A global-scale instrumental temperature record that has not been contaminated by (a) artificial urban heat (asphalt, machines, industrial waste heat, etc.), (b) ocean-air affected biases (detailed herein), or (c) artificial adjustments to past data that uniformly serve to cool the past and warm the present . . . is now available.
Composed of 450 instrumental records from temperature stations sheltered from ocean-air/urbanization/adjustment biases throughout the world, a new 20th/21st century global temperature record introduced previously here very closely aligns with paleoclimate evidence from tree rings, ice cores, fossil pollen and other temperature proxies.
The Alignment Of Paleoclimate Proxy Data & Instrumental Records
The paleoclimate proxy data for the Northern Hemisphere (NH) consistently show an oscillation rather than a linear warming trend between 1900 and 2010: (a) a substantial warming trend between 1900 and the early 1940s, (b) a substantial cooling trend between the 1940s and 1970s, and (c) a subsequent warming trend since the 1980s that matches or comes close to matching the warming peaks in the 1930s and early 1940s (rather than greatly exceeding it).
In 2016, Dr. Pei Xing and co-authors unveiled a new method (MVDM) for calibrating low-frequency NH tree-ring data (utilizing 126 tree-ring records) for the last 1,200 years in The Extratropical Northern Hemisphere Temperature Reconstruction during the Last Millennium Based on a Novel Method. The proxy evidence shows an oscillation — including substantial cooling between the 1940s and 1970s — and no net warming since the early 1940s.
Image Source: Xing et al., 2016 (MDVM Reconstructed NH Temperature)
Christiansen and Lungqvist (2012) utilize proxies from 91 locations across the extra-tropical Northern Hemisphere to reveal no net warming since the 1940s.
Image Source: Christiansen and Lungqvist (2012)
Schneider et al., 2015 use proxy evidence from 15 IPCC-referenced locations in the Northern Hemisphere to document no net warming since the 1940s.
Image Source: Schneider et al., 2015
Stoffel et al., 2015 used proxy data from 22 Northern Hemisphere locations to illustrate there has been no net warming since the 1940s.
Image Source: Stoffel et al., 2015
A New Instrumental Record Of The Northern Hemisphere
In a ground-breaking new paper (Lansner and Pepke Pedersen, 2018) published in the journal Energy and Environment, an analysis of land surface instrumental records from across the globe’s ocean air sheltered (OAS) regions reveals that, like the proxy evidence presented above, most of the modern era warming occurred prior to the 1940s, and the there has effectively been no net warming since then.
Lansner and Pepke Pedersen (2018) point out that, due to the divergent rates of warming and cooling for land vs. ocean water, there is a significant difference in the range of temperature for the regions of the world influenced by their close proximity to oceans and coastal wind currents (ocean air affected, or OAA) and the inland regions of the world that are unaffected by ocean air effects and coastal wind because they are sheltered by hills and mountains or located in valleys (ocean air sheltered, or OAS).
The two authors acknowledge that it is “difficult” to isolate the influence of the ocean’s effects on temperature changes and the influence of climate- or radiation-induced changes in driving temperature change. So the two authors chose to “retrieve temperature data where impact of the ocean temperature trends has been reduced as much as possible.”
The results they obtained in analyzing “thousands” of instrumental temperatures from across the globe are especially noteworthy. To summarize, Lansner and Pepke Pedersen (2018) found that the OAS regions of the world reached annual temperatures that were just as warm or warmer during the 1920s to 1940s as they have been in recent decades. There has been no net warming — and, in fact, an overall slight cooling — since the 1940s for the OAS temperature stations.
“We found that in any land area with variation in the topography, for the period 1900-2010 we can divide the meteorological stations into the more warm-trended ocean air-affected OAA-stations, and the more cold-trended ocean air-sheltered OAS-stations. The methods used in this work are meant to give a rough picture of the large differences in temperature trends between OAS and OAA stations. … When we isolated temperature trends 1900–2010 with as little ocean influence as possible – the OAS areas – we found a warm period 1920–1950 with temperatures similar to recent decades for all investigated areas worldwide. We have not found any area with numerous OAS/Valley stations available where the majority of temperature stations show a different result.”
“In contrast, the OAA locations like islands, coasts, hills facing dominating ocean winds, etc., did not reflect the warm period 1920–1950 well. … Therefore, the lack of warming in the OAS temperature trends after 1950 should be considered when evaluating the climatic effects of changes in the Earth’s atmospheric trace amounts of greenhouse gasses as well as variations in solar conditions.”
“In locations best sheltered and protected against ocean air influence, the vast majority of thermometers worldwide trends show temperatures in recent decades rather similar to the 1920–1950 period. This indicates that the present-day atmosphere and heat balance over the Earth cannot warm areas – typically valleys – worldwide in good shelter from ocean trends notably more than the atmosphere could in the 1920–1950 period.”
1. “[W]e show in Figure 3 the results for the Scandinavian area where we have used a total of 49 OAS stations and 18 OAA stations. The large number of stations available is due to the use of meteorological yearbooks as supplement to data sources such as ECA&D climate data and Nordklim database. … For the years 1920–1950, we thus find temperatures in the OAS area to be up to 1 K warmer than temperature in the OAA area.”
2. “Another example is from Central Siberia (Figure 4), where a total of 18 OAS stations and 17 OAA stations were used. All data were taken from GHCN v2, raw data. … Again we find that the temperature trends from the OAS area show more warming in the 1920-1950 period with about 0.5–1.5 K higher temperatures than the OAA areas.”
3. “In the Central Balkan area [Poland, Slovakia, Austria, Hungary, Slovenia, Croatia, Serbia, Rumania, Greece, and Turkey] (Figure 5), 41 OAS stations and 25 OAA stations were used … data from meteorological yearbooks and statistical yearbooks supplemented with GHCN v2 raw (NOAA) and BEST raw data. … The temperature trends from the OAS area from the 1925 to 1950 period are found in most years to be around 1 K warmer than temperature trends from the OAA areas.”
4. “For the USA (Figure 6), we defined the OAS area as consisting of eight boxes, each of size 5° X 5°. … A total of 236 temperature stations were used from this area. … All data were taken from GHCN v2 raw data. … Again the temperature trends from the OAS area as defined above show the 1920–1955 period in most years to be around 1 K warmer than temperature trends from the OAA areas.”
5. “For Central China (Figure 7), 14 OAS stations and 12 OAA stations were used. All data were taken from GHCN v2 raw data. …The temperature trends from the OAS area show the 1920–1950 period around 0.5–1.5 K warmer than temperature trends from the OAA areas.”
6. “For the Pakistan/NW India area (Figure 8), 10 OAS stations and 8 OAA stations were used. All data were taken from GHCN v2 raw data. … The temperature trends from the OAS area show the 1930–1955 period to be around 1–1.5 K warmer than temperature trends from the OAA areas.”
7. “In the Sahel area (Figure 9), 34 OAS stations and 11 OAA stations were used. All data were taken from GHCN v2 raw data. The temperature trends from the OAS area show the 1930–1950 period to be around 0.2–1 K warmer than temperature trends from the OAA areas.”
8. “For Southern Africa (Figure 10), 13 OAS stations and 15 OAA stations were used. All data were taken from GHCN v2 raw data. The temperature trends from the OAS area as defined show the 1920–1945 period to be around 0.2–1.5 K warmer than temperature trends from the OAA areas.”
9. “For South East Australia (Figure 11), 18 OAS stations and 24 OAA stations were used and all data were taken from GHCN v2 raw data. … The temperature trends from the OAS areas show the 1925–1950 period to be around 0.3–0.5 K warmer than temperature trends from the OAA areas.”
10. “Finally, for Central South America (Figure 12), 17 OAS stations and 13 OAA stations were used. Data were taken from GHCN v2 raw data and also from the BEST raw data base. … The temperature trends from the OAS area as defined show the 1930–1965 period to be around 0.5–1 K warmer than temperature trends from the OAA areas.”
Global Temperatures In Non-Urban Areas Have Warmed By 0.375 K/Century Since 1900
Combining the OAS temperatures and OAA temperatures and using the century-scale trends for each identified in the paper (-0.03 K/century and +0.78 K/century, respectively), it may be concluded that instrumental temperature stations located in non-urban areas and not subjected to artificial urban heating bias produce an overall warming trend of just 0.375 K/century (0.038 K/decade) during 1900-2010.
“For the OAS areas, we find a linear temperature trend over the whole period from, 1900 to, 2010 of -0.03 K/century whereas we find 0.78 K/century for the OAA areas. We recognize the remarkable temperature increase in temperature in the years after the 1918/1919 strong El Nino. After this warming, the OAS temperature data appear to have jumped by around 0.5 K to a new level, indicative of a shift to a new climatic regime. The OAA data fail to show this abrupt change.”
This much milder rate of warming over the 20th/21st centuries underscores just how influential urbanization might have been in driving up warming artificially, or non-climatically, during the modern era.
The phenomenon of artificially-driven warming rates has been documented in many other analyses.