The sixth report on the state of the Earth's ice cover was prepared for the international climate summit SOR27, held in Sharm el-Sheikh, by a group of well-known scientists in the field of glaciology and permafrost.
The authors of the study, pointing to the rate of melting of polar ice sheets, mountain glaciers and permafrost, describe the catastrophic consequences to which this may lead in the near future. A separate chapter is devoted to the alarming situation in the Arctic, RIA Novosti writes.
Data from regular observations show that the volume of ice in the world is decreasing at an increasing rate. The main reason for this, scientists call global warming, which provokes atmospheric and hydrological processes that multiply the effect of even a slight increase in temperature.
As scientists warn, despite all measures to reduce greenhouse gas emissions, in 2022 the CO2 level, as in the previous two decades, will increase by about 2.5 ppm per year.
As a result, it rained in East Antarctica in March, and the temperature was 40 degrees Celsius above normal. In Greenland, for the first time in the history of observations, the peak of ice melting occurred in September. In the Alps, glaciers lost more than 5% of their volume in one summer, and due to the active melting of permafrost, the release of methane into the atmosphere, a greenhouse gas more powerful than CO2, sharply increased.
As RIA Novosti notes, the next assessment report of the UN Intergovernmental Panel on Climate Change, released this year, states that even under the most favorable scenario, in which the increase in global temperatures by 2100 will not exceed 1.6 degrees, it will not be possible to stop the melting of ice, at least in the Arctic.
Ice-free, the vast dark surface of the Arctic Ocean will continue to actively absorb solar energy, which will further increase warming. Previously, paleoclimatologists who have been studying climate change for millions of years warned: there is a possibility that irreversible ice loss in the presence of a feedback loop will begin at temperatures lower than those laid down in standard models. And the processes themselves can happen much faster - within decades, not centuries, as previously thought.
Arctic sea ice is an important temperature regulator on the planet. In the last 125,000 years, it has been performing the function of a "global refrigerator". A huge area of the northern ice during the entire polar summer reflects the bulk of the falling sunlight back into space around the clock. At the same time, the darker water of the open ocean absorbs heat, increasing Arctic and general global warming.
Every year, the ice cover of the Arctic Ocean reaches a minimum in September, and a maximum in March. In September 2022, the area of ice in the Arctic amounted to 4.87 million square kilometers - 32% less than the average for the period 1981-2010. Ice has decreased by about 13% in a decade. The lows were recorded in 2007, 2012 and 2020.
Paleoclimatic records show that although the area of Arctic ice has fluctuated greatly over the past fifteen hundred years, the current decrease is unparalleled and goes far beyond the range of natural variability.
Scientists have been regularly measuring the thickness of the ice cover in the Arctic since the 1980s. Its thickness is an indirect indicator of the age of sea ice: having survived the melting season, it becomes thicker next winter. Ice with a thickness of at least three meters, which has survived at least two annual cycles of growth and melting, is called pack ice.
In addition to age, thickness indicates resistance to physical impact, or, as experts say, the survival of ice. Young thin ice is more easily destroyed in stormy conditions, even at subzero temperatures.
According to observations, in the mid-1980s, up to a third of the Arctic ice was pack ice. In 2020, their share did not exceed five percent. This means that not only the area of ice distribution has changed, but also their quality. The presence of a large proportion of thin annual ice in the composition of the ice sheet creates another feedback loop, reducing the likelihood that this ice will survive the summer.
The authors of the report call the condition of the long-term Arctic ice critical. That is, the first abnormally warm or stormy summer will lead to the complete disappearance of pack ice, which will never recover.
Negative consequences for ecosystems are still difficult to predict. The disappearance of ice means the loss of habitat for marine mammals such as polar bears, walruses and seals, as well as disruption of the feeding cycle of subglacial biosociety.
According to scientists, the restoration of the long-term ice cover in the Arctic will not be achieved, even if the task - the maximum of the Paris Agreement - is to keep the global average temperature below 1.5 degrees. In order for pack ice to form again, this indicator should not exceed one degree from pre-industrial values. Given that the Arctic is warming up about four times faster than the rest of the world today, this is absolutely impossible, RIA Novosti writes.
It is obvious that in the coming decades only thin seasonal ice will remain in the Arctic Ocean. This means that there will soon be year-round navigation here. Already, the Northern Sea Route is open to ordinary vessels for three to four weeks longer than 20 years ago.
Despite the fact that it has a positive effect, some economic losses are likely. Ocean warming and changes in the food chain will inevitably affect the number and habitat of commercially important fish species, and increased storm activity will lead to the destruction of the coastline.
The authors of the report consider four scenarios of development: what will happen when the global temperature rises by 2100 by 1.6-1.8; 1.9; 2.7-3.1 and 4-5 degrees, respectively. The first two are considered optimistic. They will require the implementation of a large set of measures at the global level. The third one is more realistic, but for its implementation, the governments of most countries of the world have to do a lot at least at the national level.
The fourth is if you leave everything as it is.
According to the first scenario, the transition of the global cryospheric threshold (as the authors call the disappearance of long-term ice in the Arctic) will inevitably occur before 2050. However, the amount of winter ice will be able to stabilize. The melting of the Greenland ice sheet will continue, as well as carbon emissions due to the melting of permafrost.
With the second option, the ocean will be open from June to November. Disturbances in ecosystems will begin, Arctic species will gradually be replaced by more heat-loving ones that came from the south.
According to the third model, the cryosphere threshold will be reached by 2040. The ice will remain only in the winter season. Ecosystem disturbance will become more widespread and will spread to the Arctic basins of the Barents, Bering and North Seas. The salinity will decrease and the acidity of sea waters will increase. These changes will disrupt the growth of plankton and algae, which will entail cascading effects in the marine food web.
The authors characterize the fourth scenario in short - the collapse of the ecosystem. If nothing is done, it will come by 2030, RIA Novosti quotes the opinion of scientists.
Alex Shishlo for Rough&Polished
