Comparing Individual Climate Projections Generates Most Divergent Climate Futures Across Different Timescales

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A new study by North Central CASC researcher Brian Miller and the National Park Service Climate Change Response Program finds that not all approaches for developing climate futures are equally effective across different time spans.

Image: Rio Grande at Boquillas Canyon Entrance, Big Bend National Park

View of the Rio Grande River at the entrance to Boquillas Canyon.

(Credit: Stewart Tomlinson, U.S. Geological Survey. Public domain.)

Resource managers are often tasked with planning for a future that could look completely different from today. To help manage potential unknowns, agencies use climate change scenario planning to explore and prepare for a broad range of possible futures. Through this process, scientists and adaptation specialists use global climate model outputs to identify the potential climate conditions a location could experience at a particular time. Based on these possible climate futures, they work with resource managers and subject-matter experts to identify the range of plausible impacts on natural and cultural resources and create plans that account for this uncertainty.

There are multiple ways to develop climate futures that serve as the basis for scenario planning. In a new study, researchers from the North Central CASC and the National Park Service Climate Change Response Program compared different approaches for developing climate futures to evaluate their effectiveness at informing near-, mid-, and long-term planning. They used Big Bend National Park as a test case, where managers were interested in understanding the costs and benefits of revamping antiquated water supply infrastructure.

The authors found that climate futures developed using the industry-standard representative concentration pathway (RCP) approach, wherein climate metrics are calculated by averaging output of climate models run under different future greenhouse gas concentrations, gave limited views of potential conditions in short-term projections. In comparison, the quadrant approach (which summarizes output from models that predict similar conditions (e.g., “warm and wet”, “hot and dry”), and especially the individual projection approach (where researchers directly compare output from divergent climate models) captured a broad range of potential futures across time spans (early-, mid-, and late-twenty-first century). The individual projection approach effectively captured the range of uncertainty in future conditions over all time periods and can identify potential climate extremes. These results indicate that both the quadrant and individual projection approaches are broadly useful in creating resource management plans under both short and long timescales and that the individual projection approach is especially helpful in supporting decision making that seeks to account for the broadest potential range of future conditions.

This research was funded in part by the North Central CASC project, “Supporting the National Park Service in Climate Adaptation Planning.