If you are intellectual about it, then you will be impractical. Seeking conceptual clarity, theoretical simplicity, and logical consistency means possibly lacking in one or more among empirical validity, practicality, urgency, and popular appeal.
If you are too activistic, then will be short on rigor
If you take it too seriously, you become sanctimonious
If you talk incremental changes, they might not scale up or lead to big changes that appear necessary
If you talk big changes, there is a risk of large unintended harmful consequences
If you don't endure real pain and hardship in its pursuit, then you are not authentic.
If you sacrifice and endure hardship, it still does not mean you have the right to ask others to sacrifice for the sake of greater good or belittle others' choices.
If you feel good about helping the cause, then you are deriving personal benefits and not truly altruistic
If you don't feel good about it, then you are probably not going to do what it takes
If you are paid to study or sell it, then you are not unbiased
If you are not paid to do it but yet do it, it is a choice or worse a privilege
If you are not paid to work on it and it is not out of choice, then you have some real skin in the game which makes you biased but authentic. I prefer biased and authentic over inauthentic. Unbiasedness is too much to ask whereas authenticity is indispensable.
And then there are things we dont know that we dont know.
I am not convinvced that many people talking about Sustainability and Climate change are themselves enduring real and meaningful pain and hardship. Often they are people who also get paid for it and feel it is more important what they have to say or contribute financially or believe in the power of technology or energy rather than being honest about how their own wealth and consumption is excessive. Effective altruism is a philosophy that supports this world view but them Sam Bankman-Fried was the most popular face of effective altruism.
In sum, sustainability, for me, is about doing the hard stuff that requires real personal sacrifice. But then we are ingenious at finding solutions to make the hard stuff easy and that is the source of all problems. So do the hard stuff and keep it hard which is hard because we live in a society where we are told the most important thing is to maximize pleasure or happiness. But if the one truth about human nature is that we seek happiness, and if that has what has led to an unsustainable world, then may be it is our pursuit of happiness which is the root of the problem and not simply fossil fuels and evil corporations.