Habitat loss and extinction of species

Land changes

Habitat loss for native species has taken place and is continuing due to land changes associated with agricultural activities, mining & drilling and further changes resulting from activities by people.

According to a 2015 study led by Thomas Crowther, the number of trees worldwide has decreased by 46% since the start of civilization. The 2022 global Living Planet Index shows an average 69% decline in monitored vertebrate wildlife populations.

According to a 2023 World Bank report, subsidies for fossil fuels, agriculture, and fisheries exceed $7 trillion in explicit and implicit subsidies, which is around 8% of global GDP.  Agriculture subsidies are responsible for the loss of 2.2 million hectares of forest per year - or 14% of global deforestation. Fossil fuel usage—incentivized by subsidies—is a key driver of the 7 million premature deaths each year due to air pollution. Fisheries subsidies, which exceed $35 billion each year, are a key driver of dwindling fish stocks, oversized fishing fleets, and falling profitability.

[ from earlier post ] 

Another contributor to habitat loss is construction of buildings, parking spaces and infrastructure. While intercity railway tracks and highways may take up a relatively small amount of surface area, they can have strong impact by causing fragmentation of habitat, reducing DNA exchange and thus shrinking the DNA pool for species to below-survivable levels, making the species functionally extinct. This is one reason why air taxis constitute a more sustainable method of transport and travel, compared to railways and roads, if transport and travel over longer distances is needed at all.

The post Transforming Society calls for land changes in numerous ways, including: 
  • by transitioning to vegan-organic food, grown in community gardens, permaculture and food forests 
  • by transitioning away from fossil fuel and biofuel 
  • by pyrolyzing biowaste and adding the resulting biochar to the soil
  • by transitioning away from infrastructure such as roads, highways, railway tracks, tunnels and bridges, toward doing more things online, more walking and cycling, and using more eVTOL air taxis, etc. 
Temperature rise


Above image by Song et al. (2021) shows how major mass extinctions over the past 541 million years (the Phanerozoic) are linked to temperature rises higher than 5.2°C and rates of change higher than 10°C/Myr. Guy McPherson et al. point at the image in their 2021 study Environmental thresholds for mass extinction events and, in a video associated with the study, authors point out that, next to temperature rise and rates of change, there are further variables such as rates of deforestation, ocean acidification and spreading of toxic substances that can additionally contribute to cause species to disappear.

Species are under threat both on land and in the air and in rivers, lakes and oceans. Coastal estuaries and marshes that now provide breeding grounds for numerous marine species, are increasingly dredged and filled for expansion of pasture and urban areas, while pollution and effluent from land cause loss of dissolved oxygen, stratification and acidification in oceans. Erosion can add further pollution including silt that blocks sunlight that is needed by species (including coral reefs) to grow and survive.

Habitat loss for native species can also occur due to introduction of non-native species, due to hunting, and due to the temperature rise and associated changes, such as more extreme weather including more frequent and intense storms, flooding, droughts and fires. 

Rapidly rising temperatures constitute tipping points in several ways

Firstly, there is a biological threshold beyond which rising temperatures become lethal for humans, as discussed in the post Wet Bulb Globe Temperature Tipping Point.

Secondly, there is a biological tipping point that threatens annihilation of species via the ongoing sixth mass extinction, as Gerardo Ceballos describes in the video below and in a 2017 analysis. 


A 2017 study led by Gerardo Ceballo with the title Biological annihilation via the ongoing sixth massextinction signaled by vertebrate population losses and declines concludes that: Beyond global species extinctions, Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a “biological annihilation” to highlight the current magnitude of Earth’s ongoing sixth major extinction event. 

Researchers such as Gerardo Ceballos (2020), Kevin Burke (2018) and Ignation Quintero (2013) have for years warned that mammals and vertebrates cannot keep up with the rapid rise in temperature. 

A 2018 study by Strona & Bradshaw found that at 5°C rise, most life on Earth will be extinct (see box below on the right, from an earlier post). Accordingly, many species are likely to go extinct at rises much lower than 5°C. Humans - who depend on many species - could go extinct with a 3°C rise, as the above-mentioned earlier post concluded.

A 2013 study led by Ignatio Quintero concludes that projected rates of climate change exceed typical rates of climatic niche evolution among vertebrate species by 10 000-fold or more.  

A 2018 study led by Matt Davis has the title: Mammal diversity will take millions of years to recover from the current biodiversity crisis. Humans are both vertebrates and mammals, humans are vertebrate mammals, as Guy McPherson says in the video below. 

Humans are classified as vertebrate mammals, indicating that we will not avoid the fate of extinction, Guy McPherson (2020) adds.

Thirdly, there are further tipping points, e.g. social-political ones. On the one hand, it would be good if people became more aware, as this could prompt more people into supporting the necessary action. On the other hand, as temperatures keep rising, there is also a danger that panic will break out, dictators will grab power and civilization as we know it will collapse abruptly, as warned about earlier, e.g. in 2007.

In the video below, Science Snippets: ENSO Looms Large, Guy McPherson discusses the situation. 



Links

• World Bank - Detox Development: Repurposing Environmentally Harmful Subsidies

• 69% average decline in wildlife populations since 1970, says new WWF report

• Air Taxis (group at facebook)

• Which policy can help EVs most?

• How we found out there are three trillion trees on Earth - by Henri Glick & Thomas Crowther (2015)

• Rates of projected climate change dramatically exceed past rates of climatic niche evolution among vertebrate species - by Ignatio Quintero et al. (2013) 
https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.12144

• Mammal diversity will take millions of years to recover from the current biodiversity crisis - by Matt Davis et al. (2018)
https://www.pnas.org/doi/10.1073/pnas.1804906115

• When will humans go extinct?

• Climate change to push species, reduce their habitats (2023) 

Abrupt expansion of climate change risks for species globally - by Alex Pigot et al. 
https://www.nature.com/articles/s41559-023-02070-4

• Biodiversity risks to persist well beyond future global temperature peak (2022)

Risks to biodiversity from temperature overshoot pathways - by Andreas Meyer et al.
 
• Climate change could cause sudden biodiversity losses worldwide (2020)
https://www.ucl.ac.uk/news/2020/apr/climate-change-could-cause-sudden-biodiversity-losses-worldwide

The projected timing of abrupt ecological disruption from climate change - by Christopher Trisos et al.

• Polar bears of the past survived warmth (2023)

Ancient bears provide insights into Pleistocene ice age refugia in Southeast Alaska - by Flavio da Silva Coelho et al. 
https://onlinelibrary.wiley.com/doi/10.1111/mec.16960

• The Hypertopia Option - by Mark McMenamin (2019)
https://www.researchgate.net/publication/335798471_The_Hypertopia_Option#pf3

• Pliocene and Eocene provide best analogs for near-future climates - by Kevin Burke et al. (2018) 

• Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines - by Gerardo Ceballos et al. (2017) 

• Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction - by Gerardo Ceballos et al. (2020) 

• More than half NSW forests lost since 1750 and logging ‘locking in’ species extinction, study finds
https://www.facebook.com/groups/arcticnews/posts/10160656270809679

The impacts of contemporary logging after 250 years of deforestation and degradation on forest-dependent threatened species - by Michelle Ward et al.
https://www.biorxiv.org/.../2023.02.22.529603v1.abstract

• Rapid Loss of Habitat for Homo sapiens - by Guy McPherson (2021)
https://guymcpherson.com/wp-content/uploads/2021/04/Academia-Letters-Number-498-Rapid_Loss_of_Habitat_for_Homo_sapiens.pdf

• Earth is in the Midst of Abrupt, Irreversible Climate Change - by Guy McPherson (2020)

• Environmental thresholds for mass-extinction events - by Guy McPherson et al. (2021) 
• ‘Insects need our help in a warming world, now’ - 70 scientists’ warning on climate change effects
https://www.eurekalert.org/news-releases/970420

Entomologists Issue Warning About Effects of Climate Change on Insects
https://cmns.umd.edu/news-events/features/4999

Scientists' warning on climate change and insects - by Jeffrey Harvey et al. (2022) 

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