Complex sentence: Arctic shrinkage is the decrease in size of the Arctic region (as defined by the 10 ° C (50 ° F) July isotherm), due to changes in the regional climate as a result of global warming.
Split into simpler sentences: Arctic shrinkage is the decrease in size of the Arctic region (as defined by the 10 ° C (50 ° F) July isotherm). This is caused by to changes in the regional climate as a result of global warming.