What is the term for the theory that the earth is gradually warming due to environmental issues?

The term that specifically refers to the gradual increase in Earth's average temperature due to human activities and environmental issues is "Global Warming." This concept emphasizes the rise in temperatures that can lead to various climatic changes, such as melting ice caps, rising sea levels, and altered weather patterns. Global warming is a subset of the broader phenomenon known as climate change, which encompasses a variety of changes in the climate, including shifts in precipitation, storm patterns, and more.

While "Climate Change" represents the wide-ranging effects of global warming, including both increases and decreases in temperatures and various climate patterns, "Global Warming" zeroes in on the temperature aspect specifically. The "Greenhouse Effect" refers to the process whereby certain gases in the atmosphere trap heat from the sun, contributing to global warming, but it is not synonymous with it. "Environmental Crisis" is a more general term that can describe a variety of environmental issues, making it less precise in context to the specific temperature increase described by global warming. Hence, among the given options, the term that most accurately captures the theory of the earth's gradual warming due to environmental issues is Global Warming.