1 - general introduction to human impacts Flashcards
how many major mass extinctions have been recognized in the Earth’s history?
5
when were the 5 major mass extinctions in the Earth’s history?
- about 450 million years ago (shortly after the evolution of the first land-based plants)
- about 350 million years ago (led to the formation of the coal forests)
- about 250 - 200 million years ago (during the Triassic period)
- 65 million years ago (the great extinction at the end of the Cretaceous Period)
extinctions per thousand species per millennium
marine defaunation
- experience less advanced than terrestrial
- due to recent industrialization of the harvesting, an era of marine wildlife decline is initiated
- if unmanaged: marine habitat alternation + climate change = marine defaunation
average declines of marine species
40-90%
Overview of human history, urban growth, development of agriculture, technology and
industry as well as corresponding links to economic growth (GDP), environmental changes and changes in land use (Modified after Costanza et al. 2007)
what’s the Anthropocene?
an era, when humans are a dominant geological force
(we have entered the Anthropocene)
Humans as a dominant geological force
- “Anthropocene” = human impacts are at least as important as natural process
- new term for new geological epoch to emphasize the central role of mankind in geology and ecology
- basic concept is that humans are now a major geological and environmental force, as important as, or more important than, natural forces
- start of this period not yet agreed, but term is widely adopted
what are changes in the atmosphere approaching? what suggestion is there?
why do we talk about the urban age?
- over half of humanity now lives in towns and cities
- by 2030 that fraction will have increased to 60 %
- Many of the global economic, social and environmental challenges have a strong urban dimension
where are the most largest cities?
- they are coastal
the UN 2030 Agenda
Paris Agreement on Climate Change
The new urban agenda - Urbanization as a tool and engine for sustainable development
when did marine resources exploitation start?
- since at least the Palaeolithic
during the Roman times marine coastal landscapes were far from pristine
what is estuarine and coastal areas degradation related to?
human population growth and impact
what about the temporal sequence of human impacts on coastal and marine ecosystems?
- the temporal sequence is distinct
(eine klare zeitliche Abfolge)
Predicted importance and direction of the different impacts
what’s, historically occurred, the oldest cause of human extinction of species?
overfishing
(MAIN HUMAN IMPACT)
impacts of fishery – direct and indirect affects
direct effect on fished species
example of direct effect on fished species
what is an effect of some fishing practices?
- damaging fishing practices have a direct effect on habitat destruction
- world oceans have been altered down to > 800 m in depth by destructive bottom trawling
- bottom trawling produces comparable effects on the deep sea floor to those generated by agricultural ploughing on land