Future of Earth

These include the chemistry at Earth's surface, the cooling rate of the planet's interior, gravitational interactions with other objects in the Solar System, and a steady increase in the Sun's luminosity.

[8][9] Over time intervals of hundreds of millions of years, random celestial events pose a global risk to the biosphere, which can result in mass extinctions.

[11] The luminosity of the Sun will steadily increase, causing a rise in the solar radiation reaching Earth and resulting in a higher rate of weathering of silicate minerals.

[14] Then, in about 2–3 billion years, the planet's magnetic dynamo may cease, causing the magnetosphere to decay, leading to an accelerated loss of volatiles from the outer atmosphere.

Risks that humans pose to themselves include climate change, the misuse of nanotechnology, a nuclear holocaust, warfare with a programmed superintelligence, a genetically engineered disease, or a disaster caused by a physics experiment.

Similarly, several natural events may pose a doomsday threat, including a highly virulent disease, the impact of an asteroid or comet, runaway greenhouse effect, and resource depletion.

The last surviving structures would most likely be open-pit mines, large landfills, major highways, wide canal cuts, and earth-fill flank dams.

[26] A close stellar encounter could cause a significant reduction in the perihelion distances of comets in the Oort cloud—a spherical region of icy bodies orbiting within half a light-year of the Sun.

[30] Based on results from the Gaia telescope's second data release from April 2018, an estimated 694 stars will approach the Solar System to less than 5 parsecs in the next 15 million years.

[31] The energy released from the impact of an asteroid or comet with a diameter of 5–10 km (3–6 mi) or larger is sufficient to create a global environmental disaster and cause a statistically significant increase in the number of species extinctions.

Among the deleterious effects resulting from a major impact event is a cloud of fine dust ejecta blanketing the planet, blocking some direct sunlight from reaching the Earth's surface thus lowering land temperatures by about 15 °C (27 °F) within a week and halting photosynthesis for several months (similar to a nuclear winter).

On average, a supernova explosion occurs within 32 light-years once every few hundred million years, resulting in a depletion of the ozone layer lasting several centuries.

Computer simulations of the Solar System's evolution over the next five billion years suggest that there is a small (less than 1%) chance that a collision could occur between Earth and either Mercury, Venus, or Mars.

The primary astronomical drivers are a higher than normal orbital eccentricity, a low axial tilt (or obliquity), and the alignment of the northern hemisphere's summer solstice with the aphelion.

At some point, perturbation effects will probably cause chaotic variations in the obliquity of the Earth, and the axial tilt may change by angles as high as 90° from the plane of the orbit.

In the introversion model, the younger, interior, Atlantic Ocean becomes preferentially subducted and the current migration of North and South America is reversed.

In the extroversion model, the older, exterior, Pacific Ocean remains preferentially subducted and North and South America migrate toward eastern Asia.

[59] Christopher Scotese and his colleagues have mapped out the predicted motions several hundred million years into the future as part of the Paleomap Project.

[55] In their scenario, 50 million years from now the Mediterranean Sea may vanish, and the collision between Europe and Africa will create a long mountain range extending to the current location of the Persian Gulf.

In 1992, Hoffman predicted that the continents of North and South America would continue to advance across the Pacific Ocean, pivoting about Siberia until they begin to merge with Asia.

[75] The loss of the magnetosphere will cause an increase in erosion of light elements, particularly hydrogen, from the Earth's outer atmosphere into space, resulting in less favorable conditions for life.

[81][83][84][85] Researchers at Caltech have suggested that once C3 plants die off, the lack of biological production of oxygen and nitrogen will cause a reduction in Earth's atmospheric pressure, which will counteract the temperature rise, and allow enough carbon dioxide to persist for photosynthesis to continue.

[13] Plants—and, by extension, animals—could survive longer by evolving other strategies such as requiring less carbon dioxide for photosynthetic processes, becoming carnivorous, adapting to desiccation, or associating with fungi.

[12] Before this happens, it is expected that life would concentrate at refugia of lower temperatures such as high elevations where less land surface area is available, thus restricting population sizes.

Smaller animals would survive better than larger ones because of lesser oxygen requirements, while birds would fare better than mammals thanks to their ability to travel large distances looking for cooler temperatures.

Even if sufficient oxygen were to remain in the atmosphere through the persistence of some form of photosynthesis, the steady rise in global temperature would result in a gradual loss of biodiversity.

This process would start with the loss of freshwater species and conclude with invertebrates,[12] particularly those that do not depend on living plants such as termites or those near hydrothermal vents such as worms of the genus Riftia.

[14] With no water to serve as a lubricant, plate tectonics would likely stop and the most visible signs of geological activity would be shield volcanoes located above mantle hotspots.

If all of the water on Earth has evaporated by this point (via the "moist greenhouse" at ~1 Gyr from now), the planet will stay in the same conditions with a steady increase in the surface temperature until the Sun becomes a red giant.

[104]: IIC After fusing helium in its core to carbon, the Sun will begin to collapse again, evolving into a compact white dwarf star after ejecting its outer atmosphere as a planetary nebula.

A dark gray and red sphere representing the Earth lies against a black background to the right of an orange circular object representing the Sun
Conjectured illustration of the scorched Earth after the Sun has entered the red giant phase, about 5–7 billion years from now [ 1 ]
Horne foundry copper smelter in Rouyn-Noranda , Canada, graphically demonstrating human-generated gaseous emissions
Anti-nuclear weapons protest march in Oxford , 1980
The Barringer Meteorite Crater in Flagstaff , Arizona , showing evidence of the impact of celestial objects upon Earth
An artist's impression of ice age Earth at glacial maximum.
A small gray circle at the top represents the Moon. A green circle centered in a blue ellipse represents the Earth and its oceans. A curved arrow shows the counterclockwise direction of the Earth's rotation, resulting in the long axis of the ellipse being slightly out of alignment with the Moon.
The rotational offset of the tidal bulge exerts a net torque on the Moon, boosting it while slowing the Earth's rotation (not to scale).
An irregular green shape against a blue background represents Pangaea.
Pangaea was the last supercontinent to form before the present.
A rough approximation of Pangaea Ultima, one of the four models for a future supercontinent
Evolution of the Sun's luminosity , radius and effective temperature compared to the present Sun. After Ribas (2010). [ 78 ]
In the far future, most of Earth's land will likely be a barren desert, like this location in White Desert National Park , Egypt.
Light brown clouds wrap around a planet, as seen from space.
The atmosphere of Venus is in a "super-greenhouse" state. Earth in a few billion years could likely resemble present Venus.
A large red disk represents the Sun as a red giant. An inset box shows the current Sun as a yellow dot.
The size of the current Sun (now in the main sequence ) compared to its estimated size during its red giant phase
The Helix nebula , a planetary nebula similar to what the Sun will produce in 8 billion years