We very much welcome this useful opinion on ways to strengthen atmospheric research in the Global South.

The tropical tropopause region (14-18km altitude) plays an important role in the climate system, but the technical difficulties of making measurements in this region are severe. This paper reports observations of very thin tropical tropopause cirrus clouds made using a new lidar instrument carried on long-duration balloon flights, lasting several weeks and travelling about 20000km, from the Indian Ocean to the Central Pacific. The sensitivity of the new instrument reveals that clouds are much more frequent in this part of the atmosphere than had been identified previously. The quantitative significance for the large-scale climate system, e.g. for the radiation balance, is yet to be assessed, but it is clear that these observations will be a valuable resource for scientists studying this truly remote part of the atmosphere.

The core element of climate change is the sensitivity of the Earth's climate system to the balance between incoming solar radiation and outgoing terrestrial radiation at the top of the atmosphere. CO2 is one of the key atmospheric parameters controlling the outgoing longwave radiation. In this paper, hyper-spectral satellite data of the outgoing long wave radiation from a decade of observations are successfully used for the first time to disentangle the radiative effect of CO2 increase from those of other relevant parameters such as temperature and water vapour variations. The paper demonstrates convincingly that the observed radiative changes agree excellently with theoretical predictions of outgoing long wave radiation changes due to the observed CO2 increase. While solely based on observations from space, these results confirm a fundamental theoretical underpinning of the science of global warming.