PREDICTING THE CLIMATE OF THE COMING DECADE

地球的气候正在发生变化，有强有力的证据表明，在过去的50年里，人类造成了大部分的变暖。直到最近，气候科学的大部分焦点都集中在对未来一个世纪可能发生的事情进行更详细的预测，特别是为决策者提供有关气候变化可能产生的影响的信息。这方面的认识促使人们改变减少温室气体排放的政策，即减缓政策。然而，一些额外的气候变化是不可避免的，无论采取何种缓解政策，都需要适应。由于迫切需要适应不断变化的气候，预测未来十年的气候是至关重要的。例如，对非洲未来低降雨量的预测将有助于提前规划潜在的干旱。在判断何时更换铁路轨道时，可能会考虑到热浪导致铁路弯曲的风险，就像2003年8月在英国发生的那样。多样化的应用范围确保了预测未来十年的气候是一项迷人而引人入胜的挑战，具有潜在的巨大社会和经济效益。为了确保做出适当的选择，决策者需要相信气候科学家的预测。但是，根据最近的一项调查，40%的英国公众认为气候变化的威胁被夸大了。为了说服持怀疑态度的公众并帮助决策，建立对用于预测的复杂气候模型的信任至关重要。每天，类似的超级计算机模型都被用来进行天气预报，然后将其与实际情况进行比较。这种持续的评估可以改进模型，建立对其预测的信任，并确保预测更加准确。该奖学金旨在帮助建立对用于预测气候的模型的同样信任，特别是在未来十年。然而，为了对未来十年作出准确的气候预测，必须认识到气候变化有两个原因：(i)温室气体和太阳输出等因素，以及（ii）自然波动。这种波动可以暂时增强或减弱任何长期趋势，特别是在区域尺度上，造成气温迅速升温的几十年和气温稳定甚至降温的几十年。例如，预计未来几十年的三分之一将显示英国的气温下降，也就是说，我们预计在变暖的气候中会看到气温下降的时期。如果不考虑这些波动，预测将是不准确的，从而降低对气候预测的信任，因此需要一种新的策略。这项拟议的研究将设计一个改进的系统，通过分析最近的过去来进行预测，例如，只使用1990年的现有数据来预测接下来的十年。通过改进对过去的预测，我们可以建立对未来预测的信任。为了预测这些自然波动，我们首先需要了解它们的原因。答案主要在于海洋，与大气相比，海洋的变化相对缓慢。海洋是自然年代际波动的主要来源，因为它们的热容很大，而且海洋环流变化缓慢。预测未来十年海洋将如何变化对预测气候至关重要。然而，海洋预测需要海洋测量，而海洋测量既棘手又昂贵，尤其是在地表以下。瞄准特定地点比瞄准整个海洋更具成本效益。这项合作的另一个重要方面是确定海洋的敏感区域，以及更广泛的“地球系统”组成部分，如海冰，在这些区域，微小的不确定性会导致预测不准确。这项研究将改进有效监测系统的设计，以减少不确定性，并确保改进对未来十年气候的预测。

The Earth's climate is changing, and there is strong evidence that humans have caused most of the warming in the past 50 years. Until recently, much of the focus of climate science has been on making more detailed predictions of what might happen over the coming century, and especially on providing information to decision makers on likely impacts of a change in climate. This knowledge has motivated changes in policies to reduce greenhouse gas emissions, i.e. mitigation. However, some additional climate change is inevitable, which will require adaptation, regardless of the mitigation policies pursued. Predicting the climate of the next decade is essential because of the urgent need to adapt to a changing climate. For example, a prediction of low future rainfall in Africa would allow advance planning for potential droughts. A judgment on when to replace railway track might include the risks of a heatwave causing lines to buckle, as happened in the UK in August 2003. The diverse range of applications ensures that predicting the climate of the next decade is a fascinating and engaging challenge, with potentially enormous social and economic benefits. To ensure appropriate choices are made, decision makers need to trust the predictions made by climate scientists. But, according to a recent survey, 40% of the British public think the threat of climate change has been exaggerated. To convince a sceptical public and aid decision making, it is essential to build trust in the sophisticated climate models used to make predictions. Every day, similar supercomputer models are used to make weather forecasts which are later compared to what actually happened. This continual assessment allows the models to be improved, building trust in their predictions and ensuring forecasts are more accurate. This fellowship aims to help build the same trust in the models used to predict climate, especially for the coming decade. However, to make accurate climate predictions for the next decade, it is important to realise that the climate changes for two reasons: (i) factors such as greenhouse gases & solar output, and (ii) natural fluctuations. Such fluctuations can temporarily enhance or reduce any long-term trends, especially on regional scales, producing decades where temperatures are warming rapidly and decades when temperatures are stable or even cooling. For example, one third of future decades are predicted to show decreasing temperatures for the UK, i.e. we expect to see periods of cooling temperatures in a warming climate. Without accounting for these fluctuations, the forecasts would be inaccurate, reducing the trust in climate predictions, and so a new strategy is needed. This proposed research will design an improved system for making predictions by analysing the recent past, for example, by only using data available in 1990 to predict the subsequent decade. By improving predictions of the past we can build trust in predictions of the future. To predict these natural fluctuations, we first need to understand their causes. The answers mainly lie in the oceans, which change relatively slowly compared to the atmosphere. The oceans are the main source of natural decadal fluctuations, due to both their large heat capacity and slow changes in ocean circulation. Predicting how the oceans will change over the next decade is essential to predict climate. However, ocean predictions require ocean measurements, which are tricky and expensive to obtain, especially below the surface. It would be more cost effective to target particular locations, rather than the whole ocean. Another vital aspect of this fellowship is identifying sensitive regions of the oceans, and wider 'Earth system' components, such as sea-ice, where small uncertainties cause forecasts to be inaccurate. This research will improve the design of efficient monitoring systems to reduce uncertainty and ensure improved predictions of the climate of the coming decade.