The issue focused on alleged weaknesses in standard calculations for atmospheric greenhouse gases that led to disputes between scientists that contributed to the breakdown of global warming discussions and contributed to the advent of global cooling and subsequent cooling periods in the 1980s and 1990s. Both papers concluded that temperature variations could not be attributed to greenhouse gases alone and instead pointed to external influences such as volcanic eruptions and solar variability as causes of temperature fluctuations. Both papers concluded that observed warming since 1950 could not be attributed to greenhouse gases alone and instead pointed to external