Human impact on natural world

How has human success impacted other species?

Over-harvesting (timing of extinctions more closely match human arrival rather than climate change), habitat loss (human have altered habitats using fire), invasive species

What was the past state of the Amazon, Mauritius, and the great whales?

The Amazon

• A large majority went extinct at the end of the Pleistocene, likely due to human arrival

• After European contact, most of the native population got wiped out, which led to farm abandonment and forest regrowth

Mauritius

• Also suffered dramatic biodiversity loss following human arrival

• Overhunting and the introduction of invasive species

The great whales

• Humans have hunted great whales for meat, oil, and other products

• Whales are ecosystem engineers - they feed at depth and defecate near the surface, which helps recycle nutrients
  Their migration and eventual death also recycles nutrients

What is the great acceleration?

Since WW2, human activity has intensified (driven by economic growth, technological innovation, and industrial changes)

This has had great impacts on biodiversity

• Rising extinction rates

• Uneven threat distributions across groups

• Widespread population declines

• Disruption of ecological processes

• Changes in community composition

We are not yet in the sixth mass extinction, but current extinction rates are at the high end of natural background rates

What conservation attempts have been introduced?

• Environmental laws e.g. the 1992 Convention on Biological Diversity to help regulate harmful activities and promote conservation

• Conservation NGOs and intergovernmental organisations

• Protected areas and other effective conservation measures

• Habitat management focuses on removing threats (e.g. invasive species) and restoring ecological processes disrupted by species loss

• Species-specific management aims to protect threatened species and promote sustainable harvesting

What is the present state of the Amazon, Mauritius, and the great whales?

The Amazon

• Deforestation increased and then declined again due to expanded protected areas, and then increased again due to relaxed enforcements

Mauritius

• Deforestation continued which led to the endangerment of endemic species

• Conservation efforts began reversing declines

The great whales

• Industrial whaling continued after WW2 (targeting smaller whales as larger one became depleted)

• International Whaling Committee formed in 1946 imposed a commercial whaling moratorium in 1986

• Some whale populations have recovered, while others remain low

What can we expect in the future?

• Population growth is expected to slow

• Economic growth is expected to outpace population growth

• Habitat conversion will continue due to increased food demand

• Non-native species introductions will increase

• Ocean acidification will worsen

How can we scale-up conservation responses?

• Conservationists are addressing root causes by reducing cropland demand through cutting food waste, promoting plant-based diets in wealthier countries, and increasing crop yields

• Public concern for the environment is rising globally

• Many conservation measures also benefit other global issues

What will the future state of the Amazon, Mauritius, and the great whales be like?

The Amazon

• Unsustainable hunting and deforestation is increasing - loss of biodiversity and carbon sink

• Reasons for cautious optimism - rising carbon prices may incentivise forest conservation through carbon credit payments, deforested land now has the potential for recovery

Mauritius

• Captive breeding and reintroduction programs are expanding to other species like endemic invertebrates and habitats such as caves

• Innovative ecological replacement projects involve introducing Aldabran tortoises to substitute extinct native tortoises, restoring key ecological functions such as seed dispersal and vegetation control

• A controversial gene-editing effort to “replicate” the extinct dodo, though many consider such de-extinction projects distracting from more practical conservation work

The great whales

• Whalewatching has increased

• New threats - noise pollution (from ships), ship strikes, fishing gear entanglement