Effects of Greenhouse Gases

a) Changes to plant growth and nutrition levels
Greenhouse gases, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), have an impact on plant growth and nutrition levels. These gases trap heat in the atmosphere, leading to global warming. As a result, temperature and precipitation patterns are altered, affecting plant growth and distribution. Some of the effects include:

1. Increased Photosynthesis: Higher levels of CO2 can stimulate photosynthesis, leading to increased plant growth. This can be beneficial in certain agricultural practices.

2. Nutrient Availability: Changes in temperature and precipitation can affect the availability of essential nutrients in the soil. For example, increased rainfall can cause leaching of nutrients, making them less available to plants.

3. Altered Phenology: Rising temperatures can disrupt the timing of plant growth stages, such as flowering and fruiting. This can have cascading effects on plant-pollinator interactions and ecosystem dynamics.

b) Ozone depletion
While greenhouse gases contribute to global warming, they are not directly responsible for ozone depletion. Ozone depletion is primarily caused by the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS) used in aerosols, refrigerants, and industrial processes. These substances break down the ozone layer in the stratosphere, which protects us from harmful ultraviolet (UV) radiation.

c) Smog pollution
Smog pollution, often referred to as ground-level ozone, is not directly caused by greenhouse gases. Smog is formed when sunlight reacts with pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) emitted from vehicles, power plants, and industrial processes. However, the formation of smog can be influenced by certain weather conditions that are linked to climate change.

In summary, the correct answer is option (d) - a, b, and c. Greenhouse gases have multiple effects, including changes to plant growth and nutrition levels, ozone depletion (although not directly caused by greenhouse gases), and the potential to influence the formation of smog pollution through climate-related factors.