Hottest Oceans in 400 Years Endanger Great Barrier Reef

FILE PHOTO: Peter Gash, owner and manager of the Lady Elliot Island Eco Resort, snorkels during an inspection of the reef's condition in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. REUTERS/David Gray/File Photo
FILE PHOTO: Peter Gash, owner and manager of the Lady Elliot Island Eco Resort, snorkels during an inspection of the reef's condition in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. REUTERS/David Gray/File Photo
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Hottest Oceans in 400 Years Endanger Great Barrier Reef

FILE PHOTO: Peter Gash, owner and manager of the Lady Elliot Island Eco Resort, snorkels during an inspection of the reef's condition in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. REUTERS/David Gray/File Photo
FILE PHOTO: Peter Gash, owner and manager of the Lady Elliot Island Eco Resort, snorkels during an inspection of the reef's condition in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. REUTERS/David Gray/File Photo

Water temperatures in and around Australia's Great Barrier Reef have risen to their warmest in 400 years over the past decade, placing the world's largest reef under threat, according to research published on Thursday.
The reef, the world's largest living ecosystem, stretches for some 1,500 miles (2,400 km) off the coast of the northern state of Queensland. The research is rare in putting the effects of man-made climate change into historical context, as other surveys on damage to the reef have a shorter time frame.
A group of scientists at universities across Australia drilled cores into the coral and, much like counting the rings on a tree, analyzed the samples to measure summer ocean temperatures going back to 1618.
Combined with ship and satellite data going back around a hundred years, the results show ocean temperatures that were stable for hundreds of years begin to rise from 1900 onwards as a result of human influence, the research concluded.
From 1960 to 2024, the study's authors observed an average annual warming for January to March of 0.12°C (0.22°F) per decade, Reuters reported.
Since 2016, the reef has experienced five summers of mass coral bleaching, when large sections of the reef turn white due to heat stress, putting them at greater risk of death.
These summers were during five of the six warmest years in the last four centuries, the study showed.
"The world is losing one of its icons," said Benjamin Henley, an academic at the University of Melbourne and one of the study's co-authors.
"I find that to be an absolute tragedy. It's hard to understand how that can happen on our watch in our lifetime. So it's very, very sad."
The last temperature data point, from January to March of this year, was the highest on record and "head and shoulders" above any other year, Henley said.
Coral reefs protect shorelines from erosion, are home to thousands of species of fish, and are an important source of tourism revenue in many countries.
At least 54 countries and regions have experienced mass bleaching of their reefs since February 2023 as climate change warms the ocean's surface waters, the US National Oceanic and Atmospheric Administration (NOAA) has said.
The Great Barrier Reef is not currently on UNESCO's list of world heritage sites that are in danger, though the UN recommends it should be added.
Australia has lobbied for years to keep the reef - which contributes A$6.4 billion ($4.2 billion) to the economy annually - off the endangered list, as it could damage tourism.
Lissa Schindler, Great Barrier Reef campaign manager at the Australian Marine Conservation Society, said the research showed Australia needed to do more to reduce its emissions.



Nearby Sculptor Galaxy Revealed in Ultra-Detailed Galactic Image

This undated handout image released by European Southern Observatory on June 17, 2025 shows a detailed, thousand-color image of the Sculptor Galaxy captured with the MUSE instrument at ESO’s Very Large Telescope (VLT). (Handout / European Southern Observatory / AFP)
This undated handout image released by European Southern Observatory on June 17, 2025 shows a detailed, thousand-color image of the Sculptor Galaxy captured with the MUSE instrument at ESO’s Very Large Telescope (VLT). (Handout / European Southern Observatory / AFP)
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Nearby Sculptor Galaxy Revealed in Ultra-Detailed Galactic Image

This undated handout image released by European Southern Observatory on June 17, 2025 shows a detailed, thousand-color image of the Sculptor Galaxy captured with the MUSE instrument at ESO’s Very Large Telescope (VLT). (Handout / European Southern Observatory / AFP)
This undated handout image released by European Southern Observatory on June 17, 2025 shows a detailed, thousand-color image of the Sculptor Galaxy captured with the MUSE instrument at ESO’s Very Large Telescope (VLT). (Handout / European Southern Observatory / AFP)

The Sculptor galaxy is similar in many respects to our Milky Way. It is about the same size and mass, with a similar spiral structure. But while it is impossible to get a full view of the Milky Way from the vantage point of Earth because we are inside the galaxy, Sculptor is perfectly positioned for a good look.

Astronomers have done just that, releasing an ultra-detailed image of the Sculptor galaxy on Wednesday obtained with 50 hours of observations using one of the world's biggest telescopes, the European Southern Observatory's Chile-based Very Large Telescope.

The image shows Sculptor, also called NGC 253, in around 4,000 different colors, each corresponding to a specific wavelength in the optical spectrum.

Because various galactic components emit light differently across the spectrum, the observations are providing information at unprecedented detail on the inner workings of an entire galaxy, from star formation to the motion of interstellar gas on large scales. Conventional images in astronomy offer only a handful of colors, providing less information.

The researchers used the telescope's Multi Unit Spectroscopic Explorer, or MUSE, instrument.

"NGC 253 is close enough that we can observe it in remarkable detail with MUSE, yet far enough that we can still see the entire galaxy in a single field of view," said astronomer Enrico Congiu, a fellow at the European Southern Observatory in Santiago, and lead author of research being published in the journal Astronomy & Astrophysics.

"In the Milky Way, we can achieve extremely high resolution, but we lack a global view since we're inside it. For more distant galaxies, we can get a global view, but not the fine detail. That's why NGC 253 is such a perfect target: it acts as a bridge between the ultra-detailed studies of the Milky Way and the large-scale studies of more distant galaxies. It gives us a rare opportunity to connect the small-scale physics with the big-picture view," Congiu said.

Sculptor is about 11 million light-years from Earth, making it one of the closest big galaxies to the Milky Way. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).

Like the Milky Way, it is a barred spiral galaxy, meaning it has an elongated structure extending from its nucleus, with spiral arms extending from the ends of the bar. Its diameter of about 88,000 light-years is similar to the Milky Way's, as is its total mass. One major difference is Sculptor's rate of new star formation, estimated to be two to three times greater than that of the Milky Way.

Nearly 30% of this star formation is happening near the galaxy's nucleus in what is called a starburst region, as revealed in colorful emissions shown in the new image.

The observations have given information on a wide range of properties such as the motion, age and chemical composition of stars and the movement of interstellar gas, an important component of any galaxy.

"Since the light from stars is typically bluer if the stars are young or redder if the stars are old, having thousands of colors lets us learn a lot about what stars and populations of stars exist in the galaxy," said astronomer Kathryn Kreckel of Heidelberg University in Germany, a study co-author.

"Similarly for the gas, it glows in specific bright emission lines at very specific colors, and tells us about the different elements that exist in the gas, and what is causing it to glow," Kreckel said.

The initial research being published from the observations involves planetary nebulae, which are luminous clouds of gas and dust expelled by certain dying stars. Despite their name, they have nothing to do with planets. These nebulae can help astronomers measure the precise distances of faraway galaxies.

The researchers marveled at the scientific and aesthetic value of the new view of Sculptor.

"I personally find these images amazing," Congiu said. "What amazes me the most is that every time I look at them, I notice something new - another nebula, a splash of unexpected color or some subtle structure that hints at the incredible physics behind it all."