Scientists FINALLY Know What Froze Antarctica

Earth has two regions defined by extreme cold: Antarctica at the South Pole and the Arctic at the North Pole.

Because both regions receive similar amounts of sunlight over the course of a year, scientists long expected that they would have developed large ice sheets at roughly the same time.

Geological evidence, however, has shown that this was not the case. Antarctica became covered by a massive ice sheet millions of years before the Arctic developed permanent large-scale ice coverage.

For decades, researchers have worked to explain this difference. A new study conducted by researchers from the United Kingdom and Germany now offers a possible explanation based on the interaction between Earth’s climate and geological processes beneath the planet’s surface.

Antarctica contains the largest ice sheet on Earth. It covers more than five million square miles, an area comparable to the combined size of the United States and Mexico.

The continent stores approximately seven million cubic miles of ice. Scientists estimate that if the entire Antarctic ice sheet were to melt, global sea levels would increase by about 190 feet.

Such a rise would reshape coastlines around the world and significantly affect low-lying regions. Understanding how this enormous ice sheet formed has remained one of the major questions in Earth science.

Previous research identified a significant decline in atmospheric carbon dioxide as one of the key events that cooled the planet.

Around 34 million years ago, during the Eocene-Oligocene transition, Earth experienced a major climate shift.

Carbon dioxide concentrations in the atmosphere declined, reducing the greenhouse effect and allowing global temperatures to decrease.

While this explanation accounted for part of the cooling, it did not fully explain two major observations found in the geological record.

The first unanswered question involved the timing of ice formation. Antarctica developed its large ice sheet approximately 34 million years ago, yet the Arctic remained largely free of permanent extensive ice for another 25 million years.

Since both polar regions experienced the same overall planetary cooling, scientists expected both ends of the Earth to respond in similar ways.

Instead, Antarctica entered a period of extensive glaciation long before the Northern Hemisphere. The second question concerned ocean temperatures surrounding Antarctica.

Geological evidence suggested that the Southern Ocean remained relatively warm for nearly 10 million years after the Antarctic ice sheet began expanding.

If global cooling alone had produced the ice sheet, researchers expected nearby ocean temperatures to decline at roughly the same pace.

Instead, a large frozen continent existed beside waters that remained warmer than anticipated. These two observations suggested that additional geological processes were involved.

According to the new research, the explanation begins much earlier than the appearance of Antarctic ice.

Scientists traced the process back approximately 170 million years, when the continents were arranged very differently from today.

At that time, Antarctica and Africa were connected within the ancient supercontinent known as Gondwana.

Over millions of years, the continental plates slowly separated. As Antarctica gradually drifted toward the South Pole, changes beneath the Earth’s surface also began.

Researchers explain that when continents separate, hot material from the mantle rises beneath the newly forming gap.

As this material cools, it sinks again, producing slow-moving circulation within the mantle. The process resembles the movement seen inside a lava lamp, although it occurs over millions of years within slowly flowing rock beneath Earth’s cruSt.

These underground movements are known as mantle waves. Mantle waves travel beneath continents over very long periods and can extend for more than 620 miles.

As they move, they influence the rocks above them in several important ways. Scientists have previously linked mantle waves to volcanic activity because they can transport magma upward from deep within the Earth.

Some volcanic eruptions associated with these processes have also carried diamonds from deep underground toward the surface.

The new study focuses on another effect produced by mantle waves. As they move beneath continents, they can remove portions of dense rock from the base of the continental cruSt. Once this heavy material is removed, the land above becomes lighter and slowly rises.

Researchers used advanced computer simulations to reconstruct how Antarctica changed over tens of millions of years.

Their models combined information about continental movement, geological activity, and changes beneath Earth’s surface to estimate how mantle waves affected the continent after Gondwana broke apart.

The simulations showed that the coastline experienced stretching as the continent separated from Africa. This stretching produced steep rocky features near the continental margin.

Farther inland, however, the mantle waves gradually removed dense rock from beneath East Antarctica. As this material disappeared, the land surface slowly rose.

Scientists compare the process to removing weight from a balloon. Once the heavy material beneath the continent was reduced, the land gradually lifted higher over millions of years.

This uplift eventually produced an extensive elevated plateau across parts of East Antarctica. Natural erosion then reshaped the rising landscape.

Rivers, rainfall, wind, and early ice slowly modified the terrain while uplift continued moving farther inland.

According to the computer models, this geological process required approximately 100 million years to extend toward the Gamburtsev Mountains, a mountain range now completely buried beneath Antarctica’s ice sheet.

The elevation of these mountains became a critical factor in the development of permanent ice.

Temperature generally decreases with altitude. Researchers estimate that air becomes approximately five and one-half degrees Fahrenheit colder for every one thousand feet of elevation gained.

Earlier in their history, the Gamburtsev Mountains were not high enough for snow to remain throughout the entire year.

Seasonal snowfall melted during warmer periods, preventing glaciers from developing. The new study suggests that continuous uplift gradually increased the height of these mountains until conditions changed.

By approximately 50 million years ago, the mountains had risen sufficiently for snow to survive the summer months.

As snow accumulated year after year, glaciers began forming across higher elevations. Researchers estimate that by around 45 million years ago, much of East Antarctica had become both high enough and cold enough to support expanding mountain glaciers.

This timing closely matches geological evidence for the beginning of Antarctic ice sheet formation. During the same period, global temperatures had already declined by roughly 18 degrees Fahrenheit because of lower atmospheric carbon dioxide levels.

Scientists believe these two processes worked together. The reduction in carbon dioxide cooled the global climate, while the higher elevation created by mantle-driven uplift provided local conditions cold enough for snow and ice to remain throughout the year.

Once glaciers formed in the mountains, additional natural processes accelerated ice growth. One important factor involved sunlight.

Snow and ice reflect much more incoming solar radiation than exposed rock. As expanding glaciers covered larger portions of Antarctica, more sunlight reflected back into space rather than being absorbed by the surface.

This increased reflection allowed temperatures across the region to continue declining. Researchers also identified another important climate effect.

Cold air contains less water vapor than warm air. Since water vapor acts as a greenhouse gas that helps retain heat within the atmosphere, lower moisture levels reduced the amount of heat remaining above Antarctica.

With both increased sunlight reflection and lower atmospheric water vapor working together, temperatures continued falling across the continent.

Individual glaciers gradually expanded beyond mountain valleys. Over time, neighboring glaciers merged into increasingly larger ice masses until they formed the continuous Antarctic ice sheet that exists today.

The study also provides a possible explanation for why the Arctic remained largely free of permanent ice for millions of additional years.

Although global temperatures declined during the Eocene-Oligocene transition, northern land areas generally lacked the high elevations needed for extensive snow accumulation.

Without large elevated regions where snow could survive year after year, permanent ice sheets could not develop despite overall planetary cooling.

Scientists conclude that the Arctic required additional reductions in atmospheric carbon dioxide and further global cooling before conditions became suitable for widespread glaciation.

This delayed the formation of major Northern Hemisphere ice sheets by approximately 25 million years compared with Antarctica.

The research also addresses the long-standing question surrounding the relatively warm Southern Ocean. According to the study, atmospheric cooling over Antarctica became sufficient for glacier formation on elevated land before surrounding ocean temperatures declined substantially.

As a result, Antarctica was able to develop a massive continental ice sheet while nearby ocean waters remained comparatively warm for millions of years.

This explanation suggests that atmospheric conditions over elevated terrain responded differently from conditions within the surrounding ocean.

The study concludes that declining carbon dioxide alone cannot fully explain Antarctica’s early glaciation. Instead, geological uplift created conditions that allowed snow and ice to persist long enough for self-reinforcing climate processes to begin.

The findings also help explain why Antarctica remains colder than the Arctic today. Although both polar regions receive similar annual amounts of sunlight, important geographical differences remain.

The North Pole consists primarily of sea ice floating above the Arctic Ocean. Water beneath the ice stores heat and moderates air temperatures.

Antarctica differs because it is a high continental landmass covered by a thick ice sheet extending across elevated terrain.

Its greater elevation naturally produces colder temperatures. Strong atmospheric circulation around the continent also limits the movement of warmer air from lower latitudes into the interior.

Together, these geographical features allow Antarctica to maintain lower average temperatures than the Arctic despite receiving similar amounts of solar energy throughout the year.

Researchers say the buried Gamburtsev Mountains continue to play an important role in understanding Antarctica’s climate history.

Although they are hidden beneath thousands of feet of ice, the mountains helped establish the conditions necessary for the continent’s first major glaciers to develop.

Scientists believe that improving knowledge of how these mountains formed may also improve future climate projections.

By understanding how elevation contributed to Antarctic ice formation millions of years ago, researchers may better estimate how rising global temperatures could affect the stability of the Antarctic ice sheet in the future.

The study presents a combined explanation involving both climate and geology. Lower atmospheric carbon dioxide created cooler global conditions, while mantle-driven uplift raised parts of Antarctica high enough for glaciers to develop earlier than elsewhere on Earth.

Once ice began expanding, natural feedback processes strengthened cooling across the continent, allowing separate glaciers to merge into the world’s largest ice sheet.

According to the researchers, this combination of underground geological activity and atmospheric change provides a more complete explanation for why Antarctica became permanently frozen millions of years before the Arctic.