Global variations in regional degradation rates since the Last Glacial Maximum mapped through time and space

• Published in: Quaternary Research
• Main Authors: Madoff, Risa D., Putkonen, Jaakko
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2022
• Subjects: General Earth and Planetary Sciences; Earth-Surface Processes; Arts and Humanities (miscellaneous); Arctic; Subarctic
• Online Access: http://dx.doi.org/10.1017/qua.2022.4; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589422000047

Abstract Topographic diffusivity is an often-used metric of regolith mobility. It accounts for the collective effects of climate, substrate, fauna, flora, and other factors on hillslope degradation and is used to model natural lowering in landscapes. The present study assesses where temporal variations in diffusivity derived from known past climate fluctuations have occurred. We also determine where significant differences might result when modeling landscape degradation if a long-term constant diffusivity is applied instead of diffusivity that varies through time. A space-for-time substitution approach was implemented. Through use of a transfer function that correlates current diffusivities with air temperatures, we mapped the relative diffusivities globally at a 500 yr temporal resolution for 21 ka. The analyses spanned all land areas from the tropics to the poles with a spatial resolution of 3.70° latitude by 3.75° longitude using paleo-temperature data from the TraCE-21ka global paleoclimate model. The results show Arctic and subarctic regions with the highest relative maximum diffusivities and largest variance from current values. The results suggest strong surficial dynamics in the Arctic and subarctic regions driven by local and spatially transient deglaciation and long-term stability in the tropics that correlates with relatively stable climate there through the past 21 ka.