Speaker
Description
As emissions and atmospheric concentrations of greenhouse gases have been increasing over the past decades, aerosol emissions have stabilized and subsequently largely decreased in most areas of the world. This has resulted in a growing rate of both regional and global net forcing increase.
This correlates with stronger regional brightening and warming, notably over the European continent, which has brightened (less solar radiation reflected to space) by about +15 W/m². Reductions in aerosols are a result of clean air regulations, enforcement and compliance.
In 2015 strict regional regulations on ship sulfur fuel content came into effect over Emission Control Areas over the North Sea and around North America, reducing maximum sulfur fuel content from 1 to 0.1%
January 1st 2020 global sulfur fuel content regulation from the International Maritime Organisation came into effect, reducing maximum sulfur fuel content from 3.5 to 0.5%.
There is strong correlation between areas of active shipping and increased regional Absorbed Solar Radiation from NASA CERES (Clouds and the Earth's Radiant Energy System) satellite observations and increasing Sea Surface Temperatures.
The rate of net radiative forcing increase coincides with an increase in Earth's Energy Imbalance from both satellite and in-situ assessments. There is a preliminary signal of an increased rate of global surface air temperature increase, which is more clear when taking into account ENSO cycles. This is expected to become more apparent with the current El Niño and in case of a positive Pacific Decadal Oscillation.
Global warming and the effects thereof are becoming more apparent, while there is no clear sign of a decrease in greenhouse gas emissions.This has led some to argue in favor of intentional emissions of aerosols in both the troposphere and the stratosphere. The loading of stratospheric aerosols to achieve a given cooling effects is expected to be much less than for tropospheric cooling with aerosols and aerosol-cloud interactions, as indicated by inadvertent experiments, including the 1991 Mount Pinatubo volcano eruption injecting ~30 Tg of aerosols into the stratosphere.
