New paleoclimatic evidence of an extraordinary rise in temperature in the Northern Hemisphere in the last 3-4 decades.

Prognosis of temperature changes in the Northern Hemisphere for the period 1980-2020 was made using four temperature paleoreconstructions covering the last 1-2 millennia and ending 1979-1993. A part of paleodata before 1860 (prior to the beginning of a noticeable anthropogenic impact) was used as an information bank. Forecasts were made using nonlinear prediction method which is based on the reconstruction of the trajectory of the predicted series dynamic system in a pseudo-phase space. In all four cases, the forecast gave either a decrease or a very slight increase in temperature during 1980-2020. Statistical experiments performed with using prediction errors have shown that a rise in temperature by 0.15-0.20°C degrees in the indicated epoch is not excluded, but its probability is low (P <0.15). This means that if the climate in the 20th - early 21st century was controlled by the same dynamic system as before 1860, the noticeable warming of the Northern Hemisphere in 1980-2020 should not be observed. While the actual rise of the recorded temperature is sharp and reaches 1.0°C. Such divergence indicates that the climate of the Northern Hemisphere in the last 30-40 years was significantly affected by an additional factor that did not act in the previous 1-2 millennia. The possible influence of the problem of divergence in tree-ring research on the result obtained is discussed.