The Deep-Time Model Intercomparison Project (DeepMIP)

对未来气候的预测对保护社会和生态系统至关重要，它以地球系统的数值模式为基础。这些模型通常是根据现代地球系统的观测结果进行测试的，在许多情况下，这些模型都是根据现代地球系统的观测结果进行调整的。然而，模式对本世纪末气候的预测在很大程度上超出了这一评估期，因为预估的未来二氧化碳强迫比观测记录中看到的要大得多。事实上，最近重建过去二氧化碳的工作表明，就二氧化碳浓度而言，与22世纪最接近的类似物是数千万年前的“深时间”。古气候模拟比对项目（PMIP）提供了一个框架（但没有资金！），通过该框架，古气候模拟界可以相对于过去的气候数据评估最先进的气候模型。传统上，PMIP集中在相对较近的中全新世（6000年前）和末次冰期（21000年前），但这些时期的二氧化碳含量甚至低于现代（分别为~280和~180 ppmv，而现代为~400 ppmv）。最近，PMIP已经扩展到其他时期，最明显的是上新世中期（300万年前），但即使在那时，二氧化碳很可能低于现代值（~380 ppmv）。当二氧化碳水平接近本世纪末的预测值时，建模界显然会从“深时间”气候的相互比较中受益。我们将为两个研讨会组织并提供资金，目的是撰写论文，描述一个新的气候模式比较项目的实验设计和结果-“DeepMIP”，重点关注过去的气候，其中大气二氧化碳浓度与本世纪末的预测相似。这些论文将根据过去的地质数据评估这些模型，并旨在了解模型-模型差异和模型-数据（不）一致的原因，为IPCC提供相关信息。以前NERC拨款NE/K014757/1，目前旨在通过地质时间评估气候敏感性（地表气温对大气二氧化碳增加一倍的反应）。该项目关注多个时间段，但只有一个模型。这个IOF将补充该项目，并通过专注于一个特定的时间段，但有许多模型来带来附加价值。因此，我们将解决模型依赖的关键问题。

Predictions of future climate, essential for safeguarding society and ecosystems, are underpinned by numerical models of the Earth system. These models are routinely tested against, and in many cases tuned towards, observations of the modern Earth system. However, the model predictions of the climate of the end of this century lie largely outside of this evaluation period, due to the projected future CO2 forcing being significantly greater than that seen in the observational record. Indeed, recent work reconstructing past CO2 has shown that the closest analogues to the 22nd century, in terms of CO2 concentration, are tens of millions of years ago, in 'Deep-Time'. The Palaeoclimate Modelling Intercomparison Project (PMIP) provides a framework (but no funding!) by which the palaeoclimate modelling community assesses state-of-the-art climate models relative to past climate data. Traditionally, PMIP has focussed on the relatively recent mid-Holocene (6,000 years ago) and Last Glacial Maximum (21,000 years ago), but these time periods have even lower CO2 than modern (~280 and ~180 ppmv respectively, c.f. ~400 ppmv for the modern). Recently, PMIP has expanded into other time periods, most notably the mid-Pliocene (3 million years ago), but even then, CO2 was most likely less than modern values (~380 ppmv). The modelling community would clearly benefit from an intercomparison of 'Deep-Time' climates, when CO2 levels were close to those predicted for the end of this century.We will organise and provide funding for 2 workshops, with the aim of producing papers describing the experimental design and outputs from a new climate Model Intercomparison Project - "DeepMIP", focussing on past climates in which atmospheric CO2 concentrations were similar to those projected for the end of this century. The papers will evaluate the models relative to past geological data, and aim to understand the reasons for the model-model differences and model-data (dis)agreements, providing information of relevance to the IPCC.A previous NERC grant, NE/K014757/1, is currently aiming to assess climate sensitivity (the response of surface air temperature to a doubling of atmospheric CO2), through geological time. That project is focussing on many time periods, but with only one model. This IOF will complement that project, and bring added-value, by focussing on one particular time period, but with many models. As such we will address the crucial issue of model-dependence.