From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

After two years of fabricated alarmism about the apparent shift upwards in global temperatures, scientists have now established that the main culprit has been the reduction in sulfate emissions from shipping!

Abstract

The summer of 2023 saw an anomalous increase in temperatures even when considering the ongoing greenhouse-gas-driven warming trend. Here we demonstrate that regulatory changes to sulfate emissions from international shipping routes, which resulted in a significant reduction in sulfate particulate released during international shipping starting on 1 January 2020, have been a major contributing factor to the monthly surface temperature anomalies during the last year.

We do this by including the appropriate changes to emission databases developed for the Climate Model Intercomparison Project version 6 (CMIP6) in Community Earth System Model (CESM2) simulations. The aerosol termination effect simulated by the updated CESM2 simulations of W m⁻² and 0.08 K±0.03 K is consistent with observations of both radiative forcing and surface temperature, manifesting a similar delay as the one observed in observational datasets between the implementation of the emission changes and the anomalous increase in warming. Our findings highlight the importance of considering realistic near-future changes in short-lived climate forcers for future climate projections, such as for CMIP7, for an improved understanding and communication of short-term climatic changes.

https://esd.copernicus.org/articles/15/1527/2024

This really should not have come as a surprise to anyone, which strengthens the impression that the climate establishment have deliberately ignored sulfate emissions, in order to focus the public’s minds on greenhouse gases.

It has long been recognised that sulfate pollution was a factor in the global cooling between the Second World War and the 1970s. As countries began to clean their air, temperatures naturally rose. Even the Met Office admitted this was probably why UK temperatures rose in the 1980s and 90s.

Cornell University have more detail on their researchers’ study:

Mandated reductions in sulfate emissions from international shipping routes in 2020 are partly responsible for the record high temperatures, the researchers found. Reducing the amount of aerosol particles in the atmosphere reduces cloud coverage; thus, clouds’ ability to reflect solar radiation back to space is diminished. The paper’s findings suggest future policy decisions around abrupt reductions in tropospheric aerosols should take into account their surface temperature impact.

Past research indicated that such change would lead to a minor increase in the global temperature due to a reduction in cloud formation, but Visioni and co-author Ilaria Quaglia, postdoctoral researcher in the Sibley School of Mechanical and Aerospace Engineering (Cornell Engineering), used Earth system model simulations to prove the significance of the sudden drop in sulfate shipping emissions.

These changes in the shipping industry had been discussed for years, Visioni said, with the International Maritime Organization (IMO) making a decision in 2014 to begin enforcing stricter sulfate emissions by 2020. Fuels with lower sulfur are much more expensive, so it took some time for the industry to adjust, he said.

The regulation required ships to use fuel with a sulfur content of no more than 0.5%, down from the previous limit of 3.5%. This reduction led to a more than 80% decrease in total sulfur oxide emissions from shipping.

And while there was some talk of this tradeoff within the shipping industry, he said, there was little attempt to call widespread attention to the potential effect.

The Cornell researchers looked at monthly global temperature anomalies over the period 2020-23, removing the assumed linear contribution from greenhouse gases and seasonality, in order to determine the shipping industry’s impact on temperature anomalies. They found that removing sulfur dioxide from shipping fuel likely increased the planet’s temperature by 0.08 degrees Celsius.

“The unprecedented heat became a normal warm year once you accounted for that,” Visioni said.

https://news.cornell.edu/stories/2025/01/shipping-emissions-mandate-led-spike-global-temperatures

That last sentence is worth repeating:

“The unprecedented heat became a normal warm year once you accounted for that,”