We report 80 10Be ages on 14 moraines from Irish cirques that show a previously unrecognized signal of at least eight millennial-scale fluctuations between 24.5±0.7 ka and 11.0±0.3 ka. Several moraine ages may be correlative with abrupt warming at the onset of the Bølling (14.7 ka) and the end of the Younger Dryas (11.7 ka), suggesting a forced response. Our ages also identify glacier fluctuations that occurred when regional temperatures were relatively stable. This finding is consistent with modeling results showing several hundred-meter-scale glacier fluctuations in response to interannual variability. At the same time, our composite record of cirque-glacier average equilibrium line altitudes (ELAs) shows a response to warming due to increasing greenhouse gases and summer insolation modulated by abrupt climate changes. Our new 10Be chronology thus records both forced and unforced millennial-scale glacier fluctuations superimposed on a lower frequency ELA signal of forced response to climate change.
- Ice Sheet
Barth, A. M., Clark, P. U., Clark, J., Roe, G. H., Marcott, S. A., McCabe, AM., Caffee, M. W., Cuzzone, J. K., & Dunlop, P. (2018). Persistent millennial-scale glacier fluctuations in Ireland between 24 ka and 10 ka. Geology, 46(2), 151-154. https://doi.org/10.1130/G39796.1