Final answer:
Volcanic eruptions can cool the climate by releasing gases and solids that block out sunlight. Sunspots have a minimal effect on climate and cannot explain the recent warming of Earth.
Step-by-step explanation:
Volcanic eruptions can affect climate by releasing solids and gases into the atmosphere, which can influence the climate over a period of a few years. The gases and solids released by volcanic eruptions, such as carbon dioxide and sulfur dioxide, can cool the climate by blocking out sunlight and triggering lower global temperatures. For example, the eruption of volcanoes in Iceland in 1783 caused haze-effect cooling and some of the lowest winter temperatures on record in Europe and North America.
On the other hand, sunspots, which are dark spots on the surface of the Sun, have a minimal effect on climate. While variations in solar activity can affect the upper atmosphere and regional rainfall patterns, they do not explain the global warming that has occurred in the past 50 years. Solar variability has been relatively constant since the mid-20th century and cannot account for the recent warming of Earth.