Nature, in the broadest sense, is the natural, physical, material world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are part of nature, human activity is often understood as a separate category from other natural phenomena.[1]
Well the insects eat the plant and the small animals eat the insects and so on.if the insects die the food chain is broken.
The burning of fossil fuels releases carbon dioxide and other greenhouse gases these carbon emissions raise global temperatures by trapping solar energy in the atmosphere.