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 located in the thoracic cavity, in the portion of the chest known as the mediastenum-the region between the pleural sacs and containing all the thoracic viscera except the lungs.The pericardium is the thin sac or membrane which contains the heart and the roots of the great blood vessels.hen you refer to a body cavity, you would say the heart lies in the thorax or thoracic cavity. Within that cavity, it lies within the mediastenum, and is surrounded by the pericardium.