What is something you could do now that would positively effect the world around you?

Plenty of thing I can do now to affect the world around me,but the personal ability is quite limited,cause the efforts we should amke together so that it can perform its maxmium power to get the things we want,for example,planting trees,as we all know,the flood killed more 70 people at the beginning of this summer,if we had planted enough trees to hold the ground,would those people die of flood?The answer should be no,this is my answer,thank you.