I was reading an essay about the environment and how we can save the forests.
But actually while reading I felt that the following sentence is not correct, it used the plural are instead of is as I think it should.
Look the sentence:
…Is this a problem? Yes it certainly is.
First, rising CO2 levels are causing global warming.
I think the (rising) in CO2 levels is the cause of the global warming, then the sentence must use the singular is. Why did it use the plural? How can you explain this?
Sorry if the question is too basic.
Best Answer
You can say:
"The rising in CO2 levels is causing..."
"The rising CO2 levels are causing..."
"The rising CO2 level is causing..."
All of these are correct grammatically but are slightly different in what is being stated.
In the first "the rising" (a noun) is the singular subject. In the second "CO2 levels" is the plural subject (rising is an adjective). In the third "CO2 level" is the singular subject (rising is an adjective).
There is really only one global CO2 level since atmospheric mixing is quick and efficient on the scale of the release process, so a singular is technically correct (but "levels" is okay also).