From CLIMATE DEPOT
Early aerial expedition photos reveal 85 years of glacier growth and stability in East Antarctica

Published: 25 May 2024 – Mads Dømgaard,  Anders Schomacker,  Elisabeth Isaksson,  Romain Millan,  Flora Huiban,  Amaury Dehecq, Amanda Fleischer,  Geir Moholdt,  Jonas K. Andersen &  Anders A. Bjørk 

Nature Communications: Our results demonstrate that the stability and growth in ice elevations observed in terrestrial basins over the past few decades are part of a trend spanning at least a century, and highlight the importance of understanding long-term changes when interpreting current dynamics. … However, in Antarctica, the scarcity of historical climate data makes climate reanalysis estimates before the 1970s largely uncertain^10,23, and observed trends cannot clearly be distinguished from natural variability^24,25. 

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By Marc Morano

https://www.nature.com/articles/s41467-024-48886-x

Early aerial expedition photos reveal 85 years of glacier growth and stability in East Antarctica

Published: 25 May 2024 – Mads Dømgaard,  Anders Schomacker,  Elisabeth Isaksson,  Romain Millan,  Flora Huiban,  Amaury Dehecq, Amanda Fleischer,  Geir Moholdt,  Jonas K. Andersen &  Anders A. Bjørk 

Nature Communications 

Abstract (Emphasis added) 

During the last few decades, several sectors in Antarctica have transitioned from glacial mass balance equilibrium to mass loss. In order to determine if recent trends exceed the scale of natural variability, long-term observations are vital. Here we explore the earliest, large-scale, aerial image archive of Antarctica to provide a unique record of 21 outlet glaciers along the coastline of East Antarctica since the 1930s. In Lützow-Holm Bay, our results reveal constant ice surface elevations since the 1930s, and indications of a weakening of local land-fast sea-ice conditions. Along the coastline of Kemp and Mac Robertson, and Ingrid Christensen Coast, we observe a long-term moderate thickening of the glaciers since 1937 and 1960 with periodic thinning and decadal variability. In all regions, the long-term changes in ice thickness correspond with the trends in snowfall since 1940. Our results demonstrate that the stability and growth in ice elevations observed in terrestrial basins over the past few decades are part of a trend spanning at least a century, and highlight the importance of understanding long-term changes when interpreting current dynamics.

Introduction

The East Antarctic Ice Sheet (EAIS) contains more than 52 m of potential sea level equivalent (SLE)¹. Recent observations indicate that the EAIS is more vulnerable than previously anticipated², and has made a considerable contribution to the continent-wide mass loss during the past decades³. The losses have primarily occurred in some of the marine-based catchments in Wilkes Land⁴, and are largely attributed to the intrusion of modified Circumpolar Deep Water (CDW)². The terrestrial catchments, where the majority of the ice is grounded above sea level, have recently shown a mass gain caused by increased accumulation^5,6,7,8, which has balanced some of the overall mass loss^9,10. Observational time series of glaciers in East Antarctica pre-dating the satellite era are rare¹¹ and consequently not long enough to determine if recent trends are independent of natural fluctuations^2,12. Historical datasets from early expeditions serves as a crucial link connecting records from the pre-satellite era, such as those derived from ice cores¹³ or geological¹⁴ and geomorphological evidence¹⁵, to quantitative observations of mass change acquired from satellites^5,6,7. While geological and geomorphological records cover longer time scales with temporal uncertainties of up to thousands of years^14,15, SMB estimates from ice cores are generally very local and spatially confined¹⁶. In contrast, data from historical aerial expeditions often provide extensive coverage across large areas, with detailed temporal and spatial information^17,18,19. Additionally, historical data provide an important baseline for forward modeling of glacier dynamics, allowing for long-term reanalysis data and more accurate model calibration²⁰. In Greenland and Svalbard, long-term observations from historical aerial images have been vital for determining the historical response of glaciers to climate change^18,19,21,22. However, in Antarctica, the scarcity of historical climate data makes climate reanalysis estimates before the 1970s largely uncertain^10,23, and observed trends cannot clearly be distinguished from natural variability^24,25.

Here, we rediscover and utilize the images from the earliest large-scale aerial photography campaign conducted on the Antarctic continent, allowing us to extend the era of observational records of glacier evolution back to the 1930s. Since the beginning of the 20^th century, several expeditions were launched to Antarctica with the aim of exploring and capturing aerial images for the production of geographical maps^{26,27,28,29,30}. However, just a handful of studies have previously used these data for generating digital elevation models (DEMs) and only for glaciers located in West Antarctica and the Antarctic Peninsula^11,31,32, dating back to 1947³². On the Antarctic Peninsula, these observations show widespread near-frontal surface lowering and inland stability since 1960³¹. On the other hand, historical observations of the Byrd Glacier over the past 40 years indicate a constant surface elevation, stable grounding line, and surface flow velocity¹¹.

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Currently, the earliest ice-sheet wide mass balance estimates start in the late 1970s^3,6,7, and since then all the sub-regions examined in this study have exhibited either an overall mass gain or been relative unchanged.

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Regardless of potential climatic changes, our results indicate that the glacier in Kemp and Mac Robertson Land and along Ingrid Christensen Coast, have accumulated mass during the past 85 years which inevitably have mitigated parts of the more recent mass loss from the marine basins in East Antarctica and the West Antarctic Ice Sheet (WAIS). This positive accumulation trend and positive mass balance is anticipated to persist as snowfall is expected to increase over the entire EAIS in the next century^54,55, and ice sheet modeling studies project positive mass balance estimates in all three sub-regions across all future RCP scenarios⁵⁶.

Lastly, we determine frontal changes of 21 glaciers from 1937 to 2023 (Table S1 and Fig. S11). From the 85 years of observations, we find two distinct regional patterns; one of constant glacier surface elevations and one of ice thickening.

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Guest Post by Willis Eschenbach

Every few years we get another media piece about the “first climate refugees”. I’ve written about the latest one below.

Here are the first through sixth first climate refugees, and the seventh, ninth, and eleventh-tenth first climate refugees. Where are the eighth first climate refugees? No clue, it’s hard to keep track of them all. Oh, and here are the twelfth first climate refugees.

So where are the 13th first climate refugees? They are some of the Kuna (or Guna) people. They live in Panama, on a tiny island named Gardi Sugdub. And by tiny, I mean minuscule. It is about 1200 feet (366 meters) long and 450 feet (137 meters) wide. The media piece about them is called “Panama prepares to evacuate first island in face of rising sea levels“. Inter alia it says:

The Gunas of Gardi Sugdub are the first of 63 communities along Panama’s Caribbean and Pacific coasts that government officials and scientists expect to be forced to relocate by rising sea levels in the coming decades.

and

Steven Paton, director of the Smithsonian Institution’s physical monitoring program in Panama, said that the upcoming move “is a direct consequence of climate change through the increase in sea level.”

Bear in mind that the person commenting works for the Smithsonian Institute, which will be of interest later.

And below is a view of the island.

Figure 1. Google Earth view of Gardi Sugdub. The word “overpopulation” comes to mind …

So … is “climate change” the reason why the island is going to be abandoned? Are we humans truly to blame?

Well … yes, humans are to blame, but it’s not the result of “climate change”. From the Smithsonian Institute, you know, the Institute that Steven Paton quoted above works for, I find the following (emphasis mine):

Natural Disturbances and Mining of Panamanian Coral Reefs by Indigenous People

HÉCTOR M. GUZMÁN,* CARLOS GUEVARA, AND ARCADIO CASTILLO
Smithsonian Tropical Research Institute

Abstract: Before the 1980s, coral reefs were considered relatively stable and healthy in Kuna-Yala, Caribbean Panama. During the 1980s, however, several natural disturbances changed the reef’s community structure. We evaluated historical changes in coral cover and for the first time provide quantitative evidence of a large-scale process of reef degradation.

This process started long before the onset of these disturbances as a result of demographic growth and the traditional practices of the Kuna people. Living coral cover declined 79% in 30 years (1970–2001) while the indigenous population increased 62%. We measured 20 km of seawall built with mined reef corals (16,000 m3) and an increase in island surface area of 6.23 ha caused by coral land filling. Consequently, coastal erosion has increased as a result of the lack of a protective natural barrier and a 2.0 cm/year local increase in sea level. Coral-mining and land-filling practices to accommodate population expansion and mismanagement of resources have significantly modified the reef ecosystem and will have serious long-term consequences.

So no, the problem is neither “climate change” nor “rising sea levels”. It’s overpopulation resulting in coral mining, landfilling, and reef destruction that are forcing the move. There’s much more good stuff in the study, interesting reading.

And in any case, how much has “climate change” increased the sea level trend in the area? Well … not at all. Here’s the nearest station with data up to the present. In the last 100 years, the sea level has risen by 137 mm (just over five inches).

Figure 2. Sea level in Balboa, Panama. Note that there is no visible acceleration in the rate of sea level rise from the start of the record in 1910 up to the present.

I’ve written before about how if you destroy the reef, you destroy the island. It’s discussed in a piece called Floating Islands and another called Why The Parrotfish Should Be The National Bird. If you’re interested in preserving the coral atolls, you might give those posts a read.

w.

PS: Yeah, you’ve heard it before—when you comment please quote the exact words you are discussing. It avoids endless misunderstandings. And if you want to show that I’ve made some error(s), please read this short thread that tells you How To Show That Willis Is Wrong