What is global climate change?

Climate change occurs when new weather patterns that remain in place for an extended period of time happen on Earth. This length of time can be as short as a few decades to as long as billions of years. Since the Industrial Revolution, the climate has increasingly been affected by human activities. The terms "climate change" and "global warming" are often used interchangeably, especially when referencing the change since the Industrial Revolution.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.