Final answer:
Variations in weather and climate are driven by a combination of natural causes and human activities, with the latter becoming the dominant force since the mid-20th century. Changes in solar energy, volcanic eruptions, and greenhouse gases play significant roles, yet current climate change is mostly attributed to human-induced alterations such as the increased greenhouse effect.
Step-by-step explanation:
The major factor causing variation in weather and climate is a combination of natural causes, including changes in solar energy, volcanic eruptions, and natural changes in greenhouse gas concentrations. Before industrialization, these natural factors sufficiently explained climate variability. However, since the mid-20th century, the prominent driver of climate change has been human activities, notably the combustion of fossil fuels which amplify the greenhouse effect.
Climate refers to atmospheric effects that persist over long periods, while weather represents short-term variations. Human-induced climate changes have widespread impacts, such as affecting farming yields and potentially leading to significant sea-level rise due to glacier melt. Natural causes, such as Milankovitch cycles, solar activity changes, and volcanic eruptions, still play a role but cannot account for the rapid and sustained increases in carbon dioxide and global temperatures observed in recent times.
Natural influences like changes in the sun's intensity and volcanic activity, as well as internal climate system processes like ocean currents, continue to impact the climate. Yet, the evidence strongly indicates that current changes are primarily due to human influence, making it an urgent issue for global attention.