Time just published a special issue about climate change. One article described a tree planting effort in sub-Saharan Africa. Among the trees being used was moringa, or harseradish tree as we called it a couple weeks ago. This tree is very hardy, can handle the dry, and is useful in many ways. In particular it provides very efficient filters for water purification. So who cares if it's invasive. In fact, in that location we all better hope for its success!