Claims that modern temperatures are globally warmer than they were during Medieval times (~800 to 1250 A.D.) have been contradicted by a flurry of new (2019) scientific papers.
Southern Ocean/SE Pacific (SSTs)
The Medieval Warm Period (1100 years BP) was 1.5°C warmer than today (14°C vs. 12.5°C) in the SE Pacific or Southern Ocean.
Collins et al., 2019
Antarctica/Southern Ocean (SSTs)
Elephant seals used to breed on the Victoria Land Coast ~1000 years ago because there was open water access back then whereas this region is locked in sea ice today. To escape the reach of modern sea ice, elephant seal breeding colonies are now located ~2,400 km further north (sub-Antarctic islands) of where they bred during Medieval times.
Koch et al., 2019
Peru coastal region (SSTs)
There has been a rapid drop (approximately -1°C to -1.5°C) in sea surface temperatures during the last 50 years near the coast of Peru. 1-2°C warmer temperatures persisted ~1,000 years ago and there were 4°C warmer temperatures during the Mid-Holocene in this region.
Salvatteci et al., 2019
Canadian Arctic (SSTs)
During the Medieval Warm Period, bowhead whales occupied Canadian Arctic waters that are today sea ice-covered and inaccessible. During the Mid-Holocene (5000 to 3000 years ago), bowhead whales swam in the open-water Canadian Arctic.
No warming during 1955-2013 is apparent in the northeastern Mediterranean region. There were far more prevalent warm extremes during the Medieval Warm Period than during the last 450 years (including just one single high temperature extreme year since 1900).
Klippel et al., 2019
Greenland Ice Sheet
Greenland was at least 1°C warmer during Medieval times. The ice sheet cooled by nearly 2°C from the 1930s to 1980s.
Adamson et al., 2019 (citing Kobashi et al., 2017).
Pacific, Atlantic Ocean (heat content)
“Finally, we note that OPT-0015 indicates that ocean heat content was larger during the Medieval Warm Period than at present”
Modern mean annual temperatures range between 0.0 to 0.5°C, whereas Medieval Warm Period mean annual temperatures ranged between 2-6°C and Holocene Thermal Maximum temperatures reached 10.5°C.
Liu et al., 2019
Russia (360 km NW of Moscow)
Today’s mean annual temperatures are 4.1°C. During Medieval times mean annual temperatures were about 5°C, and during the Holocene Thermal Maximum mean annual temperatures were 2°C warmer than today.
Alaska (western, Yukon-Kuskokwim Delta)
This region was about 1°C warmer during Medieval times and has undergone an overall cooling trend of about -0.7°C since 1800.
Antarctica was approximately 0.5 to 1°C warmer than today during the entire 1st millennium, and the modest warming in the last century has in recent decades turned into a non-warming or cooling trend for West Antarctica, the Antarctic Peninsula, and East Antarctica.
South China Sea
The South China Sea was about 0.5°C to 0.7°C warmer during Medieval times and still warmer than today during the Little Ice Age.