Earth System science (ESS) is the application of systems science to the Earth. In particular, it considers interactions and 'feedbacks', through material and energy fluxes, between the Earth's sub-systems' cycles, processes and "spheres"—atmosphere, hydrosphere, cryosphere, geosphere, pedosphere, lithosphere, biosphere, and even the magnetosphere—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, geography, geology, glaciology, meteorology, oceanography, climatology, paleontology, sociology, and space science. 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 fluxes and processes, the resulting spatial organization and time evolution of these systems, and their variability, stability and 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.
The Science Education Resource Center, Carleton College, offers the following description: "Earth System science embraces chemistry, physics, biology, mathematics and applied sciences in transcending disciplinary boundaries to treat the Earth as an integrated system. It seeks a deeper understanding of the physical, chemical, biological and human interactions that determine the past, current and future states of the Earth. Earth System science provides a physical basis for understanding the world in which we live and upon which humankind seeks to achieve sustainability".
Earth System science has articulated four overarching, definitive and critically important features of the Earth System , which include:
- Variability: Many of the Earth System's natural 'modes' and variabilities across space and time are beyond human experience, because of the stability of the recent Holocene. Much Earth System science therefore relies on studies of the Earth's past behaviour and models to anticipate future behaviour in response to pressures.
- Life: Biological processes play a much stronger role in the functioning and responses of the Earth System than previously thought. It appears to be integral to every part of the Earth System.
- Connectivity: Processes are connected in ways and across depths and lateral distances that were previously unknown and inconceivable.
- Non-linear: The behaviour of the Earth System is typified by strong non-linearities. This means that abrupt change can result when relatively small changes in a 'forcing function' push the System across a 'threshold'.
For millennia, humans have speculated how the physical and living elements on the surface of the Earth combine, with gods and goddesses frequently posited to embody specific elements. The notion that the Earth, itself, is alive was a regular theme of Greek philosophy and religion. Early scientific interpretations of the Earth system began in the field of geology, initially in the Middle East and China, and largely focused on aspects such as the age of the Earth and the large-scale processes involved in mountain and ocean formation. As geology developed as a science, understanding of the interplay of different facets of the Earth system increased, leading to the inclusion of factors such as the Earth's interior, planetary geology and living systems.
In many respects, the foundational concepts of Earth System science can be seen in the holistic interpretations of nature promoted by the 19th century geographer Alexander von Humboldt. In the 20th century, Vladimir Vernadsky (1863–1945) saw the functioning of the biosphere as a geological force generating a dynamic disequilibrium, which in turn promoted the diversity of life. In the mid-1960s, James Lovelock first postulated a regulatory role for the biosphere in feedback mechanisms within the Earth system. Initially named the "Earth Feedback hypothesis", Lovelock later renamed it the Gaia hypothesis, and subsequently further developed the theory with American evolutionary theorist Lynn Margulis during the 1970s. In parallel, the field of systems science was developing across numerous other scientific fields, driven in part by the increasing availability and power of computers, and leading to the development of climate models that began to allow the detailed and interacting simulations of the Earth's weather and climate. Subsequent extension of these models has led to the development of "Earth system models" (ESMs) that include facets such as the cryosphere and the biosphere.
As an integrative field, Earth System science assumes the histories of a vast range of scientific disciplines, but as a discrete study it evolved in the 1980s, particularly at NASA, where a committee called the Earth System Science Committee was formed in 1983. The earliest reports of NASA's ESSC, Earth System Science: Overview (1986), and the book-length Earth System Science: A Closer View (1988), constitute a major landmark in the formal development of Earth system science. Early works discussing Earth system science, like these NASA reports, generally emphasized the increasing human impacts on the Earth system as a primary driver for the need of greater integration among the life and geo-sciences, making the origins of Earth system science parallel to the beginnings of global change studies and programs.
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, that is, one which cannot be fully understood without regarding it as a single integrated entity. It is also a 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 E. 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".
Relationship to the Gaia hypothesis
The Gaia hypothesis posits that living systems interact with physical components of the Earth system to form a self-regulating whole that maintains conditions that are favourable for life. Developed initially by James Lovelock, the hypothesis attempts to account for key features of the Earth system, including the long period (several billion years) of relatively favourable climatic conditions against a backdrop of steadily increasing solar radiation. Consequently, the Gaia hypothesis has important implications for Earth system science, as noted by NASA's Director for Planetary Science, James Green, in October 2010: "Dr. Lovelock and Dr. Margulis played a key role in the origins of what we now know as Earth system science".
Although the Gaia hypothesis and Earth system science take an interdisciplinary approach to studying systems operations on a planetary-scale, they are not synonymous with one another. A number of potential Gaian feedback mechanisms have been proposed—such as the CLAW hypothesis—but the hypothesis does not have universal support within the scientific community, though it remains an active research topic.
Earth System science can be studied at a postgraduate level at some universities, with notable programs at such institutions as the University of California, Irvine, Pennsylvania State University, and Stanford University. In general education, the American Geophysical Union, in cooperation with the Keck Geology Consortium and with support from five divisions within the National Science Foundation, convened a workshop in 1996, "to define common educational goals among all disciplines in the Earth sciences". In its report, participants noted that, "The fields that make up the Earth and space sciences are currently undergoing a major advancement that promotes understanding the Earth as a number of interrelated systems". Recognizing the rise of this systems approach, the workshop report recommended that an Earth System science curriculum be developed with support from the National Science Foundation. In 2000, the Earth System Science Education Alliance was begun, and currently includes the participation of 40+ institutions, with over 3,000 teachers having completed an ESSEA course as of fall 2009".
- Biosphere – The global sum of all ecosystems on Earth
- Earth science – all fields of natural science related to Earth.
- Earth System Science Partnership
- Earth systems engineering and management
- Ecological economics
- Ecosystem ecology – The study of living and non-living components of ecosystems and their interactions
- Gaia hypothesis – Hypothesis that living organisms interact with their surroundings in a self-regulating system
- Geosphere – A collective name for the lithosphere, the hydrosphere, the cryosphere, and the atmosphere
- Global change
- Planetary boundaries
- Systems geology
- Stanley, Steven M. (2005). Earth System History. Macmillan. ISBN 9780716739074.
- Jacobson, Michael; et al. (2000). Earth System Science, From Biogeochemical Cycles to Global Changes (2nd ed.). London: Elsevier Academic Press. ISBN 978-0123793706. Retrieved 7 September 2015.
- Kump, Lee; et al. (2004). The Earth System (2nd edition). New Jersey: Prentice Hall. ISBN 978-0-13-142059-5.
- Christiansen, E.H.; Hamblin, W.K. (2014). Dynamic Earth. Jones & Bartlett Learning. ISBN 9781449659028.
- Harris, Charles; Murton, Julian B. (2005). Cryospheric Systems: Glaciers and Permafrost. Geological Society of London. ISBN 9781862391758.
- Cockell, Charles (28 February 2008). An Introduction to the Earth-Life System. Cambridge University Press. ISBN 9780521493918.
- Ohtani, Shin-ichi; Fujii, Ryoichi; Hesse, Michael; Lysak, Robert L. (2000). Magnetospheric Current Systems. American Geophysical Union. ISBN 9780875909769.
- Ehlers, Eckart; Moss, C.; Krafft, Thomas (2006). Earth System Science in the Anthropocene: Emerging Issues and Problems. Springer Science+Business Media. ISBN 9783540265900.
- Butz, Stephen D. (2004). Science of Earth Systems. Thomson Learning. ISBN 978-0766833913.
- Hergarten, Stefan (2002). Self-Organized Criticality in Earth Systems. Springer-Verlag. ISBN 9783540434528.
- Tsonis, Anastasios A.; Elsner, James B. (2007). Nonlinear Dynamics in Geosciences. Springer Science+Business Media. ISBN 9780387349183.
- Neugebauer, Horst J.; Simmer, Clemens (2003). Dynamics of Multiscale Earth Systems. Springer. ISBN 9783540417965.
- Merritts, Dorothy; De Wet, Andrew; Menking, Kirsten (1998). Environmental Geology: An Earth System Science Approach. W. H. Freeman. ISBN 9780716728344.
- Martin, Ronald (2011). Earth's Evolving Systems: The History of Planet Earth. Jones & Bartlett Learning. ISBN 9780763780012.
- Wilkinson, David M. (2006). Fundamental Processes in Ecology: An Earth Systems Approach. Oxford University Press. ISBN 9780198568469.
- Pidwirny, Michael; Jones, Scott (1999–2015). "Physical Geography".
- Marsh, William M.; Kaufman, Martin M. (2013). Physical Geography: Great Systems and Global Environments. Cambridege University Press. ISBN 9780521764285.
- Cornell, Sarah E.; Prentice, I. Colin; House, Joanna I.; Downy, Catherine J. (2012). Understanding the Earth System: Global Change Science for Application. Cambridge University Press. ISBN 9781139560542.
- "Earth System Science in a Nutshell". Carleton College. Retrieved 10 March 2009.
- Tickell, Crispin (2006). "Earth Systems Science: Are We Pushing Gaia Too Hard?". 46th Annual Bennett Lecture - University of Leicester. London: University of Leicester. Retrieved 21 September 2015.
- Fielding H. Garrison, An introduction to the history of medicine, W.B. Saunders, 1921.
- Asimov, M. S.; Bosworth, Clifford Edmund (eds.). The Age of Achievement: A.D. 750 to the End of the Fifteenth Century : The Achievements. History of civilizations of Central Asia. pp. 211–214. ISBN 978-92-3-102719-2.
- Jackson, Stephen T. "Alexander von Humboldt and the General Physics of the Earth" (PDF). Science. 324. pp. 596–597.
- Kasting, James (24 April 2014). "The Gaia Hypothesis is Still Giving Us Feedback". Retrieved 25 July 2015.
- Schneider, Stephen; Boston, Penelope (1992). "The Gaia Hypothesis and Earth System Science" (PDF). University of Florida. MIT Press. Retrieved 21 September 2015.
- Highfield, Roger (April 2014). "Unlocking Lovelock, science's greatest maverick". The Telegraph. The Telegraph. Retrieved 25 July 2015.
- Gribbon, John and Mary (2009). James Lovelock: In Search of Gaia. Princeton, NJ: Princeton University Press.
- Edwards, P.N. (2010). "History of climate modelling" (PDF). Wiley Interdisciplinary Reviews: Climate Change. 2: 128–139. doi:10.1002/wcc.95. hdl:2027.42/79438.
- Washington, W.M.; Buja, L.; Craig, A. (2009). "The computational future for climate and Earth system models: on the path to petaflop and beyond". Phil. Trans. Roy. Soc. A. 367 (1890): 833–846. Bibcode:2009RSPTA.367..833W. doi:10.1098/rsta.2008.0219. PMID 19087933.
- Mooney, Harold; et al. (26 February 2013). "Evolution of natural and social science interactions in global change research programs". Proceedings of the National Academy of Sciences. 110 (Supplement 1, 3665–3672): 3665–3672. Bibcode:2013PNAS..110.3665M. doi:10.1073/pnas.1107484110. PMC 3586612. PMID 23297237.
- Mann, Michael. "Earth System Science Center". Penn State University. Retrieved 25 July 2015.
- NASA, 50th Anniversary Symposium: Seeking Signs of Life. "Opening Keynote - 'Exobiology in the Beginning'". livestream.com. Retrieved 7 September 2015.
- Charlson, R. J., Lovelock, J. E., Andreae, M. O. and Warren, S. G. (1987). "Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate". Nature. 326 (6114): 655–661. Bibcode:1987Natur.326..655C. doi:10.1038/326655a0.CS1 maint: multiple names: authors list (link)
- Kirchner, James W. (2002), "Toward a future for Gaia theory", Climatic Change, 52 (4): 391–408, doi:10.1023/a:1014237331082
- Volk, Tyler (2002), "The Gaia hypothesis: fact, theory, and wishful thinking", Climatic Change, 52 (4): 423–430, doi:10.1023/a:1014218227825
- Beerling, David (2007). The Emerald Planet: How plants changed Earth's history. Oxford: Oxford University Press. ISBN 978-0-19-280602-4.
- Tyrrell, Toby (2013), On Gaia: A Critical Investigation of the Relationship between Life and Earth, Princeton: Princeton University Press, ISBN 9780691121581
- Hamilton, W.D.; Lenton, T.M. (1998). "Spora and Gaia: how microbes fly with their clouds". Ethology Ecology & Evolution. 10 (1): 1–16. doi:10.1080/08927014.1998.9522867. Archived from the original (PDF) on 23 July 2011.
- Lenton, TM; Lovelock, JE (2000). "Daisyworld is Darwinian: Constraints on adaptation are important for planetary self-regulation". Journal of Theoretical Biology. 206 (1): 109–14. doi:10.1006/jtbi.2000.2105. PMID 10968941.
- Kirchner, James W. (2003). "The Gaia Hypothesis: Conjectures and Refutations". Climatic Change. 58 (1–2): 21–45. doi:10.1023/A:1023494111532.
- Quinn, P.K.; Bates, T.S. (2011), "The case against climate regulation via oceanic phytoplankton sulphur emissions", Nature, 480 (7375): 51–56, Bibcode:2011Natur.480...51Q, doi:10.1038/nature10580, PMID 22129724
- "Shaping the Future of Undergraduate Earth Science Education". American Geophysical Union. Archived from the original on 16 September 2008. Retrieved 12 May 2009.
- "Earth System Science Education Alliance". Retrieved 25 July 2015.