Arctic warming : Explain why ice melt has slowed since 2007 in the Arctic

An international team of scientists has revealed the mechanism of warming of the Arctic Ocean, and explained why the melting of ice has slowed since 2007.

Science magazine indicates that it has become clear to scientists that the characteristic of the atmosphere in the Arctic, known as the dipole, plays a major role in this process.

This feature is a system consisting of two pressure areas - a high over Eurasia and a low over North America, which radically affects the Arctic warming process. It has been shown that this characteristic helps the penetration of warm southern winds into the northern regions, which accelerates the melting of ice.

Satellite observations and ground-based monitoring stations showed that the 15-year dipole cycle is approaching a new stage. The current stage, which began in 2007, is characterized by high atmospheric pressure over the Canadian regions of the Arctic, where winds blow clockwise, while low pressure areas over the Siberian polar region, winds blow counterclockwise.

This situation has contributed to a decrease in the flow of water from the Atlantic Ocean to the Arctic Ocean through the Fram Strait located east of Greenland and an increase in currents from the Atlantic Ocean to the Barents Sea. In addition, counterclockwise winds carry fresh water from Siberian rivers to the Canadian sector of the Arctic Ocean.

It turns out that the westward movement of freshwater from 2007 to 2021 helped slow the melting of Arctic sea ice compared to the period from 1992 to 2006. The depth of the freshwater layer also increased, making it too thick and stable to mix with the heavier salt water. located below. So warm, salty water cannot melt sea ice. But changing the dipole system could have major climate consequences, including faster sea ice loss in Arctic and subarctic climate systems.

 

Science: An ozone hole is opening over Antarctica early this year and scientists are revealing why

The ozone hole over Antarctica opened up unusually early this year, and scientists believe the catastrophic eruption of the Hunga Tonga volcano in January 2022 may be the cause.

Ozone experts predicted earlier this year that the eruption, which injected 50 million tons (45 million metric tons) of water vapor into Earth's atmosphere, is likely to have an impact on Earth's protective ozone layer in the years following the eruption.

Concentrations of water vapor in the stratosphere, the second-lowest layer of Earth's atmosphere where the ozone layer resides, have risen by 10% as a result of the undersea volcanic eruption. This, according to Paul Newman, chief scientist for atmospheric sciences at NASA's Goddard Space Flight Center, has led to a "significant cooling" in the stratosphere, which is bad news for ozone levels.

And new data from the European environmental monitoring agency Copernicus suggests that predictions were likely correct. Ozone concentrations over Antarctica fell to a very low level in early July.

The Copernicus Agency said in a statement that such an early start to the destruction of the ozone layer has only been recorded about a dozen times in the 43 years since the beginning of scientific measurements. According to the data, the size of the ozone hole in August 2023 ranks tenth.

The hole is currently more than 16 million square kilometers (6 million square miles) in size. It will continue to grow until about the end of September when Antarctica begins to warm as it moves into the spring period. The hole will take until at least the end of November to close, but it could remain for much longer than that.

Stratospheric cooling resulting from increased water vapor concentrations in the stratosphere leads to the frequent formation of polar stratospheric clouds.

Scientists believe that these strange iridescent clouds that form at altitudes of 15 to 25 km (9 to 15 miles) provide the right chemical environment for stratospheric ozone-depleting substances (ODS) to do their destructive work.

Although most of these substances, such as CFCs and HFCs previously used in aerosol sprays and refrigerators, are banned under the 1987 Montreal Protocol, their natural degradation takes decades, and their concentrations in the atmosphere remain high.

Vincent-Henri Beutsch, director of the Copernicus Atmosphere Monitoring Service (CAMS), explained in the statement that although scientists cannot say with certainty whether the Hunga Tonga volcano is responsible for above-average ozone depletion this year, they hope to find out. More measurements in the coming months.

Adding: “Our ability to provide 3D analyzes and predictions of ozone at the poles is a powerful way to monitor how ozone holes are evolving in real time, and to assess the main drivers behind what is being observed. This gives us insights into how specific events influence the development of this Antarctic ozone hole.” This year, such as the eruption of the Honga Tonga-Hunga Haapai volcano last year, which increased the amount of water vapor in the stratosphere.

The effects of the eruption of the Hunga Tonga volcano is a completely new area for scientists, as no previous volcanic eruption in documented history has pumped so much water into the atmosphere.

However, there are other factors at play when it comes to the unusual behavior of the ozone layer, according to the Copernicus Agency.

The past three years have seen very large and prolonged ozone holes, although those holes opened up later in the season than this year.

Scientists believe that ongoing climate change may contribute to ozone depletion despite the gradual decrease in atmospheric concentrations of ozone-depleting substances. The processes in the atmosphere are complex, and models suggest that while temperatures near Earth's surface are undoubtedly rising, the stratosphere is in fact cooling (even without the extra water from Honga Tonga), meaning more ozone layer destruction.

 

Naval Today : Indonesia is developing a new generation of warships

Naval Today announced that Indonesia has started manufacturing a new generation of warships for its navy.

A post on the site reads: "At PT Pal's shipyard in Surabaya, the process of manufacturing two warships of a new generation for the Indonesian Navy has begun. The ships will be modified versions of the Arrowhead-140 ships being developed by the British Babcock company."

Depending on the location, the new ships will be manufactured within the framework of contracts signed by the British Babcock Company with Indonesian institutions.

During a ceremony devoted to the start of the manufacturing of the two Indonesian ships, the CEO of Babcock said: “We congratulate PT Pal on this important achievement. The development of the Miecznik frigates, and the Polish shipyard Remontowa began manufacturing the first of the new ships.

The length of each Arrowhead-140 ship is 140 meters, and its water displacement is equivalent to 5,600 tons. These ships can move at a speed of 26 nautical knots and travel 9,000 nautical miles on each mission.

The ships' armament systems include anti-air missiles and 57 mm cannons, in addition to the ships being equipped with platforms to carry helicopters.