Who fell the mango tree?

Extinction

​Extinction signifies disappearance. When the last individual of a species dies, the species becomes extinct.

Extinction can be a natural part of life on Earth and of different species. In the last 450 million years, Earth has experienced five mass extinctions, with a large number of species disappearing at the same time. One such mass extinction took place 66 million years ago, at the end of the Cretaceous period, when most dinosaurs disappeared from Earth. However, one branch of small dinosaurs (Theropoda, Avialae) survived, and continues to live on Earth forming the current diverse family of birds. The reason for the mass extinction at the end of the Cretaceous period was possibly an asteroid that happened to hit the Earth during a time when also environmental conditions had rapidly changed. The combined effect of these events and circumstances, which was possibly fortified by a series of volcanic eruptions, lead to the extinction of dinosaurs and many other species. For many species, it was difficult to adapt to the rapid change in the conditions on Earth. Life on Earth has recovered after each waves of mass extinction, albeit slowly. It took millions of years until the Earth once again was inhabited by as many species, as it was before the latest wave of extinction.

According to researchers, Earth is currently experiencing its sixth mass extinction, which is caused by humans. This current extinction is also happening faster than before. Researchers also speak about a decrease in biodiversity. By this they mean the loss of genetic variation in ecosystems, plants, animals and other organisms. 

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In the last 50 years, Earth’s nature has been altered most by:
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  1. Changes in the use of land and oceans: for example, cutting down forests for plantations and cattle.
  2. Exploiting animals, plants and other organisms, such as over hunting and fishing.
  3. Climate change and the extreme weather conditions it has caused – such as dryness.
  4. Contamination: such as air pollution and microplastics in the oceans.
  5. Invasive alien species, introduced by humans, like the Cane toad in Australia.

Biodiversity loss can be slowed down, or partly even stopped, if we manage to work together on a global scale. To save and protect diversity in nature, we need research, common decision making and policies, funding and environmentally sustainable actions from each and every one of us.
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What should decision makers, companies and people do:

  • Establish more areas where the nature is protected. In Finland this means, for example, that we protect the rest of the remaining old growth forests and decide to do so quickly, as well as other habitats valuable for biodiversity.
  • Speeding down climate change for example by switching to renewable energy sources and cutting down energy consumption in our everyday life.
  • Compensate for the damages that are done to nature and its biodiversity: for example, the damages caused by the inevitable construction of the environment should be compensated for by protecting nature in other areas.
  • Reducing consumption: to resist buying every piece of clothing or gadget that we would like to have, and to instead carefully consider what we really needed and whether it would be possible to purchase it second hand, or perhaps borrow or rent it.
  • Eating more vegetarian food instead of a meat-based diet.
  • Combatting the spreading of invasive alien species: for example, removing plants that are spread by humans outside their natural geographic area and displace diverse vegetation.

Can you come up with other ways for protecting animals, plants, or our common habitats?

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References:
* Ceballos G., Ehrlich P.R. & Raven P.H. 2020. Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction. PNAS. www.pnas.org/cgi/doi/10.1073/pnas.1922686117
* Chiarenza A.A., Farnsworth A., Mannion P.D., Lunt D.J., Valdes P.J., Morgan J.V. & Allison P.A. 2020. Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction. PNAS 117: 17084–17093. www.pnas.org/cgi/doi/10.1073/pnas.2006087117
* Díaz S., Settele J., Brondízio E.S., Ngo H.T., Agard J., Arneth A., Balvanera P., Brauman K.A., Butchart S.H.M., Chan K.M.A., Garibaldi L.A., Ichii K., Liu J., Subramanian S.M., Midgley G.F., Miloslavich P., Molnár Z., Obura D., Pfaff A., Polasky S., Purvis A., Razzaque J., Reyers B., Chowdhury R.R., Shin Y-J., Visseren-Hamakers I., Willis K.J. & Zayas C.N. 2019. Pervasive human-driven decline of life on Earth points to the need for transformative change. Science 366, doi:10.1126/science.aax3100.
* Forslund T. 2021. Kiertotalous on avain luontokadon pysäyttämiseen. https://www.sitra.fi/artikkelit/kiertotalous-on-avain-luontokadon-pysayttamiseen/
* Heikkilä M. 2021. Sukupuuttoaaltoja on ollut aina, mikä nyt on toisin? https://www.helsinki.fi/fi/uutiset/luontokato/sukupuuttoaaltoja-ollut-aina-mika-nyt-toisin
* IPBES 2019. Global assessment report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Brondízio E. S., Settele J., Díaz S., Ngo H. T. (eds). IPBES secretariat, Bonn, Germany.
IUCN 2007. Species Extinction - The Facts.
IUCN 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. Gland, Switzerland and Cambridge, UK.
* Kotiaho J. S., Ahlvik L., Boström C., Bäck J., Herzon I., Jokimäki J., Kallio K. P., Kulmala L., Lehikoinen A., Nieminen T. M., Oksanen E., Pappila M., Pöyry J., Saarikoski H., Sinkkonen A., Sääksjärvi I. & Ketola T. 2021. Keskeiset keinot luontokadon pysäyttämiseksi. Luontopaneelin viestit hallituksen puoliväliriiheen. Suomen Luontopaneelin julkaisuja 2/2021. doi: https://doi.org/10.17011/jyx/SLJ/2021/2.
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