Category: Oceans

Century-Old Maps Reveal Long-Term Abundance of Kelp Beds

Published on by Jonathan Crowe

Comparing century-old maps of kelp beds in the Pacific Northwest to modern aerial surveys, a University of Chicago professor was able to track the long-term abundance and health of the beds, which in most cases remained remarkably constant: Journal of Ecology article. The kelp bed maps, made from surveys in 1911 and 1912, were the result of U.S. concern about the nation’s potash supply, which in the runup to World War I was largely imported from Germany. The kelp beds were, for some reason, seen as an alternative fertilizer source. That plan never came to fruition, but the maps remained, to be put to use for an entirely different purpose more than a century after they were made. [WMS]

Ecological Atlas of the Bering, Chukchi, and Beaufort Seas

Published on by Jonathan Crowe
Audubon Alaska, Ecological Atlas of the Bering, Chukchi, and Beaufort Seas.

Audobon Alaska’s Ecological Atlas of the Bering, Chukchi, and Beaufort Seas maps the environment, biota and wildlife in the three seas surrounding the Bering Strait, as well as the human activity that puts them at risk. The cartography is by Daniel Huffman and not by coincidence excellent. It’s available for download as PDF files, either chapter-by-chapter or a whopping 125-megabyte single download; a print copy costs $125 with shipping and handling. [NACIS]

18th-Century Maps Reveal Florida’s Missing Coral Reefs

Published on by Jonathan Crowe
From McClenachen et al., “Ghost reefs: Nautical charts document large spatial scale of coral reef loss over 240 years,” Science Advances 3, no. 9 (6 Sept 2017). Creative Commons licence.

In the 1770s British surveyor George Gauld mapped the Florida Keys, taking careful note of the location and depth of Florida reefs. A study published last month in Science Advances compares Gauld’s maps with modern-day satellite imagery and concludes that half of the area occupied by coral in the eighteenth century has disappeared. As the Washington Post reports, the cause of the coral’s disappearance is unclear, though several potential human and natural factors are put forward. [WMS]

The Last Unmapped Places

Published on by Jonathan Crowe

Lois Parshley’s essay on the last unmapped, mysterious places—Greenlandic fjords, the slums of Haiti, the ocean’s depths, black holes in space—is a long read worth reading. Originally published last month as “Here Be Dragons: Finding the Blank Spaces in a Well-Mapped World” in the Virginia Quarterly Review, it’s been reprinted by the Guardian, in an edited, tighter version, as “Faultlines, Black Holes and Glaciers: Mapping Uncharted Territories.”

Mapping the Ocean Floor by 2030

Published on by Jonathan Crowe

Newsweek looks at efforts by a group of scientists and mariners to map most of the ocean floor by the year 2030. The objective was endorsed by a meeting of GEBCO, the General Bathymetric Chart of the Oceans, last June. The scale of the project is vast:

To date, more than 85 percent of the seafloor has not been mapped using modern methods. Since 70 percent of the Earth is covered in oceans, this means that we quite literally don’t know our own planet. “We know the surface of Mars better than we do the seafloor,” says Martin Jakobsson, a researcher at Stockholm University.

[Leventhal/MAPS-L]

Marie Tharp: Continental Drift as ‘Girl Talk’

Published on by Jonathan Crowe

tharp-heezenAnother profile of ocean cartographer Marie Tharp, this time from Smithsonian.com’s Erin Blakemore. As Blakemore recounts, Tharp crunched and mapped the sonar sounding data collected by her collaborator, Bruce Heezen; her calculations revealed a huge valley in the middle of a ridge in the North Atlantic seafloor.

“When I showed what I found to Bruce,” she recalled, “he groaned and said ‘It cannot be. It looks too much like continental drift.’ … Bruce initially dismissed my interpretation of the profiles as ‘girl talk’.” It took almost a year for Heezen to believe her, despite a growing amount of evidence and her meticulous checking and re-checking of her work. He only changed his mind when evidence of earthquakes beneath the rift valley she had found was discovered—and when it became clear that the rift extended up and down the entire Atlantic. Today, it is considered Earth’s largest physical feature.

When Heezen—who published the work and took credit for it—announced his findings in 1956, it was no less than a seismic event in geology. But Tharp, like many other women scientists of her day, was shunted to the background.

I really ought to get to Hali Felt’s 2012 biography of Tharp, Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor, at some point. Amazon (Kindle), iBooks.

Previously: Marie Tharp Profile; Soundings: A Biography of Marie Tharp; Marie Tharp and Plate Tectonics; Marie Tharp.

Canada Maps the Arctic Seafloor

Published on by Jonathan Crowe

CBC News reports on the Canadian Coast Guard’s project to map the continental shelf under the Arctic Ocean, now in its third and final year. This is part of Canada’s attempt to stake a claim to the continental shelf (and seas above it) beyond the 200-mile nautical limit, which other Arctic countries (hello, Russia) are also trying to do.

Previously: Arctic Maritime Jurisdiction Map.

Canada’s Arctic Waters Are ‘Dangerously Unmapped’

Published on by Jonathan Crowe

Climate change has made the Arctic increasingly open to shipping, and more ships travel the Canadian Arctic every year. But as Claire Eamer argues in Hakai magazine, the lack of mapping makes such voyages a dangerous proposition. “[J]ust because the ice is melting it doesn’t mean the waterways are safe. The federal Canadian Hydrographic Service (CHS) is responsible for mapping Canada’s waters. So far, they’ve only managed to map roughly 10 percent of Arctic waterways in accordance with international standards.” [CCA]

Monterey Bay Area Seafloor Maps Released

Published on by Jonathan Crowe
Bathymetry of Monterey Canyon and the Soquel Canyon tributary
Bathymetry of Monterey Canyon and the Soquel Canyon tributary
Geologic Map of Monterey Canyon and the Soquel Canyon tributary
Geologic Map of Monterey Canyon and the Soquel Canyon tributary

New seafloor maps of the Monterey Bay area have been released as part of the California Seafloor Mapping Program. The maps “reveal the diverse and complex range of seafloor habitats along 130 kilometers (80 miles) of the central California coast from the Monterey Peninsula north to Pigeon Point.” [Leventhal Map Center]

Previously: Mapping the California Sea Floor.

Mapping Global Sea Surface Height

Published on by Jonathan Crowe
jason3-20160315
Credit: NASA/JPL Ocean Surface Topography Team.

Jason-3 is the latest earth observation satellite tasked with measuring global sea surface height; its data will be used in weather and climate research (e.g., El Niño, climate change). Launched on January 17, it’s now in its six-month checkout phase and has produced its first complete map, which corresponds well with the map produced by the still-operational Jason-2 satellite, so that’s a good sign. [via]

Seafloor Gravity Map

Published on by Jonathan Crowe
seafloor
NASA Earth Observatory map by Joshua Stevens

The ocean floor is still very much terra incognita: only 5 to 15 percent of it has been mapped via bathymetry. But using military satellite measurements of the Earth’s shape and gravity field, a new map of the ocean floor has been created. “The result of their efforts is a global data set that tells where the ridges and valleys are by showing where the planet’s gravity field varies. […] Shades of orange and red represent areas where seafloor gravity is stronger (in milligals) than the global average, a phenomenon that mostly coincides with the location of underwater ridges, seamounts, and the edges of Earth’s tectonic plates. Shades of blue represent areas of lower gravity, corresponding largely with the deepest troughs in the ocean.”