Question

A) Please explain the difference between negative and positive feedback loops as it applies to climate change. Give an example of each.

B) Bird migrations (to breeding areas) are often linked to day length which has changed extremely slowly for millions of years. Temperatures have change very rapidly recently and now insects are hatching up to two weeks earlier than they used to. Why is this a problem for birds that depend on those insects for food for their chicks?

Answer 1

Answer :

A)

Positive feedback amplifies change in first quantity. Negative feedback reduces it. Climate change feedback is an important part in global warming. Feedback loop means a process forms a product and product either inhibit or favours the process. If it inhibit its negative feedback and if it favours its positive feedback. In climate change it can be described as the climate change has some effects and the effect can influence climate change.

Carbon cycle feedback is an example of positive feedback in climate change. Global warming causes loss of carbon from terrestrial ecosystems. This leads to increase in atmospheric carbon dioxide. Carbon dioxide is a greenhouse gas and inturn it adds to global warming.

Another example of positive feedback is global warming causes methane release in the artic. This causes increased methane in atmosphere. Methane is a greenhouse gas and it adds to global warming.

An example of negative feedback is chemical weathering. With global warming weathering is increasing. The formation of shells by organisms in the ocean take up carbon dioxide from sea permanently to another form and finally to limestone. This decreases global warming and thus a negative feedback.

Another example of negative feedback is net primary production. With increasing carbon dioxide net primary production increases and carbon gets fixed. This decreases green house gas carbon dioxide and decreases global warming.

B)

Bird migration is for breeding. Bird migration depends on day length only, its independent of temperature change or global warming. Day length is influenced by rotation of earth, inclination of earth on its axis and position of sun and rarely part of sun facing earth. Day length can increase temperature but day length is not affected by temperature.

Where as insect hatching is dependent on temperature. Warm climate is required. So with global warming in last century insect eggs started hatching very early.

For a migratory bird spring time in the northern hemisphere means bugs and babies. In the first few warm days of the year insects emerge in millions to eat young leaves. Migratory birds eat those bugs and feed their chicks. Birds time their thousand mile migration to coincide with this insect hatching. Missing the mark can be fatal for the young ones of the birds. With global warming birds migrate on same time as the day length is unchanged. But insects hatch many weeks before with global warming. This made survival chances of migratory birds difficult both for mother and chicks.