For some time now, climate scenarios that ran to the end of the century were aimed sufficiently far enough into the future to define long-term climate risks and set international emissions targets. Time has since advanced, while our modelling projection time horizons have not. The projections that were once considered outcomes our grandchildren might face now describe the potential futures of children born today.

When the climate community first started examining the prospect of human-induced climate change via climate models in the 1970s and 1980s, 2100 was more than 100 years away. We are now nearing 75 years from the turn of the century. The existing suite of long-term projections, which typically run to the year 2099 or 2100, are insufficient to understand and plan for impacts on key sectors and industries, such as agriculture and forestry, water resource planning and energy infrastructure. For example, civil engineering projects such as dams and bridges are often built to last for a century or more; both the Afsluitdijk dyke in the Netherlands and the Hoover Dam in the United States are more than 80 years old. Meanwhile, the need for integrating long-term projections into capital improvement projects and climate resilience planning is growing¹.

一段时间以来，一直持续到本世纪末的气候情景都瞄准了足够远的未来，以定义长期气候风险并设定国际排放目标。时间已经过去了，而我们的建模预测时间范围却没有。曾经被认为是我们的孙辈可能面临的结果的预测现在描述了今天出生的孩子的潜在未来。

当气候界在 20 世纪 70 年代和 80 年代首次开始通过气候模型研究人类引起的气候变化的前景时，距离 2100 年还有 100 多年。距离世纪之交已经接近 75 年了。现有的一系列长期预测通常持续到 2099 年或 2100 年，不足以了解和规划对农业和林业、水资源规划和能源基础设施等关键部门和行业的影响。例如，水坝和桥梁等土木工程项目通常会持续一个世纪或更长时间；荷兰的阿夫鲁戴克大堤和美国的胡佛水坝都有80多年的历史。与此同时，将长期预测纳入资本改善项目和气候适应能力规划的需求日益增长¹ 。