I have become pessimistic in the "Planet of the Humans" sense. Part of this is because we are able to take every piece of the problem and minimize it individually. This is what the movie showed. If you question the mining of lithium, you're pointed to the planting of trees. If you question the effectiveness of reforestation projects, you're shown the solar panels. If you ask about storage, you're shown the battery factories. And now we're back to the lithium. Did you see that we're planting trees?

You put up solar panels. You destroy the ecosystem underneath. You dam a river for hydroelectric. You destroy the upstream forest that depended on the undammed river. You switch to electric cars, you still have to produce batteries and cars. You get everyone eating more calories, you get more people demanding more from more desirable sources. As the planet heats up, we install more air conditioning that creates waste heat to move it out of the living space, and eventually leaks high-GWP refrigerant. But don't worry, those air conditioners will be replaced by other ones that use lower-GWP refrigerant...after they have leaked it.

Everything we are doing burns carbon. It's not just too much fossil fuel. It's too much activity.

And then, the shell game. We need to show we're not using carbon. So, we burn forests instead because forests are carbon-neutral if they grow back. But we are mortgaging today's energy carbon over 30 years of forest carbon-capture, which I imagine will just be burned again, along with all of the fossil fuels available in the ground, because alternatives make the fossil fuels cheaper.

Meanwhile, the environmentalists, as represented by the Sierra Club and various green-tech interests, are attacking anyone who says that we have too many people, who travel too much, and eat too much, who live too comfortably, by destroying ecosystems. And they're quiet when confronted by the people you mention, who want to keep the merry-go-round running at any cost, lest the hard times come in their lifetime.

I also think the academic community and environmentalists you refer to are rarely willing to grapple with the actual implications of the data. We really need population decline. We will need new ways of reallocating resources than endless growth. We need to figure out how to make less waste of carbon sources, especially by reducing travel and waste heat generation. And in doing so we need to strictly limit the production of fossil carbon.
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Although you didn't mention the film, it causes strong reactions in people. I have dutifully read the criticism of the film and looked into both sides' claims and my working conclusion is:

1. Jeff Gibbs had some factual inaccuracies, overstatements, and out-of-date imagery.

2. There was no reason to be singling out one person like Bill McKibben and it made the film seem like an attack on him rather than an indictment of the whole green-tech enterprise.

3. His critics are hoping you focus on the above points so that you go back to believing in the bankrupt electric-car, electric-plane, one-billion-Americans, 12-billion-humans, vegan Zymo-veal Soylent vision of individual responsibility and careful technical management that will "maintain our way of life". The fear of the message of the film is very telling.