A coral reef during a bleaching event. All the zooxanthellae has been expelled, losing the colouration of the coral, revealing the white skeleton. Photo source: https://sites.psu.edu/ichen/2016/04/12/warning-coral-bleaching/
1. A coral reef during a bleaching event. All the zooxanthellae has been expelled, losing the colouration of the coral, revealing the white skeleton. Photo source: https://sites.psu.edu/ichen/2016/04/12/warning-coral-bleaching/

On  the 9th November shock waves were sent throughout the world as America had one of the most controversial election results in their history. Donald Trump will be the next President of the United States of America. A man who ‘does not believe in climate change’. A man who wants ‘to unleash America’s untapped shale, oil, and natural gas reserves, plus hundreds of years in clean coal reserves’. A man who wants to ‘destroy the Obama Administration’s anti-coal regulations’. What is the future of our environment with the threat of Donald Trump’s reign on the horizon?

What is Global Warming?

Energy consumption in the United States of America is ranked the second highest in the world. In 2014, the US emitted 16.5 tonnes per CO2 per capita/person, one of the highest levels in the world and the emission rate is increasing. Carbon dioxide (CO2) is known as a greenhouse gas (see video). Heat trapping gases such as CO2 absorb the sun’s radiation energy and reflect the heat back to the Earth causing additional heating known as global warming. Global air temperature has increased by 0.74°C in the 20th century. The increase in temperature is melting the ice sheets causing sea level rise at a rate of 1.7±0.3 mm yr−1. The ocean also acts as a carbon sink absorbing around 25% of the CO2 emitted into the atmosphere by anthropogenic activity. Carbon dioxide when mixed with water, reacts to produce carbonic acid. Carbon acid decreased the pH of the ocean by 0.1, the equivalent to a 30% increase in acidity. The addition of carbon acid to the ocean reduces the amount of carbonate available to form the physical structure of organisms. Calcium carbonate is crucial to form the shells of clams, oysters, the skeletons of sea urchins, and are essential to form coral reefs. However as a result of ocean acidification, problems are occurring during calcification as the structures are weakening and effecting the fitness of the species.

The world’s CO2 emissions. Source: https://www.youtube.com/watch?v=fJ0o2E4d8Ts  

Too hot to handle

Coral reefs are extremely sensitive to the changing environment. Algae called zooxanthellae are found within coral giving the reefs their colouration (image 4). The algae carry out photosynthesis which takes in the CO2 released when the coral polyps respire. This symbiotic relationship is vulnerable to changes in the environment. During periods of sea temperature rise, corals expel the zooxanthellae turning the coral white. The process is a defence mechanism known as bleaching (image 1). It is normal for bleaching to occur when the physical conditions change during. After short periods, zooxanthellae is reabsorbed when the environment returns back to normal. However, prolonged environmental change can cause mass mortalities as observed during El Niño events.  El Niño is an infrequent natural event of high global sea temperatures lasting for more than six months. Anomalies of an increase in sea temperature by 1°C for 10 weeks has been found to co-occur with severe coral loss. Without zooxanthellae, photosynthesis cannot be carried out leaving corals damaged and degraded, sometimes leading to death as in 1997/98.

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2. Two predicted scenarios of the probability of severe bleaching events in the years of 2030, 2050, and 2100. The colouration key states the percentage probability. Photo source: http://link.springer.com/article/10.1007/s00338-011-0866-8/fulltext.html

Crumbling Coral Catastrophe

The current environmental conditions are the absolute extreme limit for some coral species to survive in. It is estimated that 11% of coral reefs have been lost, with 16% of corals severely damaged. Coral reefs are under imminent threat by global warming. The current global CO2 concentration is 380ppm. Increasing at a rapid rate in the past century by 100ppm since the industrial revolution. It is predicted that at the current acceleration, the CO2 concentration will exceed 1000ppm by 2100. The global sea temperature is predicted to increase by 2°C within this century. The climate is changing and it is predicted that there will be an increased occurrence of El Niño events in the future (image 2). In 2014, it was recorded to be one of the world’s warmest years. It was followed by a severe record El Niño event in 2015. Sea surface temperatures presently still remain at a deadly high (image 3). It is not known fully the extent of the coral damage as a result of this long period of high sea surface temperatures. However, it has been reported that the northern part of the Great Barrier Reef has experienced a 67% loss of coral cover in the worst bleaching event on record. Regrowth of the reef shall be painfully slow as coral calcification rates have reduced by 14.2% since 1990. Unless proper action is taken immediately, restoration of reefs will remain an uphill battle.

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3. After the largest El Niño event in 2015, the areas in the world with a 60% probability of coral bleaching during February- March 2016 and December- March in 2017. The colouration key explains the stress level and the potential bleaching intenisity. Photo source Feb- May 2016: http://www.orbit.nesdis.noaa.gov/star/news2015_201510_WorldCoralBleaching.php Photo source Dec- Mar 2017: http://coralreefwatch.noaa.gov/satellite/bleachingoutlook_cfs/outlook_cfs.php

What is being done?

In 2005 the United Nations Framework Convention on Climate Change put together the Paris Agreement to reduce rate of global temperature rise. Currently predictions state that the global temperature could rise by 4.5°C by 2100. Targets have been put in place by 115 countries to reduce CO2 emissions with the overall aim to keep global temperature rise below 2°C in this century. The US is part of the agreement, stating it will reduce carbon emissions by 26-28% by 2025. Also in August 2016, the expansion of the US Papahānaumokuākea Marine National Monument was announced. It is now the largest marine protected area in the world. It has been found that by protecting large marine areas the communities can thrive.

Make America Great Again?

The recent environmental awareness by America and the action plan that is in place is promising. However, Donald Trump has stated that he wants to remove US involvement in the Paris Agreement. And it is still uncertain whether he shall follow the climate initiatives put in place by Barack Obama. If the carbon reductions were followed, America could drastically help to reduce the rate of global temperature rise and the extremely high threat to coral reefs. However, that fate lies in the hands of a charismatic business man who has charmed the US nation into believing that he is the best for the country. Only time will tell for certain, whether this is true.

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4. A healthy thriving coral reef. Can coral reefs be great again? Photo source: Alamy
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