  Conventional climate models have predicted continuous warming on the Earth's
surface and cooling in the upper stratosphere. Here we report observations of
regional and global upper stratosphere temperature (UST) and surface
temperature and of various climate drivers including greenhouse gases (GHGs),
ozone, aerosols, solar variability, snow cover extent, and sea ice extent
(SIE), combined with calculations of global mean surface temperature (GMST) by
a conceptual physics model. We strikingly found warming trends of 0.8(+/-0.6)
and 0.7(+/-0.2) K/decade in UST at altitudes of 35-40 km in the Arctic and
Antarctic respectively and no significant trends over non-polar regions since
2002. According to the well-recognized climate models, these UST trends provide
fingerprints of decreasing (no significant trends) in total GHG effect in polar
(non-polar) regions. Correspondingly, we made the first observation of both
surface cooling trends in the Antarctic since 2002 and the Arctic since 2016
once the SIE started to recover. But surface warming remains at mid-latitudes,
which caused the recent rise in GMST. The latter is quantitatively explained by
the positive short-term radiative forcings of aerosols and ozone due to
improved air quality. The observed GMST changes agree well with calculated
results by the physics model based on halogen-containing GHGs, whose
destruction is consistent with the characteristics of the cosmic-ray-driven
reaction mechanism with larger rates at higher latitudes. With observations of
rapidly lowered aerosol loading, projected halogenated GHGs and stopped Arctic
amplification, we predict to observe an emerging long-term GMST reversal that
started at the end of 2023.
