The Future

The future of Earth is rather mysterious and difficult to predict. Our planet will be affected by many things, both internal and external. Our climate will shift, as it has done for millions of years, as will the position of the continents. In approximately 4 billion years, our sun will reach the red giant stage, incinerating and possibly consuming what is left of the planet.

This page will have a look at several speculations about the planet's future.

Global Warming

Perhaps the most widely known phenominon affecting the future of Earth is global warming.

As stated on the Climate Page, scientists have found evidence of recent warming trend linked with an increased output of carbon dioxide. This increase is commonly attributed to human activity.

The effect of global warming is generally considered negative to life on Earth. By 2100, the IPCC predicts that global carbon dioxide levels will be higher than any time in the past 650,000 years. Up to 30% of recorded species may become extinct because of changes in the world's climate systems. Global warming may even affect the Earth's rotation. Expansion of oceans towards the poles could make Earth days 0.12 milliseconds shorter by 2200.[1]

While undoubtedly catastrophic for a large portion of the world's population, global warming will probably not wipe out humanity. It may even be averted by changes in human emmisions. Regardless of whether humanity survives, it will not be the end of Earth itself.

Supernova

Scientists theorise that the average lifecycle of a star like the sun is approximately 10 billion years long. In approximately 4 billion years, the sun will reach the red giant stage, possibly consuming Earth. The sun's transformation to a red giant, and eventually a white dwarf, is unavoidable, but scientists are not convinced that Earth will be consumed by it. As the sun expands, it will lose mass along the way, possibly allowing Earth to escape the predicted 1.2AU radius of the red giant. Other factors may complicate things, however. Drag from the suns outermost layers could cause Earth to drift in towards the expanding sun.

It is very difficult to account for all of the variables involved in these calculations, so more study is required before we can accurately predict what will happen to the Earth.

Even if the Earth avoids being consumed and subsequently vaporised by the red giant, it will be rendered scorched and uninhabitable. Humanity may survive by moving to a new world, or even moving the Earth itself.[2]

Further Reading: Red Giants.

These diagrams illustrate some of the processes our sun may go through when it transforms in to a red giant.

End of the Universe

Regardless of the fate of our planet, the universe itself may eventually end. There are several theories, based on the theory of the big bang, that predict the end of the universe.

The first of these theories is the 'big freeze', or heat death theory. As the universe expands, its contents may eventually reach a minimum temperature: absolute zero. Under these conditions, the transfer of energy is impossible and all life and activity in the universe will cease. This is the most widely accepted scenario for the end of the universe.

Second is the 'big rip', or finite lifespan, theory. This theory states that the density of phantom dark energy increases over time. This will cause the rate of the universe's acceleration to increase. All forms, starting with galaxies and eventually affecting all forms regardless of size, will be ripped apart, disintegrating in to unbound elementary particles and accelerating away from eachother. The end state is a singularity, as the density and expansion rate of phantom dark matter becomes infinite.

Next is the 'big crunch' theory. Since the big bang, the universe has been expanding. The big crunch theory postulates that it will eventually begin contracting, perhaps resulting in the opposite of the big bang. The entire universe could be compressed in to a singularity. One theory arising from this is that of an oscilatory universe. As the universe collapses in to a singularity, another big bang occurs and the process begins again.

These theories are all based on what we know of dark energy. Since we don't know much about it, and the dark energy present today may be a entirely different form to that present during the big bang. This makes the ultimate fate of the universe uncertain, and until we have a clear idea of the physics of dark matter, the speculation may prove false.
For more information regarding this subject, feel free to follow the source link at the bottom of the page.[3]

Bibliography.