In Earthâs history before the Industrial Revolution, Earthâs climate changed due to natural causes not related to human activity. Most often, global climate has changed because of variations in sunlight. Tiny wobbles in Earthâs orbit altered when and where sunlight falls on Earthâs surface.e know this because scientists closely monitor the natural and human activities that influence climate with a fleet of satellites and surface instruments. Remote meteorological stations (left) and orbiting satellites (right) help scientists monitor the causes and effects of global warming.
The heart is a muscular organ about the size of a fist, located just behind and slightly left of the breastbone. The heart pumps blood through the network of arteries and veins called the cardiovascular system.The heart has four chambers:he heart is a muscular organ about the size of a fist, located just behind and slightly left of the breastbone. The heart pumps blood through the network of arteries and veins called the cardiovascular system. The heart has four chambers:
Anatomy of the Heart. Your heart is located under your ribcage in the center of your chest between your right and left lungs. Its muscular walls beat, or contract, pumping blood to all parts of your body. The size of your heart can vary depending on your age, size, and the condition of your heart. A normal, healthy, adult heart usually is the size of an average clenched adult fist. Some diseases can cause the heart to enlarge.