Showing posts with label sea level rise. Show all posts
Showing posts with label sea level rise. Show all posts

Tuesday 16 January 2024

SEA LEVEL RISE 2024 : It's later than you think



Most of what we the general public think we know about sea level rise calculations by inundation height and rate is derived from models which did not anticipate global land and sea surface temperatures accelerating as sharply as they have in the last two years nor thought that an average annual global temperature anomaly of 1.5°C above pre-industrial levels was quite literally just around the corner.


So it is highly possible that what is quoted below by way of text and maps is an underestimation of what the Australian East Coast will begin to experience between now and 2030. While it is also likely that the most common established timelines of climate change milestones which run out to 2100 will be truncated to a marked degree.


UN Intergovernmental Panel on Climate Change (IPCC), AR6 Synthesis Report (2020-23), Headline Statements, excerpt:


Continued greenhouse gas emissions will lead to increasing global warming, with the best estimate of reaching 1.5°C in the near term in considered scenarios and modelled pathways. Every increment of global warming will intensify multiple and concurrent hazards (high confidence).


AdaptNSW, excerpt, retrieved 15 January 2024:


IPCC modelling suggests slightly higher sea level rise to the north of the state and slightly lower to the south. These projections do not include processes associated with the melting of ice sheets which for NSW could result in sea level rise of up to 2.3m by 2100 and 5.5m by 2150.


In the longer term, the IPCC show sea level is committed to rise for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and will remain elevated for thousands of years.


  • If warming is limited to 1.5°C, global mean sea level will rise by about 2 to 3m.

  • for 2°C, 2 to 6m is expected, and

  • for 5° 19 to 22m is expected. [my yellow highlighting]


National Oceanography Centre, Clarence Coast Mean Sea Level 1986 – 2022


YAMBA










NASA, Projected Sea Level Rise Under Different SSP Scenarios, Yamba:









Clarence Valley Sea Level Rise 2030 onwards based on Climate Central Interactive Mapping


Extent of inundation at 2 metre rise





Extent of inundation at 3 metre rise






Rise by 2030 - six years time




Rise by 2040 - sixteen years time





Friday 8 September 2023

This next Southern Hemisphere Summer may bring more unwelcome news for Australia's coastal zone

 

Climate breakdown has begun”

[U.N. Secretary-General Antonio Guterres, 6 September 2023]



NOAA Research, Global ocean roiled by marine heatwaves, with more on the way, 28 June 2023, excerpts:


This map depicts predicted marine heatwave conditions in September 2023 as generated by the Physical Sciences Laboratory’s experimental forecast model.







Credit: NOAA Physical Sciences Laboratory. *Click on image to enlarge*


The experimental forecast, which tracks the NOAA Climate Prediction Center’s official outlook, is based on a large ensemble of climate model predictions spanning June 2023 through May 2024….


A marine heatwave is defined as a monthly regional sea surface temperature anomaly that ranks in the top 10% of warmest months compared with the 1991–2020 average. Long-term ocean warming trends also contribute to unusually high ocean temperatures, but even with the effects of long-term warming removed, models predict 25% of the global ocean will experience sharp upward departures from more recent conditions by September…..


In this scenario it appears that the Southern Ocean waters are within a probability range of between 60-80 per cent for the occurrence of marine heatwave which might have also lead to a rise in Antarctic sea surface temperatures.


Which begs the questions:

How will the over 60km long Halloween Crack in west Antarctica react to any additional stressors on the Brunt Ice Shelf?

Will the East Coast Ice Sheet which is said to contain four fifths of the world’s ice again lose ice shelf through iceberg calving as it did with C-37 (144 sq.km) & C-38 (415 sq. km) in March 2022?

Just how big are these Anthropocene Age icebergs going to grow – given many are the size of cities already? and

How long does the Southern Hemisphere have before sea level rise beyond the Antarctic Circle increases exponentially past millimetres into metres?



BACKGROUND


NASA Earth Observatory, retrieved from website 7 September 2023:


Antarctica’sBrunt Ice Shelf Finally Breaks




January 24, 2023


In February 2019, a rift spanning most of the Brunt Ice Shelf in Antarctica appeared ready to spawn an iceberg about twice the size of New York City. The question among scientists was not if the growing rift would finish traversing the shelf and break, but when? Now, nearly four years later, it has done just that.


According to the British Antarctic Survey (BAS), the break occurred late on January 22, 2023, and produced a new iceberg with an area of 1550 square kilometers (about 600 square miles). The U.S. National Ice Center has named it Iceberg A-81. The berg is visible in this image, acquired on January 24, 2023, with the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.


The glacial ice in the shelf flows away from the interior of Antarctica and floats on the eastern Weddell Sea. (For reference, the Antarctic Peninsula and its ice shelves are located on the opposite side of the Weddell.) The shelf has long been home to the British Antarctic Survey’s Halley Research Station, where scientists study Earth, atmospheric, and space weather processes. BAS reported that the station, which was relocated farther inland in 2016 as the chasm widened, was unaffected by the recent break.


January 12, 2021


The break occurred along a rift known as Chasm 1. This chasm started growing in the 1970s, followed by a period of dormancy, and then resumed growth in 2012. It continued to lengthen for almost a decade, extending by as much as 4 kilometers (2.5 miles) per year in early 2019. But even this growth spurt slowed. That is, until the 2022–2023 Antarctic summer when the chasm sped up and ultimately broke past the McDonald Ice Rumples—a submerged knob of bedrock that served as a pinning point for this part of the shelf. Several factors may have contributed to the completion of the break, including a lack of sea ice to help resist, or “push back,” against the stresses on the shelf ice in 2023.


The second image, acquired with the Operational Land Imager (OLI) on Landsat 8, shows the extent of Chasm 1 on January 12, 2021, about two years prior to the break. Notice several other cracks across the northeast part of the shelf. The “new crack” in that image ultimately separated in February 2021 and formed Iceberg A-74.


The rapid formation of subsequent rifts—to long-standing Chasm 1 and 2—and recent calving to the northeast makes it clear that these shelf areas are dynamic with poorly understood stresses,” said Christopher Shuman, a University of Maryland, Baltimore County, glaciologist based at NASA’s Goddard Space Flight Center.


The breaking (calving) of icebergs from ice shelves is part of a natural, cyclical process of growth and decay at the limits of Earth’s ice sheets. As glacial ice flows from land and spreads out over the sea, shelf areas farthest from shore grow thinner. These areas are stressed by storms and tides and thin as they are melted from above or below, ultimately making them more prone to forming rifts and breaking away.


As for the “new” Brunt, it remains to be seen how the complex floating glacial ice responds to the most recent calving event. According to Shuman: “We have no solid idea what ‘normal’ really is for this unusual ice shelf.”


NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview and Landsat data from the U.S. Geological Survey. Story by Kathryn Hansen.


~~~~~~~~~~~~~~~~~


Other large iceberg calvings


NASA Earth Observatory






Early on July 12, 2017, satellites captured imagery of the new, massive iceberg that broke away from Larsen C—an ice shelf on the east side of the Antarctic Peninsula…..On July 13, the U.S. National Ice Center issued a press release confirming the new iceberg and officially naming it A-68.




February 22 - March 21, 2022

Collapse of the ice shelf in front of both the Glenzer Glacier (C-37and Conger Glacier (C.38)commencing around 12 March 2022.


Sunday 6 August 2023

In 2023 Science has the tools to refine its climate change predictive scenarios, never-the-less the Earth's land masses & oceans continue to heat up because neither world leaders, governments nor industry will accept what is now the increasingly urgent evidence of their own eyes

 

Warming oceans cause sea levels to rise, both directly via heat expansion, and indirectly through melting of ice shelves. Warming oceans also affect marine ecosystems, for example through coral bleaching, and play a role in weather events such as the formation of tropical cyclones” [The Conversation, 14 September 2021, reporting on research by Kewei Lyu, Xuebin Zhang & John A. Church]


This is a Australian Bureau Of Meteorology visualisation of sea surface temperatures around the Australian coastline on 4 August 2023 as El Niño conditions continue to be expected to arrive within weeks.











On 1 August BOM stated:


The Bureau's El Niño Alert continues, with El Niño development considered likely in the coming weeks, despite the current lack of atmospheric response. When El Niño Alert criteria have been met in the past, an El Niño event has developed around 70% of the time.


Sea surface temperatures (SSTs) in the tropical Pacific are exceeding El Niño thresholds, with climate models indicating this is likely to continue at least through to the end of the year. In the atmosphere, however, wind, cloud and broad-scale pressure patterns mostly continue to reflect neutral ENSO conditions. This means the Pacific Ocean and atmosphere have yet to become fully coupled, as occurs during El Niño events. El Niño typically suppresses winter–spring rainfall in eastern Australia.


And this is what is being discussed by climate scientists in our region.


Asia Oceania Geosciences Society, 20th Annual Conference, Axford Medal Lecture given by UNSW Emeritus Professor John Church, 2 August 2023:


What do we really know about 20th and 21st Century Sea-Level Change?


Abstract: Accelerating sea-level rise in much of the world will result in growing impacts through the 21st century and beyond. Despite the clear identification of an accelerating rise, many uncertainties remain. Understanding historical sea-level change is a prerequisite for building confidence in useful and accurate predictions of future changes.


For many decades, our limited knowledge of the contributions to sea-level change could not explain the rise measured by coastal tide gauges – the sea level enigma. New and improved in situ and satellite observations of the ocean, improved understanding of the “solid Earth”, and better understanding and improved modelling of the climate system have helped resolve this enigma. A number of recent studies have argued that the sum of contributions from both observations and model estimates to sea-level change over the satellite era, the last half century and since 1900 adequately explains the observed sea-level rise, which means the sea-level budget is closed. The major contributions are from ocean thermal expansion and contributions from glaciers, with an accelerating ice sheet contributions over the recent decades.


Our recent work has explored the sensitivity of global and regional sea-level reconstructions to poorly known land motions and the factors causing temporal and regional variations in the rate of rise. With this knowledge, existing reconstructions of global mean sea level are mostly not significantly different to each other from 1900 to the present, both in the time-averaged rate and the temporal variability. However, while the average rate over 1900 to present is similar to that from the sum of contributions, the rate of reconstructed GMSL rise is significantly smaller/larger than the sum of contributions prior to 1940/after 1970. Why is this? What do we really know? What are potential explanations for this continuing enigma?


And what can we project about future sea level, both for the 21st century and beyond. And can we constrain projections for the 21st century and beyond?


One of the notable take-aways from this lecture appears to be:


..that one of the main impacts of sea level on society will be how we adapt.


We will have to adapt to that sea level rise we can no longer prevent. Of particular concern is very significantly increased rates of coastal flooding events and eventually inundation of some coastal areas,” Prof. Church said.


We are already experiencing more severe and more frequent coastal flooding events impacting an increasing number of people.


This century, we could expect up to about a metre of sea level rise with unmitigated emissions. This could rise to several metres over coming centuries. Today, an estimated 200 million people live within one metre of current high tide level, and by mid-century over a billion people are likely to live in the low elevation coastal zone, which is within 10 metres of current sea level.” [UNSW Newsroom, “'Urgent action is required’: UNSW climate expert on what’s to come as sea levels rise”, 2 August 2023]


A reminder that much of the NSW Northern Rivers coastal region is predicted to experience significant levels of inundation at an average global surface temperature rise of 1.5°C.




Climate Central, north-east NSW (Northern Rivers) mapping, 2021. Click on image to enlarge



BACKGROUND


John Church is an Emeritus Professor in the Climate Change Research Centre, University of New South Wales. He has published across a broad range of topics in oceanography.


His area of expertise is the role of the ocean in climate, particularly anthropogenic climate change, and in understanding global and regional sea-level rise. He is the author of over 180 refereed publications, over 110 other reports and co-edited three books. He was co-convening lead author for the Chapter on Sea Level in the IPCC Third and Fifth Assessment Reports. He was awarded the 2006 Roger Revelle Medal by the Intergovernmental Oceanographic Commission, a CSIRO Medal for Research Achievement in 2006, the 2007 Eureka Prize for Scientific Research, the 2008 AMOS


R.H. Clarke Lecture, the AMOS Morton Medal in 2017, a joint winner of the BBVA Frontiers of Knowledge Climate Change Category Prize in 2019, the AAS Jaeger Medal in 2021 and the Royal Society of NSW James Cook Medal in 2022. He is an Officer of the Order of Australia, a Fellow of the Australian Academy of Science, the Australian Academy of Technology and Engineering, the American Geophysical Union, the American Meteorological Society and the Australian Meteorological and Oceanographic Society.



Monday 27 February 2023

CSIRO: new research shows that stronger El Niño may speed up warming of deep waters in the Antarctic shelf, making ice shelves and ice sheets melt faster

 

CSIRO News, 21 February 2023:


Stronger El Niño could cause irreversible melting of Antarctica


Totten Glacier. Photo: Esmee Van Wijk













New research led by scientists at CSIRO, Australia’s national science agency, has shown that future increases in the strength of El Niño may accelerate the irreversible melting of ice shelves and ice sheets in Antarctica.


The results, published in Nature Climate Change, used climate models to show how an increase in the variability of El Niño Southern Oscillation (ENSO) leads to reduced warming near the surface, but accelerated warming of deeper ocean waters.


ENSO is a key driver of climate variability, as both its warm phase, El Niño, and its colder phase, La Niña, influence weather conditions around the world, including in Australia.


Wenju Cai, lead author of this study and global expert on the relationship between climate change and ENSO, said the research was a critical step in further understanding how Antarctica will be affected by climate change.


Climate change is expected to increase the magnitude of ENSO, making both El Niño and La Niña stronger,” Dr Cai said.


This new research shows that stronger El Niño may speed up warming of deep waters in the Antarctic shelf, making ice shelves and ice sheets melt faster.


Our modelling also revealed that warming around the edges of floating sea ice is slowed during this process, slowing down the melting of sea ice near the surface.


Models with increased ENSO variability show a reduced upwelling of deeper, warmer waters, leading to slower warming of the ocean surface,” he said.


The associated winds around Antarctica are the mechanism driving this result.


When ENSO variability increases, it slows the intensifying westerly winds along the shelf. As a result, the upwelling of warm water around Antarctica is not able to increase as much.


The research team examined 31 climate models that participated in Phase 6 of the Coupled Model Intercomparison Project (CMIP6) under historical forcings and a high-emissions scenario.


Co-author Ariaan Purich from Securing Antarctica’s Environmental Future at Monash University said the effects of increasing ENSO variability go beyond extreme weather risks, and affect changes in Antarctic sea ice and ice shelves and sheets.


This could have broad implications for the global climate system, so continuing to understand how ENSO will respond to climate change is a critical area of climate research,” Dr Purich said.


There is still a lot more we need to understand about processes influencing shelf temperatures, and the finding is an important piece of the puzzle," she said.


Wednesday 19 October 2022

So, you are looking to buy a house or land in Yamba on the Clarence Coast in NSW?

 


A recent local newspaper article of 12 October 2022 stated that Clarence Valley Council would not release the results of a circa 2014 floor level survey of an unstated number of Yamba homes.


This survey was apparently undertaken to assess flood risk vulnerability against potential flood height modelling for Yamba township and environs.


The reason Council gave for withholding this information appears to be; “Premature release of the floor level data might (for instance) result in one or more sales falling through without the statutory immunity of Council being assured.”


By Census Night in August 2021 there were 4,073 residential dwellings recorded for a Yamba population of 6,376 people.


It is possible that conservatively between 30% to 53% of this housing stock is vulnerable to varying degrees during heavy rainfall associated with adverse weather events and Lower Clarence River flooding. A smaller percentage of Yamba dwellings above flood height on Pilot Hill and environs may be still be at risk - from land slippage during prolonged heavy rain and high seas.


Now according to propertyvalue.com.au there have been 142 houses sold in Yamba and environs in the last twelve months with a median price of $925,000.


Looking at online real estate sites there are also a number of dwellings in the town currently for sale – ranging from modest houses on manufactured relocatable housing estates through to 3-4 bedroom brick family homes and onto million dollar plus residences of up to 5 bedrooms & 2 bathrooms with all the mod cons.


There’s no easy way to establish floor levels in Yamba just by viewing real estate websites or looking at documents currently publicly available on Council’s own website. The only historic information publicly available ‘guesses’ dwelling floor heights in many of the town’s streets based on the surveyed height of the adjacent road surface.


An estimation method which clearly had its drawbacks in March 2022 when this overview of a section of Yamba Road was taken.



Embed from Getty Images



If Clarence Valley Council is determined to cloak in secrecy a more accurate extant list of floor heights, perhaps it’s time that the Yamba community began to help people who want to move here make informed choices before committing themselves to a mortgage or spending their hard-earned retirement savings?


Remembering that the Lower Clarence River estuary has flooded on average every three years since the 1990s, looking at Google Earth as well as basic digital flood modelling that Clarence Valley Council has available online and, then sampling from the over 50 dwellings currently advertised for sale for an example of each of the three aforementioned housing types:


  • that sweet little 3 bedroom home in one of Yamba’s manufactured home estates is probably only est. 4m above mean sea level and, if its floor level doesn’t turn out to be at least 2.84m AHD then there is a statistical 1 in 100 chance in any given year that it will have stormwater and/or floodwater running across the bedroom carpeting;


  • the 4 bedroom brick home with a tidy garden is probably est. 4m above mean sea level but if its floor level isn’t high enough then there is a statistical 1 in 50 chance in any given year that flood water will enter the property and threaten the house. There is also a 1 in 100 chance in any given year that with a floor below or even at 2.84m AHD the river will come knocking at the door and take possession of the house for as many days as it pleases;


  • when it comes to one of those houses with the million dollar plus price tag, well it is an est. 3-4m above mean sea level. However if its floor level falls short of 2.84m AHD then it may be uncomfortable to live in as there is a statistical 1 in 50 chance in any given year that flood water will enter the property but possibly not the house. However, there is also a 1 in 100 chance in any given year that storm water and/or flood water will enter the property and threaten the ground floor areas of this house.


Needless to say all three example residences are highly likely to be inundated during an extreme flood event given that modelled flood water heights would reach above the ceiling of the average single storey house design and above ceiling level on the ground floor of the average two-story design.


I rather suspect that Council is not voluntarily offering up that information to prospective home buyers, unless they happen to ask a precisely framed question in writing over the signature of their solicitor and perhaps not even then – given how many hundreds of land or house & land packages property developers are hoping to sell over the next five to twenty-five years in Yamba and how attractive future increases in rate income are to local government. 


Although quite frankly with Australia’s climate already having warmed on average by 1.44 ± 0.24 °C since national records began in 1910 [Dept. Planning and Environment, AdaptNSW 2022] and the possibility being canvassed that the world and Australia will reach long-term 1.5°C warming as early as the 2030s, Clarence Valley Council has more to worry about than riverine flooding.


In a worst case scenario due to the expected increase in sea-level rise this warming will bring, a significant amount of land within Yamba town precincts will be begin to go under water at high tide in another 8-17 years time.


Climate Central Inc. interactive mapping
Sea-level rise at 1.5°C global warming
Click on image to enlarge


Saturday 16 July 2022

Tweet of the Week



Cronulla Beach, July 2022


I suspect that the majority of Australians will forever be unforgiving of Liberal MP for Cook Scott John Morrison's past