Forecasting the response of Earth's surface to future climatic and land use changes: A review of methods and research needs

Abstract

In the future, Earth will be warmer, precipitation events will be more extreme, global mean sea level will rise, and many arid and semiarid regions will be drier. Human modifications of landscapes will also occur at an accelerated rate as developed areas increase in size and population density. We now have gridded global forecasts, being continually improved, of the climatic and land use changes (C&LUC) that are likely to occur in the coming decades. However, besides a few exceptions, consensus forecasts do not exist for how these C&LUC will likely impact Earth-surface processes and hazards. In some cases, we have the tools to forecast the geomorphic responses to likely future C&LUC. Fully exploiting these models and utilizing these tools will require close collaboration among Earth-surface scientists and Earth-system modelers. This paper assesses the state-of-the-art tools and data that are being used or could be used to forecast changes in the state of Earth's surface as a result of likely future C&LUC. We also propose strategies for filling key knowledge gaps, emphasizing where additional basic research and/or collaboration across disciplines are necessary. The main body of the paper addresses cross-cutting issues, including the importance of nonlinear/threshold-dominated interactions among topography, vegetation, and sediment transport, as well as the importance of alternate stable states and extreme, rare events for understanding and forecasting Earth-surface response to C&LUC. Five supplements delve into different scales or process zones (global-scale assessments and fluvial, aeolian, glacial/periglacial, and coastal process zones) in detail.

Short-lived increase in erosion during the African Humid Period: Evidence from the northern Kenya Rift

“…Climate change in the tropics and subtropics associated with rapid changes in erosion, soil thickness, and vegetation cover is the focus of many recent research efforts to better understand the impact of environmental change on landscapes (e.g., Pelletier et al, 2015;Schildgen et al, 2016). Paleo-environmental changes recorded by proxy indicators in marine and terrestrial sediments may serve as powerful proxies of landscape response to both present-day climate variability and future climate change (e.g., deMenocal et al, 2000;Shanahan et al, 2015).…”

Views on grand research challenges for Quaternary geology, geomorphology and environments

“…There is compelling research in the modeling of the CZ in the past and into the future with parameterization for earth surface processes, land use changes and pedogenesis (e.g., Nordt et al, 2012Pelletier et al, 2015). Challenges remain on quantifying non-linear, thresholdresponse interactions, particularly with extreme states, amongst such factors as topography, vegetation, land use, and sediment flux.…”

Simulating and quantifying legacy topographic data uncertainty: an initial step to advancing topographic change analyses

“…These two recent research trends also highlight a need to be able to examine recent topographic changes in the context of longer-term rates of change. This task will require greater reliance on integrating legacy and more recent high-resolution topography (HRT) data sources to aid in our understanding of environmental change (Glennie et al 2014;Pelletier et al, 2015). However, the integration of disparate topographic data sources introduces numerous opportunities to increase uncertainty in measurements through space and time.…”