Every person makes a difference in climate change, but most are completely unaware of how much.
Climate has gone through many changes in the past, some of them significant enough to take out all complex life on land.
How much humans will alter the “natural” changes is an open question, and it is definitely significant on current trends.
I strongly suspect that if we manage to establish a form of global cooperation that is not global control, but is real cooperation, with real respect for individual life and individual liberty, real acceptance of diversity and error, then we will be able to manage the climate to within reasonable limits that prevent the worst of disasters, and keep sea level stable. The technology to do that is relatively easy, but the social consequences of using such technology in a competitive context are very high risk.
There is the possibility of ideas spreading that move us towards this sort of high level cooperative context.
Every individual that picks up, and makes a conscious effort to hold and spread such ideas, makes a difference, in ways that many have no real ability to appreciate in detail, yet they do make a real difference in reality. Reality seems to have that attribute, and every single human being is far more complex than any human being can possibly appreciate in detail; yet many are “captured” by relatively simple behavioural structures in many common contexts.
And there are very real tipping points, where all those seemingly tiny and insignificant changes do actually create major systemic change. And often they are very difficult to see, right up to the point that change happens.