You'd think Matthew's idea is motivated by climate change. It is. But it's also something a little more. We are all in some way constrained by our time bias. We do things that reward us or others soon. The sooner, the better, in most cases. Matthew's idea is in protest of this - planting 50 trees over a prolonged period of time that will take decades and centuries to grow. He'll never see or even know the impact. And that's the point.