  In this paper, we study the galactic cosmic ray (GCR) variations over the
solar cycles 23 and 24, with measurements from the NASA's ACE/CRIS instrument
and the ground-based neutron monitors (NMs). The results show that the maximum
GCR intensities of heavy nuclei (nuclear charge 5-28, 50-500 MeV/nuc) at 1 AU
during the solar minimum in 2019-2020 break their previous records, exceeding
those recorded in 1997 and 2009 by ~25% and ~6%, respectively, and are at the
highest levels since the space age. However, the peak NM count rates are lower
than those in late 2009. The difference between GCR intensities and NM count
rates still remains to be explained. Furthermore, we find that the GCR
modulation environment during the solar minimum P24/25 are significantly
different from previous solar minima in several aspects, including remarkably
low sunspot numbers, extremely low inclination of the heliospheric current
sheet, rare coronal mass ejections, weak interplanetary magnetic field and
turbulence. These changes are conducive to reduce the level of solar
modulation, providing a plausible explanation for the record-breaking GCR
intensities in interplanetary space.
