Thomas observed a graph showing changes in Earth's glaciers. After looking at the graph, he came to a conclusion about Earth's climate and stability. Based on the graph below, what conclusion did Thomas make about Earth's climate? Earth's climate appears to be irregularly cooling and warming.

Earth's climate appears to be cooling over a period of time.

Earth's climate goes through long-term cycles of cooling and warming.

Earth's climate goes through short-term cycles of cooling and warming.