As low-lying islands lacking a surrounding shallow shelf, the communities of Tuvalu are especially susceptible to changes in sea level and undissipated storms. At its highest, Tuvalu is only  above sea level. Tuvaluan leaders have been concerned about the effects of rising sea levels. It is estimated that a sea level rise of 20–40 centimetres (8–16 inches) in the next 100 years could make Tuvalu uninhabitable. A study published in 2018 estimated the change in land area of Tuvalu's nine atolls and 101 reef islands between 1971 and 2014, indicating that 75% of the islands had grown in area, with an overall increase of more than 2%. Enele Sopoaga, the Prime Minister of Tuvalu, responded to the research by stating that Tuvalu is not expanding and has gained no additional habitable land. Sopoaga, has also said that evacuating the islands is the last resort.