A simple explanation of global warming and climate change - in less than 100 words!

It is greenhouse gases that keep the Earth some 30 degrees warmer than the moon.  As we have continued to produce more of those gases the planet has become warmer.  That warming causes the oceans to rise through thermal expansion and the melting of land based ice.  The warmer planet also increases evaporation from the land causing longer droughts.  That same evaporation puts more moisture into the air, which then leads to heavier rain falls and heavier snow falls.  Finally, the increased temperature and the increased moisture supercharges our atmosphere giving us more powerful storms.