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

Abstract

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

A jelenkori felmelegedés lehetséges hatótényezőiről • On the Potential Drivers of Current Global Warming

“…Egy másik -az IPCC WG1 AR6-tal egy időben megjelent, tizennégy ország huszonhárom kutatójának tollából származó -tanulmány szerint azonban a magabiztos IPCC-állítás megalapozatlan és elsietett volt (Connolly et al, 2021a). Összefoglaljuk Ronan Connolly és szerzőtársai (2021a) fő megállapításait, a tanulmány nemzetközi fogadtatását (beleértve a Magyar Tudományos Akadémiáét is), valamint a Connolly és szerzőtársai köre által a kritikák hatására készített és nemrég megjelent két újabb, még alaposabb elemzés eredményeit (Connolly et al, 2023;Soon et al, 2023). E két cikk megerősíti és részletgazdag módon kiegészíti Connolly és szerzőtársai (2021a) következtetéseit, miszerint a jelenkori felmelegedés oka továbbra is nyitott kérdés.…”

Ninety-Nine Percent? Re-Examining the Consensus on the Anthropogenic Contribution to Climate Change

“…We find it useful to give a practical example for this case. In a recent paper [8], Soon and co-authors examined the role of the urban heat island (UHI) effect as a possible source of bias in estimations of northern-hemisphere temperatures over the last century, showing that indeed the UHI effect may lead to a bias of ~40%. Importantly, the first three authors of the paper are very publicly out-spoken climate skeptics who have expressed their objections to the AGW hypothesis on many occasions, for instance, in a recent joint podcast appearance [9].…”

Terrestrial Temperature, Sea Levels and Ice Area Links with Solar Activity and Solar Orbital Motion

“…Bottom plot-The variations of the temperature (black curve) versus versus the averaged sunspot numbers (yellow curve). [80,81]. However, if the sum of TSI calculated for the whole year, the deposited solar radiation has a wide variation in magnitudes imposed by the smaller SIM effects remaining though nearly a constant wide strip over the time of two centuries.…”

“…The fact that the ocean level correlates with the spring-summer TSI magnitudes, which is not considered when producing the solar forcing for the terrestrial temperature models [3] is likely to create the discrepancy between the solar heating function used in the current temperature models. Besides any increases of the terrestrial temperature caused by the temperature measurements in urban conditions where Natural Science temperature by default is higher [80,81]., there is additional solar heating caused by solar orbital motion induced by the gravitation of large planets.…”