Climate change is a gradual shift in the average weather conditions and patterns over an extended period of time, typically decades to centuries. It is caused by various natural and human activities that alter the Earth's climate system. While you can observe changes in temperature, weather patterns, and other climate-related phenomena, it's important to understand that climate change requires long-term data analysis and scientific research to fully comprehend its impacts. Checking a thermometer alone does not provide a comprehensive perspective on climate change. Scientists use various methods and datasets to monitor and study long-term climate trends and patterns.