sentences: period is used to byproducts lite warming
docs: global_warming is heating. wave_emission is generating. sulfur_hexafluoride is greenhouse_gas. partially_blocking_sunlight has effect_of_cooling_earth photon_emission is emitting. greenhouse_effect is heating_air. global_warming is temperature_change. sunlight has effect_of_heating_earth global_warming is heating_air. heat_production is emitting.