With the development of science,scientists have discovered more about the world.(1)____________________________.No matter what action is taken, scientists say there are already enough greenhouse gases in the atmosphere to cause a major warming.As a result,scientists and government officials are focusing on how society might adapt to rising sea levels,changing agricultural zones, changing climates and other problems.(2)___________________________________________________.Agricultural researchers are developing heat-resistant and draught-resistant crops that might replace traditional crops if the climate changes.How long it will take for maximum warming to be reached is uncertain because the oceans slow such warming.Most scientists expect the maximum warming to take place by the second half of this century.(3)____________________________________________.Some leading experts regard a rise of 1 meter,a little more than three feet.