Gaia. When James Lovelock, the Oxford professor, first put forth the notion in the 1960s, it was either ignored or derided as some weird new-age religion. The Gaia theory is hard to sum up in a brief way, but Lovelock suggested that we think of the whole earth as a living entity, with all its parts–living or not–contributing to its stability. "We now see that the air, the ocean and the soil are much more than a mere environment for life; they are a part of life itself," he’s written. "Thus the air is to life just as is the fur to a cat or the nest for a bird. Not living but something made by living things to protect against an otherwise hostile world." Lovelock has gotten increased attention–along with some continued derision–from environmental scientists over the years. Now, with a brief letter to Nature, he and his colleague Chris Rapley invite more of each. Rapley is director of the British Antarctic Survey and the Science Museum in London. "Sir," they write, "We propose a way to stimulate the Earth’s capacity to cure itself, as an emergency treatment for the pathology of global warming." And what might that way be? They suggest giant tubes–100 to 300 meters long, standing vertically in the world’s oceans, to draw up nutrients from the deep and create algae blooms on the surface. The algae would absorb carbon dioxide, and create compounds that would seed the formation of sunlight-reflecting clouds in the air. "Such an approach may fail, perhaps on engineering or economic grounds," they write. "And the impact on ocean acidification will need to be taken into account. "But the stakes are so high that we put forward the general concept of using the Earth system’s own energy for amelioration. The removal of 500 gigatonnes of carbon dioxide from the air by human endeavour is beyond our current technological capability. If we can’t ‘heal the planet’ directly, we may be able to help the planet heal itself." The full text of their letter is HERE. And Nature has a news piece HERE. There have been a lot of large-scale geoengineering ideas before–dropping iron into the oceans as a nutrient, launching giant sunshades into orbit–but this one seems new. Attention or derision? What ought this to bring?