Human effects on ecosystems Flashcards
3 human effects on ecosystems
Climate change
Depletion of biological resources
Loss of biodiversity
What is the IPCC
Intergovernmental panel on climate change - analyses research from scientists on climate change and produces regular unbiased reports based on all the available data to be used by politicians and decision makers globally
The greenhouse effect
Greenhouse gases reduce heat loss from earth maintaining the temperature level on earth as suitable for life. If the level of greenhouse gases (e.g. carbon dioxide) increases, earths temperature will increase
Evidence for global temperature increase
Met office daily weather records going back to 1869 show a temperature increase in recent years
Frozen isotopes mean we can drill into the ice cores to find the oxygen isotopes that reflect the temperatures at the time
How do we confirm radiocarbon dating
Dendrochronology
Peat bog dating
Evidence for increasing levels of carbon dioxide
Mauna loa curve - a series of readings taken in Hawaii showing an increase in CO2 in recent years
Ice core data
Role of methane
Is a greenhouse gas that has a 72 times greater effect on warming the atmosphere than carbon dioxide however much less of it is produced
What is anthropogenic carbon dioxide
Produced by people - 30% of it is absorbed by the ocean
What are the biological impacts of climate change
Risk of flooding
Effect on organisms
Change in species distribution
Risk of flooding
The thinning of the polar ice is an indication of global warming and could result in flooding
Effect on organisms
Temperature effects enzyme activity which in turn affects organisms
Increased temperature could affect rate of growth and reproduction
Temperature could affect seasonal cycles which could affect life cycles
Change in species distribution
As areas become warmer, some animals may extend their ranges northwards, but become extinct at the southern end of their current range
Could also affect world health and the spread of disease
Depletion of resources - farming
Reduces soil mineral concentration - artificial fertilisers can replace minerals in the soil but they do not support the structure making it infertile
Depletion of resources - fishing
Fish stocks are one of the most depleted resources - can affect breeding and reproduction
Caused by the size of the global fishing fleet, techniques such as bottom trawling, enormous drift nets trapping unwanted species too, nets with small mesh sizes that catch immature fish, fishing through breeding seasons
Methods of conserving fish stocks
Controlling the size of mesh in nets so only the largest are caught
Banning fishing during the breeding seasons of different fish
Encouraging less environmentally damaging fishing methods
Banning the catching of endangered fish
Extinction
The loss of all members of a species
Human causes of extinction
Habitat destruction
Eating plants and animals
Diseases
What is one international agreement to conserve biodiversity
CITES
Successes of cites
Banned international ivory trade in 1989 and since poaching has fell and elephants have increased
5 species of shark and 2 species of ray have been added to the cites list to prevent extinction
Several turtle species have been brought back from the brink of extinction as cites banned the trade of any turtle products
Limitations of CITES
Only deals with trade agreements so doesn’t protect ecosystems or habitats
Many countries haven’t signed up to CITES
There is no legal obligations to abide by CITES appendices
