Warmer, Wetter Climates Accelerate Mechanical Weathering in Field Data, Independent of Stress‐Loading

Abstract

Weathering is a foundational process in most Earth systems, but there has been a lack of data directly quantifying what influences mechanical weathering. Here we use multiple years of in situ field data, “listening” to acoustic emissions of naturally cracking rocks, to test a hypothesized link between climate and subcritical crack‐tip processes (i.e., the bond‐breaking mechanism thought to embody most mechanical weathering). Our results challenge the assumption of a singular dependence of mechanical weathering on stresses. We find that mechanical weathering rates exponentially increase as functions of atmospheric vapor pressure (VP), temperature, and relative humidity, even when controlling for stress‐loading. VP exerts the most pronounced influence on the observed mechanical weathering rates. Put in the context of global climate change, our results underscore the potential for climate‐dependent subcritical crack‐tip processes to influence all weathering‐allied problems including the long‐term stabilization of the climate by weathering‐carbon‐cycle feedbacks.

Alpine rockwall erosion patterns follow elevation-dependent climate trajectories

“…That warming and retreat will intensify frost cracking at higher elevations and in proximity to retreating glaciers, respectively, whereas at lower elevations the warming will reduce frost cracking 32 . Although lower elevations will experience a reduction of periglacial and paraglacial processes, other climate-dependent weathering processes 19 such as chemical and thermal weathering [91][92][93] may replace them as the main drivers of rockwall erosion 94 . Over time, the areas of most intense periglacial and paraglacial processes and resulting erosion will shift to higher elevations, in locations where higher topography exists.…”

Topographic and Geologic Controls on Frost Cracking in Alpine Rockwalls

“…Warming by climate change will reduce frost cracking at our observed rockwalls. Other weathering processes such as thermal (e.g., Eppes et al., 2020), chemical (Murphy et al., 2016) or biological weathering (Viles, 2013) could become more important controls on rockwall erosion. In Alpine environments, the thermal regimes enhancing frost cracking will be shifted to higher elevations which can alter rockwall erosion as well as rockfall and debris flow hazard potential.…”

Topographic and geologic controls of frost cracking in Alpine rockwalls

“…Warming by climate change will reduce frost cracking at our observed rockwalls. Other weathering processes such as thermal (e.g., Eppes et al, 2020), chemical (Murphy et al, 2016) or biological weathering (Viles, 2013) could become more important controls on rockwall erosion. In Alpine environments, the thermal regimes enhancing frost cracking will be shifted to higher elevations which can alter rockwall erosion as well as rockfall and debris flow hazard potential.…”