On a relation between shrinking of sea ice coverage and climate warming in the marine Arctic

Abstract

Arctic amplification (AA) of the climate warming is understood as the excess of the surface air temperature rise in the Arctic over the same process in the non-Arctic latitudes, and it is a fundamental characteristic of the climate during periods of warming. The positive feedback between albedo and shrinking of the sea ice coverage has been identified as the first possible cause of AA. The article presents quantitative estimates of the relationship between the summer decrease and autumn-winter restoration of the ice coverage with the rise of the surface air temperature in the marine Arctic based on data of observations. The mean monthly values of the temperature in the marine Arctic and the mean monthly values of areas covered by the sea ice in the Arctic Ocean and the Arctic seas for the period 1989–2020 were used. It has been found that the observed warming and the decrease of the ice coverage are accompanied by a growth of inter-monthly changes in the coverage and the same in the air temperature. Negative trends in increments of the ice coverage in May–July is indicative of a long-term growth in inter-monthly shrinkage of the ice coverage due to increasing melting, while negative trends in increments of the temperature in the same months is suggestive of a slowdown in the temperature rise from month to month, presumably due to the increasing heat consumption for the snow and ice melting and the water heating. The positive correlation confirms the relation between growing negative inter-monthly differences in the ice coverage and decreasing positive differences in the air temperature during these months. Based on that we determined a sensitivity of the inter-monthly increments of the temperature to the increments of the ice coverage, which was used to estimate the weakening of the positive air temperature trend in May–July over the Arctic Ocean and over the seas of the Northern Sea Route (NSR). Estimating of the relationship between month-to-month changes in temperature and ice coverage in the autumn-winter months meet difficulties due to the strong influence of external heat influx. Only in November and January a slowdown in the air temperature drop from October to November and from December to January had been revealed, with a positive trend in the ice coverage increments.