Climate-driven changes to channel erosion rates in the Mackenzie River Basin since 1985
Abstract
Recent work in high-latitude regions has shown that permafrost is melting at an unprecedented rate, with important implications for global greenhouse gas emissions. Yet, the fate of carbon-rich sediments depends partially on if, and how, they are mobilized in the environment. Here, we ask whether channelfloodplain interactions of high-latitude rivers have changed as Arctic temperatures have warmed. Using satellite imagery from 19852020 at ~4,500 study sites across the entire Mackenzie River Basin in the Canadian Arctic, we show that channel migration rates have increased throughout the basin over the study period. However, changes in channel erosion are non-uniform. River channels at the basins middle latitudes (58.7262.72 N) have experienced more rapid change than those at the southern and northernmost latitudes. In those middle latitude channels, the annual bank area eroded per 5 years has increased >50% on average since 1985. Additionally, lower-order river channels have experienced greater planform changes than the main stem of the Mackenzie. Rather than directly responding to the absolute magnitude of temperature change, our data show that regions experiencing the most rapid increase in channel migration rate are those areas experiencing the most rapid increase in degree days (summed degrees above 0 º C for each day). To the extent that the rate of change in degree days drives permafrost melting, these results suggests that the increase in erosion rates may be driven by changes in permafrost extent. Yet, significant variance in the data remain unexplained by temperature alone, especially at the highest latitudes, and we therefore discuss potential variables driving changes in the arctic beyond rising temperatures.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMEP51B..07F