From Harvard Gazette (US) : “Earth may have been a water world 3 billion years ago”

From Harvard Gazette (US)


Harvard University (US)

Calculations show that Earth’s oceans may have been 1 to 2 times bigger than previously thought and the planet may have been completely covered in water. Credit: Alec Brenner/Harvard University.

Harvard scientists calculate early ocean may have been 1 to 2 times bigger.

April 30, 2021
Juan Siliezar

In 1995, Universal Studios released what was, at the time, the most expensive movie ever made: Waterworld, a film set in the distant future where the planet Earth was almost completely covered in water and its remaining inhabitants could only dream of mythic dry land. Well, take away the future part, the exorbitant budget, the chain-smoking pirates, and the gill-sporting Kevin Costner and the movie may have been onto something.

According to a new, Harvard-led study, geochemical calculations about the interior of the planet’s water storage capacity suggests Earth’s primordial ocean 3 to 4 billion years ago may have been one to two times larger than it is today, and possibly covered the planet’s entire surface.

“It depends on the conditions and parameters we look at in the model, such as the height and distribution of the continents, but the primordial ocean could have flooded more than 70, 80, and even 90 percent of the early continents,” said Junjie Dong, a Ph.D. student in Earth and Planetary Sciences at the Graduate School of Arts and Sciences, who led the study. “In the extreme scenarios, if we have an ocean that is two times larger than the amount of water we have today, that might have completely flooded the land masses we had on the surface of the early Earth.”

The research was published in AGU Advances earlier this month. It challenges long-held assumptions that Earth’s ocean volume hasn’t changed too much since the planet’s formation. At its root, the paper delves into understanding the origins of water and the history of how its bodies have evolved.

“In the geology community, biology community, and even in the astronomy community, they are all interested in the origins of life, and water is one of the most important key elements that has to be considered,” Dong said.

Researchers weren’t looking for signs of liquid water, but its chemical equivalent, oxygen and hydrogen atoms, which bond to the interior of the planet. They compiled all the data in the scientific literature they could find on minerals that hold these signs and used the figures to calculate how much water there could be in the Earth’s mantle, which makes up the bulk of the planet’s interior. That number is referred to as the planet’s mantle water storage capacity. It changes as the interior of the planet continues to cool.

The group calculated what that number could be today and how much could have been stored a few billion years ago to see how the number had changed. The capacity back then was significantly less.

Scientists then compared those numbers to geochemical estimates of how much water is in the mantle today. Analysis found that the actual water content today is likely higher than the maximum water capacity of the mantle a few billion years ago, meaning the water today wouldn’t have been able to fit in the mantle billions of years ago. This suggests the water was someplace else — on the world’s surface. According to the researchers’ calculations the amount of water that could have gone down into the Earth’s mantle could potentially be as much as all the present-day oceans combined.

“There has been water falling into the Earth’s interior over time, which makes sense because with plate tectonics you have some of the plates on the Earth’s surface that subduct and go down into the interior and bring water down with them,” said Rebecca Fischer, the Clare Boothe Luce Assistant Professor of Earth and Planetary Sciences and the study’s other lead author. “There’s not really anywhere that water could come from besides the oceans on the surface, so that implies that the oceans had to have been larger in the past.”

The study isn’t the first to suggest Earth could have been a water world, but the researchers believe it to be the first offering quantitative evidence based on the water storage capacity of the mantle.

The researchers point out some caveats in the study, the main one being that data on the minerals used to determine the amount of water in the planet’s mantle is limited when it comes to its deeper parts, which go down thousands of kilometers.

In their next project, Dong and Fischer are looking toward Mars. They plan to use a similar model to determine the amount of water that could have been stored in its interior.

“Evidence seems to point out that the early Mars had a significant amount of water on its surface,” Dong said. “We want to investigate whether that surface water had some relations with the water that could possibly have been stored in its interior.”

See the full article here .


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Harvard University campus

Harvard University (US) is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s bestknown landmark.

Harvard University (US) has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

The Massachusetts colonial legislature, the General Court, authorized Harvard University (US)’s founding. In its early years, Harvard College primarily trained Congregational and Unitarian clergy, although it has never been formally affiliated with any denomination. Its curriculum and student body were gradually secularized during the 18th century, and by the 19th century, Harvard University (US) had emerged as the central cultural establishment among the Boston elite. Following the American Civil War, President Charles William Eliot’s long tenure (1869–1909) transformed the college and affiliated professional schools into a modern research university; Harvard became a founding member of the Association of American Universities in 1900. James B. Conant led the university through the Great Depression and World War II; he liberalized admissions after the war.

The university is composed of ten academic faculties plus the Radcliffe Institute for Advanced Study. Arts and Sciences offers study in a wide range of academic disciplines for undergraduates and for graduates, while the other faculties offer only graduate degrees, mostly professional. Harvard has three main campuses: the 209-acre (85 ha) Cambridge campus centered on Harvard Yard; an adjoining campus immediately across the Charles River in the Allston neighborhood of Boston; and the medical campus in Boston’s Longwood Medical Area. Harvard University (US)’s endowment is valued at $41.9 billion, making it the largest of any academic institution. Endowment income helps enable the undergraduate college to admit students regardless of financial need and provide generous financial aid with no loans The Harvard Library is the world’s largest academic library system, comprising 79 individual libraries holding about 20.4 million items.

Harvard University (US) has more alumni, faculty, and researchers who have won Nobel Prizes (161) and Fields Medals (18) than any other university in the world and more alumni who have been members of the U.S. Congress, MacArthur Fellows, Rhodes Scholars (375), and Marshall Scholars (255) than any other university in the United States. Its alumni also include eight U.S. presidents and 188 living billionaires, the most of any university. Fourteen Turing Award laureates have been Harvard affiliates. Students and alumni have also won 10 Academy Awards, 48 Pulitzer Prizes, and 108 Olympic medals (46 gold), and they have founded many notable companies.


Harvard University (US) was established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. In 1638, it acquired British North America’s first known printing press. In 1639, it was named Harvard College after deceased clergyman John Harvard, an alumnus of the University of Cambridge(UK) who had left the school £779 and his library of some 400 volumes. The charter creating the Harvard Corporation was granted in 1650.

A 1643 publication gave the school’s purpose as “to advance learning and perpetuate it to posterity, dreading to leave an illiterate ministry to the churches when our present ministers shall lie in the dust.” It trained many Puritan ministers in its early years and offered a classic curriculum based on the English university model—many leaders in the colony had attended the University of Cambridge—but conformed to the tenets of Puritanism. Harvard University (US) has never affiliated with any particular denomination, though many of its earliest graduates went on to become clergymen in Congregational and Unitarian churches.

Increase Mather served as president from 1681 to 1701. In 1708, John Leverett became the first president who was not also a clergyman, marking a turning of the college away from Puritanism and toward intellectual independence.

19th century

In the 19th century, Enlightenment ideas of reason and free will were widespread among Congregational ministers, putting those ministers and their congregations in tension with more traditionalist, Calvinist parties. When Hollis Professor of Divinity David Tappan died in 1803 and President Joseph Willard died a year later, a struggle broke out over their replacements. Henry Ware was elected to the Hollis chair in 1805, and the liberal Samuel Webber was appointed to the presidency two years later, signaling the shift from the dominance of traditional ideas at Harvard to the dominance of liberal, Arminian ideas.

Charles William Eliot, president 1869–1909, eliminated the favored position of Christianity from the curriculum while opening it to student self-direction. Though Eliot was the crucial figure in the secularization of American higher education, he was motivated not by a desire to secularize education but by Transcendentalist Unitarian convictions influenced by William Ellery Channing and Ralph Waldo Emerson.

20th century

In the 20th century, Harvard University (US)’s reputation grew as a burgeoning endowment and prominent professors expanded the university’s scope. Rapid enrollment growth continued as new graduate schools were begun and the undergraduate college expanded. Radcliffe College, established in 1879 as the female counterpart of Harvard College, became one of the most prominent schools for women in the United States. Harvard University (US) became a founding member of the Association of American Universities in 1900.

The student body in the early decades of the century was predominantly “old-stock, high-status Protestants, especially Episcopalians, Congregationalists, and Presbyterians.” A 1923 proposal by President A. Lawrence Lowell that Jews be limited to 15% of undergraduates was rejected, but Lowell did ban blacks from freshman dormitories.

President James B. Conant reinvigorated creative scholarship to guarantee Harvard University (US)’s preeminence among research institutions. He saw higher education as a vehicle of opportunity for the talented rather than an entitlement for the wealthy, so Conant devised programs to identify, recruit, and support talented youth. In 1943, he asked the faculty to make a definitive statement about what general education ought to be, at the secondary as well as at the college level. The resulting Report, published in 1945, was one of the most influential manifestos in 20th century American education.

Between 1945 and 1960, admissions were opened up to bring in a more diverse group of students. No longer drawing mostly from select New England prep schools, the undergraduate college became accessible to striving middle class students from public schools; many more Jews and Catholics were admitted, but few blacks, Hispanics, or Asians. Throughout the rest of the 20th century, Harvard became more diverse.

Harvard University (US)’s graduate schools began admitting women in small numbers in the late 19th century. During World War II, students at Radcliffe College (which since 1879 had been paying Harvard University (US) professors to repeat their lectures for women) began attending Harvard University (US) classes alongside men. Women were first admitted to the medical school in 1945. Since 1971, Harvard University (US) has controlled essentially all aspects of undergraduate admission, instruction, and housing for Radcliffe women. In 1999, Radcliffe was formally merged into Harvard University (US).

21st century

Drew Gilpin Faust, previously the dean of the Radcliffe Institute for Advanced Study, became Harvard University (US)’s first woman president on July 1, 2007. She was succeeded by Lawrence Bacow on July 1, 2018.