Human Effects On Ecosystems Flashcards
Why was there a human population explosion?
One reason is that we have medicine that help to keep us alive
What is the difference about this time our climate is changing compared to the other times?
This time it is happening fast and there is a growing body of evidence that the changes are the direct result of human activities
Why are biogical resources being depleted?
Because in the more economically developed parts of the world people have gone beyond simply fulfilling the basic needs of life. They eat far more food than they need and want a greater variety of different foods. As a result biological resources are being depleted and ecosystems destroyed both on the land and in the seas and oceans
What activities lead humans to reduce biodiversity?
Overfishing, habitat reduction and as a result of climate change
What is a valid study?
A valid study has been properly designed to answer the questions being asked
What is a reliable study?
Other scientists can repeat the methodology and obtain similar results
When evaluating a study to decide whether or not to take notice of the conculsions what are the factors that you should take into account?
- you need to examine the methodoly to see if it is valid (properly designed to answer the questions being asked)
- you need to know the size of the study and to see if the measurements have been carried out with precision and accuracy
- it is also important to see if other scientists have been able to repeat the experiment and obtain similar results
- knowing who carried out the research, who funded the study and where it was published can also help you decide whether anything might have affected or biased the study
What does it mean if a study is biased?
It has been influenced in some way to deliver a particular conclusion
What does the intergovernmental panel on climate change (IPCC) do?
Analyses research from scientists on climate change and produces regulat unbiased reports based on all tbe available data to be used by politicians and decision makers globally
Over the last few years what has a large body of evidence built up to show? (Regarding climate change)
- global temperatures are increasing, having an inevitable effect on global climate
- the levels of carbon dioxide and other greenhouse gases in the atmosphere are increasing at an unprecedented rate
Why do greenhouse gases have an important role for life on earth?
They maintain the temperature at the surface of the earth at a level suitable for life (14°c)
What are three greenhouse gases?
Methane, carbon dioxide and water vapour
What is the greenhouse effect?
When radiation from the sun reaches the Earth some is reflected back into space by the atmosphere and by the surface of the earth and some is absorbed by the atmosphere. The Infrared radiation that reaches the earth is of fairly short wavelength. It is absorbed by the surface of the earth and then radiated from the surface at a longer wavelength. Some of this radiation is absorbed and re-radiated back to the earths surcace by greenhouse gas molecules in the atmosphere
How are antartic and greenland ice cores used to find temperature proxies?
Scientists drill deep down into the ice and tben analyse the air trapped in the different layers. This provides a record that goes back thousands of years. The oxygen isotopes reflect the air temperature when the ice layer was laid down. Atmospheric CO2 levels can also be measured
What can dedrochronology and peat bog dating show?
They are used to confirm radiocarbon dating
How can peat bog samples of known age be dated from radiocarbon measurements?
They use the remains of plants and pollen grains which give an indication of climatic conditions when those plants are alive and the results compared to give a form of callibration. This gives scientists clear reference points that they can use to determine their estimations of age
What is the Mauna Loa curve?
A series of readings taken at regular intervals at the Mauna Loa observatory on Hawaii. The air is sampled continuously at the top of four 7m tall towers and an hour average of CO2 is takeb. The air in the area is relatively free from local pollutants and scientists believe it is representative of the air in the northern hemisphere. The curve has been increasing
How are scientists measuring CO2 levels in the sea?
By measuring the amount of CO2 dissolved in the surface of the water and the changes in pH. The more carbon dioxide dissolved in the water the lower the pH
Why have methane levels risen by about 150% since 1750?
- levels of rice production have increased to feed the growing population. rice paddy fields are waterlogged during much of the time the rice is growing and bacteria in this waterlogged soil release methane as they grow.
- as the human population grows so do the number of animals we depend on for food inclusing cattle who release methane from their digestive systems
What is a more potent greenhouse gas, CO2 or methane?
Methane but there is far less of it than carbon dioxide
What are the main reasons carbon dioxide concentrations have increased about 40% since pre-industrial times?
Primarily from fossil fuel emissions and secondarily from changes in land use for example deforestation
What has caused ocean acidification?
The ocean absorbing about 30% of the emitted anthropogenic carbon dioxide
Why can it be difficult to decide whether increases in greenhouse gases are causing the rising temperatures or are the result of rising temperatures?
The correlation between the rise in carbon dioxide and other greenhouse gases in the atmosphere and the increase in global temperatures is so close
What is dendrochronology?
The dating of past events using tree ring growth
What does anthropogenic mean?
Produced by people
What is climate?
The average weather pattern in an area over many years
What is happening with rainfall patterns?
Some areas are experiencing high water stress ehilst others are experiencing heavy above average rainfall
What happens as the ice melts?
The volume of water in the seas and oceans of the world will increase causing sea levels to rise. Also as the water gets warmer its volume increases resulting in an even bigger impact on sea levels
How does temperature affect organisms?
It affects enzyme activity which in turn affects the whole organism
What processes could temperature have an effect on and how could this make greenhouse warming worse?
Growth and reproduction. It plants grow slower they will take up less CO2 and remove less feom the atmosphere
Why will it be catastrophic if insects start to become extict?
They are vital as pollinaties of the many flowering plants and if they go so do the plants and then the animals that feed on them
At higher latitudes what do seasonal cycles do?
Affect life cyclee
At higher latitudes what do seasonal cycles do?
Affect life cyclee
Global warming appears to be affecting the knset of seasons. What will this then affect?
Life cycles and the distribution of species
What do warmer temperatures mean in regard to life cycles?
That plants grow and flower earlier and insects such as moths and butterflies become active earlier as the plant food they need for their caterpillars is available. Some birds can adapt to these changes and move their breeding cycle forwards. However others still miss the caterpillars ect. So are rasing fewer chicks
Why has the (WHO) warned that global warming could be responsible for a major increase in insect borne diseases in Britain and Europe m?
Because increased temperatures often make life easier for disease carying organisms and so patterns of world health could change
Why do soil mineral concentrations rapidly decrease as a result of farming?
Because when we farm we remove the crops before the plants die and therefore break the natural cycles that return the minerals to the soil
Why do monocultures decrease minerals in the soil more than other typesnof farming?
Because monocultures absorb large quantities of particular minerals
What happens when soil biodiversity is lost?
The soil structure breaks down and it becomes infertile even when fertilisers are used
What are the problems with overfishing?
If we take too many fish or take fish at the wrong time of year the fish cannot breed and replenish the populations and fishing becomes unsustainable
What are the factors that are causing the large scale depletion of the fish stock?
- The size of the global fishing fleet - the fleet is currently almost twice the size that would be needed to take a sustainable supply of fish
- techniques such as bottom trawling where nets are dragged along the seabed damaging the seabed habitat and catching a wide variety of species; many of which are not wanted
- enourmous drift nets that are almost invisible and catch and kill many species accidently
- nets with small net sizes that catch immature fish as well as adult fish
- fishing through the breeding seasons
What are the environmental conditions the depletion of fish can be caused by as well as the human fishing quotas?
Global water temperatures, levels of pollution and numbers of natural predators
How do rising sea temperatures affect the depletion of fish?
- rises and falls in sea temperatures can affect the amount of phytoplankton which are the producers in most marine food chains and this can affect the food available for fish higher up the food chain
- many fish spawn in relatively shallow coastal waters which are more affected by temperature changes than the deep ocean
What is sustainability?
The production of a decent standard of living for everyone now, without comprising the need of future generations or the ecosystems around us
What are the methoda of protecting fish populations that have already been put in place?
- controlling the size of the mesh in the fishing nets so only the largest fish are caught
- banning fishing during the breeding seasons of different fish
- imposing very strict quotas on fishing fleets and individual fishing vessels
- encouraging the use of fishing methods that are less damaging to the ecosystems
- banning the catching of severely endangered species of fish altogether
What is the problem with the methods for conserving our fish stocks?
The controls need to be policed and introducing then deprives people of their livelihoods
What is aquaculture?
The farming of fish or shellfish in tanks or in containers in rivers, lakes or the sea
In which countries is aqualculture becoming increasingly used?
China, UK, USA and many parts of Africa
Why is aqualculture useful?
As it means we are not removing fish from the ocean
What are the problems with aquaculture?
Fish farms are not carbon neutral and use electricity and produce greenhouse gases. Furthermore often the food they feed their fish is made of other fish so it doesn’t entirely prevent overfishing
What are the direct human influences on ecosystems that lead to a loss of biodiversity?
Deforestation, farming, overfishing, building and the introduction of alien species
What are the indirect human influences that can lead to biodiversity being lost?
Soil, air and water pollution and global warming and climate change
What is localised extinction?
When a species becomes extinct in an area or country
When do individual species become extinct?
When something changes in their habitat, for example changes in temperature may affect food supplies, a rise in sea level can cause flooding or a new predator or disease may arrive
What is the natural extinction rate and how much higher than this is the extinction rate now?
The natural extinction rate is between 1 and 100 species per year. The current extinction rate is about 100 to 10 000 times higher than this
How are threatned species classified?
- critically endangered - facing an extremely high risk it extinction in the wild
- endangered - facing a very high risk of extinction in the wild
- vulnerable - facing a high risk of extinction in the wild
What is the international union for conservation of nature (IUCN)m
The largest global environmental organisation and produces the regularly updated red list of threatened species. This takes into account data from over 11 000 voluntary scientists
What will the species that will go extinct most frequently?
Fungi, invertebrates, protists and bacteria
What are some of the causes of extinction?
- people eating plants and animals can drive them to extinction
- habitat destruction
- pollution of seas rivers and lakes
- as a result of other animals, plants or diseases introduced by people
Why do people fear that climate change may cause extinction?
- Because it may move the ranges of species as they will not be able to survive the temperatures but if they have nowhere else to go then extinction will be inevitable
- climate change may also interfere with food webs within an environment. Some species may peak earlier and so will then not be around when their prey arrives
What is CITES ( the convention on international trade in endangered species of wild fauna and flora?
An international agreement designed to protect endangered animals and plants by regulating trade in both the living organisms and the products made from them
What are used against parties who have signed up to the CITES convention and then break the agreement?
Trade sanctions?
How does CITES workM
It states strict rules about the import of export of threatened animals and plants and materials made from them. Some entire groups of organisms are protected and in some fases it is simply a sub-species that is protected or the popluation of an animal or plant in a particular country
What are the appendices the protected organisms are split into?
- Appendix 1: organisms in appendix 1 are threatned with extinction and no trade in wild-collected specimens or their products is allowed. They include the gorilla species, tigers, cheetahs, Asian elephants and dugongs
- Appendix 2: These organisms are not yet threatened by extinction but they are endangered and could become threatened if they are not protected. CITES applies strict trade controls to these species. Organisms in appendix 1 that are bred in captivity are treated as members of appendix 2 making it possible for severely endangered animals and plants to be moved internationally for breeding programmes. Examples: biglead mahogany tree, African grey parrot
- Appendix 3: organisms in appendix 3 are there because one country has asked CITES members to helo to protect a local population. The species may be threatened with extinction in that country byt not globally. E.g. two toed sloth of Costa Rica and walruses
What are the limitations to CITES?
- it only deals with trade agreements. It does not protect ecosystems or attempt to legislate for protection of breeding areas and threatened habitats
- many countries have not signed up to CITES
- strong commerical interests can override scientific evidence for the need for protection
- there is no leval obligation to abide by the CITES appendices
