Environmental Science - 2.1.2 - Feedback mechanisms and tipping points
what is a negative feedback loop
environmental change causes other changes that decrease the rate of initial change, moving towards equilibrium
how is increased low-level cloud a feedback loop
higher temperatures cause more evaporation of water, therefore more condensation and more cloud formations. Clouds reflect the incoming UV rays due to their high albedo, so warming is decreased.
how is increased photosynthesis a negative feedback loop
higher temperatures increase the rate of photosynthesis, removing more CO2 and storing in plant tissue, reducing levels in atmosphere and decreasing the enhanced greenhouse effect
what is a positive feedback loop
environmental change causes other changes that increase the rate of original change, moving away from equilibrium and exacerbating the change
how is melting permafrost a positive feedback loop
land under the north and south pole regions have soil that is permanently water logged and frozen, which holds dead organic matter that has decomposed and released methane which is trapped in the permafrost. warming causes permfrost to melt, releasing the trapped methane and enhancing the greenhouse effect
how is ocean acidification a positive feedback loop
lots of released CO2 has been dissolved in the sea, produing carbonic acid and making the oceans more acidic. This causes corals to die and reduces carbon intake as coral use it for photosynthesis, increasing levels in the atmosphere
how is reduced albedo a positive feedback loop
ice and snow have a high albedo and reflect alot of UV. Warming causes snow and ice to melt, reducing the Eraths albedo and allowing more UV to be absorbed and warming the earth, causing more melting
how is melting methane hydrate a positive feedback loop
dead matter under lots of pressure and low temperatures in the sea bed decompose to produce methane hydrate. Increasing sea temperature causes the MH to melt, releasing methane into the atmosphere and enhancing the greenhouse effect
how is increased forest and peat fires a positive feedback loop
peat bogs have waterlogged soil where dead organic matter has been decomposed, so they are a large carbon sink. when high temps cause them to dry out, peat fires release lots of sequestered carbon dioxide, enhancing the greenhouse effect. dry conditions cause forest fires to be longer and more extensive, releasing more CO2
how is soil decomposition a positive feedback loop
rate of decomposition is often controlled by temperature. high temps means more aerobic decomposition of organic matter in soils, causing trapped carbon to be released, increasing atmosphere temp and decomposition further
what is a tipping point
the idea that human action causes changes to natural processes that result in climate change in such a way that it is irreversible and changing human actions would not stop climate change
how is snow melting a tipping point
reduces earths albedo, sunlight is absorbed more, causing more snow to melt and hgher temperature
how are tipping points importnat in climate change
climate change should be managed before tipping points are reached