A massive Atlantic Ocean current system, which affects climate, sea levels and weather systems around the world, may be about to be fatally disrupted.
A new report in the journal Nature Climate Change describes how a series of Atlantic Ocean currents have reached “an almost complete loss of stability over the last century” as the planet continues to warm. The report, authored by Dr. Niklas Boers, specifically analyzes data on ocean temperature and salinity to demonstrate that their circulation has weakened over the past few decades. If current trends continue unabated, they may slow to a dangerous level or even shut down entirely.
The series of currents in question is known as the Atlantic Meridional Overturning Circulation, or AMOC for short. The current system is sometimes likened to a series of conveyer belts: one “belt” flows north with warm water that, upon reaching the northern Atlantic, cools and evaporates, in the process increasing the salinity of water in that region. The saltier water becomes colder and heavier, sinking and flowing south to create a second “belt.” Those two currents are in turn connected by other oceanic features in the Southern Ocean, the Labrador Sea and the Nordic Sea.
The study reinforces earlier scientific studies which found the Atlantic Meridional Overturning Circulation system to be at its weakest in 1,600 years.
This so-called conveyer belt system has been in place for thousands of years or more, and ocean life is adapted to its rhythms. Indeed, AMOC, which scientists believe can slow down or turn off abruptly when temperatures increase, is also vital to maintaining humanity’s way of life. If it shuts down, temperature will plummet in Europe while the number of storms increases; changing weather conditions will lead to food shortages in South America, India and Western Africa; and rising sea levels along the North American eastern seaboard will force millions to flee their homes. Considering that AMOC is already starting to decline, this is a serious threat that could radically alter our planet in a matter of mere decades.
“This decline may be associated with an almost complete loss of stability over the course of the last century, and the AMOC could be close to a critical transition to its weak circulation mode,” the analysis explains.
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This is not the first troubling news which has emerged about AMOC. In February another study disclosed that AMOC could be weakened by 34% to 45% by the end of the century as Arctic ice and the Greenland Ice Sheet continue to melt. The new report, however, increases the growing sense of scientific alarm about AMOC’s integrity.
“This work provides provides additional support for our earlier work in the same journal Nature Climate Change suggesting that a climate change-induced slowdown of the ocean ‘conveyer belt’ circulation already underway, decades ahead of schedule, yet another reminder that uncertainty is not our friend,” Dr. Michael E. Mann, a distinguished professor of atmospheric science at Penn State University, wrote to Salon. “There are surprises in store, and they are likely to be unpleasant ones, when it comes to the climate crisis.”
Cristian Proistosescu, an assistant professor at the University of Illinois–Urbana-Champaign who studies climate dynamics and global warming consequences, was more measured in his assessment.
“If the worst-case scenario comes to pass — and that’s a big if — we can certainly expect to see dramatic changes in climate in the far north of Europe,” Proistosescu told Salon by email. He described a world in which Scandinavian winters are no longer mild, where precipitation patterns shift as far south as central Africa and in which other meteorological patterns alter radically. The worst case scenarios may be “somewhat unlikely,” he added, noting that the majority of updated climate models predict a gradual deterioration over the 21st century rather than an abrupt showdown.
“The data we have is too short to say with any real confidence whether the collapse of the North Atlantic Overturning Circulation is truly imminent,” Proistosescu concluded. “The question for me is how risk-averse should we be in the face of uncertainty, and how much do we want to avoid a high cost–low probability worst-case scenario? Given the how high the costs would be, we should be fairly risk averse.”
Not every climate expert is impressed with the new study’s conclusions. Kevin Trenberth, who is part of the Climate Analysis Section at the US National Center for Atmospheric Research, told Salon by email that the new report is “a bunch of total BS. They do not refer to any of our publications about the Atlantic and what is going on there and they get it all wrong.” He added that based on “the best and longe[st] record than they have, the N[orth] Atlantic is dominated by natural variability and they can not say anything about the longer term changes.”
American atmospheric scientist Ken Caldeira also warned against overstating the situation with AMOC. He wrote to Salon that “it should also be noted that paleo-climate data indicates that a shut-down of the North Atlantic circulation may have more widespread consequences than is predicted by the climate models.” The problem is that even our most sophisticated climate models do not contain enough details to be able to anticipate with certainty what is going to happen in our climate system.
Like Proistosescu, Caldeira urged erring on the side of being safe. “In this case, uncertainty means risk, and, because effects of our CO2 emissions are effectively irreversible, this risk should motivate a high degree of caution,” he concluded.
Bird reports rose during lockdowns | Cornell Chronicle – Cornell Chronicle
Around 80% of bird species examined in a new study were reported in greater numbers in human-altered habitats during pandemic lockdowns, according to new research based on data from the eBird program at the Cornell Lab of Ornithology.
In the paper, “Reduced Human Activity During COVID-19 Alters Avian Land Use Across North America,” published Sept. 22 in Science Advances, researchers compared online eBird observations from the United States and Canada from before and during the pandemic. They focused on areas within about 100 km of urban areas, major roads, and airports.
Vast amounts of data from a likewise vast geographic area were vital for this study. The researchers used more than 4 million eBird observations of 82 bird species from across Canada and the U.S.
“A lot of species we really care about became more abundant in human landscapes during the pandemic,” said study senior author Nicola Koper of the University of Manitoba, which led the research. “I was blown away by how many species were affected by decreased traffic and activity during lockdowns.”
Reports of bald eagles increased in cities with the strongest lockdowns. Ruby-throated hummingbirds were three times more likely to be reported within a kilometer of airports than before the pandemic. Barn swallows, a threatened species in Canada, were reported more often within a kilometer of roads than before the pandemic.
A few species decreased their use of human-altered habitat during the pandemic. Red-tailed hawk reports decreased near roads, perhaps because there was less roadkill when traffic declined. But far more species had increased counts in these human-dominated landscapes.
The authors filtered pandemic and pre-pandemic eBird reports so that the final data sets had the same characteristics, such as location, number of lists, and level of birdwatcher effort.
“We also needed to be aware of the detectability issue,” said co-author Alison Johnston, assistant director of the Center for Avian Population Studies and Ecological Data in the Lab of Ornithology. “Were species being reported in higher numbers because people could finally hear the birds without all the traffic noise, or was there a real ecological change in the numbers of birds present?”
The study tested whether better detectability might be a factor in the larger bird numbers reported. If it was, the scientists expected that to be more noticeable for smaller birds, which are harder to detect beneath traffic noise. However, effects were noticed across many species, from hawks to hummingbirds, suggesting that the increased numbers were not only caused by increased detectability in the quieter environments.
“Having so many people in North America and around the world paying attention to nature has been crucial to understanding how wildlife react to our presence,” says lead author Michael Schrimpf, a postdoctoral fellow at the University of Manitoba. “Studies such as this one rely on volunteer birdwatchers, so if you enjoy watching wildlife, there are many projects out there, like eBird and iNaturalist, that can use your help.”
The study was funded by Natural Sciences and Engineering Research Council of Canada with in-kind support provided by Environment and Climate Change Canada and the Cornell Lab of Ornithology.
SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space – Californianewstimes.com
Give a few seconds (or a minute or two if needed) to startle and gaze at the Earth’s scenery from the recently launched SpaceX Crew Dragon above.
on Wednesday,Tied to the SpaceX Crew Dragon with one of the upgrades: Cupola. The transparent dome at the top of the Dragon Capsule provides the Inspiration 4 crew with the best views of the Earth that up-and-coming astronauts can dream of. This is the first time a cupola has been installed on a dragon. Dragons typically carry astronauts and cargo to the ISS, with docking ports at the top instead of windows.
A short video posted to the SpaceX Twitter account hours after the launch shows the cupola’s transparent dome against the Earth, which is a pale blue marble.
As the Crew Dragon orbits from a height of 585 kilometers (more than 360 miles), our planet is exposed to the sun and slowly roams around the orbs.
Inspiration 4’s crew (commander Jared Isaacman, doctor’s assistant, childhood cancer survivor Haley Arseno, aerospace engineer Chris Sembroski, African-American geology professor Sian Proctor) are in orbit for three days. Ride and stare at the cupola and the earth.
And did you say that the cupola is right next to the dragon’s toilet? Yeah, the view of the earth should be visible from the crew dragon’s bathroom. Isaacman told insiders Toilets are one of the few places where you can separate yourself from others with privacy curtains and have the best toilet windows of mankind. “When people inevitably have to use the bathroom, they will see one view of hell,” he said.
Astronauts who have been to space often talk about a phenomenon called the “overview effect.” Looking at the planet from above, the idea is that the way we think about the planet and the mass of humankind that depends on it will change. There may be a lot of revelation at the end of the Inspiration 4 journey, as I don’t know if they thought of it while sitting in the can.
The mission is the first mission to take off from the Florida coast on Wednesday night and be launched with four civilians. It is expected to return to Earth on Saturday and land in the Atlantic Ocean.
SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space Source link SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space
Oldest human footprints in North America found in New Mexico – Al Jazeera English
Fossilised footprints dating 23,000 years push back the known date the continent was colonised by thousands of years.
Footprints dating back 23,000 years have been discovered in the United States, suggesting humans settled North America long before the end of the last Ice Age, according to researchers.
The findings announced on Thursday push back the date at which the continent was colonised by its first inhabitants by thousands of years.
The footprints were left in mud on the banks of a long-since dried up lake, which is now part of a New Mexico desert.
Sediment filled the indentations and hardened into rock, protecting evidence of our ancient relatives, and giving scientists a detailed insight into their lives.
The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists at the United States Geological Survey recently analysed seeds stuck in the footprints to determine their approximate age, ranging from 22,800 to 21,130 years ago.
“Many tracks appear to be those of teenagers and children; large adult footprints are less frequent,” write the authors of the study published in the American journal Science.
“One hypothesis for this is the division of labour, in which adults are involved in skilled tasks whereas ‘fetching and carrying’ are delegated to teenagers.
“Children accompany the teenagers, and collectively they leave a higher number of footprints.”
Researchers also found tracks left by mammoths, prehistoric wolves, and even giant sloths, which appear to have been approximately at the same time as the humans visited the lake.
The Americas were the last continent to be reached by humanity.
For decades, the most commonly accepted theory has been that settlers came to North America from eastern Siberia across a land bridge – the present-day Bering Strait.
From Alaska, they headed south to kinder climes.
Archaeological evidence, including spearheads used to kill mammoths, has long suggested a 13,500-year-old settlement associated with so-called Clovis culture – named after a town in New Mexico.
This was considered the continent’s first civilisation, and the forerunner of groups that became known as Native Americans.
However, the notion of Clovis culture has been challenged over the past 20 years, with new discoveries that have pushed back the age of the first settlements.
Generally, even this pushed-back estimate of the age of the first settlements had not been more than 16,000 years, after the end of the so-called “last glacial maximum” – the period when ice sheets were at their most widespread.
This episode, which lasted until about 20,000 years ago, is crucial because it is believed that with ice covering much of the northern parts of the continent, human migration from Asia into North America and beyond would have been very difficult.
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200,000-year-old handprints may be the world's oldest artwork, scientists say – CBC.ca
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