The interval from 1450 to 1850 CE (Little Ice Age, LIA) was characterized by cooler conditions and the last 150 years are characterized by a continuous warming until recent times.
The reconstructions roughly agree on the timing of three characteristic periods: a multi-centennial warm period ca. 900 1200 CE, the cold "Little Ice Age" ca. 1450 1850s CE and a continuous warming after the 1850s.
It also shows how the two coldest decades 1812-1821 and 1832-1841, both during a period known as the Little Ice Age are followed by near continuous warming to today.
They all indicate a multi-century warm period around 900 1200 CE followed by a multi-century long cool period around 1450 1850 CE and a continuous warming tendency after the 1850s decade with the modern warming during the second half of 20th century.
A study published in Nature in 2013 by Yu Kosaka and Shang-Ping Xie of the Scripps Institution of Oceanography, in San Diego, argued that cooling in the eastern Pacific explained most of the difference between actual temperatures and models of the climate that predict continuous warming.
The continuous warming trend observed in Svalbard and northwest Russia since the 1980s are creating concerns related to the stability and durability of existing infrastructure on permafrost and uncertainties related to the design of new structures and infrastructure in the region.
