Final answer:
The volcanoes in Hawaii are formed over a 'hot spot' and erupt in a relatively calm manner. They contribute to the creation of a long chain of islands. These volcanoes and others globally can impact the climate, generally causing a cooling effect.
Step-by-step explanation:
The volcanic activity in Hawaii arises from what is known as a hot spot in the mantle of the earth; an area where heat rises far from plate boundaries. Hawaii, being situated above one such hot spot, witnesses continued volcanic activity. These volcanoes have contributed to a chain of islands that extend over 3500 kilometers.
The significant difference between eruptions in Hawaii and others such as Mount St. Helens is due to the nature of these hot spot volcanoes. Their eruptions are less explosive and are characterized by effusive eruptions; where the lava flows out of the volcano's vent, creating relatively calmer eruptions than stratovolcanoes like Mount St. Helens. In contrast, stratovolcanoes are typically located at plate boundaries and can erupt violently due to the highly viscous magma formed from subduction zone material.
Finally, these volcanic eruptions influence our climate. Gases and solids released by volcanic eruptions including carbon dioxide, water vapor, sulfur dioxide, among others, can cause short-term climate changes. Generally, volcanic eruptions cool the climate, an example being the eruption in Iceland in 1783 which led to a global cooling effect.
Learn more about Hot Spot Volcanoes