Planetary Climate Change – February 26, 2020


In a time when climate change is often on people’s minds, let’s talk about it – starting with our home. Here on planet Earth, the root cause of recent climate change is us – humans and all our activity on the planet. Increases in carbon dioxide emissions is causing temperature increases, as well as extreme weather events. While the planet has experienced climate changes in the past due to natural causes (and this is known from chemistry extracted from bubbles trapped in ancient ice), at no other point in recorded geological history has the planet experienced such change in such a short timeframe. That is the key – the timing. Given enough time (e.g., thousands to millions of years), the planet and ecosystems could adapt accordingly. But we’re doing this on the decadal to century timescale. We’re stressing the system in a way it’s never been stressed before – and we have yet to see the results of our experiment.

Carbon dioxide concentrations in our atmosphere are miniscule when compared with amounts of other major gases, like nitrogen (78%) and oxygen (21%). In fact, carbon dioxide is considered a “trace” gas, as its presence in our atmosphere is less than 1%. If small increases in this gas are enough to cause global warming on Earth, what about the other terrestrial planets? Why is Mars cold if its atmosphere is 95% carbon dioxide? And what about Mercury and Venus?

The recipe for a planet’s surface temperature has a few major ingredients: atmospheric composition, atmospheric density, water content, and distance from the Sun. On Earth, the balance of these ingredients makes our planet habitable. Mercury is the closest planet to the Sun, which should make it warm, but it has a very thin atmosphere and the surface experiences huge temperature fluctuations. Venus is second from the Sun and it is incredibly hot (462 C/864 F). Its atmosphere is very rich in carbon dioxide – 96.5% – but its atmosphere also happens to be very dense, trapping the heat. There’s a natural runaway “greenhouse effect.” Finally, Mars, while having an atmosphere also rich in carbon dioxide (95%), is located further from the Sun and is very dry. It is this combination that makes Mars an incredibly cold place, despite its richness in carbon dioxide. The absence of water makes the temperature of the planet fluctuate drastically (e.g., a few degrees above Celsius during the day and down to -80 degrees Celsius at night).

You may think – a few degrees of temperature change on Earth – what’s the big deal? Well, think about how you feel when your temperature rises a few degrees. You have a fever. Right now, our planet Earth has a fever and it’s trying to shake it. Climate fluctuations like the ones we’re seeing on a worldwide scale – that’s a warning from the planet and we should listen. Enough arguing about the cause – the science is solid. Our recent climate change is due to us and the more we try to deny and ignore it, the harder of a problem it becomes to solve.

#sciencewednesdays #summitssongsandscience