to put it in very "simple" terms
more pollution = traps more heat in the atmosphere coming from the sun
more heat = warmer temperatures
warmer temperatures = melting glaciers/ice that would normally stay as ice all year round
melting ice = more water in ocean
more water= higher sea level
higher sea level = flooding in coastal areas
if flooding is high enough, pretty much reduced space on islands and thus extreme crowding or displaced people thus meaning a refugee crisis
