This sobering possibility bolsters the case for learning all we can about Antarctica’s frozen realm, not only for its inherent scientific value but for its far-reaching implications for global climate and sea-level trends. Enter Bedmap3, the latest and greatest Antarctic bedrock map on record, courtesy of an international team, led by the British Antarctic Survey, making use of pioneering methods. This map is a technological tour de force, showing with unparalleled clarity the ancient, rocky foundation beneath 6.5 million cubic miles of ice.
Antarctica’s ice sheets, however, while appearing everlasting, are geologically young. Below them is a landscape hundreds of millions of years older than the ice. Bedmap3 provides a window into this subterranean landscape, revealing deep chasms, high mountain ranges and large areas of bedrock that are below current sea levels. One crevasse is shrouded with a wall of ice almost three miles thick vertical height that eclipses symbolic buildings like the Shard skyscraper in London.
But Bedmap3 is not only eye-candy it is an essential tool for scientists wrestling with the implications of melting ice sheets. With humans continuing to pump greenhouse gases into the atmosphere, Antarctica’s ice is thinning and melting. Knowing how the bedrock is shaped and where it is weak helps researchers forecast how meltwater will reach the oceans and potentially change sea levels around the world. The map also highlights where warm ocean currents penetrate subglacial channels, hastening ice loss in sections that are already below sea level.
Bedmap3 was a massive undertaking. The map is the third in a series dating back to the early 2000s. Each subsequent version has built upon what came before, adding ever more complex techniques to boost resolution and accuracy. The most recent effort used a suite of cutting-edge technologies, including ice-penetrating radar, laser altimetry and gravimetry. These methods were employed from planes, snowmobiles and even sleds drawn by dogs, enabling scientists to gather an astounding 82 million individual data points.
Ice-penetrating radar, or radio echo sounding (RES), was a key tool. By shooting radio waves through the ice and measuring their echoes, the researchers could map the ice’s thickness and the bedrock’s shape below. Gravimetry and other complementary techniques measured differences in the local gravity fields resulting from concentrations of mass, such as mountains or valleys. At times scientists even set off controlled explosions to create seismic waves, which offered bonus insights into the bedrock’s structure.
Much of Bedmap3’s accuracy comes from its very high-resolution grid, which is set at 500 meters, the granularity of earlier maps, like Bedmap2, was in 1-kilometer intervals. This finer scale enables scientists to determine detailed characteristics such as subtle subglacial troughs and grounding zones incredibly accurately. As reported by the British Antarctic Survey’s publication in Nature, “93% of the 500 m Bedmap3 grid cells of ice thickness are populated by interpolated values,” highlighting the incredible density of data collected as part of the project.
The map also reveals something about Antarctica’s geological history. Around 35 million years ago at the Palaeogene−Neogene boundary, the continent changed from a warm, forested landscape to its present frozen form. These changes were driven by the opening of the Drake Passage and the emergence of the Antarctic Circumpolar Current. The rise of this oceanic barrier isolated Antarctica from warmer currents, setting the stage for its deep freeze.
Bedmap3’s implications reach well beyond Antarctica. By entering its data into complex climate models, scientists can take predictions about global sea-level rise and how it will affect coastal cities to the next level. The interconnectedness of Earth’s systems from tectonic movements to temperature changes also serves as a reminder of how these systems can shape Earth’s future, the map reminds.
Bedmap3, Andrews rightly observes, is not only a scientific triumph, but an aesthetic one. It provides a “It just so happens that this map is also an aesthetic marvel, a painterly vision of a long-lost version of Earth that no human has ever seen. It was created by science, sure. But the end result is a little magical too.” To science buffs, climate sleuths and geophysics pros, it’s a tribute to the power of technology and collaboration in peeling away the curtain of mystery that shrouds our world.
