why is the use of fossil fuels not a long term solution to the worlds energy needs.

Well, we will run out of fossil fuel first of all. It is by definition not "long term" because we are using it up faster than plants are turning into coal and oil and even gas.

However there are more immediate obvious problems such as air pollution and land pollution and water pollution. Medium term you have the warming effect of increasing concentrations of CO2 and Methane(natural gas) in the atmosphere leading to reduced heat radiation from earth and therefore rising temperature.

For one, there is not an infinite supply. Secondly, they contribute to increased CO2 in the atmosphere and other pollution.

The use of fossil fuels, such as coal, oil, and natural gas, as a primary source of energy has been prevalent for many years. However, it is not a long-term sustainable solution for several reasons:

1. Limited Availability: Fossil fuels are finite resources that took millions of years to form. Once these reserves are depleted, they cannot be replenished within a human timescale. As a result, we are consuming fossil fuels at a much faster rate than they are being created, leading to their eventual depletion.

2. Environmental Impact: Burning fossil fuels releases substantial amounts of carbon dioxide (CO2), a greenhouse gas that contributes to climate change. The excessive accumulation of CO2 in the atmosphere is causing global warming, which leads to rising sea levels, extreme weather events, and other detrimental effects on ecosystems and human health.

3. Air Pollution: The combustion of fossil fuels also releases various pollutants, such as nitrogen oxides (NOx), sulfur dioxide (SO2), and particulate matter, which contribute to air pollution. These pollutants have adverse effects on air quality and human respiratory health, leading to respiratory diseases, cardiovascular problems, and increased mortality rates.

4. Renewable Energy Alternatives: The development and adoption of renewable energy sources, such as solar, wind, hydropower, and geothermal, offer sustainable alternatives to fossil fuels. Unlike fossil fuels, these sources are abundant, indefinitely available, and have significantly less impact on the environment. Furthermore, advancements in renewable energy technologies have led to cost reductions, making them increasingly economically viable.

To address the world's long-term energy needs, transitioning away from fossil fuels towards renewable energy sources is crucial. This requires investing in research and development, adopting supportive policies, and promoting energy efficiency and conservation measures to ensure a sustainable and cleaner energy future.