https://issuesinsights.com/2023/04/05/why-we-need-an-independent-global-climate-temperature-database/
Ever since the beginning of the global warming debate, now labeled “climate change,” there has been one immutable yet little-known fact: All of the temperature data stations used to make determinations about the state of Earth’s temperature are controlled by governments.
In June 1988, when Dr. James Hansen, then-director of NASA’s Institute for Space Studies in Manhattan, went before the Senate Energy and Natural Resources Committee to say that, “global warming has begun,” he was using temperature data collected by governments worldwide from a weather station network that was never intended to detect a “global warming signal.”
In fact, Dr. Hansen had to develop novel statistical techniques to tease that global warming signal out of the data. The problem is, these weather station networks were never designed to detect such a signal in the first place. They were actually designed for weather forecast verification, to determine if forecasts issued by agencies such as the U.S. Weather Bureau (now the National Weather Service) were accurate. If you make temperature and precipitation forecasts for a location, and there is no feedback of the actual temperatures reached and the rainfall recorded, then it is impossible to improve the skill of forecasting.
The original network of weather stations, called the Cooperative Observer Program (COOP), was established in 1891 to formalize an ad hoc weather observation network operated by the U.S. Army Signal Service since 1873. It was only later that the COOP network began to be used for climate because climate observations require at least 30 years of data from weather stations before a baseline “normal climate” for a location can be established. Once the Cooperative Observer Program was established in the United States, other countries soon followed, and duplicated how the U.S. network was set up on a global scale.