Global Warming: Three bad (very bad!) news

Our planet is getting warmer, with an increasing pace. This month, there were three bad, very bad news about global warming. According to a study published in Proceedings of the National Academy of Sciences, Antarctica is losing six times more ice mass annually now than 40 years ago. Another study, published in the scientific journal Advances in Atmospheric Sciences concluded that 2018 was the hottest year ever recorded for the Earth’s oceans. And, according to research released in the online journal Nature Communication, Permafrost is warming at a global scale – the temperature of the frozen ground in continuous permafrost zones rose by an average of 0.3 degrees Celsius between 2006 and 2017.

Compared to 40 years ago, today Antarctica is losing 6 times more ice mass annually

Researchers evaluated the state of the mass balance of the Antarctic Ice Sheet over the last four decades and they found that Antarctica is losing six times more ice mass annually.

According to the new study, between 1979 and 1989, Antarctica lost 40 billion tons of melting ice to the ocean annually. Beginning in 2009, that figure rose to 252 billion tons lost per year.

Lead author of the study, Eric Rignot, an Earth-systems scientist for the University of California at Irvine (UCI) and NASA said that: “That’s just the tip of the iceberg, so to speak. As the Antarctic ice sheet continues to melt away, we expect multi-meter sea level rise from Antarctica in the coming centuries.”

Antarctica contains an ice volume that translates into a sea-level equivalent (SLE) of 57.2 meters (188 feet). In other words, if all the ice on Antarctica melted, the Earth’s oceans would rise 57.2 meters (188 feet).

For this study, Rignot and his collaborators Notes 1 conducted the longest-ever assessment of remaining Antarctic ice mass using a comprehensive, precise satellite record and output products from a regional atmospheric climate model to document its impact on sea-level rise. The mass loss is dominated by enhanced glacier flow in areas closest to warm, salty, subsurface circumpolar deep water, including East Antarctica, which has been a major contributor over the entire period. The same sectors are likely to dominate sea-level rise from Antarctica in decades to come as enhanced polar westerlies push more circumpolar deep water toward the glaciers.

Global warming -Antarctica
Antarctica is Earth’s southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometers (5,400,000 square miles), it is the fifth-largest continent. For comparison, Antarctica is almost twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km (1.2 mi; 6,200 ft) in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula. Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with annual precipitation of only 200 mm (8 in) along the coast and far less inland. Image: The Planet D

2018 was the hottest year ever recorded for the Earth’s oceans

According to a study published on January 15 in the scientific journal Advances in Atmospheric Sciences, 2018 was the hottest year ever recorded for our planet’s oceans since global records began in 1958.

Researchers say the vast majority of global warming heat ends up deposited in the world’s oceans, and ocean heat content (OHC) change is one of the best—if not the best—metric for climate change (Cheng et al., 2019). In 2018, continued record heat was measured in the Earth’s climate system. In fact, 2018 has set a new record of ocean heating, surpassing 2017, which was the previous warmest year ever recorded.

According to researchers, by absorbing more heat than was previously known, the Earth’s oceans are warming faster than scientists thought. That will result in a six-fold increase in ocean warming by 2081-2100, compared to the past 60 years.

Global warming - oceans absorb most of the excess heat
Earth’s oceans absorb most of the excess heat from greenhouse gas emissions, leading to rising ocean temperatures.

The ocean’s ability to absorb excess heat has shielded humans from even more rapid changes in climate. Without this oceanic buffer, global temperatures would have risen much more than they have done to date.

Ocean warming leads to deoxygenation – a reduction in the amount of oxygen dissolved in the ocean – and sea-level rise – resulting from the thermal expansion of sea water and continental ice melting. The rising temperatures, coupled with ocean acidification (the decrease in pH of the ocean due to its uptake of CO2), affect marine species and ecosystems.

Marine fishes, seabirds and marine mammals all face very high risks from increasing temperatures, including high levels of mortalities, loss of breeding grounds and mass movements as species search for favourable environmental conditions. Coral reefs are also affected by increasing temperatures which cause coral bleaching and increase their risk of mortality.

The rise in sea surface temperatures is also causing more severe hurricanes and the intensification of El Niño events bringing droughts and floods. This can have significant socio-economic and health effects in some regions of the world.

Warming ocean temperatures are linked to the increase and spread of diseases in marine species. Humans risk direct transmission of these diseases when consuming marine species, or from infections of wounds exposed in marine environments.

Global warming is leaving more and more apparent scars in the world’s permafrost regions

A recent study published on Nature says “permafrost is warming at a global scale”.

Permafrost Notes 2 warming has the potential to amplify global climate change because when frozen sediments thaw it unlocks soil organic carbon.

The research concluded that “during the reference decade between 2007 and 2016, the ground temperature near the depth of zero annual amplitude in the continuous permafrost zone increased by 0.39 ± 0.15 °C. Over the same period, discontinuous permafrost warmed by 0.20 ± 0.10 °C. Permafrost in mountains warmed by 0.19 ± 0.05 °C and in Antarctica by 0.37± 0.10 °C. Globally, permafrost temperature increased by 0.29 ± 0.12 °C.”

In the northern circumpolar region, permafrost contains 1700 billion tons of organic material equaling almost half of all organic material in all soils. This pool was built up over thousands of years and is only slowly degraded under the cold conditions in the Arctic. The amount of carbon sequestered in permafrost is four times the carbon that has been released to the atmosphere due to human activities in modern time.

The consequence of permafrost warming is thawing soil, which may be weaker, and release of methane (a very strong greenhouse gas), which contributes to an increased rate of global warming as part of a feedback loop.

Notes

  1. Co-authors of this study are Jeremie Mouginot, UCI associate researcher in Earth system science; Bernd Scheuchl, UCI associate project scientist in Earth system science; Mathieu Morlighem, UCI associate professor of Earth system science; and Michiel van den Broeke and Jan M. “Melchior” van Wessem of the Netherlands’ Utrecht University. Funding and support were provided by NASA’s cryospheric sciences and Measures programs, the Netherlands Organization for Scientific Research’s polar program and the Netherlands Earth System Science Centre.
  2. In geology, permafrost is ground, including rock or soil, at or below the freezing point of water 0 °C (32 °F) for two or more years. Most permafrost is located in high latitudes (in and around the Arctic and Antarctic regions), but at lower latitudes, alpine permafrost occurs at higher elevations.

Sources

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