One third of the coral reefs in the world will suffer degradation by 2030 due to climate change

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According to a new study on climate change and its effects,  a group of scientists have found that the chances of saving world’s coral reef population from the ill effects of climate change is thinning day by day as the greenhouse emissions are increasing.

Great Barrier Reef
Image courtesy:  Richard Ling

The danger to coral reefs is almost impossible to be averted, indicates the study which is published in the journal Nature Climate Change. One third of the coral reefs in the world will suffer long term degradation due to climate change by 2030, finds the study even though the estimation is based on the most optimistic IPCC estimations on emissions.

“One-third (9–60%, 68% uncertainty range) of the world’s coral reefs are projected to be subject to long-term degradation under the most optimistic new IPCC emissions scenario, RCP3-PD.”, says the study

"The window of opportunity to preserve the majority of coral reefs, part of the world's natural heritage, is small," said Malte Meinshausen, a co-author of the paper to Reuters news agency. This will happen even if the emission cuts are made stricter, shows the study.

Bleaching and decalcification of corals

The scientists have assessed the impact of emissions on 2160 coral reefs in different parts of the globe, with the help of climate models. The study points out that the emission of Carbon dioxide, a greenhouse gas, has increased by more than 3 percent last year. As a result, the average temperature of the globe has also increased by 0.8 degree Celsius approximately, during the last century.

The increasing global temperature and warmer oceans will bleach the corals to death. Thus, the reefs turn pale when the warm sea surface triggers mass bleaching events across the globe, says the study.

Even if the corals survive the ill effects of bleaching, it is difficult for them to survive a prolonged period of heating up of the ocean. According to the study, when the oceans stayed hot for a prolonged period during 1998, 16 percent of corals vanished from the face of earth.

Acidification is more fatal to the survival of corals than the bleaching events. Acidification of ocean is directly proportional to the presence of Carbon dioxide in the ocean surface. With the acidification increasing, the rate of calcification - a process which is crucial to the existence of corals - gets disrupted, leaving them to corrode to death.

Location of Corals in the world

2 degree Celsius limit is no safer zone for corals

The study also points out that the present notions of safe emission levels and safe temperature rise levels may not save coral reefs. 2 degree Celsius is widely considered as a safe emission limit to avoid the devastating effects like droughts, sea level rise or failure of cultivation. However, it will not help corals to avoid the serious threats of global warming, shows the study.

According to the scientists, the chances of survival for at least half of the coral reefs in the world will remain live only if the average mean temperature rise stay below 1.2 degrees compared to that of pre-industrial period.  

Though the reefs’ ability to adapt and evolve with changing quality of the habitat may make a difference in their survival to the acidification and bleaching events. However, their ability to adapt significantly within a matter of decades (which is a very small period for evolutionary processes), in an atmosphere of continuously changing ocean temperatures is still uncertain.

Moreover, the rate and magnitude of warming, which the globe is going to face, has no equals in the past, points out the scientists. They are doubtless that the prominence of coral reefs in coastal ecosystems will plummet, if the global mean temperatures exceed 2 degree Celsius above that of the pre-industrial era. 

Climate change to badly affect bat life, says new research review

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Climate change is speculated to affect almost all living creatures on the earth. Some will be severely hit due to their close relation to the climatic conditions of their habitat while some other may adapt and survive these changes. Bats, however, make it to the first category, points out a new review published by the journal Mammal Review.

According to the study, changing climate pattern is already taking its toll on many bat species. Based on a review of existing empirical data on the impact of climate change on bats, the scientists point out the bats are yet to face worst things. 

Indian Flying Fox (Pteropus giganteus),
Image Courtesy: Wikimedia Commons

"Climate influences the biogeography of bats, their access to food, timing of hibernation, reproduction and development, frequency and duration of torpor and rate of energy expenditure", says the study. 

Analysing the data on the foraging, roosting, reproduction and biogeography of bats, in relation with extreme weather events and indirect effects of climate change, the review finds seven risk factors associated with bats as a result of climate change.

Bat risk factors in a changing climate

Bats distributed in geographically smaller ranges and high altitude and latitude ranges will be severely affected since climate change will leave them with no other home to move on. Bats which are distributed in the areas which may come under water stress as a result of changing climatic conditions also will be victimised.

However, their eating habits also will risk certain types of bats. For example, aerial hawking bats which live on an insect diet will have to travel more to find food. Similarly, since they lack body adaptations to prevent water loss, they will have to fly more to quench thirst when the climate gets warmer. This will adversely affect feeding mothers more, points out the study.

The hibernation patterns will also be changed. Bats which are known to undergo torpor or temporary hibernation periods with minimal physiological activity to conserve energy will have to wake up from it earlier than usual, in warmer conditions. It may jumble up their energy conservation tactics.

The reproduction pattern may change, but need not be in negative direction, says the study. Though there is a lack of enough data to assess the impact on reproduction, the researchers think that a warmer climate may help females to give birth and grow their child earlier than usual.

Threatened bats species under risk

The study has used the case of European and north-west African bats to identify the risk associated with climate change. It finds that 38 out of 47 species among these bats will be affected by climate change. Among them, 11 species which live on tress or caves will be severely hit, says the study.

All these bat species are presently categorized as endangered, critically endangered or vulnerable by IUCN. So their status is less likely to improve with the climate change, suggest the study.

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Climate change will bring unprecedented marine life extinction in near future, says scientists

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As the impact of a gradually growing climate change is secretly creeping into our life, a group of leading scientists point out that it is the marine life on earth that will be hard hit with maximum number extinctions due to climate change. As per a review published in the Trends in Ecology and Evolution Journal, the climate change will cause unprecedented levels of mass extinctions in marine life.

Map showing that the Earth is getting warmer
Note: Image not relted to the reserach mentioned in the report
Image courtesy: Wikimedia commons

By analyzing the causes and patterns of marine extinctions and extinction risks with the help of fossil, historical and modern records, the paper argues that many periods in the past had similar climatic conditions estimated to take place in the future. Apparently, the effects also could be the same. 

“Even if the ultimate drivers of extinctions have changed over time, the proximal effects experienced by organisms might be similar”, says the paper. 

For instance, the increase in atmospheric CO₂ in the Permian era was due to volcanic activity but now it is caused by the burning of fossil fuels. Both ways, it has taken the toll on the marine organisms. However, it makes the extinction rates in the Permian era a better indicator to that in the immediate future. 

Lessons from the past

By analyzing geo chemical data and fossil records in the past, the researchers have found that three among the five largest extinctions in the past were related to global warming and ocean acidification. Similarly, the study has also found that loss of oxygen, habitat loss due to human intervention and pollution have also contributed to large scale extinction rates in the past. 

History of carbon dioxide concentrations
Note: Image not relted to the reserach mentioned in the report
Image courtesy: Wikimedia commons

Based on the lessons they learned by joining the jigsaws of data from fossil, historic and modern records, the study estimates that the marine organisms with a restricted geographical range will be more prone to extinction risk from habitat loss due to climate change. 

“As such, extinction risk in the future might shift from larger-bodied species to those with restricted geographic ranges as marine ecosystems respond increasingly to habitat loss and the environmental disturbances associated with climate change.” says the study.

Though over-exploitation and habitat loss were major reasons for extinctions in the past, acidification and warming will become more important drivers of extinction in the present times, despite cases of over-exploitation still existing, says the review. 

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