For most people, climate change is pretty much the only world-scale issue they've heard of. That makes it very important (in relative terms); climate change has a world-scale impact, and no other issues they're familiar with do, so it's very important.

LessWrong has a history of dealing with other world-scale issues, and EA (an overlapping neighboring community) likes to make a habit of pointing out all the cause areas and weighing them against each other. When climate change is weighed against AI risk, animal welfare, biosafety, developing-world poverty, and various meta-level options... well, AGW didn't get any less important in absolute terms, but you can see why people's enthusiasm and concern might lie elsewhere.

As a secondary issue, this is a community that prides itself on having high epistemic standards, so when the advocates of a cause area have conspicuously low epistemic standards, it winds up being a significant turn-off. When you have a skeptical eye, you start to automatically notice when people make overblown claims, and recommend interventions that obviously won't help or will do more harm than good. Most of what I see about AGW on social media and on newspaper front pages falls into these categories, and while this fact isn't going to show up on any cause-prioritization spreadsheets, on a gut level it's a major turnoff.

For an example of what I'm talking about, look into the publicity surrounding hydrogen cars. They're not a viable technology, and this is obvious to sufficiently smart people, but because they claim to be relevant to AGW, they get a lot of press anyways. The result is a con-artist magnet and a strong ick-feeling which radiates one conceptual level out to AGW-interventions in general.

Epistemic status: You asked, so I'm answering, though I'm open to having my mind changed on several details if my assumptions turn out to be wrong. I probably wouldn't have written something like this without prompting. If it's relevant, I'm the author of at least one paper commissioned by the EPA on climate-related concerns.

I don't like the branding of "Fighting Climate Change" and would like to see less of it. The actual goal is providing energy to sustain the survival and flourishing of 7.8+ billion people, fueling a technologically advanced global civilization, while simultaneously reducing the negative externalities of energy generation. In other words, we're faced with a multi-dimensional optimization problem, while the rhetoric of "Fighting Climate Change" almost universally only addresses the last dimension, reducing externalities. Currently 80% of worldwide energy comes from fossil fuels and only 5% comes from renewables. So, simplistically, renewables need to generate 16x as much energy as they do right now. This number is "not so bad" if you assume that technology will continue to develop, putting renewables on an exponential curve, and "pretty bad" if you assume that renewables continue to be implemented at about the current rate.

And we need more energy generating capacity than we have now. A lot more. Current energy generation capacity only really provides a high standard of living for a small percentage of the world population. Everybody wants to lift Africa out of poverty, but nobody seems interested in asking many new power plants that will require. These power plants will be built with whatever technology is cheapest. We cannot dictate policy in power plant construction in the developing world; all we can do is try to make sure that better technologies exist when those plants are built.

I have seen no realistic policy proposal that meaningfully addresses climate change through austerity (voluntary reduced consumption) or increased energy usage efficiency. These sorts of things can help on the margins, but any actual solution will involve technology development. Direct carbon capture is also a possible target for technological breakthrough.

I believe climate change will provide a significant (>90%) net-negative (>90%) impact on future human welfare in the forseeable future. I believe (>90%) that climate change is a large-scale policy and technology problem i.e. individual self-regulation has more to do with fuzzies than utilons. I have triaged climate change as a less-than-optimal target of my limited resources. Climate change therefore deserves no more further attention from me.

To put it bluntly, I believe

1. Strong AGI is potentially imminent.
2. If strong AGI is imminent then it outweighs all other large-scale altruistic concerns.
3. I personally have a non-negligible probability of impacting the trajectory of AGI.

AGI therefore overwhelms all my other actionable large-scale altruistic concerns. In particular, climate change is a relatively minor (>%75) threat I am unlikely to significantly influence directly via intentional action (>95%). Furthermore, climate change is likely (>75%) to have relatively minor (affecting <10% of my overall material standard of living) negative personal impact on me. Thought climate change is important to human welfare, I ought not to be "concerned" about it at all.

As for mass media's respresentation of climate change, I think it's crap—just like all other propaganda. This is by design.

I'll bite --- as a "not feeling alarmed" sort of person. First, though, I'll clarify that I'm reading"climate change" as shorthand for "climate change that is net-negative for human welfare" (herein CCNNHW), since obviously the climate is in a state of constant change.

Confidence levels expressed as rough probabilities:

0.70 : we are observing CCNNHW

0.80 : current human behavior increases probability of CCNNHW

0.10 : future magnitude of  CCNNHW will be massive

0.98 : future human behavior will change, given CCNNHW

0.90 : some current and proposed mitigations are themselves NNHW

0.60 : some proposed mitigations have negative effects rivaling that of CC

0.50 : it's possible to design a net-positive mitigation [1]

0.10 : it's possible to implement a net-positive mitigation [2]

Taken together, I assign higher risk to collective, politically directed efforts to mitigate CC than to CC itself.

---

[1] non-linear feedback effects depress this value

[2] political processes depress this value

Human acitivies contribute to climate change. 

Changing to renewable energy is both very expensive as we don't have a good way to store energy and provides systemtic risk because sun and wind are unreliable in many geographies and especially as more of our infrastracture depends on electricity instead of oil an electricity outage of one or two week produces bigger problems. 

There were studies that modeled hydropower plants as being able to store a lot of energy and release it when needed but that's not how hydropower plants work. If a hydropower plant releases much more energy then on average in a shorter timeframe it floods the regions further down the river. 

The electricity system requires that the amount of energy that gets pulled from the system is equal to the electricity that's put into the system. If that equality breaks down, the system breaks down. We don't have good mechanisms to reduce power consumption, so if not enough energy gets produced we usually have to create full power outages in a region. 

There's not enough political will to switch our energy system to either renewable energy or nuclear plants in a timeframe that's enough to prevent undesirable climate changes on it's own. Given that a single actor can implement geoengineering, geoengineering will be used starting between 2030 and 2060 decades to reduce climate impact. 

Nitrogen and phosphorus pollution should likely get more attention as it's currently getting as those lifecycles are not working well. 

Coal kills many people through direct airpollution. In cities non-electric cars emit both airpollution and noise pollution. That means that it's desireable to switch to electric cars and less coal plants besides climate change concerns.

There's a good chance that the great stagnation is partly caused by the stagnation in energy prices that good cheaper year-by-year before the great stagnation. This means it's very valuable for future technological growth to have cheap energy.

Both AI safety, bio-safety and global peace seem more important cause areas as they have more associated risk then climate change.

I agree with the other answers that say climate change is a big deal and risky and worth a lot of resources and attention, but it’s already getting a lot of resources and attention, and it’s pretty low as an existential threat.

Also, my impression is that there are important facts about how climate change works that are almost never mentioned. For example, this claim that there are diminishing greenhouse effects to CO2: https://wattsupwiththat.com/2014/08/10/the-diminishing-influence-of-increasing-carbon-dioxide-on-temperature/

Also, I think most of the activism I see around climate change is dumb and counterproductive and moralizing, e.g. encouraging personal lifestyle sacrifices.

Climate change is obviously real and getting worse. We are seeing the early effects already, and they are straining our emergency measures beyond capacity. Immediate and widespread systemic changes are needed to alter course.

I am powerless to effect such changes.

I suspect that climate change is both overhyped and underhyped. 

I expect that the current models underestimate the rate of change, and that the Arctic, permafrost, Greenland and eventually Antarctic will melt much sooner than projected, with the corresponding sea level rise. A lot of formerly livable places will stop being so, whether due to temperature extremes or ending up underwater.

That said, even the highest possible global warming will not exceed what happened 50 million years ago. And that time was actually one of the best for the diversity of life on Earth, and it could be again. What we have now is basically frozen leftovers of what once was. 

That said, the scale of the warming is unprecedented, and so a lot of wildlife will not be able to adapt, and will go extinct, only for the new varieties of species to take their habitats.

That said, humans will suffer from various calamities and from forced migration north into livable areas. There will be population pressures that will result in disappearance of the current Arctic states like Russia, Canada and Denmark's Greenland. And this will not happen without a fight, hopefully not a nuclear one, but who knows.

That said, there are plenty of potential technological ways to cool the planet down, and some may end up being implemented, whether unilaterally or consensually. This may happen as a short-term measure until other technologies are used to remove carbon dioxide from the atmosphere.

TL;DR: Climate change is a slow-moving disaster, but not an X-risk.

I am generally concerned, and also think this makes me an outlier. I don't have any specific model of what will happen.

This is a low information belief that could definitely change in the future. However, it doesn't seem important to figure out how dangerous climate change is exactly because doing something about it is definitely not my comparative advantage, and I'm confident that it's less under-prioritized and less important than dangers from AI. It's mostly like, 'well the future of life institute has studied this problem, they don't seem to think we can disregard it as a contributor to existential risk, and they seem like the most reasonable authority to trust here'.

A personal quibble I have is that I've seen people dismiss climate change because they don't think it poses a first-order existential risk. I think this is a confused framing that comes from asking 'is climate change an existential risk?' rather than 'does climate change contribute to existential risk?', which is the correct question because existential risk is a single category. The answer to the latter question seems to be trivially yes, and the follow-up question is just how much.

1. Climate change is only negative insofar as it causes negative change in human welfare.
   1.  Human welfare in this framework is a function of natural environment (which includes climate) and all improvements added to this environment by human effort (e.g. roads, houses, electricity network etc.), which I will refer to as "capital".
   2. If the climate of an area changes to one that is better suited for human welfare (e.g. allows better crop yields, lessens the need of energy consumption for heating or cooling etc.), climate change has a positive effect.
   3. As capital needs to be replaced over a time period (e.g., infrastructure has to be repaired and maintained, which can be measured in a ratio of cost of maintenance/cost of  production, lets call this "replacement rate"), climate change will have a negative effect on human welfare if the change causes the replacement rate to increase (e.g., if expenses on air conditioning rise faster due to climate change then they drop on insulation from cold).
2. For advanced civilizations climate change is inevitable.
   1. One cannot drain energy from a system without affecting it.
      Hence, the higher we are on the Kardashev scale the larger the impact of our energy consumption on our environment.
   2. Even if we change to other energy sources, the environment will still be affected. I do not see serious research into this. Even worse, it seems most people have the illusion that other energy sources might have zero effect on the environment. Large dams already show otherwise for hydroelectric, but it is not so clear on other sources.
      As a thought experiment: imagine we are living in a world where the ratio of fossil fuel and wind energy usage is exactly the opposite. As CO2 emission is 1-2% of our world's, we would not be able to find negative effect from this on climate. To me it is plausible that that is the same case with other sources of energy.
3. We are bad at figuring out what climate will do in the future and what how consumption affects it.
   1. I am not very familiar with contemporary publications on this, but I am quite sceptical about our ability to make accurate predictions, especially as it is the local climate that mostly affects human welfare, global average temperature is a very weak estimation for this.
   2. In case of human consumption, all supply chain through the whole product lifecycle must be mapped if we desire an accurate top-down solution. I do not see this in the proposed solutions. I have the impression they are only dealing with CO2 production during operation, ignoring production and decomission and all other negative externalities.
4. The climate change issue is a discussion of an externality problem with weak understanding of causal effects and very large number of participants.
   1. There is a classic economics example: 
      Two firms located on a river. Upstream firm pollutes the river, reducing output for the downstream firm.
   2. To modify this to climate change: replace the river with an ocean, increase the number of actors to 8 billion, allowing them to create non-fixed sets (e.g., companies, towns, families), have them all affect each other in a very small way, which if summed up changes the pollutedness in a specific direction but which still increase production is some beaches of the ocean, but we do not know to what extent exactly. (and here we haven't even elaborated on different jurisdictions).

As per above, it is a difficult question. However, even if we found a good solution, the issue has become so politicised that carrying out any plan without massive disruption by interest groups is unavoidable.

When I began writing this, I thought very little good could be done by working on climate change, since of how popular the topic is. But as I wrote, and thought about the issue, I realized that you have a point, and that working on effective solutions to the problem has a high chance of being effective, if not particularly suited for me. I would enjoy seeing more in-depth analyses which do actual research, and attach numbers to the vague feelings of importance I express here.

Using EA's usual decision matrix of Scale, Solvability, and Neglectedness :

Neglectedness, at first glance, seems very low. For the past 20 years there's been a huge media campaign to get people to "solve" climate change, and everyone's aware of it. However, very little effort is expended working & advocating for effective solutions to the problem (ie helping developing countries prepare), and much of the effort seems to be going to low-Solvability & Scale tasks such as attempting to prevent carbon emissions. Thus, despite near-constant media attention, it seems likely that effective solutions are actually very Neglected.

Scale seems pretty large. Those hit hardest will be the people with the least ability to invest in mitigation technologies, and most reliance on nature. Aka: developing countries. Thus lifting developing countries out of their poverty will be much harder in the near-term future. Notably, this poses little risk to the long-term flourishing of the human race, whereas other global catastrophic risks such as dangerous AI, nuclear war, biological war, etc. seem to have both a higher Scale, and higher Neglectedness.

Solvability seems like it'd range from insurmountably low to medium-high, depending on what you choose to focus on. Many of the problems that affect more affluent nations seem like they'd be solved through mitigating technologies, and not through reversing climate change's effects. Things like dams and levees are technologies we already have, and things that the Dutch (note: I looked that up, so I could provide a source, but I knew it was a thing already from an Environmental Science course I took during high school) already use to keep their cities above sea-level. I would bet there are other, similarly low-hanging technologies which would vastly lower the effects of climate change on developing countries. These developing countries would likely develop and implement these technologies once effects from climate change are seen, regardless of what they believe the cause of such climate change is.

Increases in resources here though, seem like they'd have little impact on the outcome for these developing countries. Since there is a large incentive for cities and companies to make and invest in these technologies, they will likely be developed regardless of what interventions are worked on.

By my understanding, even if we stopped all of our carbon output immediately, there'd still be a devastating 2C increase in the average temperature of the earth. And developing countries would be at a great disadvantage developing the infrastructure needed to mitigate it's effects, so the Solvability here is incredibly low.

Thus the goal of "fighting" climate change should focus on providing developing countries the infrastructure they need to be prepared. This doesn't seem like particularly interesting work to me, nor particularly suited to my skills when compared to other ways of improving the world. However, I'd need more knowledge about the effects and the current effective interventions to be confident in my conclusions. Currently, counter to what I thought before writing this, the field seems promising.

I am greatly concerned about the risks associated with climate change and have been for several years now, though earlier in my adult life I didn't know much about it and gave too much credence to skeptics such as Bjorn Lomborg. I anticipate that (barring some kind of singularity that makes a mockery of all prediction) the greatest harms from climate change this century will come from mass displacement and migration ("climate refugees"); indeed already there are folks talking about leaving California to escape the ever-growing annual fire seasons. The same will happen (is happening) for those along flooding coastlines or increasingly drought-stricken or fish-depleted regions. Also important to consider are tail-risks, the small but non-negligible possibility that actual warming turns out rather higher than the (already bad!) average-case predictions (see Martin Weitzmann's work, or David Wallace-Wells's famous NY Mag article "The Uninhabitable Earth").

If the recent hype from MIT about nuclear fusion is for real, maybe we can all breathe a sigh of great relief—it could turn out to be some of the best, and most significant, news of the century. We should have been building out old-fashioned nuclear power for decades now, but we are civilizationally inadequate to this sort of basic collective foresight and action. Other high-value actions include modernizing the electrical grid and increasing by orders of magnitude funding for basic research in clean energy, and of course a hefty carbon tax, for Christ's sake (civilizational inadequacies abound!). Geoengineering should be a last resort, since messing with the world's atmospheric/oceanic systems is what got us into this mess in the first place. They are complex nonlinear systems that we literally rely on being relatively stable for the continued existence of humanity; screwing up geoengineering, like screwing up artificial superintelligence, could be the last mistake our species makes.

Just writing out some current beliefs in steam of consciousness. Percentages in parentheses are confidence levels.

Global warming and climate change are happening, and we're well on track to pass 2.5 C total rise. The best way to mitigate this is to reduce fossil fuel use approximately yesterday, and cutting other GHG emissions (85%). The second-most-important thing to do is to adapt to the changes, and trying to sequester carbon or turn back the clock by other means is lower priority than that (60%).

The most camera-friendly impact felt by the developed world will be sea level rise, but I think the biggest problem will be drought and shifting climate patterns in the developing world (70%). A lot of people are going to die or be left in precarious situations (gut estimate: 300M displaced over the next 80 years). I think cataclysmic scenarios such as runaway greenhouse effect, releasing atmosphere-changing amounts of methane hydrates, or melting the Greenland ice sheet are relatively unlikely and not the main problem even after weighting them by importance (75%).

I am concerned about climate change, and I believe we need to have serious changes in the way our world works. We need to be more sustainability-minded in terms of economic growth, for example -- infinite growth is not reasonable. And we seriously need to switch to clean energy sources. The inflation reduction act gives me a lot of hope for this. It's ridiculous how subsidized fossil fuels are. We're dumping money into destroying ourselves when we should be investing in reversing the damage. I'm concerned, but I have to be hopeful -- otherwise I'd be constantly depressed. I don't like the word "alarmed" because I am fighting for a better future by donating, voting, protesting, etc. and "alarmed" sounds like panic, which isn't helpful. I try not to think about climate change too often or else I'd feel totally stuck. Instead I generally try to stay up-to-date on how to help environmentalist movements, try to stay up-to-date on policies and science, etc.

I'm very concerned about climate change having a large negative impact. It seems unlikely to be threatening systemic collapse, but a lot of unnecessary suffering and a slowdown of long-run progress seems likely. Some small risk of extreme scenarios also seems to exist.

My view is that it's not a technological problem but a political one: it would be easy to solve with a global governing body. We have nuclear technology for power, and temporarily reduced availability of vehicle fuel seems to be a small problem that we could easily adapt to. The standard solution of taxing negative externalities should work just as well for this as for other things.

Because of our inept institutions, I believe the only likely solution, apart from accepting a dramatic adaptation with huge biodiversity loss, is that the damages motivate a coalition of major powers to strike a deal and use economic or political leverage to force everyone else into it. Either China and the US change their minds and the EU agrees happily, or India threatens unilateral solar radiation management. Both scenarios seem a couple of decades away.

While the issue is important and interesting I'm quite pessimistic about getting a timely solution, and about the possibility of individuals to make a difference. I still believe most people in a hundred years will have a standard of living similar to Western people now, but lots of suffering will come between now and then.