re: #59 Love-Child of Cassandra and Sisyphus

So to summarize recent developments:

Hansen et. al. published a paper a few months ago asserting that climate sensitivity (which is defined as the change in global average surface temps for a doubling of CO2 in the atmosphere - a problematic definition in itself but it’s what the climatology community has decided to use) is much more than the number given by the IPCC.

Hansen et. al. argue that aerosols and their cooling effect have misled climate modelers.

Then along comes 2023 with its record high temps. And this became part of what we can call the rush to reintroduce the “hot models” - those climate models that show much more warming than what the IPCC has chosen to use.

Michael Mann comes along and disputes what Hansen et. al. are claiming.

Mann is still sticking with the consensus that found its way into the IPCC reports.

Mann also points out that one should not use a single year’s average temp as a claim that we have passed the 1.5C threshold. Mann contends that one must stick with 30 year averages.

So for a centered-mean average over 30 years, 2023 is the middle year of a window that goes from 2008 to 2038.

Thus while 2023 was above the 1.5C threshold, the 1993-2023 centered average is not. Hence the 1.5C threshold has not been crossed.

Now Hansen finds this all a bit too conservative, that with his assertion that aerosols have masked the true climate sensitivity the models are underestimating the warming for the next few decades.

So even if Mann wants to stick to a 30 year average before declaring we’ve passed 1.5C, it will all seem academic in the next 10 years as some of those years will be much warmer than 2023. And the following 10 years even much more so.

Hansen asserts that we are not sounding the alarm bells loud enough, that the IPCC is way too conservative.

Mann counters by saying that doomerism is counterproductive and scientists should not make declarations that lead to such.

That is the current hot debate in certain corners of AGW-aware community.

My take: I agree that fatalism is counterproductive to making wise choices.

Yet I hold my fellow humans in lower regard than Mann does.

We collectively have already bought a fossil fuel infrastructure for the next 3 decades, at least.

And while Mann praises Biden, I will here again remind everyone that Biden is bragging about the US record “oil” (really, liquid fuel) production.

Global carbon emissions are still going up.

One does not spend billions of dollars on a highway and not use it.

One does not spend tens of billions of dollars on a liquid NG global trading scheme and not use it.

One does not keep building sprawl and not expect to occupy those houses for the next 50 years.

We have already bought, as in paid for, several more decades of high greenhouse gas output.

We are in a hole and we keep digging.

And we are going to keep digging until it kills us.

So while I respect Dr. Mann, I think he is being way too politic in his public stances.

He (rightly) points out that the threat to democracy that Trump and the GOP deep pockets is necessary to counter.

So he has decided to project a message of hope to the American masses. He does not want to push anyone away.

That is a reasonable thing to do.

But it will not stop our continued activity that is driving climate change.