User:Gdossantos/Climate change and ecosystems

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Coral bleaching[edit]

Bleached Staghorn coral in the Great Barrier Reef.

The warming ocean surface waters can lead to bleaching of the corals which can cause serious damage and/or coral death. Coral bleaching occurs when thermal stress from a warming ocean results in the expulsion of the symbiotic algae that resides within coral tissues and is the reason for the bright, vibrant colors of coral reefs. A 1-2 degree C sustained increase in seawater temperatures is sufficient for bleaching to occur, which turns corals white. If a coral is bleached for a prolonged period of time, death may result. In the Great Barrier Reef, before 1998 there were no such events. The first event happened in 1998 and after it they begun to occur more and more frequently so in the years 2016 - 2020 there were 3 of them. A 2017 report, the first global scientific assessment of climate change impacts on World Heritage coral reefs, published by UNESCO, estimates that the coral reefs in all 29 reef-containing sites would exhibit a loss of ecosystem functioning and services by the end of the century if CO₂ emissions are not curbed significantly.

Species adaptation[edit]

A young red deer in the wild in Scotland.

In November 2019 it was revealed that a 45-year study indicated that climate change had affected the gene pool of the red deer population on Rùm, one of the Inner Hebrides islands, Scotland. Warmer temperatures resulted in deer giving birth on average three days earlier for each decade of the study. The gene which selects for earlier birth has increased in the population because does with the gene have more calves over their lifetime. Dr Timothée Bonnet, of the Australian National University, leader of the study, said they had "documented evolution in action".

In December 2019 the results of a joint study by Chicago's Field Museum and the University of Michigan into changes in the morphology of birds was published in Ecology Letters. The study uses bodies of birds which died as a result of colliding with buildings in Chicago, Illinois, since 1978. The sample is made up of over 70,000 specimens from 52 species and span the period from 1978 to 2016. The study shows that the length of birds' lower leg bones (an indicator of body sizes) shortened by an average of 2.4% and their wings lengthened by 1.3%. The findings of the study suggest the morphological changes are the result of climate change, and demonstrate an example of evolutionary change following Bergmann's rule.