Earth system science (ESS) uses the study of systems science to understand Earth. It looks at how different parts of Earth, such as the atmosphere, hydrosphere, cryosphere, geosphere, pedosphere, lithosphere, biosphere, and magnetosphere, interact with each other through the movement of materials and energy. It also examines how human activities affect these parts. ESS connects scientists from many fields, including ecology, economics, geography, geology, glaciology, meteorology, oceanography, climatology, paleontology, sociology, and space science. Like systems science, ESS focuses on how Earth's parts work together, how they are arranged in space, how they change over time, and how they remain stable or become unstable. Some areas of ESS include systems geology and systems ecology. Many parts of ESS are important to the study of physical geography and climate science.

Definition

The Science Education Resource Center at Carleton College describes Earth System science as a field that combines chemistry, physics, biology, mathematics, and applied sciences to study Earth as a single, connected system. This approach helps scientists understand how physical, chemical, biological, and human activities influence Earth’s past, present, and future. Earth System science provides a scientific foundation for understanding the world and achieving long-term sustainability.

Earth System science is defined by four key features:

• Variability: Many natural patterns and changes in Earth’s systems occur over long timescales and across large areas, beyond what humans typically experience. Because Earth has been relatively stable during the recent Holocene period, much of Earth System science relies on studying Earth’s past and using models to predict future changes caused by human and natural factors.

• Life: Biological processes, such as those involving plants, animals, and microorganisms, play a significant role in how Earth’s systems function and respond to changes. These processes are essential to all parts of Earth’s systems.

• Connectivity: Processes within Earth’s systems are linked in ways that were not previously understood, often spanning great distances and depths within Earth.

• Non-linear: Earth’s systems often behave in non-linear ways, meaning small changes in factors like temperature or carbon levels can lead to sudden and large-scale changes when Earth crosses a critical point, or threshold.

History

For thousands of years, humans have wondered how the physical and living parts of Earth work together, often imagining gods and goddesses as symbols of these elements. Many ancient Greek thinkers and religious beliefs taught that Earth itself was alive.

Early scientific studies of Earth began with geology, first in the Middle East and China. These studies focused on questions like Earth's age and how mountains and oceans form. As geology became a more organized science, scientists learned more about how different parts of Earth, such as its interior, other planets, living systems, and Earth-like worlds, connect.

The ideas behind Earth System science can be traced to the work of 19th-century geographer Alexander von Humboldt. In the 20th century, scientist Vladimir Vernadsky (1863–1945) described how the biosphere—the part of Earth where life exists—acts as a powerful force that creates an unbalanced state, which helps support the variety of life on Earth.

At the same time, other scientific fields were developing the idea of systems science, partly because computers became more powerful. This led to the creation of climate models that could simulate Earth's weather and climate in detail. These models later expanded to include Earth system models (ESMs), which study parts like the cryosphere (frozen areas) and biosphere.

In 1983, NASA formed a group called the Earth System Science Committee. NASA's first reports, Earth System Science: Overview (1986) and Earth System Science: A Closer View (1988), marked an important step in formally defining Earth system science. Early writings on Earth system science, like these NASA reports, often highlighted how human activities affect Earth's systems, showing that the start of Earth system science happened around the same time as the beginning of studies on global changes.

Climate science

Climatology and climate change have always been important parts of Earth System science, as shown by their focus in early NASA reports. The Earth's climate system is an example of a system that can only be fully understood when viewed as a whole, not just as separate parts. Human activities have greatly affected this system in recent years, making Earth System science research very important. For example, the mission of one of the first Earth System science research centers, the Earth System Science Center at Pennsylvania State University, states, "The Earth System Science Center (ESSC) works to describe, model, and understand the Earth's climate system."

The Earth's climate system is made up of five parts that work together: the atmosphere (air), the hydrosphere (water), the cryosphere (ice and permafrost), the lithosphere (Earth's upper rocky layer), and the biosphere (living things). Climate is the average weather over a long time, usually 30 years, and is influenced by processes like ocean currents and wind patterns. Air and ocean movement carry heat from warm tropical areas to cooler regions. Energy from the Sun drives this movement. The water cycle also helps move energy through the climate system. In addition, chemical elements like carbon and nitrogen move between the parts of the climate system through natural cycles.

Changes in the climate system can happen because of natural causes, such as changes in sunlight or volcanic eruptions, or because of human actions. People burning fossil fuels release greenhouse gases into the atmosphere, which cause climate change. Human activities also produce cooling particles, but these have a much smaller effect than greenhouse gases. Climate changes can become stronger because of feedbacks within the climate system's parts.

Education

Earth System science is taught in advanced programs at some universities. For general education, the American Geophysical Union, along with the Keck Geology Consortium and with help from five groups in the National Science Foundation, organized a workshop in 1996 to set shared learning goals for Earth science subjects. The report said that Earth and space science fields are changing a lot, helping people see Earth as connected systems. Because of this systems approach, the report suggested creating an Earth System science curriculum with help from the National Science Foundation. In 2000, the Earth System Science Education Alliance (ESSEA) started. Today, more than 40 organizations are involved, and over 3,000 teachers have finished an ESSEA course by fall 2009.

Related concepts

Earth system law is a type of earth system governance. Earth system governance is part of earth system sciences, which are studied using social science methods. As of 2021, earth system law is still very new.