Too many tree promises. Not enough land.

An inconvenient truth: there is not enough space on earth for offset tree planting pledges. Add ocean kelp to the mix. If there is one climate solution everyone seems to love, it’s planting trees. For years, companies and countries have made bolder and bolder tree-planting pledges to offset their greenhouse gas emissions. Switzerland, for example, has announced plans to offset 12.5% of its emissions through carbon credit projects in Peru and Ghana. Some of the world’s largest fossil fuel companies –– Shell , BP and Eni –– want to grow…