His latest paper released on 14/06/2023 http://www.columbia.edu/~jeh1/mailings/2023/ElNino2023.14June2023.pdf discusses the coming El Nino and the current conditions that combine to make it very concerning. Much of Hansen’s work is on the biosphere and the thermal balance that measures how much heat from the sun is captured to create global warming.
The Earths atmosphere is a big and complicated subject but there are certain events that alter the atmosphere and can be measured and one of these was the Pinatubo volcano that erupted in 1991 the second-largest eruption of the 20th century. The ash plume height reaching more than 40 km (28 mi) high and ejecting more than 10 km3 of magma and the ash plume, plus the sulphur, cooled the planet by a global decrease of about 0.4 °C (0.7 °F).
The ash and sulphur in the atmosphere reflect the suns heat back out into space and cool the planet counteracting the CO2 that is warming the planet. The ash and sulphur are described as aerosols and they are not the only ones that help cool the planet. Coal fired power stations, dust from farming, industrial activity and jet planes are also contributors and as we switch to cleaner forms of energy, we reduce their cooling effect and it is this that Hansen describes as a Faustian bargain, and he suggests that a significant payment in accelerated global warming is now coming due.
Although we are most concerned about the atmosphere, 90% of the heat from the sun is absorbed into the oceans and here we have a fleet of 3500 Argo floats which are spread around the world’s seas and measure temperature and salinity of the top layer of the sea. They have a pattern of sinking one kilometre and stay there for ten days to get an idea of current flow and then they dive to two kilometres before coming to the surface to send the data to a satellite in space and then relayed to the Argo project.
Measuring the combined results of the Argo float from 2005 to2015 shows an energy imbalance for the planet of +0.71C watts per sq. mt but this has risen to +1.18C wattspsqm in the last decade but +1.33C Wpsqmin the last four years.
Hansen admits that there are many complex forces at play but the underlying figures show that we are in a very bad position with global warming and if we get a strong El Nino it may very well be much worse than predicted and go well beyond the 1.5C forecast.