Step 1 : Introduction to the question "Tuvalu threw itself behind the 350.org campaign, started by American, Bill McKibben. This is not surprising because 350.org's activities centre around which of the following, that is seen as a major threat to Tuvalu's existence?"
...Tuvalu is particularly vulnerable to any rises in sea level as its highest point is a mere 15 feet above sea level. Experts predict that, if present trends continue, the islands will become unsustainable within the next 50 years. "350" relates to carbon dioxide levels within the atmosphere and the "safe" levels, recommended by some scientists, expressed as 350 parts per million. Sea levels around Tuvalu have, in fact, been rising for the last few thousand years. In 1986, scuba divers discovered an underwater cave on the Tuvaluan island of Nanumanga which showed evidence of human activity and had, at one time, had fires lit within it. Remarkably, this cave is more than 130 feet below present sea levels and has forced experts to reconsider the point at which the islands were first populated.
