How long the world exists

Observational or experimental evidence is hard to come by. Instead, I explored the same question through modelling. Using a computer program designed to simulate climate evolution on planets in general not just Earth , I first generated , planets , each with a randomly different set of climate feedbacks. Climate feedbacks are processes that can amplify or diminish climate change — think for instance of sea-ice melting in the Arctic, which replaces sunlight-reflecting ice with sunlight-absorbing open sea, which in turn causes more warming and more melting.

In order to investigate how likely each of these diverse planets was to stay habitable over enormous geological timescales, I simulated each times. Each time the planet started from a different initial temperature and was exposed to a randomly different set of climate events.

These events represent climate-altering factors such as supervolcano eruptions like Mount Pinatubo but much much larger and asteroid impacts like the one that killed the dinosaurs. The simulation results give a definite answer to this habitability problem, at least in terms of the importance of feedbacks and luck. It was very rare in fact, just one time out of , for a planet to have such strong stabilising feedbacks that it stayed habitable all times, irrespective of the random climate events.

In fact, most planets that stayed habitable at least once, did so fewer than ten times out of On nearly every occasion in the simulation when a planet remained habitable for 3 billion years, it was partly down to luck.

At the same time, luck by itself was shown to be insufficient. Ask Smithsonian The Earth is very old. But how old, exactly? And how can we know with any degree of confidence?

In fact, less today than 40 years ago, when I measured it. Patterson had an even bigger impact by publishing a article on the extent of toxic lead pollution on Earth, which helped to start a movement to get rid of dangers such as lead paint and leaded gasoline, according to this article from the CalTech website. Sign up for our Newsletter! Mobile Newsletter banner close.

Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. The Solar System. Then, around 12, years ago, humans began to grow food and change their surroundings in order to survive and eat. As food became more sustainable, and living became easier, humans began to produce more.

As humans developed and grew, their bodies changed. Their brains became bigger, which helped them to develop new tools, including language. They changed the world around them to better survive harsh and changeable weather.