Our planet is getting warmer, at an increasing pace. This month, there was 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
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.
The 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 a 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 (see notes 1) conducted the longest-ever assessment of the 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.
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- metrics 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.
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 seawater 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 favorable 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 (see 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 into the atmosphere due to human activities in modern times.
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
- 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.
- 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
- Study: Four decades of Antarctic Ice Sheet mass balance from 1979-2017 on Proceedings of the National Academy of Sciences (PNAS)
- Study: 2018 Continues Record Global Ocean Warming on Advances in Atmospheric Sciences
- “Ice loss from Antarctica has sextupled since the 1970s, new research finds” on Washington Post
- “UCI/JPL: Antarctica losing six times more ice mass annually now than 40 years ago” on University of California at Irvine (UCI) News
- Press release: “The pace at which the world’s permafrost soils are warming” on Alfred Wegener Institut (AWI) website
- “2018 was the hottest year ever recorded for the planet’s oceans” on CNN
- “Ocean Warming” on IUCN website
- Study: 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 (Nature).
- Permafrost on Wikipedia
