Berliner Boersenzeitung - Antarctic octopus DNA reveals ice sheet collapse closer than thought

EUR -
AED 4.298308
AFN 81.92842
ALL 98.084438
AMD 449.658082
ANG 2.094583
AOA 1073.261444
ARS 1468.279515
AUD 1.797333
AWG 2.106729
AZN 1.991668
BAM 1.950584
BBD 2.361684
BDT 142.702048
BGN 1.952874
BHD 0.441244
BIF 3442.161504
BMD 1.170405
BND 1.495414
BOB 8.082386
BRL 6.37672
BSD 1.169772
BTN 100.183093
BWP 15.616838
BYN 3.827896
BYR 22939.94066
BZD 2.349537
CAD 1.601886
CDF 3377.78954
CHF 0.933357
CLF 0.02875
CLP 1103.282348
CNY 8.396545
CNH 8.408618
COP 4742.04856
CRC 591.323751
CUC 1.170405
CUP 31.015736
CVE 110.718148
CZK 24.646426
DJF 208.0043
DKK 7.461362
DOP 70.350158
DZD 151.75855
EGP 58.145374
ERN 17.556077
ETB 159.672582
FJD 2.63493
FKP 0.862316
GBP 0.862764
GEL 3.171819
GGP 0.862316
GHS 12.166116
GIP 0.862316
GMD 83.688631
GNF 10131.027064
GTQ 8.990189
GYD 244.728101
HKD 9.187663
HNL 30.84028
HRK 7.530413
HTG 153.519463
HUF 400.091736
IDR 19027.510373
ILS 3.917797
IMP 0.862316
INR 100.486011
IQD 1533.230728
IRR 49303.316231
ISK 142.964601
JEP 0.862316
JMD 186.69553
JOD 0.829797
JPY 172.183562
KES 151.572338
KGS 102.35198
KHR 4706.199287
KMF 492.135958
KPW 1053.33889
KRW 1609.04963
KWD 0.357653
KYD 0.974835
KZT 607.784679
LAK 25222.230108
LBP 104868.299941
LKR 351.638671
LRD 234.666446
LSL 20.82134
LTL 3.455902
LVL 0.707966
LYD 6.317227
MAD 10.539461
MDL 19.797818
MGA 5184.89504
MKD 61.456221
MMK 2457.274227
MNT 4200.068068
MOP 9.458292
MRU 46.470981
MUR 52.797044
MVR 18.017904
MWK 2032.412478
MXN 21.795138
MYR 4.979492
MZN 74.859293
NAD 20.821752
NGN 1792.545747
NIO 43.012461
NOK 11.837998
NPR 160.294714
NZD 1.958001
OMR 0.450015
PAB 1.169682
PEN 4.148497
PGK 4.827984
PHP 66.236151
PKR 332.687497
PLN 4.243969
PYG 9322.309495
QAR 4.260981
RON 5.080258
RSD 117.17157
RUB 91.876031
RWF 1678.360965
SAR 4.389513
SBD 9.757579
SCR 16.795029
SDG 702.829472
SEK 11.168743
SGD 1.499763
SHP 0.919755
SLE 26.33756
SLL 24542.814783
SOS 668.884838
SRD 43.683615
STD 24225.023271
SVC 10.234892
SYP 15217.759559
SZL 20.821484
THB 38.256993
TJS 11.235231
TMT 4.108122
TND 3.388456
TOP 2.741205
TRY 46.869412
TTD 7.935846
TWD 34.069936
TZS 3090.09425
UAH 48.858496
UGX 4204.755761
USD 1.170405
UYU 46.96561
UZS 14893.405655
VES 131.422218
VND 30603.168287
VUV 139.633925
WST 3.222549
XAF 654.218686
XAG 0.032033
XAU 0.000356
XCD 3.163078
XDR 0.812997
XOF 651.915763
XPF 119.331742
YER 283.061714
ZAR 20.832029
ZMK 10535.048293
ZMW 28.335227
ZWL 376.869976
  • CMSC

    0.0900

    22.314

    +0.4%

  • CMSD

    0.0250

    22.285

    +0.11%

  • RBGPF

    0.0000

    69.04

    0%

  • SCS

    0.0400

    10.74

    +0.37%

  • RELX

    0.0300

    53

    +0.06%

  • RIO

    -0.1400

    59.33

    -0.24%

  • GSK

    0.1300

    41.45

    +0.31%

  • NGG

    0.2700

    71.48

    +0.38%

  • BP

    0.1750

    30.4

    +0.58%

  • BTI

    0.7150

    48.215

    +1.48%

  • BCC

    0.7900

    91.02

    +0.87%

  • JRI

    0.0200

    13.13

    +0.15%

  • VOD

    0.0100

    9.85

    +0.1%

  • BCE

    -0.0600

    22.445

    -0.27%

  • RYCEF

    0.1000

    12

    +0.83%

  • AZN

    -0.1200

    73.71

    -0.16%

Antarctic octopus DNA reveals ice sheet collapse closer than thought
Antarctic octopus DNA reveals ice sheet collapse closer than thought / Photo: Sophie RAMIS, Sophie STUBER - AFP

Antarctic octopus DNA reveals ice sheet collapse closer than thought

Scientists investigating how Antarctica's ice sheets retreated in the deep past have turned to an innovative approach: studying the genes of octopuses that live in its chilly waters.

Text size:

A new analysis published Thursday in Science finds that geographically-isolated populations of the eight-limbed sea creatures mated freely around 125,000 years ago, signaling an ice-free corridor during a period when global temperatures were similar to today.

The findings suggest the West Antarctic Ice Sheet (WAIS) is closer to collapse than previously thought, threatening 3.3-5 meters of long term sea level rise if the world is unable to hold human-caused warming to the 1.5 degrees Celsius target of the Paris Agreement, said the authors.

Lead author Sally Lau of James Cook University in Australia told AFP that as an evolutionary biologist focused on marine invertebrates, "I understand and then apply DNA and biology as a proxy of changes to Antarctica in the past."

Turquet's octopus made an ideal candidate for studying WAIS, she said, because the species is found all around the continent and fundamental information about it has already been answered by science, such as its 12-year-lifespan, and the fact it emerged some four million years ago.

About half-a-foot (15 centimeters) long excluding the arms and weighing around 1.3 pounds (600 grams), they lay relatively few, but large eggs on the bottom of the seafloor. This means parents must put significant effort into ensuring their offspring hatch -- a lifestyle that prevents them traveling too far away.

They are also limited by circular sea currents, or gyres, in some of their modern habitats.

- 'Tipping point close' -

By sequencing the DNA across genomes of 96 samples that were generally collected inadvertently as fishing bycatch and then left in museum storage over the course of 33 years, Lau and colleagues found evidence of trans-West Antarctic seaways that once connected the Weddell, Amundsen and Ross seas.

The history of genetic mixing indicated WAIS collapsed at two separate points -- first in the mid-Pliocene, 3-3.5 million years ago, which scientists were already confident about, and the last time in a period called the Last Interglacial, a warm spell from 129,000 to 116,000 years ago.

"This was the last time the planet was around 1.5 degrees warmer than pre-industrial levels," said Lau. Human activity, primarily burning fossil fuels, has so far raised global temperatures by 1.2C compared to the late 1700s.

There were a handful of studies prior to the new Science paper that also suggested WAIS collapsed some time in the past, but they were far from conclusive because of the comparatively lower resolution genetic and geological data.

"This study provides empirical evidence indicating that the WAIS collapsed when the global mean temperature was similar to that of today, suggesting that the tipping point of future WAIS collapse is close," the authors wrote.

Sea level rise of 3.3 meters would drastically alter the world map as we know it, submerging low-lying coastal areas everywhere.

Writing in an accompanying commentary piece, Andrea Dutton of the University of Wisconsin-Madison and Robert DeConto of the University of Massachusetts, Amherst described the new research as "pioneering," adding it posed intriguing questions about whether ancient history will be repeated.

They flagged however that several key questions remained unanswered -- such as whether the past ice sheet collapse was caused by rising temperatures alone, or whether other variables like changing ocean currents and complex interactions between ice and solid Earth were also at play.

It's also not clear whether the sea level rise would be drawn out over millennia or occur in more rapid jumps.

But uncertainties such as these can't be an excuse for inaction against climate change "and this latest piece of evidence from octopus DNA stacks one more card on an already unstable house of cards," they wrote.

(U.Gruber--BBZ)