Among the many scary changes happening on our planet, you may have heard of acid rain.
It’s not the most hotly debated environmental problem — but it continues to be one even so.
What is its cause? Some people claim it is deforestation, while others argue it isn’t.
Let’s take a look at the facts and find the answer.
What is acid rain?
Let’s start with a quick review of what acid rain is.
Basically, it’s any form of precipitation that has acidic (rather than basic) pH levels. This can be rain, but also snow, fog, or dust that settles on the ground.
Normal rain is already slightly acidic at 5.6, because C02 in the atmosphere dissolves in it to form weak carbonic acid.
What we call acid rain usually has a pH of 4.0-4.5. In extreme cases, it may be even lower at pH 2.0, which is even more acidic than lemon juice.
This acidic quality is caused by nitric and sulfuric acids.
The effects of acid rain first started becoming apparent in the 1970s. By the 80s, this phenomenon was widespread around the globe, and especially bad in eastern North America, north-west Europe, eastern Asia, and parts of the southern hemisphere like Brazil.
What causes acid rain?
There are a number of things that can cause rain to be more acidic.
As mentioned above, C02 in the atmosphere makes rain naturally slightly more acidic, at pH 5.6.
Rotting vegetation and erupting volcanoes also release some chemicals that can cause rain to be more acidic.
However, the primary cause of acid rain is human activity: specifically, coal-burning factories and vehicles.
These things burn fossil fuels, releasing sulfur dioxide and nitrogen oxide into the atmosphere.
Those air pollutants then react with water, oxygen, and other substances to create fulsuric and nitric acid in the air.
Winds can spread them over hundreds of miles, and when it rains, these substances fall down onto Earth.
That’s where it flows into water systems and gets absorbed into the soil, affecting entire ecosystems.
Is deforestation the main cause of acid rain?
If you’ve read the sections above, you’ll already know that the simple answer to this is no.
Let’s break it down and go over why.
Deforestation is the destruction and removal of trees and forests. The main problem with this is there are fewer trees to remove C02 from the atmosphere.
Therefore, deforestation leads to a higher concentration of C02 in the air.
As we’ve already said, C02 can and does make rain slightly more acidic — normal rain has a pH of 5.6, slightly acidic for this very reason.
But what we consider “acid rain” is much more acidic than that — typically around 4.0-4.5, or even lower.
This is caused by sulphur dioxide and nitrogen oxide being released into the air and dissolving into acids when mixed with water and oxygen.
And these two substances are the direct result of burning fossil fuels in factories, power plants, and vehicles.
So, there you have it: the main cause of acid rain is pollution caused by human activity.
Deforestation is definitely an environmental problem as well, but it is not strongly related to the problem of acid rain.
If you’d like to hear from a few more experts, here’s how a former industrial chemist explains it:
“The cause of acid rain is the burning of sulphur-containing compounds, which produces SO2 which in turn is oxidised in the air to SO3. This combines with atmospheric moisture to form sulphuric acid, the cause of acid rain.
“Deforestation reduces the amount of material that can absorb CO2 and is therefore undesirable but can have very little effect on the acidity of rain.”
Another former climate scientist further points out that it may actually be the other way around:
“Deforestation does not cause acid rain, while acid rain may damage trees. Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide from power generation. These oxides react with water in the atmosphere to produce acids. Acid rain does not usually kill trees directly. Instead, it may weaken trees by damaging their leaves, limiting nutrients uptake, or poisoning them with toxic substances released from the soil.”
What are the effects of acid rain?
Why is acid rain such a problem for our environment?
1) It causes health problems for people
Acid rain does not cause health problems directly, in the sense that it is not dangerous for people to touch acidic water or swim in it.
However, sulfur dioxide and nitrogen oxide, the main causes of acid rain, constitute air pollution.
When we breathe in these pollutants, they lead to respiratory diseases or can worsen already existing health problems. These can include asthma or chronic bronchitis.
In addition, nitrogen oxides in particular lead to ground-level ozone. This is another cause of of respiratory health problems like pneumonia and bronchitis.
These issues can even result in permanent lung damage.
2) It damages forests
As we’ve seen above, deforestation is not the main cause of acid rain.
However, acid rain is contributing to deforestation.
When it’s absorbed into the ground, acidic rain dissolves nutrients that are essential to keep trees healthy, like magnesium and calcium.
Acid rain also releases aluminum into the soil. This prevents trees from soaking up water.
Trees at higher altitudes, such as spruce or fir trees which are found in mountainous regions, are at particularly high risk because they are also more exposed to acidic clouds and fog.
These actually have an even higher amount of acid than rain or snow. They strip essential nutrients from trees’ leaves and needles, leading to damage from infections, insects, and cold weather.
3) It pollutes water systems
Without acid rain and other types of pollution, most lakes and streams would have a pH level of around 6.4.
However, acid rain that drains into these lakes and streams has made many of them much lower on the pH scale as well.
This is especially bad in the spring, when snow melts in large quantities releasing a huge amount of acid into the lakes at once.
They are further affected by aluminum that is soaked into the ground and eventually absorbed into the lakes and streams as well.
The effects can be deadly to aquatic ecosystems and the animals that live in them, including phytoplankton, fish, frogs, and many other creatures.
As all ecosystems are ultimately connected, this has very far-reaching consequences on other animals that eat the fish, including birds and even humans.
What can we do about acid rain?
Though it’s not talked about nearly as much as other environmental issues, it’s obvious that acid rain is a problem that we need to deal with.
What can we do about it?
The obvious answer is that we must reduce the pollutants that are released into the air and that mix with water and oxygen to create acid rain: namely, sulphur dioxide and nitrous oxide.
This means burning fewer fossil fuels and maintaining better air quality standards.
For example, the U.S Clean Air Act of 1990 was focused primarily on acid rain, and implemented limits that helped cut sulfur dioxide emissions by 88 percent by the year 2017.
Air quality standards have also reduced nitrogen dioxide emissions in the US by 50% in the same period.
These changes have helped red spruce forests in New England and certain fish populations recover from the damages caused by acid rain.
However, it will take much longer for other parts of the ecosystem to stabilize, including the quality of the soil.
When we get down to it, acid rain will continue to pose a problem as long as we continue to use fossil fuels.
Countries that rely heavily on burning coal, such as China for electricity and steel production, will be particularly affected.
It is up to each country and its leaders to take action to mitigate these effects.
But don’t forget the power you have as an individual to power positive change as well.
You can start by becoming more educated on the manufacturing processes of different brands that you support, and making wise choices.
You can also talk to people you know about this problem in order to increase their awareness and inspire them to take similar positive action.