Modelling interactions between ocean ecosystems, biogeochemical cycles and climate change

证据的份量是，全球范围内的气候正在变暖，人类排放的二氧化碳和其他气体是罪魁祸首。对下个世纪气候变化演变的预测对政策制定至关重要，其依据是对包括陆地和海洋生物圈在内的全球海洋-大气系统的超级计算机模拟。到目前为止，这些模拟中最不确定的部分是描述生态系统如何应对气候变化并进而影响大气中温室气体数量的模型。这项研究项目将处理模特界相对较少关注的两个问题。第一个问题是，模型如何应对物种和生态系统不是被动的这一事实，而是主动地对环境的变化做出反应并适应变化。第二个问题是如何准确地表示复杂的食物网相互作用对生态系统动力学的影响，而不必显式地模拟组成生态系统的无数物种。我将尝试解决这两个问题的方法是，使用适用于整个生态系统水平的模式来定义组成部分必须如何组装才能适应这些模式。我将特别关注基于稳定性理论的生态系统层面的规则，即试图了解生态系统如何适应并在扰动和变化中保持下去。我将与学生、研究助理和国际合作者一起开发和测试可纳入生态系统动力学模拟的适应性规则。这项工作一般包括三个步骤：(1)审查和设计生态系统一级的适应性规则，利用生态数据的合成来提取有用的模式；(2)在“数字实验室”评估规则，以确保它们导致真实的模型行为；以及(3)在海洋生态系统模拟中与涵盖广泛海洋环境的数据集相比较，评估规则。长期目标是建立海洋生态系统模型，以正确反映海洋目前的生态和生物地球化学状态。如果能够实现这一点，就会有更大的信心使用这些模型来预测未来。

The weight of evidence is that the climate is warming on a global scale and that human release of carbon dioxide and other gases is responsible. Projections of the evolution of climate change over the next century are critical to policy development and are based on supercomputer simulations of the global ocean-atmosphere system, including the terrestrial and marine biospheres. The most uncertain parts of these simulations by far are the models that describe how ecosystems respond to a changing climate and in turn influence the amount of greenhouse gases in the atmosphere. This research project will deal with two issues that have received relatively little attention in the modelling community. The first is how do models cope with the fact that species and ecosystems are not passive but respond actively to changes in their environment and adapt to change. The second is how to accurately represent the impact of complex food web interactions on ecosystem dynamics without having to explicitly simulate the myriad of species that make up an ecosystem. The approach I will try to tackle both issues is to use patterns that apply at the level of whole ecosystems to define how the constituent parts must assemble to fit those patterns. I will focus specifically on ecosystem-level rules based on stability theory, that is on attempts to understand how ecosystems adapt and persist through perturbations and change.  I will work with students, a research associate and international collaborators in developing and testing adaptive rules that can be incorporated in simulations of ecosystem dynamics. This work will generally involve 3 steps: (1) review and design ecosystem-level adaptive rules, using syntheses of ecological data to extract useful patterns, (2) evaluate the rules in a 'numerical laboratory' to ensure that they lead to realistic model behaviour, and (3) evaluate the rules in simulations of marine ecosystems compared to data sets covering a wide range of ocean environments. The long-term goal is to get ocean ecosystem models to correctly represent the present ecological and biogeochemical state of the ocean. If that can be achieved, there will be greater confidence in using these models to make projections about the future.