It is likely that land use changes associated with farmland erosion and natural atmospheric variability also played roles. (chimalaya.org)
We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability.» (wattsupwiththat.com)
Burgman, R.J., A. C. Clement, C. M. Mitas, J. Chen, and K. Esslinger: Evidence for atmospheric variability over the Pacific on decadal timescales, GEOPHYSICAL RESEARCH LETTERS, VOL. (usclivar.org)