The Detection and Attribution of Northern Hemisphere Land Surface Warming (1850–2018) in Terms of Human and Natural Factors: Challenges of Inadequate Data

A statistical analysis was applied to Northern Hemisphere land surface temperatures (1850–2018) try identify the main drivers of observed warming since mid-19th century. Two different temperature estimates were considered—a rural and urban blend (that matches almost exactly with most current estimates) a rural-only estimate. The indicates long-term 0.89 °C/century 1850, while 0.55 °C/century. This contradicts common assumption that thermometer-based global indices are relatively unaffected by biases. Three climatic considered, following approaches adopted Intergovernmental Panel on Climate Change (IPCC)’s recent 6th Assessment Report (AR6): two natural forcings (solar volcanic) composite “all anthropogenic combined” time series recommended IPCC AR6. volcanic alternative solar forcing datasets contrasted. One Total Solar Irradiance (TSI) other TSI apparently overlooked It found altering estimate and/or choice dataset resulted in very conclusions as primary warming. Our focused Hemispheric component this is data-rich component. reveals important challenges remain for broader detection attribution problem warming: (1) urbanization bias remains substantial data; (2) it still unclear which (if any) many literature accurate past TSI; (3) scientific community not yet position confidently establish whether 1850 mostly human-caused, natural, or some combination. Suggestions how these might be resolved offered.