Final answer:
Human activities such as burning fossil fuels, deforestation, and the use of fertilizers and pesticides can have negative effects on the environment, including climate change, increased carbon dioxide levels, and soil pollution.
Step-by-step explanation:
Human activities can have various effects on the environment. Burning fossil fuels, such as coal, oil, and natural gas, releases greenhouse gases into the air, contributing to climate change. Deforestation reduces the number of trees that absorb carbon dioxide and release oxygen, leading to an increase in carbon dioxide levels in the atmosphere. The use of fertilizers and pesticides in agriculture can pollute fertile soil with toxic chemicals, making it vulnerable to erosion.