Researchers in Israel have found that forests of the hardy salt cedar tree, indigenous to old-world deserts, have the potential to significantly offset the amount of carbon dioxide that human communities produce. What's more, they can flourish when nourished with low-quality waste water, and the trees themselves can be used as "biofuel" crops to reduce dependence on traditional fossil fuels like coal.

Source: Researchers nurture innovative biofuel crops to reduce our carbon footprint