Arctic climate warming: discrepancies between global climate
 models and observations and possible causes

Abstract

Global climate models are used to predict anthropogenic climate change and to plan social and economic activities under changing climatic conditions. At the same time, there are discrepancies between model projections and observed climate changes, especially in low latitudes and polar regions. One reason for the discrepancy may be insufficient attention to natural forcings on the climate system. Therefore, studies of the role of natural factors in the development of modern warming are relevant for
 improving the reliability of forecasts for the development of the climatic situation on Earth. Particular attention is paid to the impact of climate change in low latitudes on the Arctic. A significant contribution to these changes can be made by a long-term increase in low-latitude insolation. Most of the low latitudes
 are occupied by the ocean, which absorbs the bulk of the incoming solar radiation. The contribution of the increase in insolation to the increase in ocean surface temperature at low latitudes is estimated from the available data on insolation of the upper boundary of the atmosphere. The changes in SST at low latitudes are compared according to reanalysis data and calculations of global climate models. Comparison of climate changes in low latitudes and in the Arctic is made. The influence from low latitudes on the reduction in the area of sea ice and the increase in water temperature in the Arctic basin is estimated. Changes in the characteristics of the atmosphere and ocean at low latitudes, associated with an increase in insolation, after
 3 years are manifested in changes in the characteristics of the climate and sea ice in the Arctic. This indicates the potential for improved global modeling of warming in the Arctic and at low latitudes when taking into account slow changes in radiative forcing at the upper boundary of the atmosphere due to the Earth’s orbital dynamics. Insolation trends at low latitudes are maximum in spring, i.e., in the vicinity of the vernal equinox in the Earth’s orbit. This indicates the influence of precession — a slow shift of the equinox point, when the influx of solar radiation to low latitudes is maximum, to the perihelion, where it will be 3 W/m2more.