Ecology 4 Flashcards
What happens with sun rays:
1) Some longer wavelengths absorbed before they reach the atmosphere
2) Some strike the atmosphere and are reflected back to space
75% of solar radiation is absorbed/enters the atmosphere (shorter wavelengths) – converted into longer wavelengths (IR = heat!)
3) Some of the heat absorbed by the crust (heating the Earth’s core)
4) Some of the heat reflected from Earth and escapes into space
5) Some of the heat reflected from Earth and absorbed by greenhouse gases
What is the greenhouse effect?
a natural phenomenon that would exist without any human activities – it makes the Earth habitable (otherwise mean temperature would be -18°C) – enhanced GE is due to increase in anthropogenic GG
Name greenhouse gases. What does the relative impact of a certain GG depend on?
CO2, H2O (g), CH4, N-oxides and S-oxides
1. Its ability to absorb long wave radiation
2. Its prevalence in the atmosphere (CH4 causes more warming per molecule but its % is low, CO2 is the most abundant)
3. Its lifespan (CO2 has the longest)
Where is methane produced? Where are N and S oxides produced?
Methane produced by methanogenic Archeans (process called methanogenesis forms CH4 from partially digested organic compounds) – found in swamps (marsh gas, anoxic conditions in water habitats) and inside mammals – there are also anthropogenic sources – CH4 can be oxidized into CO2
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Which changes to the climate does global warming cause and how?
- Wind direction/increased wind speed/intense hurricanes/typhoon – greater T difference between surface and atmosphere
- Increased rainfall/extreme draughts
- Increased cloud cover
Correlation between atmospheric concentration of CO2 and average global temperature. How were the results obtained?
Strong positive – repeating pattern of rapid periods of warming followed by longer periods of gradual colling – also periods of higher c(O2) coincide with periods when Earth was warmer –
Analyzing air composition: data obtained from analysis of ice columns drilled from Antarctica (3000 m depth), measurements for 400 000 years ago, air spaces between water molecules in ice contain gases that were present in the atmosphere at that time
Positive feedback mechanisms connected with the greenhouse effect/global warming
increased T increases evaporation which increases water vapor which increases GE
albedo reduced
Methane concentration – melting of permafrost, trapped organic matter gets decomposed
consequences of global warming:
- Melting of polar ice caps
- Water acidification
- Coral reef habitats
- Boreal forest reduced
- Ocean ecosystem
- Oceans desalinized (mixing of water and sea currents disturbed)
- Sea levels rise
- Shifting climate zones
Explain in detail the melting of polar ice caps
Albedo – reflection of sun from a wight surface (ice caps)
Melting of polar caps caused by increased T = albedo reduced, more heat absorbed, permafrost also melting
Explain in detail the effect of increased CO2 concentrations on coral reef habitats
corals (a keystone species) composed of polyps that build their calcium carbonate exoskeleton (remains there after they die)
CO2 dissolves in oceans – carbonic acid formed, lowers pH -> pH of surface ocean waters fallen by 0.1 pH units – this is a 30% increase in acidity
Carbonic acid formed by CO2 dissolving – carbonic acid dissociates into ions but not completely because it’s a weak acid – dissociates onto H+ and HCO3- – CO32- is usually used by corals to build their exoskeleton but the H+ ions react with it to form more HCO3- ions – prevents deposition of CaCO3 (stealing it) – they are unable to maintain their exoskeletons (decay at faster rate than the rate at which they are rebuilt) – soft body unprotected, attacked by pathogens, it dies) – CO2 increases atmospheric temperature – warmer oceans cause corals to expel their symbiotic bacteria zooxanthellae, bleaching of corals, enzymes denaturated – corals are keystone species, their habitat will be lost
Reason for a larger percentage of corals being infected with white syndrome on reefs with a higher cover of corals: the closer the corals are (to each other) the easier the transmission because other organisms in the community may act as vectors.
Explain the effect of the global warming on the boreal forest (taiga)
Majority of drinking water situated in deciduous forests and green cover is a very important carbon sink (large biodiversity) – endangered by deforestation and forest fires
Higher T increase the rate of CR (of decomposers) = more CO2 released
Higher T decrease the solubility of gases in water = more CO2 in the atmosphere (already dissolved CO2 bubbles out)
Higher T increase the chances of a forest fire (drier trees) = more CO2 in the atmosphere (combustion)
Explain the effect of global warming on ocean stratification
Ocean stratification – property of the ocean where two layers of water with different densities resist mixing: warmer and less salty water on the surface, higher salinity and colder water on the lower level – ocean currents mix them, as well as the (bigger) organisms that go from one into another, winds and Earth’s rotation
Mixing is important so that CO2, O2 and heat can reach the lower layer, otherwise it will be anoxic
Global warming increases stratification by making the warmer and less saline layer of the ocean thicker (increases resistance to mixing)
Explain the effect of global warming on nutrient upwelling
Nutrient upwelling – colder, deeper water brough upwards together with nutrients in it (displaces the warmer water and increases the growth of producers and availability of food for consumers – nutrients such as CaCO3, HCO3 ions, ammonia and NO3- which is the only nitrogen ion that can be used by organisms to create a-a) – upwelling occurs in productive biological communities
In warmer water (caused by GW), there is less upwelling (deep cold water does not rise towards the surface)
El Nino events
Explain the effect of global warming on climate zones
Climate zones (tropical, subtropical and polar) shift towards the poles (the tropical zones expand) – hardiness zones (plant growing zones) change so that cold-blooded organisms expand their habitat (pests, insects) – saprotrophs benefit from warmer temperature (positive feedback mechanism)
Carbon sequestration
Capturing and storing CO2 from the atmosphere
natural sequestration: photosynthesis and accumulation of partly decomposed organic matter
anthropogenic: reforestation and afforestation (planting trees on a soil they grew on a long time ago) and increasing the amount of peat by restoration of wetlands (peat is non or partly decomposed dead organic matter)
Phonology and global warming
Phenology – part of ecology that studies the timing of seasonal change – deciduous trees shed their leaves once a year (during dry season) to prevent transpiration since no rainfall for almost four months.
Plants “orient” in seasons in one of to ways: using photoperiod, the ratio between light and dark period of the day, or temperature which is impacted by global warming. Those that measure T start flowering earlier (e.g. spring flowers)
