Global Warming, now called Climate Change, is a divisive political issue, often science-free. It has been hijacked by politicians, environmental pressure groups, and other leftists. Earth's climate is always changing. ‘Climate’ is defined as average weather over a 30-year or longer period. The difference between the annual average temperature, and its 30-year average, is the temperature anomaly. Temperature measurements are not evenly distributed over the globe, especially over the oceans, and at high latitudes. Questionable schemes are used to extrapolate ( aka "infill" ) sparse data to approximate global coverage. Filling in data is making up data.
4) Greenhouse gas emissions
6) Unknown causes of variations of a
complex, non-linear system