IBDP Biology- How climate change impacts the environment

In this IBDP Biology blog post, we will be looking at how the ocean is impacted by the climate changes within the enviornment, let's go!

Threats to coral reefs from increasing concentration

Emissions of carbon dioxide have an effect on the oceans

• Over 500 billion tonnes of CO2 released by humans since the start of the Industrial Revolution have dissolved in the oceans
• This has caused the pH to drop this repersents 30% acidification
• Ocean acidification will become more severe if CO2 concentrations in the atmosphere continue to rise
• Reef-building corals that deposit calcium carbonate in their skeletons need to absorb carbonate ions from seawater

There is a low concentration of carbonate ions in the water and the dissolved carbon dioxide makes the concentration even lower

• Carbon dioxide reacts with carbonate to form carbonic acid which disassociates into hydrogen ions and hydrogen carbonate ions
• Hydrogen coverts carbonate into hydrogen carbonate
• Reduced carbonate concentrations in water prevent calcium carbonate from being created but the calcium carbonate within the coral reefs are dissolved  

Ocean acidification - causes and effects  

The ocean abosrbs about 25% of the CO2 emitted into the atmosphere

As atmospheric CO2 increases so do ocean levels

Since the 1800s the pH of seawater has fallen by 0.1 units this is a 30% increase in acidity

As more CO2 accumulates in the ocean, the pH of the ocean decreases

Estimates of future CO2 levels predict a further decrease of 0.5 units in pH which translates to 150% acidification

When CO2 dissolves in water it forms a variety of molecules:

• Carbonic acid [affects pH]
• Carbonate [releases hydrogen ions affecting pH]
• Bicarbonate [releases hydrogen ions affecting pH]
• Free Carbon Dioxide  

Ocean acidification - risks and benefits 

Species at risk are

• Marine calcifying species [oysters, sea urchins, sea corals, calcerous plankton]

Benefit: Photysynthetic algae and sea grasses

These species need to:

• Absorb carbonate ions from seawater to make calcium carbonate in skeletons

Benefit: Low CO2 is a limiting factor for photosynthesis

Shelled organisms are very important in aquatic food chains - put the whole food chain at risk

Example: Pteropod tiny sea creatures that are a main food source for North Pacific juvinile salmon 

That's all!

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References:

• https://www.google.com/url?sa=i&url=https%3A%2F%2Fgoinggreenrecyclingnigeria.org%2Fgreenhouse-pollution-and-the-dangers-of-ocean-acidification%2F&psig=AOvVaw0x1WNNwfY0NNyNrM3-hiaM&ust=1626287842878000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCJjwhL3Y4PECFQAAAAAdAAAAABAI
• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.iucn.org%2Ftheme%2Fmarine-and-polar%2Four-work%2Fclimate-change-and-ocean%2Focean-acidification&psig=AOvVaw17TJQ3nInmYue9Con0qGXm&ust=1626287901608000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCJi1mtjY4PECFQAAAAAdAAAAABAD

Drafted by Venetia (Biology)