5 unexpected ways humans are changing the planet

1: We are making the Earth wobble more

It would not be hard to believe that we literally hold the Earth in the palm of our hand

Since 1899, the Earth’s axis of rotation has shifted around 34 feet. This is partially due to anthropogenic activities. The distribution of mass around the Earth determines the spin and two major sources of mass are glaciers and the sea. Melting ice as a result of global warming and rising sea levels, particularly around Greenland have contributed to a changing mass balance. The melting of glaciers has a double effect. It also causes uplift of land. When the weight of the ice is removed once it melts, the land is now free of a load so the crust starts to return to its original shape. You can visualise this by imagining laying on a memory foam mattress, when you get off the mattress still retains some depression from the weight of your body, but gradually the depression disappears and the surface becomes flat once again. When this occurs with the Earth crust the process is known as flexural isostasy. Additionally, the building of massive artificial lakes and damming of rivers has also been attributed to the change in the axis of rotation. Thankfully, there are no bad consequences associated with this change in rotation, as it has been happening throughout Earth history. However, it just demonstrates the power of the human race – that we can change the distribution of water so significantly to alter the orbit of our planet.1

2: The colour of the sky has changed

Hazy skies can be caused by aerosols, other pollutants or simply weather conditions

We have actually made the sky appear more milky than it once was. This is because of the aerosols we have released into the atmosphere. This does not mean aerosol deodorant and other things in pressurised cans, but, particles that cause more sunlight to be reflected back into space. This occurs when aerosol particles (often sulphate) act as a nuclei for cloud droplets to form around. White and light colours reflect more light than dark colours, creating the white milky colour we see in the sky most days. 2 It should be noted that the majority of aerosols come from natural sources, and humans only contribute around 10% of aerosols worldwide but it greatly varies by region. Other sources include volcanic eruptions. In fact, 1816 is known to some as ‘the year without a summer’, due to the massive explosion of Mount Tambora, emitting a huge amount of aerosols which reflected a lot of sunlight back into space, reducing global temperatures and triggering crop failures.3 Thankfully, humans are nowhere near replicating that kind of disaster.

3: Extreme radiation is better for wildlife than we are

Chernobyl Nuclear Exclusion Zone

OK – this one is a bit of a stretch so let me explain. It is all to do with the Chernobyl nuclear reactor and the exclusion zone. Although all humans were evacuated from this 30km exclusion zone within hours, of course, the wildlife remained. For a few years, undoubtedly there were biodiversity impacts. Vast swaths of trees died off, and some creatures suffered mutations and infertility, particularly soil invertebrates who had to endure the initial fallout, then runoff from vegetation and surrounding areas which carried radioactive isotopes. However, it is reported that species diversity returned to original levels within a decade. Now, the exclusion zone is home to a profusion of wildlife including 50 endangered species. Recognising the value of this area, 28 endangered Przhevalsky wild horses were introduced in 1998 and numbers had doubled by 2004, in just 6 years.4 I am in no way saying nuclear radiation and reactor meltdown is good, but it just proves how much of an impact human activity has on biodiversity, but also how quickly nature can bounce back. Wolf packs roaming around derelict buildings and abandoned cars, hunting deer and boar must be quite a sight to behold. For once, it is an example of nature reclaiming what humans have taken.

4: Plastic is now found in all the Earths spheres

A pile of garbage, washed onto the beach by tide

Honestly, this fact may not be that unexpected, but plastic now pollutes all parts of the Earth. The Earth can broadly be split into 4 spheres: The lithosphere (land), biosphere (living things), hydrosphere (water and oceans), and the atmosphere (air). It is not surprising plastic is found on land, every day you will all walk past many pieces of discarded plastic, whether you notice it or not. The same goes for oceans and other bodies of water that plastic gets washed into, plastic bags have even been found floating in the deepest parts of the oceans, 36,000 feet below sea level, in the Mariana Trench.5 Also, due to the high concentrations of discarded plastic, unfortunately, it is inevitable that plastic is consumed by organisms. Thus, entering the biosphere. Lastly, there are even plastic particles floating around in the air. These are microplastics – the same type that bioaccumulates in organisms and can be passed from mother to infant through milk. They have even been found raining down in remote mountainous regions.6 So, next time you are eating meat, going for a walk, swimming in the sea, or flying to an exotic destination – just remember – you are surrounded by plastic, no matter what you do or where you are.

5: Humans are having a greening effect

More CO2 means more growth but don’t expect miracles

I wanted to end this article on a positive note, because I have tried to make this more of a short and fun piece. The good news is; because humans are pushing atmospheric carbon dioxide levels higher than they have been for hundreds of thousands of years there is a CO2 fertilisation effect, resulting in a greening of the planet. We all know plants use carbon dioxide to photosynthesise, we also know because of fossil fuel burning, carbon dioxide levels are increasing. As a result, plants are experiencing higher rates of growth because more CO2 = more photosynthesis. Fortunately for us, this actually provides a bit of a buffer since vegetation acts as a carbon sink, converting CO2 to oxygen with the added benefit of more vegetation making the world a greener place.7 Unfortunately, like many environmental issues, there is a bit of a catch-22 situation. This is because the fertilisation effect decreases over time as plants adapt to the higher levels of carbon dioxide. Also, the fertilization effect is too small to make any significant impact on atmospheric carbon dioxide levels. Additionally, the increased vegetation must not be cleared or cut down, otherwise the carbon dioxide will re-enter the atmosphere anyway. So really, the fertilization effect isn’t a major benefit for anyone, but it isn’t something many people associate with higher CO2 levels proving good things can be found in the most unlikely of situations.

Author note

Although I have tried to provide accurate references where possible, my inspiration for the article came from the book I am currently reading: ‘The God Species‘ by Mark Lynas. From this book I learned about the first three facts. Then, reading the references included in the book and doing some reading online to beef out the details. The 4th depressing fact I found while researching for an article on ocean plastic for the magazine Science Connected, which you can read Here (link opens in new tab). The last fact came from my studies, which I dredged up from the depths of my memory, in an effort to find one vaguely positive, non-obvious, impact of human activity. Hopefully you’ve learned something new, and please leave a comment if you have any other interesting ways humans have impacted the planet.

References

1https://www.scientificamerican.com/article/humans-contribute-to-earth-rsquo-s-wobble-scientists-say/

2https://earthobservatory.nasa.gov/features/Aerosols

3https://www.sciencedaily.com/releases/2019/09/190917193624.htm#:~:text=The%201815%20eruption%20of%20Mount,made%20as%20early%20as%201913.&text=The%20eruption%20injected%20a%20huge,oxidising%20to%20form%20sulphate%20aerosols.

4https://www.iaea.org/publications/7382/environmental-consequences-of-the-chernobyl-accident-and-their-remediation-twenty-years-of-experience

5https://www.nationalgeographic.org/article/plastic-bag-found-bottom-worlds-deepest-ocean-trench/#:~:text=A%20recent%20study%20revealed%20that,feet)%20inside%20the%20Mariana%20Trench.

6https://www.nationalgeographic.com/environment/2019/04/microplastics-pollution-falls-from-air-even-mountains/

7https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fertilization-greening-earth

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