Ascientist notices an increase in the glycose production in the plants he is studying . what are the possible reasons ?

If u mean glucose here is ur answer

increase in the intensity (brightness) of the light that illuminates the plant leavesIncrease in the duration of light that illuminates the plant leaves

Iwould say overuse ( but not 100% sure ) in the u.s. we tend to overuse water by leaving it running, throwing it away, taking long showers, etc.