Ocean Acidification | Environment for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
 
OCEAN ACIDIFICATION 
Page 2


 
 
OCEAN ACIDIFICATION 
When carbon dioxide (CO
2
) is absorbed by 
seawater, chemical reactions occur that reduce 
seawater pH. 
Seawater is slightly basic (meaning pH > 7), 
and ocean acidification involves a shift towards 
pH-neutral conditions rather than a transition to 
acidic conditions (pH < 7). 
These chemical reactions are termed as "ocean 
acidification"  
Ocean acidification is sometimes called “climate 
change’s equally evil twin,” and for good reason: 
it's a significant and harmful consequence 
of excess carbon dioxide in the atmosphere. 
Page 3


 
 
OCEAN ACIDIFICATION 
When carbon dioxide (CO
2
) is absorbed by 
seawater, chemical reactions occur that reduce 
seawater pH. 
Seawater is slightly basic (meaning pH > 7), 
and ocean acidification involves a shift towards 
pH-neutral conditions rather than a transition to 
acidic conditions (pH < 7). 
These chemical reactions are termed as "ocean 
acidification"  
Ocean acidification is sometimes called “climate 
change’s equally evil twin,” and for good reason: 
it's a significant and harmful consequence 
of excess carbon dioxide in the atmosphere. 
Carbon dioxide is naturally in the air: plants need it to 
grow, and animals exhale it when they breathe. 
 Most of this CO
2
 collects in the atmosphere and, 
because it absorbs heat from the sun, creates a 
blanket around the planet, warming its temperature.  
But some 30 percent of this CO
2
 dissolves into seawater, 
where it doesn't remain as floating CO
2
molecules.  
A series of chemical changes break down the 
CO
2
molecules and recombine them with others. 
When water (H
2
O) and CO
2
 mix, they combine to form 
carbonic acid (H
2
CO
3
).  
The weaker carbonic acid may not act as quickly, but it 
works the same way as all acids: it releases hydrogen 
ions (H
+
), which bond with other molecules in the 
area. 
 
Page 4


 
 
OCEAN ACIDIFICATION 
When carbon dioxide (CO
2
) is absorbed by 
seawater, chemical reactions occur that reduce 
seawater pH. 
Seawater is slightly basic (meaning pH > 7), 
and ocean acidification involves a shift towards 
pH-neutral conditions rather than a transition to 
acidic conditions (pH < 7). 
These chemical reactions are termed as "ocean 
acidification"  
Ocean acidification is sometimes called “climate 
change’s equally evil twin,” and for good reason: 
it's a significant and harmful consequence 
of excess carbon dioxide in the atmosphere. 
Carbon dioxide is naturally in the air: plants need it to 
grow, and animals exhale it when they breathe. 
 Most of this CO
2
 collects in the atmosphere and, 
because it absorbs heat from the sun, creates a 
blanket around the planet, warming its temperature.  
But some 30 percent of this CO
2
 dissolves into seawater, 
where it doesn't remain as floating CO
2
molecules.  
A series of chemical changes break down the 
CO
2
molecules and recombine them with others. 
When water (H
2
O) and CO
2
 mix, they combine to form 
carbonic acid (H
2
CO
3
).  
The weaker carbonic acid may not act as quickly, but it 
works the same way as all acids: it releases hydrogen 
ions (H
+
), which bond with other molecules in the 
area. 
 
 
WHY ACIDITY MATTERS? 
 The acidic waters from the CO
2
 seeps can dissolve 
shells and also make it harder for shells to grow 
in the first place. 
Many chemical reactions, including those that are 
essential for life, are sensitive to small changes 
in pH.  
A small change in the pH of seawater can have 
harmful effects on marine life, impacting 
chemical communication, reproduction, and 
growth. 
The building of skeletons in marine creatures is 
particularly sensitive to acidity. 
 
Page 5


 
 
OCEAN ACIDIFICATION 
When carbon dioxide (CO
2
) is absorbed by 
seawater, chemical reactions occur that reduce 
seawater pH. 
Seawater is slightly basic (meaning pH > 7), 
and ocean acidification involves a shift towards 
pH-neutral conditions rather than a transition to 
acidic conditions (pH < 7). 
These chemical reactions are termed as "ocean 
acidification"  
Ocean acidification is sometimes called “climate 
change’s equally evil twin,” and for good reason: 
it's a significant and harmful consequence 
of excess carbon dioxide in the atmosphere. 
Carbon dioxide is naturally in the air: plants need it to 
grow, and animals exhale it when they breathe. 
 Most of this CO
2
 collects in the atmosphere and, 
because it absorbs heat from the sun, creates a 
blanket around the planet, warming its temperature.  
But some 30 percent of this CO
2
 dissolves into seawater, 
where it doesn't remain as floating CO
2
molecules.  
A series of chemical changes break down the 
CO
2
molecules and recombine them with others. 
When water (H
2
O) and CO
2
 mix, they combine to form 
carbonic acid (H
2
CO
3
).  
The weaker carbonic acid may not act as quickly, but it 
works the same way as all acids: it releases hydrogen 
ions (H
+
), which bond with other molecules in the 
area. 
 
 
WHY ACIDITY MATTERS? 
 The acidic waters from the CO
2
 seeps can dissolve 
shells and also make it harder for shells to grow 
in the first place. 
Many chemical reactions, including those that are 
essential for life, are sensitive to small changes 
in pH.  
A small change in the pH of seawater can have 
harmful effects on marine life, impacting 
chemical communication, reproduction, and 
growth. 
The building of skeletons in marine creatures is 
particularly sensitive to acidity. 
 
 One of the molecules that hydrogen ions bond 
with is carbonate (CO
3
-2
), a key component of 
calcium carbonate (CaCO
3
) shells. 
 To make calcium carbonate, shell-building 
marine animals such as corals and oysters 
combine a calcium ion (Ca
+2
) with carbonate 
(CO
3
-2
) from surrounding seawater, releasing 
carbon dioxide and water in the process. 
Like calcium ions, hydrogen ions tend to bond 
with carbonate —but they have a greater 
attraction to carbonate than calcium.