Final answer:
The true statement regarding atmospheric change is that humans are now adding impurities to the atmosphere at a rate previously unknown. Efforts like the Montreal Protocol have been effective against the ozone hole, unlike broader climate change challenges which have not been halted by international treaties due to complexities in transitioning away from a carbon economy.
Step-by-step explanation:
In terms of atmospheric change, it is true that humans are now adding impurities to the atmosphere at a rate previously unknown. Since the Industrial Revolution, human activities such as the burning of fossil fuels and large-scale deforestation have significantly increased the concentration of greenhouse gases like carbon dioxide in the atmosphere.
This has led to global warming and altered weather patterns, an effect known as the greenhouse effect. International treaties like the Montreal Protocol have had success in addressing issues like the ozone hole, but the current challenge posed by climate change is greater and more complex, as there is no easy substitute for our current carbon economy. The rapid changes we are witnessing in the environment and climate are unprecedented in the history of human civilization.
Efforts to mitigate climate change have resulted in international agreements such as the Kyoto Protocol and the Paris Agreement. However, these have not been able to halt climate change entirely, primarily due to the scale of changes needed to transition away from fossil fuels and the global economic dependence on carbon-based energy sources. While reduction in emissions and a shift towards renewable energy can slow down the effects of global warming, significant climate changes have already taken place.