10 New Reconstructions Show Today’s Temperatures Still Among The Coldest Of The Last 10,000 Years

By on 10. September 2018

Even though CO2 concentrations hovered well below 300 ppm throughout most of the Holocene, newly published paleoclimate reconstructions affirm that today’s surface temperatures are only slightly warmer (if at all) than the coldest periods of the last 10,000 years.  This contradicts the perspective that temperatures rise in concert with CO2 concentrations.

1. Even Past Cold Periods Were 0.5–1.5 °С Warmer Than Today

Nosova et al., 2018

“According to the present climate reconstruction, mid Holocene warming started only at 7,700 cal bp, with temperatures higher than now during the mid Holocene period. This warming was due to an increase in winter temperatures (1–5 °С higher than current), while summer temperatures remained relatively stable, with a July temperature<1 °С higher than now. … During the mid Holocene, two cold periods at 6,900–6,500 and at 5,300–5,000 cal bp were observed. Interestingly, during the cold periods, the temperatures exceeded the current ones by 0.5–1.5 °С.”
“The transition from the mid Holocene thermal maximum to the following period occurred without considerable climatic changes. The mean annual temperatures remained much higher than the current ones by 0.5–2.5 °С until 2,500 cal bp. Local maximum temperatures were observed at 4,800, 4,300, 3,500 and 2,900–2,700 cal bp. The present climatic reconstruction demonstrates a gradual cooling down to current levels at ca. 2,500 cal bp, and then followed by a new warming phase with up to 1–2 °С increase at approximately 1,500 cal bp.”

2. Only 3 Of 116 Holocene Temperature Anomaly Records Were Colder Than Today

Bajolle et al., 2018

“The mean annual temperature recorded at the closest meteorological station [La Sarre: 1961–1990] is 0.8 °C, with August temperature averages of 15.0 °C (1961–1990) and 15.4 °C (1981–2010). … During zone Lch1 (8500–5800 cal year BP), the average reconstructed temperature was 16.9 °C, with a decrease from 19 °C (maximum) to 17 °C at the end of the zone. In zone Lch-2 (ca. 5700–3500 cal year BP), temperatures had an average of 16.8 °C, with a decrease from 17.8 °C around 5200 cal year BP to 16.2 °C at 3400 cal year BP. Zone Lch-3 (ca. 3500–1200 cal year BP) started with inferences for high temperatures (19.3–18.5 °C), followed by a decrease to 16.8 °C between ca. 3000 and 2500 cal year BP. An increase (18.3 and 19.6 °C) was inferred for the period between 1800 and 1500 cal year BP. The average chironomid inferred temperature during Zone 3 was 17.9 °C. In the last zone (Lch-4), the temperatures decreased from ca. 17.5 °C at the beginning of the zone to 14.8 °C at the end of the zone. The average during this zone was 16.5 °C. The temperature anomalies show that throughout the whole record, only six of the inferences were colder than the climate normal of 15.4 °C and three were colder than today, with the climate normal of 15 °C (Fig. 4b). The average anomaly from 15 °C (2.10 °C) and from 15.4 °C (1.70 °C) for the whole record showed that the temperature inferences were generally, and significantly, warmer than today.”

3. New England (USA) Colder Now Than Nearly All Of The Last 11,000 Years

Oswald et al., 2018

4. Today’s Temperatures Still Just As Cold As The Global Little Ice Age

Coffinet et al., 2018

“This study represents the first detailed late Holocene quantitative air temperature reconstruction from the RVP [Rungwe Volcanic Province, southwestern Tanzania/East Africa] region. We identified a succession of cold/warm/cold events, largely in phase with the other regional East African climate records and with the cold periods identified worldwide by Wanner et al. (2011). This further supports that global scale processes may be the main drivers of the Holocene climatic variability. Moreover, warm conditions during the MCA [Medieval Climate Anomaly] followed by abrupt cooling during the LIA were observed at Kyambangunguru and elsewhere in East Africa suggesting that these two recent events occurred globally.”

5. Modern Temperatures -2.9°C Colder Than 7,000 Years Ago

Zhao et al., 2018

According to the interpolation of meteorological data of the two nearest weather stations at Linxia (ca. 46 km away; MAT [mean annual temperature] = 7.3 °C) and Minhe (ca. 54 km away; MAT [mean annual temperature] = 8.3 °C)… In this study, we reconstructed mid-late Holocene climatic changes using GDGT distributions in a loess-paleosol sequence in the Lajia Ruins of the Neolithic Qijia Culture, Guanting Basin, in the southwestern end of the Chinese Loess Plateau. … MAT [mean annual temperature] decreased from 11.9 °C to 8.0 °C [today], during the past ca. 7000 yr, and a drastic decline in MAP [mean annual precipitation] (70 mm), accompanied by a 0.8 °C decline in MAT [mean annual temperature], occurred at 3800–3400 yr BP.”

6. Temperatures 7–9°C Higher Than Modern during The Early Holocene

Zheng et al., 2018

“In this study we present a detailed GDGT data set covering the last 13,000 years from a peat sequence in the Changbai Mountain in NE China. The brGDGT-based temperature reconstruction from Gushantun peat indicates that mean annual air temperatures in NE China during the early Holocene were 5–7°C higher than today.  Furthermore, MAAT records from the Chinese Loess Plateau also suggested temperature maxima 7–9°C higher than modern during the early Holocene (Peterse et al., 2014; Gao et al., 2012; Jia et al., 2013). Consequently, we consider the temperatures obtained using the global peat calibration to be representative of climate in (NE) China. … The highest temperatures occurred between ca. 8 and 6.8 kyr BP, with occasional annual mean temperatures >8.0 ± 4.7°C, compared to the modern-day MAAT of 3°C.”

7. 1950-2015 Just 0.7°C Warmer Than Coldest Temps Of The Last 9,000 Years

Harning et al., 2018

“Iceland’s terrestrial HTM [Holocene Thermal Maximum] has previously been constrained to ~7.9 to 5.5 ka based on qualitative lake sediment proxies (Larsen et al., 2012; Geirsdottir et al., 2013), likely in association with progressive strengthening and warming of the Irminger Current (Castaneda et al., 2004; Smith et al., 2005; Olafsdottir et al., 2010). Numerical modeling experiments for Drangajokull suggest that peak air temperatures were 2.5 – 3°C warmer at this time relative to the 1961-1990 CE average (Anderson et al., 2018). … During the Little Ice Age (LIA, 1250-1850 CE), the Vestfirðir region entered the lowest multi centennial spring/summer temperature anomalies of the last 9 ka.  Based on recent numerical  modeling simulations, this anomaly is estimated to be 0.6-0.8°C below the 1950-2015 average on Vestfirðir (Anderson et al., 2018).”

8. 2004-2007 Temps Colder Than All But 3 Other Holocene Periods

Wang et al., 2018   

The average RAN15-MAAT of 18.4°C over the most recent part of the record (<0.8 ka BP) [the last 800 years BP] overlaps with the range of MAATs, ca. 16.2°C to 18.7°C (av. 17.5°C) measured since 1952 at the nearest meteorological station (Yichang, located ca. 100 km away) and is very close to the av. MAAT of 18°C measured directly outside the cave by a temperature logger between 2004 and 2007 (Hu et al., 2008a). This agreement between reconstructed temperatures and instrumental measurements increases our confidence in the potential of the RAN15 proxy. RAN15-MAATs in HS4 vary from 16.5°C to 20.6°C (av. 19°C), during the last 9 ka BP, and broadly follow a long-term trend of declining temperatures in line with declining solar insolation at 30°N in July (Laskar et al., 2004). … Interestingly, the most recent 0.9 ka BP [900 years BP] is distinguished by greater variability with the highest (20.5°C) and lowest (16.5°C) RAN15-MAATs occurring consecutively at 0.6 ka BP [600 years BP] and 0.5 ka BP [500 years BP].” [Surface temperatures dropped by -4.0°C within ~100 years.]

9. 1952-2014 Temps 4.0 to 7.0 °C Colder Than 8,000 – 10,000 Years Ago

McFarlin et al., 2018

“(Greenland)  Early Holocene peak warmth has been quantified at only a few sites, and terrestrial sedimentary records of prior interglacials are exceptionally rare due to glacial erosion during the last glacial period. Here, we discuss findings from a lacustrine archive that records both the Holocene and the Last Interglacial (LIG) from Greenland, allowing for direct comparison between two interglacials. Sedimentary chironomid assemblages indicate peak July temperatures [Greenland] 4.0 to 7.0 °C warmer than modern during the Early Holocene maximum [10,000 to 8,000 years ago] in summer insolation. Chaoborus and chironomids in LIG sediments indicate July temperatures at least 5.5 to 8.5 °C warmer than modern.”

Modern Derived Temps 0.2°C Above Coldest Of Last 14,000 Years

Wu et al., 2018

“Summer temperatures (MJT) at Xingyun Lake in the late glacial were low, increased during the early Holocene, were highest during the middle Holocene, and then decreased during the late Holocene.The range of inferred values [for the Holocene] was 21.0°- 26.5°C. The pollen inferred temperature derived from surface samples (21.2°C), is close to the modern instrumental July temperature in Kunming (22°C), supporting the reliability of reconstructions from down-core pollen assemblages.”

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September 10, 2018 at 07:45AM

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