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:
The heart is a hollow, muscular organ located between the lungs and underneath the breastbone. A muscular wall divides the heart into two sides â the right side and the left side. Each side has two chambers. The two upper chambers of the heart are called the atria. The atria are the filling chambers.