Warming oceans, rising sea levels and glacier melt
According to a Special Report on Oceans and Cryosphere (or frozen areas) in a Changing Climate released 25 September 2019, since the 1970s oceans have absorbed 90 per cent of excess heat in the climate and are warming faster than before, causing ice sheets, permafrost and glaciers to rapidly melt. While sea level has risen globally by around 15 centimetres during the 20th century, it is currently rising more than twice as fast — 3.6 mm per year — and accelerating, the report found.
The report also concluded sea levels would continue to rise for centuries, and could surge by up to 60cm by the year 2100, even if greenhouse gas emissions were sharply reduced and global warming was limited to well below 2C. Further, if emissions continue to rise rapidly, those levels could rise by up to 110cm by the end of this century. The impetus behind the expansion of our oceans is the rapid thawing of ice in Greenland and the Arctic.
Marine heatwaves have also doubled in frequency since 1982 and they're becoming more intense. While this means the threat of coral bleaching is more persistent, heatwaves can also affect entire ecosystems and reduce seagrass cover, kelp forests and mangroves. Sea level rise and changes to marine ecosystems are already being seen by some of Australia's closest neighbours, especially Pacific Island nations.
Nerilie Abram, Associate Professor at the ANU University and a coordinating author of the IPCC report. In other said that countries like Australia need to prepare for unavoidable coastal changes. She predicted that
Since the early 2000s, scientists have measured ocean heat using a network of drifting floats called Argo. The floats measure the temperature and saltiness of the upper 6,500 feet of the ocean and upload the data via satellites. Utilising such methods, scientists have been able to determine that 2016 was the warmest year on record for the Earth’s oceans, then 2017 and now 2018. Recall that, as the planet has warmed, the oceans have provided a critical buffer. They have slowed the effects of climate change by absorbing 93 percent of the heat trapped by the greenhouse gases humans pump into the atmosphere.
So the ocean is saving us from massive surface warming right now. But the surging water temperatures are already killing off marine ecosystems, raising sea levels and making hurricanes more destructive. As the oceans continue to heat up, those effects will become more catastrophic, scientists say. Rainier, more powerful storms like Hurricane Harvey in 2017 and Hurricane Florence in 2018 will become more common, and coastlines around the world will flood more frequently. Coral reefs, whose fish populations are sources of food for hundreds of millions of people, will come under increasing stress; a fifth of all corals have already died in the past three years. Sections of the Great Ocean Road are now at risk of being washed away in part due to rising sea levels on Victoria’s coast.
Because they play such a critical role in global warming, oceans are one of the most important areas of research for climate scientists. Average ocean temperatures are also a consistent way to track the effects of greenhouse gas emissions because they are not influenced much by short-term weather patterns. Absent global action to reduce carbon emissions, warming alone would cause sea levels to rise by about a foot by 2100, and the ice caps would contribute more. The IPCC projection for sea-level rise is almost 90 centimtres by the year 2100, and last year it also issued a report last year that described a climate crisis as soon as 2040. [1]
The report also concluded sea levels would continue to rise for centuries, and could surge by up to 60cm by the year 2100, even if greenhouse gas emissions were sharply reduced and global warming was limited to well below 2C. Further, if emissions continue to rise rapidly, those levels could rise by up to 110cm by the end of this century. The impetus behind the expansion of our oceans is the rapid thawing of ice in Greenland and the Arctic.
Marine heatwaves have also doubled in frequency since 1982 and they're becoming more intense. While this means the threat of coral bleaching is more persistent, heatwaves can also affect entire ecosystems and reduce seagrass cover, kelp forests and mangroves. Sea level rise and changes to marine ecosystems are already being seen by some of Australia's closest neighbours, especially Pacific Island nations.
Nerilie Abram, Associate Professor at the ANU University and a coordinating author of the IPCC report. In other said that countries like Australia need to prepare for unavoidable coastal changes. She predicted that
- "Australia's coastal cities and communities can expect to experience what was previously a once-in-a-century extreme coastal flooding event at least once every year by the middle of this century — in many cases much more frequently."
- Fisheries — and the food they produce — will decline by more than 20 per cent within the next 80 years if global warming cannot be capped.
- As oceans become more acidic, it also becomes harder for species like oysters, mussels and other shelled organisms to survive.
Since the early 2000s, scientists have measured ocean heat using a network of drifting floats called Argo. The floats measure the temperature and saltiness of the upper 6,500 feet of the ocean and upload the data via satellites. Utilising such methods, scientists have been able to determine that 2016 was the warmest year on record for the Earth’s oceans, then 2017 and now 2018. Recall that, as the planet has warmed, the oceans have provided a critical buffer. They have slowed the effects of climate change by absorbing 93 percent of the heat trapped by the greenhouse gases humans pump into the atmosphere.
So the ocean is saving us from massive surface warming right now. But the surging water temperatures are already killing off marine ecosystems, raising sea levels and making hurricanes more destructive. As the oceans continue to heat up, those effects will become more catastrophic, scientists say. Rainier, more powerful storms like Hurricane Harvey in 2017 and Hurricane Florence in 2018 will become more common, and coastlines around the world will flood more frequently. Coral reefs, whose fish populations are sources of food for hundreds of millions of people, will come under increasing stress; a fifth of all corals have already died in the past three years. Sections of the Great Ocean Road are now at risk of being washed away in part due to rising sea levels on Victoria’s coast.
Because they play such a critical role in global warming, oceans are one of the most important areas of research for climate scientists. Average ocean temperatures are also a consistent way to track the effects of greenhouse gas emissions because they are not influenced much by short-term weather patterns. Absent global action to reduce carbon emissions, warming alone would cause sea levels to rise by about a foot by 2100, and the ice caps would contribute more. The IPCC projection for sea-level rise is almost 90 centimtres by the year 2100, and last year it also issued a report last year that described a climate crisis as soon as 2040. [1]
The top 700 meters (about 2,300 feet) of ocean shows warming of 0.302 degrees F since 1969. As a result, global sea levels rose about 8 inches in the last century. The rate in the last two decades, however, is nearly double that. As sea ice continues to melt, all that excess water causes sea levels to rise, spelling disaster for coastal areas, which will inevitably flood as the water level creeps up.
Rising ocean temperatures are melting Greenland’s ice caps at three times the pre- 1997 rate, according to 2017 data analysis of meltwater runoff and ice-cap mass. The island’s melting ice caps account for a third of global sea-level rise[2]. In July 2019, the Greenland ice sheet shed its load at the rate of 12.5 billion tons of ice per day, a record outpacing all data collected since 1950, following another record-breaking episode recorded the day before. Even low-lying cities on the American east coast, such as Norfolk Virginia on the Chesapeake Bay are vulnerable, and not from a source you may expect: Antarctica’s melting ice-sheets, now melting faster than initial models predicted, with ocean currents sweeping that water northward.
“Gravity is also to blame: Antarctica’s tremendous mass exerts a huge pull on the oceans, extending all the way to the Atlantic, but as the continent loses ice, its grip will weaken, allowing that closely held water to flow toward the opposite pole. Melting mountain glaciers add more water, and higher global temperatures make the oceans warm and swell in a process called thermal expansion”[3]. The sobering assessment (by Larry Atkinson), a professor of oceanography at Old Dominion University in Norfolk, is that “Greenhouse gases can be stopped tomorrow and there will still be sea-level rise into the next century”. NOAA’s specific and detailed projections, released to help local governments such as Norfolk’s prepare themselves appear below. In nearly all scenarios, rises in the Northeast and the western Gulf of Mexico exceed the worldwide average.
Rising ocean temperatures are melting Greenland’s ice caps at three times the pre- 1997 rate, according to 2017 data analysis of meltwater runoff and ice-cap mass. The island’s melting ice caps account for a third of global sea-level rise[2]. In July 2019, the Greenland ice sheet shed its load at the rate of 12.5 billion tons of ice per day, a record outpacing all data collected since 1950, following another record-breaking episode recorded the day before. Even low-lying cities on the American east coast, such as Norfolk Virginia on the Chesapeake Bay are vulnerable, and not from a source you may expect: Antarctica’s melting ice-sheets, now melting faster than initial models predicted, with ocean currents sweeping that water northward.
“Gravity is also to blame: Antarctica’s tremendous mass exerts a huge pull on the oceans, extending all the way to the Atlantic, but as the continent loses ice, its grip will weaken, allowing that closely held water to flow toward the opposite pole. Melting mountain glaciers add more water, and higher global temperatures make the oceans warm and swell in a process called thermal expansion”[3]. The sobering assessment (by Larry Atkinson), a professor of oceanography at Old Dominion University in Norfolk, is that “Greenhouse gases can be stopped tomorrow and there will still be sea-level rise into the next century”. NOAA’s specific and detailed projections, released to help local governments such as Norfolk’s prepare themselves appear below. In nearly all scenarios, rises in the Northeast and the western Gulf of Mexico exceed the worldwide average.
Innovative solutions required for extreme situations [4]
Meanwhile, climate change has also manifested itself in apocalyptic ways like the huge Hurricane, Sandy, a one in 500-year hurricane consisting of several megastorms rolled into one, which struck the east coast of the United States in October 2012, and it wasn’t just the coastal areas which were affected. Feet of snow were dropped well inland. This has led to some innovative solutions, namely buyout and resettlement, or in other words retreat.
Using state and now federal money, whole areas of flood prone housing are now being purchased, the houses demolished and their occupants resettled inland out of harm’s way. The land where houses once stood is being turned into a flood buffer zone planted with vegetation such as saplings to create a sponge-like effect to protect the rest of the community.
As houses come down, floodplains are being restored to take their place. New Jersey could see up to twelve feet of sea-level rise by 2100. As of mid-2018, a total of 142 homeowners in Woodbridge township had accepted resettlement offers, and about 115 homes from the Watson-Crampton neighbourhood alone had been removed. most of them clustered within a grid covering about 30 acres. By 2050 the tidally influenced wetlands about the Watson-Crampton neighbourhood in New Jersey will likely be under water.
And on a global scale ...
... the giant ice-sheets of Antarctica and Greenland are melting faster than scientists previously predicted, leading to projections of a “plausible” sea level rise of between 2 and 2.7 metres by 2100[5]. Even the rise during the previous century was the fastest in at least 2800 years. Almost one-tenth of the world’s ocean surfaces were at least 30 degrees as at the end of March 2014, and the waters around Australia were the hottest in records going back to the 1950s, attributable in part to natural causes such as that band of warm ocean water in the central and east-central equatorial Pacific known as El Nino, but a substantial contribution is the result of human caused climate change. Among the changes under way is the East Australian current that brings warm waters from the tropics down Australia’s east coast which has extended further south, part of a longer term shift.
Fast forward to 2020, and we find that, according to the WMO report for that year, also noted elsewhere, sea levels have been rising by an average of 5 mm per year in the previous 5 years, compared to 3.2 mm on average since 1991, with much of the rise attributed to melting glaciers and ice sheets.
Globally over the past decade (2010 to 2019)
The experience of small island states in the Pacific
Meanwhile, in the Southern Pacific, all but one of the 33 islands in Kiribati are less than two metres above sea level. Large parts of the country are expected to be under water by 2050. Annual temperatures in South Tarawa have increased by roughly 0.18 degrees Celsius per decade since 1950, according to the conference’s briefing paper. This warming, coupled with increasingly ferocious tidal storms and coastal flooding, is destroying the island’s ecosystems.
In the Kiribati population, there has been a rise in waterborne diseases, among other climate-change-induced illnesses, including cholera and dengue fever. Warming oceans, combined with increased ocean acidification, disrupts sea life, which is the cornerstone of Kiribati identity and the country’s economy. Kiribati depends almost entirely on its fishing sector for food and revenue, but the catch potential is expected to decrease by 70 per cent by the 2050s.
Kiribati is one of 48 nations in the Climate Vulnerable Forum, a partnership of countries most under threat from global warming. These include Tuvalu, Palau, Papua New Guinea, Fiji, Vanuatu, Samoa and the Marshall Islands.
And on yet another front, the Tibetan Plateau (sometimes referred to as the third pole) is another likely casualty. It is also warming at twice the global rate. The steady melting of the glaciers on this plateau feeds the ten largest rivers in Asia, assuring a steady flow of the world’s population. The glaciers in effect act as an enormous reservoir. If they melt, the monsoon rains will flow down through these rivers with potentially devastating results[6].
[1] Source: Kendra Pierre-Louis, “Ocean Warming is rising faster than thought, new research finds”, The New York Times, 10 January 2019, relying on an anysis published in the journal Science
[2] Scientific American, June 2017, 17.
[3] Based on the US National Oceanic and Atmospheric Administration (NOAA) projections: April Reese, “Swell or High Water”, Scientific American, June 2017, 13.
[4] Jen Schwartz, “Under water – coastal communities struggling to adapt to rising seas are beginning to do what was once unthinkable – retreat” Scientific American Special Climate Change Edition, Summer 2020, 38-47.
[5] NOAA projections. See Peter Hannam, “Sea levels set to rise sharply as ice melts”, Scientific American, 23 May 2017, 8.
[6] From Associate Professor Michael Box’s, “Our Atmospheric Environment” course, op cit, 6.2.2. On glacier melt in the Himalayas, see also: https://www.nytimes.com/2019/05/30/sports/everest-bodies-global-warming.html Next
Meanwhile, climate change has also manifested itself in apocalyptic ways like the huge Hurricane, Sandy, a one in 500-year hurricane consisting of several megastorms rolled into one, which struck the east coast of the United States in October 2012, and it wasn’t just the coastal areas which were affected. Feet of snow were dropped well inland. This has led to some innovative solutions, namely buyout and resettlement, or in other words retreat.
Using state and now federal money, whole areas of flood prone housing are now being purchased, the houses demolished and their occupants resettled inland out of harm’s way. The land where houses once stood is being turned into a flood buffer zone planted with vegetation such as saplings to create a sponge-like effect to protect the rest of the community.
As houses come down, floodplains are being restored to take their place. New Jersey could see up to twelve feet of sea-level rise by 2100. As of mid-2018, a total of 142 homeowners in Woodbridge township had accepted resettlement offers, and about 115 homes from the Watson-Crampton neighbourhood alone had been removed. most of them clustered within a grid covering about 30 acres. By 2050 the tidally influenced wetlands about the Watson-Crampton neighbourhood in New Jersey will likely be under water.
And on a global scale ...
... the giant ice-sheets of Antarctica and Greenland are melting faster than scientists previously predicted, leading to projections of a “plausible” sea level rise of between 2 and 2.7 metres by 2100[5]. Even the rise during the previous century was the fastest in at least 2800 years. Almost one-tenth of the world’s ocean surfaces were at least 30 degrees as at the end of March 2014, and the waters around Australia were the hottest in records going back to the 1950s, attributable in part to natural causes such as that band of warm ocean water in the central and east-central equatorial Pacific known as El Nino, but a substantial contribution is the result of human caused climate change. Among the changes under way is the East Australian current that brings warm waters from the tropics down Australia’s east coast which has extended further south, part of a longer term shift.
Fast forward to 2020, and we find that, according to the WMO report for that year, also noted elsewhere, sea levels have been rising by an average of 5 mm per year in the previous 5 years, compared to 3.2 mm on average since 1991, with much of the rise attributed to melting glaciers and ice sheets.
Globally over the past decade (2010 to 2019)
- The Arctic experienced about 1.8 F degrees (1 degree C) of warming in the past decade alone—compared to just under 1 degree C for the planet at large over the past 50 years, and its ice and frozen landscapes are responding just as sensitively as scientists predicted they would. West Antarctica’s towering glaciers, home to enough ice to raise sea levels by 10 feet or more if they melted, have begun an inexorable retreat.
- Arctic sea ice bottomed out at its lowest ever recorded extent in 2012, and has hovered at historic lows ever since, distorting “normal” weather patterns that depend on Arctic cold.
- Almost every single glacier in Earth’s high mountains is shrinking now, reshaping life in those high elevation zones.
- A warmer ocean expands, driving those levels higher, and simultaneously, melt from Greenland and Antarctica has added about 36 millimeters of extra fresh water to the world’s oceans in the past 10 years, and the rate is jacking up every year.
The experience of small island states in the Pacific
Meanwhile, in the Southern Pacific, all but one of the 33 islands in Kiribati are less than two metres above sea level. Large parts of the country are expected to be under water by 2050. Annual temperatures in South Tarawa have increased by roughly 0.18 degrees Celsius per decade since 1950, according to the conference’s briefing paper. This warming, coupled with increasingly ferocious tidal storms and coastal flooding, is destroying the island’s ecosystems.
In the Kiribati population, there has been a rise in waterborne diseases, among other climate-change-induced illnesses, including cholera and dengue fever. Warming oceans, combined with increased ocean acidification, disrupts sea life, which is the cornerstone of Kiribati identity and the country’s economy. Kiribati depends almost entirely on its fishing sector for food and revenue, but the catch potential is expected to decrease by 70 per cent by the 2050s.
Kiribati is one of 48 nations in the Climate Vulnerable Forum, a partnership of countries most under threat from global warming. These include Tuvalu, Palau, Papua New Guinea, Fiji, Vanuatu, Samoa and the Marshall Islands.
And on yet another front, the Tibetan Plateau (sometimes referred to as the third pole) is another likely casualty. It is also warming at twice the global rate. The steady melting of the glaciers on this plateau feeds the ten largest rivers in Asia, assuring a steady flow of the world’s population. The glaciers in effect act as an enormous reservoir. If they melt, the monsoon rains will flow down through these rivers with potentially devastating results[6].
[1] Source: Kendra Pierre-Louis, “Ocean Warming is rising faster than thought, new research finds”, The New York Times, 10 January 2019, relying on an anysis published in the journal Science
[2] Scientific American, June 2017, 17.
[3] Based on the US National Oceanic and Atmospheric Administration (NOAA) projections: April Reese, “Swell or High Water”, Scientific American, June 2017, 13.
[4] Jen Schwartz, “Under water – coastal communities struggling to adapt to rising seas are beginning to do what was once unthinkable – retreat” Scientific American Special Climate Change Edition, Summer 2020, 38-47.
[5] NOAA projections. See Peter Hannam, “Sea levels set to rise sharply as ice melts”, Scientific American, 23 May 2017, 8.
[6] From Associate Professor Michael Box’s, “Our Atmospheric Environment” course, op cit, 6.2.2. On glacier melt in the Himalayas, see also: https://www.nytimes.com/2019/05/30/sports/everest-bodies-global-warming.html Next