Fast Forward

Scientists have calculated that the sun is approximately halfway through its lifetime. This means that humans have another 5 billion years in which the sun will naturally shed light on our planet…but will we survive that long? Many things must be considered when thinking about what life will look like when the sun reaches the end of its life.

While life emerged relatively quickly after the formation of the Earth, it was an additional 3.3 billion years until multicellular organisms thrived. Only 40,000 years ago humans, as we know them, entered the scene.

Yet, within the past hundred years or so humans have managed to raise the global average temperature by at least 1 degree Celsius. This may not seem dramatic, but regional changes can be even greater. Rainfall patterns have changed; potentially the cause of droughts and, by proxy, wildfires, and more violent storms, in all regards, from hurricanes to blizzards. The melting of ice caps is not only destroying the ecosystems at the poles but is also affecting sea levels across the globe and changing the composition of the water in our oceans. The human race continuing along its current path of energy consumption could be enough to drastically change what life looks like on our planet in a few billion years.

 

This graph from the textbook shows the increase in global temperature across recent centuries.

 

We also must consider external sources of destruction. Asteroids and comets are not a frequent threat to our planet, but the extensive lifetime that our sun has left increases the likelihood that collisions will pose a grave threat at some point in the future. Current calculations of the frequency of impacts spell trouble for the human race if we survive long enough to see them happen. An impact that would likely cause mass extinction will typically happen no more than once every 100 million years. Additionally, an impactor that would cause widespread devastation and climate change could happen as often as once every million years or so. If humans plan to exist on Earth for as long as possible, we will need to devise a plan for how to deal with the almost certainty of a devastating impact

 

This graph shows the frequency with which different sized impactors are likely to hit Earth.

 

The final, and most controllable, factor to consider is the potential that we will physically destroy ourselves. With tensions between countries and different groups already so high and widespread nuclear weapon capabilities, it’s debatable whether humans will live to see these other dangers come to fruition.

All things considered, how long do you think we’ll last?

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