to a metre while others will see far less (or even a lowering). This science program will use observations made from research ships and computer models of the ocean to understand where the ocean takes up heat from the atmosphere and how ocean currents transport and redistribute that heat. To study ocean currents we need a 'tracer' - something that is placed in and moves with the flow, like a chemical dye. Although not intentionally for this purpose, three varieties of tracers have been added to the atmosphere since the 1950s and have since gradually been absorbed into the ocean, and redistributed by ocean currents. These are radioactive carbon (produced by mid 20th century nuclear bomb tests), chlorofluorocarbons (historically used in refrigerators and aerosol cans, and which caused an expansion of the Ozone Hole) and more recently sulphur-hexafluoride (formerly found in tennis balls but now predominantly used in electrical industries as an insulator). These tracers have entered the ocean as distinct pulses at different times, forming a fortuitous experiment we can now observe. We will use high-precision equipment to measure these tracers in the Atlantic and Southern Oceans and collaborate with international partners to track their global fate. We will use these observations to estimate the rate at which heat is being absorbed and re-distributed throughout the ocean and to assess and improve climate model predictions of regional sea level rise.