Jim Hansen is the climate scientist who testified to Congress in 1989 about our calamitous
future if we didn’t stop burning fossil fuels that are responsible for most global warming. This
year he published a scientific article titled “Global warming has accelerated: are the United
Nations and the public well-informed?” He describes a 2-year increase of 0.7 degrees F which
was twice what was expected and could not be explained by the UN’s Intergovernmental Panel
on Climate Change (IPCC). Because the IPCC relies on incomplete global climate change models
for its predictions, Dr. Hansen advocates expanding use of current observations to improve
models and paleoclimate measurements to test models. In particular, we should focus on what
happened 120,000 years ago when the earth was as warm as it has become today: The ice
shelves in the Antarctic had melted; sea level was 50-80 feet higher; and the ocean circulation
that carries southern hemisphere heat to the northern hemisphere had shut down because of
melting of polar ice.
The mild El Nino of the last two years accounts for about half of the accelerated warming above
that from increasing CO2 from fossil fuels. The other half is due to a decrease in cloud cover in
the north Atlantic and north Pacific. In 2020, the International Maritime Organization required
ships to use low-sulfur fuel to decrease emissions of tiny particles causing heart and lung
disease. Decreasing these particles that form the nuclei for water condensation also decreased
cloud formation. Clouds reflect sunlight back into space, cooling the earth. With fewer clouds,
more sunlight is absorbed by the earth, heating it up. Global climate models did not account for
less air pollution and fewer clouds, explaining why scientists were surprised by the acceleration
of global heating. If scientists’ global climate models are incomplete, we can’t make sound
decisions about what is necessary to preserve a habitable earth.
The UN process for worldwide action to decrease fossil fuel emissions has failed and is not
controlling the increasing CO2 responsible for global warming. Dr. Hansen explains that the
accelerated heating is likely to shut off the ocean’s Atlantic Meridional Overturning Circulation
which transfers southern hemisphere heat to the eastern United States and Europe. This “point
of no return” is likely to occur within 20-30 years, lowering northern hemisphere temperatures
that allow usual agriculture. Increased heat in the southern oceans will result in the accelerated
melting of Antarctic ice, such that ocean levels will increase by 50-80 feet, as occurred 120,000
years ago. Coastal cities and land will be uninhabitable all over the world much sooner than
IPCC scientists had predicted.
Dr. Hansen asks us to read his article’s epilogue, which is non-technical and designed for all to
read (https://doi.org/10.1080/00139157.2025.2434494). If the public is unaware of what is
coming sooner than expected, we cannot hold our governments accountable to protect us. A
major transformation of government beyond partisanship is required to protect the earth.
--Kay Kreiss, Transition Sitka
