An average tree might last 30 or 100 years, sequestering CO2 and expelling oxygen, before dying and giving back its carbon to the atmosphere. That happens to be the same length of time that civilization needs to wean itself off fossil fuels to save our stable climate. There are many community tree planting projects around the world. Look up the ones that you can join, in your area! If we are to rescue our planet, right now it is tree time!!