Well, the calculation makes it look easy. Problem is, sea level rise also comes hand in hand with salt water intrusion of ground water aquifers. The rise is already making a large tract of land uncultivable because of salinity. For Bangladesh, food security is a topmost economic priority. Being the resilient country it is, people will change their livelihood, agriculture pattern. The technical term for that is, 'adaptation'. So, global warming is a concern that needs to be taken seriously but we'll come top of it In Shaa Allah.