Reading Comprehension — quick quiz

Read the passage and answer the question. Passage: Climate change poses a serious threat to coastal cities around the world. Rising sea levels, caused by the melting of polar ice caps and thermal expansion of seawater, could submerge low-lying areas. Many major cities like Mumbai, New York, and Tokyo are vulnerable. Scientists predict that if current trends continue, sea levels could rise by one meter by the end of this century. This would displace millions of people and cause enormous economic losses. Governments need to invest in coastal protection measures such as sea walls and also work to reduce carbon emissions that contribute to global warming. Question: According to the passage, which of the following is NOT mentioned as a cause of rising sea levels?