Dr. James Hansen's year-end update contains an admonishment right in the title, "A Miracle Will Occur" Is Not Sensible Climate Policy."  Those who have followed his work and his typically well-tempered writing will recognize this as a very strong indictment of what we've not done to date to address climate change. This is, for this mild-mannered scientist, the equivalent of "Hey Guys, Get your S _  _ T together!"

Dr. Hansen proceeds to call "bunk" on the assertions from both the COP 28 Chairman and the UN Secretary General who imply that the goal of keeping temperature rise to below 1.5°C is still feasible. According to Dr. Hansen, the already banked warming will take us beyond 2.0°C "if policy is limited to emission reductions and plausible CO2 removal." In other words, he makes it clear that this is now merely wishful thinking and does not reflect a realistic understanding of the way that emissions released create future warming, which he calls "Global Warming in the Pipeline" and describes in the linked paper.

The only realistic approach is to take true climate analysis that is informed by knowledge of the warming "forcing" effects and to use that to drive decisions about policy options. If we can possibly use the next several years to define and commence more effective policies and courses of action, then there is a modicum of a chance that we can still save the future for our young people. If this isn't a bomb of an alarm, it would be hard to say what else would be, especially because the IPCC has made it very clear that major ecosystems, starting with coral reefs and then, therefore, all marine life, will be threatened with substantial (90%) collapse by 1.5°C  and with 100% by 2°C.

Unfortunately, climate science is complicated and most people don't have a good understanding of the "human-made forcings that are driving Earth's climate away from the relatively stable climate of the Holocene (approximately the past 10,000 years.)" Even if they could grasp the implications about climate science from the graphs that Dr. Hansen and his team provide, very few are even reading Hansen's work. These graphs are very scary but clearly they are not being used as the basis for policy discussions by either politicians, government agencies (like the EPA), or by leading environmental groups and that is likely the primary reason why many people are still arguing about renewables versus nuclear power, thinking they have a certain luxury of time, rather than saying "Renewables and nuclear, YES!"

For his part, Dr. Hansen doesn't make it as easy as he could for those with less expertise in climate science. He spends a lot of effort discussing two major climate forcings: greenhouse gases (GHGs) and aerosols (fine airborne particles), which in fact have opposing forcings. But then goes into detail on many other related forcings. This level of detail may provide a more scientifically accurate picture of what is going on but it makes for much sparser readership. Clearly, there are many different kinds of feedback loops, including how the aerosols impact cloud formation, albedo effects and also the way the ocean absorbs a considerable amount of the warming that is happening to our climate. It's important that he understands these effects but it takes considerable sifting work to get to the point that what it all adds up to is that there is much more warming that has occurred than what we are actually now experiencing, so in fact, the effect of warming will be accelerate and we're now seeing this.

Even for those of us who finding climate science fascinating, this 14-page paper is incredibly dense and gets relatively badly bogged down with details on things like cloud forcings, albedo changes, reviewing differences between expected temperatures and real world measurements, catching up with a 40-year old mystery having to do with the last glacial maximum and describing the impacts of an "experiment" that occurred when the International Maritime Organization limited sulfur content in ship fuel and the variability introduced by El Nino and La Nina events.  The bottom line of quite extensive discussion that few will wade through, is that global warming is now accelerating. This is very important but definitely buried. The key graphic of the whole paper depicts this acceleration.

On page 7, we finally get to the implications of global warming acceleration.  As shown in the above graph, were the warming happening at a steady rate, we'd be on the green dotted line. Instead, we are veering off into the yellow zone of accelerated warming, which means that we'll "exceed the 1.5°C mark within the next few months and reach a level far above 1.5C by May 2024."

Hansen, while recognizing that there could be some up and down based upon El Nino and La Nina effects, believes that the baked in energy imbalance already "in the pipeline" means that it does not serve anybody's interests to "wait a decade to declare that the 1.5°C limit has been breached." In summary, Hansen argues that, "unless purposeful actions are taken to reduce our present extraordinary planetary energy imbalance," the 2°C global warming limit will also be breached.

By its very nature of having a delayed, baked-in response, human-made climate change makes this an intergenerational issue. What we have done in the past is already having consequences but what we do today and going forward will mostly impact the next generation for better or worse.

To his credit, Hansen dives yet again into Climate Policy, unlike most other scientists. This has been long been a huge source of frustration for him and you can almost see him stomping on his own hat, in his anger and impatience with the political processes that have thwarted action. First he reviews just what makes solving cilmate extra hard, starting with the fact that the principal source of GHGs is fossil fuels, which are in his words "extremely beneficial to humanity."  They have raised starndards of living worldwide and still provide 80% of the world's energy. "Fossil fuels are readily available, so the world will not give up their benefits without equal or better alternatives."  Because of this conundrum, we are near a point of no return, where extreme consequences can spiral out of humanity's control.

Dr. Hansen has been a first-hand witness to humanity's failure to act over the last 35 years or so and his exasperation with that and his desperation to communicate to those in power about our increasingly limited options is abundantly clear. He's been advising governments around the world on possible approaches with little of the urgent response that is warranted.  He delves into some of these details but then finally hones on in the three actions that are required to successfully address climate and achieve the bright future we desire for our children.

The first is a near-global carbon tax or fee.  It is the sine qua non required to address the "tragedy of the commons" problem" wherein fossil fuels waste products can be dumpted in the atmosphere for free.  There can be a range of approaches, yet something that penalizes those dumping GHGs is required to be enacted globally. A corollary to a carbon fee is a "clean energy portfolio standard," with government policies that are far more supportive of nuclear power.

The second major policy requirement, is the need for the West to cooperate with and support the clean energy needs of emerging and developing nations. There are economic imbalances with developed nations having caused the past emissions but emerging nations increasingly being the driver of future emissions:

The clear need is to replace the world’s huge fossil fuel energy system with clean energies,
which likely would include a combination of “renewables” and nuclear power. Even if the
renewables provide most of the energy, engineering and economic analyses indicate that
global nuclear power probably needs to increase by a factor of 2-4 to provide baseload power
to complement intermittent renewable energy, especially given growing demands of China,
India and other emerging economies. The scale of China’s energy needs makes it feasible to drive down the costs of renewables and nuclear power below the cost of fossil fuels.

Lastly, Dr. Hansen proposes that "a multitude of actions are required within less than a decade to reduce and even reverse Earth’s energy imbalance for the sake of minimizing the enormous ongoing geoengineering of the planet; specifically, we will need to cool the planet to avoid consequences for young people that all people would find unconscionable."

References:

"A Miracle Will Occur" is Not Sensible Climate Policy, by James Hansen, Pushker Kharecha, Makiko Sato, Columbia University, Earth Insitute's Climate Science & Solutions, December 7, 2023.

Columbia University, Climate Science, Awareness and Solutions Newsletter, "Groundhog Day. Another Gobsmackingly Bananas Month. What’s Up?, sent on January 4, 2024 from the same team.

"Dire Warnings from Dr. Hansen and Team, by Valerie Gardner, Nucleation Capital, Dec. 22, 2023.