US emits only 15% of global carbon dioxide. If you plant 2.4x trees, you’ll only offset 40% of global emissions. For 2.4x to cover global emissions, global emissions would have to shrink by 60%. If US emissions were reduced by that much, it would put US emissions per capita below present day Belarus and Bulgaria.

> Also, as long as you replace any trees that die with seedlings, you don't need to worry about what happens to the dead wood.

You do, though. If the wood decomposes, all the CO2 is released back to atmosphere, which puts you back at square one.