As noted in this article, aviation is responsible for just 2.5% of global anthropogenic CO2 emissions. To put that number into perspective, cars are responsible for about 10x that.

If everyone stopped flying today, the impact on climate change would be almost nothing. If everyone stopped driving, the impact would be huge. Furthermore, there are very few good alternatives to flying if you actually need to get somewhere really far away. Cars with internal combustion engines have tonnes of lower impact alternatives though - electric cars (if you have reasonably clean electricity), public transportation, biking, walking, etc.

Aviation seems like a weird sector to focus on, if you actually want to make a difference.