Final answer:
A polar vortex entering North America does not mean global warming is not happening; it's a short-term weather event, not an indicator of long-term climate trends. Global warming is a consistent trend that is not significantly impacted by short-term weather patterns or solar variability.
Step-by-step explanation:
If a polar vortex enters North America, it does not mean that global warming is not happening. Climate change and short-term weather patterns like the polar vortex are not mutually exclusive. The polar vortex is a weather-related event, which can sometimes bring cold air into temperate regions, but it is not a direct indicator of the long-term trends in global climate that are termed global warming.
Recent research suggests that the strength of the polar vortex is correlated to the size of the ozone hole, which can have global implications. However, the presence of a polar vortex is a separate phenomenon from the human-caused global warming trend observed over the past 50 years, which is not significantly affected by solar variability. In essence, weather and climate are different concepts; weather is short-term atmospheric conditions, while climate represents long-term trends.
Moreover, it's important to understand that the melting of polar ice caps due to global warming would have serious implications for modern civilization, including sea-level rise and changes in climate patterns worldwide, regardless of the presence or absence of polar vortex events.