Long-term planning requires climate projections beyond 2100
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 growing.