Some 56 million years ago the earth underwent an extreme climate change event. A surge of carbon dioxide levels sent already warm global temperatures soaring. With sea levels 220 feet higher than now and temperatures 5-9 degrees warmer than during the peak greenhouse (Paleocene) period, a freshwater sea formed around the north pole. The nitrogen-fixing capability of Azolla and its symbiont Anabaena has led to its widespread use as a fertiliser, especially in parts of Southeast Asia. The plant has bolstered agricultural productivity in China for over 1,000 years and helps Thai farmers improve their rice production today.
