This could be random variation of the atmosphere over a short period, or random measurement error, or some combination. (deepclimate.org)
Nondifferential misclassification because of random measurement errors, especially for VCAM - 1, may have attenuated the observed associations. (academic.oup.com)
OT, Fukushima radioactive tracers might be used to measure the true lenghts of oceanic cycles, I guess there are enough longlived isotopes released to find them on random measurements around the globe. (realclimate.org)