  We propose a scenario in which a simple power-like primary spectrum for
protons with sources at cosmological distances leads to a quantitative
description of all the details of the observed cosmic ray spectrum for energies
from 10^{17} eV to 10^{21} eV. As usual, the ultrahigh energy protons with
energies above E_{GZK} ~ 4 x 10^{19} eV loose a large fraction of their
energies by the photoproduction of pions on the cosmic microwave background,
which finally decay mainly into neutrinos. In our scenario, these so-called
cosmogenic neutrinos interact with nucleons in the atmosphere through Standard
Model electroweak instanton-induced processes and produce air showers which are
hardly distinguishable from ordinary hadron-initiated air showers. In this way,
they give rise to a second contribution to the observed cosmic ray spectrum --
in addition to the one from above mentioned protons -- which reaches beyond
E_{GZK}. Since the whole observed spectrum is uniquely determined by a single
primary injection spectrum, no fine tuning is needed to fix the ratio of the
spectra below and above E_{GZK}. The statistical analysis shows an excellent
goodness of this scenario. Possible tests of it range from observations at
cosmic ray facilities and neutrino telescopes to searches for QCD
instanton-induced processes at HERA.
