EARTH & EARTH SYSTEM

By: Bianca P. Antonio &Evita M. Basco

is the third planet from the Sun, the densest planet in the Solar System’s, the largest of the Solar System's four terrestrial planet, and the only astronomical object known to harbor life.

EARTH

According to radiometric rating and other sources of evidence, Earth formed about 4.54 billion years ago.

Earth gravitationally interacts with other objects in space, especially the Sun and the Moon. During one orbit around the Sun, Earth rotates about its axis 366.26 times, creating 365.26 solar days or one sidereal year. Earth's axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planet's surface within a period of one tropical year (365.24 solar days). The Moon is the Earth's only permanent natural satellite; their gravitational interaction causes ocean tides, stabilizes the orientation of Earth's rotational axis, and gradually slows Earth's rotational rate.

Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. 71% of Earth's surface is covered with water. The remaining 29% is land mass consisting of continents and islands that together has many lakes, rivers, and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth’s Magnetic field, and a convecting mantle that drives plate tectonics.

EARTH SYSTEMS

is the application of systems science to the Earth sciences. In particular, it considers interactions between the Earth's "spheres“ atmosphere, hydrosphere, cryosphere, geosphere, pedosphere, biosphere,and, even, the magnestosphere as well as the impact of human societies on these components. At its broadest scale, Earth system science brings together researchers across both the natural and social sciences, from fields including ecology, economics, geology, glaciology meteorology, oceanography, paleontology, sociology, and space scence.

EARTH SYSTEM SCIENCE (ESS)

Like the broader subject of systems science, Earth system science assumes a holistic view of the dynamic interaction between the Earth's spheres and their many constituent subsystems, the resulting organization and time evolution of these systems, and their stability or instability. Subsets of Earth system science include systems geology and systems ecology, and many aspects of Earth system science are fundamental to the subjects of physical geography and climate science.

Climatology and climate change have been central to Earth system science since its inception, as evidenced by the prominent place given to climate change in the early NASA reports discussed above. The Earth's climate system is a prime example of an emergent property of the whole planetary system which cannot be fully understood without regarding it as a single integrated entity.

CLIMATE SCIENCE AND EARTH SYSTEM SCIENCE

It is also a property of the system where human impacts have been growing rapidly in recent decades, lending immense importance to the successful development and advancement of Earth system science research. As just one example of the centrality of climatology to the field, leading American climatologist Michael M. Mann is the Director of one of the earliest centers for Earth system science research, the Earth System Science Center at Pennsylvania State University, and its mission statement reads, "the Earth System Science Center (ESSC) maintains a mission to describe, model, and understand the Earth's climate system".

Global change refers to planetary-scale changes in the Earth system.

More completely, the term “global change" encompasses: planetary scale changes to atmospheric circulation, ocean circulation, climate, the carbon cycle, the nitrogen cycle, the water cycle and other cycles, sea-ice changes, sea-level changes, food webs, biological diversity, pollution, health, fish stocks, and more.

GLOBAL CHANGE

Civilization is now a large driver of global change so the term includes population, the economy, resource use, energy, development, transport, communication, land use and land cover, urbanization, globalization.

Climate refers to the long-term average of the aggregation of all components of weather precipitation, temperature and cloudiness, for example. The climate system includes processes involving ocean, land and sea ice in addition to the atmosphere.

GLOBAL CHANGE AND CLIMATE

The Earth system encompasses the climate system. Many changes in Earth system functioning directly involve changes in climate. However, the Earth system includes other components and processes, biophysical and human, that are important for its functioning.

Some Earth system changes, natural or driven by humans, can have significant consequences without involving changes in climate. Global change should  not be confused with climate change; it is significantly more. indeed, climate change is part of this much larger challenge.