Daily Archives: September 11, 2020

High-fidelity record of Earth’s climate history puts current changes in context of orbital variation

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For the first time, climate scientists have compiled a continuous, high-fidelity record of variations in Earth’s climate extending 66 million years into the past. The record reveals four distinctive climate states, which the researchers dubbed Hothouse, Warmhouse, Coolhouse, and Icehouse.

These major states persisted for millions and sometimes tens of millions of years, and within each one the climate shows rhythmic variations corresponding to changes in Earth’s orbit around the sun. But each climate state has a distinctive response to orbital variations, which drive relatively small changes in compared with the dramatic shifts between different climate states.

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“We’ve known for a long time that the glacial-interglacial cycles are paced by changes in Earth’s orbit, which alter the amount of solar energy reaching Earth’s surface, and astronomers have been computing these orbital variations back in time,” explained coauthor James Zachos, distinguished professor of Earth and planetary sciences and Ida Benson Lynn Professor of Ocean Health at UC Santa Cruz.

“As we reconstructed past climates, we could see long-term coarse changes quite well. We also knew there should be finer-scale rhythmic variability due to orbital variations, but for a long time it was considered impossible to recover that signal,” Zachos said. “Now that we have succeeded in capturing the natural climate variability, we can see that the projected anthropogenic warming will be much greater than that.”

For the past 3 million years, Earth’s climate has been in an Icehouse state characterized by alternating glacial and interglacial periods. Modern humans evolved during this time, but and other human activities are now driving the planet toward the Warmhouse and Hothouse climate states not seen since the Eocene epoch, which ended about 34 million years ago. During the early Eocene, there were no polar ice caps, and average global temperatures were 9 to 14 degrees Celsius higher than today.

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Critical to compiling the new climate record was getting high-quality sediment cores from deep ocean basins through the international Ocean Drilling Program (ODP, later the Integrated Ocean Drilling Program, IODP, succeeded in 2013 by the International Ocean Discovery Program). Signatures of past climates are recorded in the shells of microscopic plankton (called foraminifera) preserved in the seafloor sediments. After analyzing the sediment cores, researchers then had to develop an “astrochronology” by matching the climate variations recorded in sediment layers with variations in Earth’s orbit (known as Milankovitch cycles).

“The community figured out how to extend this strategy to older time intervals in the mid-1990s,” said Zachos, who led a study published in 2001 in Science that showed the climate response to orbital variations for a 5-million-year period covering the transition from the Oligocene epoch to the Miocene, about 25 million years ago.

“That changed everything, because if we could do that, we knew we could go all the way back to maybe 66 million years ago and put these transient events and major transitions in Earth’s climate in the context of orbital-scale variations,” he said.

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Now that they have compiled a continuous, astronomically dated climate record of the past 66 million years, the researchers can see that the climate’s response to orbital variations depends on factors such as greenhouse gas levels and the extent of polar ice sheets.

“In an extreme greenhouse world with no ice, there won’t be any feedbacks involving the ice sheets, and that changes the dynamics of the climate,” Zachos explained.

Most of the major climate transitions in the past 66 million years have been associated with changes in greenhouse gas levels.

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The new climate record provides a valuable framework for many areas of research, he added. It is not only useful for testing climate models, but also for geophysicists studying different aspects of Earth dynamics and paleontologists studying how changing environments drive the evolution of species.

Source: High-fidelity record of Earth’s climate history puts current changes in context

TikTok reveals details of how its algorithm works

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TikTok Wednesday revealed some of the elusive workings of the prized algorithm that keeps hundreds of millions of users worldwide hooked on the viral video app.

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TikTok’s algorithm uses machine learning to determine what content a user is most likely to engage with and serve them more of it, by finding videos that are similar or that are liked by people with similar user preferences.

  • When users open TikTok for the first time, they are shown 8 popular videos featuring different trends, music, and topics. After that, the algorithm will continue to serve the user new iterations of 8 videos based on which videos the user engages with and what the user does.
  • The algorithm identifies similar videos to those that have engaged a user based on video information, which could include details like captions, hashtags or sounds. Recommendations also take into account user device and account settings, which include data like language preference, country setting, and device type.
  • Once TikTok collects enough data about the user, the app is able to map a user’s preferences in relation to similar users and group them into “clusters.” Simultaneously, it also groups videos into “clusters” based on similar themes, like “basketball” or “bunnies.”
  • Using machine learning, the algorithm serves videos to users based on their proximity to other clusters of users and content that they like.
  • TikTok’s logic aims to avoid redundancies that could bore the user, like seeing multiple videos with the same music or from the same creator.

Yes, but: TikTok concedes that its ability to nail users’ preferences so effectively means that its algorithm can produce “filter bubbles,” reinforcing users’ existing preferences rather than showing them more varied content, widening their horizons, or offering them opposing viewpoints.

  • The company says that it’s studying filter bubbles, including how long they last and how a user encounters them, to get better at breaking them when necessary.
  • Since filter bubbles can reinforce conspiracy theories, hoaxes and other misinformation, TikTok’s product and policy teams study which accounts and video information — themes, hashtags, captions, and so on — might be linked to misinformation.
  • Videos or creators linked to misinformation are sent to the company’s global content reviewers so they can be managed before they are distributed to users on the main feed, which is called the “For You” page.

The briefing also featured updates about TikTok’s data, privacy and security practices.

  • The company says it tries to triage and prevent incidents on its platform before they happen by working to detect patterns of problems before they spread.
  • TikTok’s chief security officer, Roland Cloutier, said it plans to hire more than 100 data, security and privacy experts by year’s end in the U.S.
  • He also said that the company will be building a monitoring, response and investigative response center in Washington D.C. to actively detect and respond to critical incidents in real time.

The big picture: Beckerman says that TikTok’s transparency efforts are meant to position the company as a leader in Silicon Valley.

  • “We want to take a leadership position and show more about how the app works,” he said. “For us, we’re new, and we want to do this because we don’t have anything to hide. The more we’re talking to and meeting with lawmakers, the more comfortable they are with the product. That’s the way it should be.”

Source: TikTok reveals details of how its coveted algorithm works – Axios

Who Emerges into Virtual Team Leadership Roles? Different people from face to face leadership

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It turns out that where in traditional face to face leadership, people prefer leaders who are vocal, charming, friendly (ascription qualities). In virtual leadership, people prefer leaders who facilitate, are organised and actually do stuff (achievement factors).

 In two independent samples—a laboratory experiment involving 86 teams (n = 340; sample one) and a semester long project involving 134 teams (n = 430; sample two)—we found that in low virtuality contexts, ascription factors accounted for incremental variance over achievement factors in predicting leadership emergence, and had larger relative importance. Conversely, in high virtuality contexts, achievement factors accounted for incremental variance over ascription factors in predicting leadership emergence, and had larger relative importance.

Source: Who Emerges into Virtual Team Leadership Roles? The Role of Achievement and Ascription Antecedents for Leadership Emergence Across the Virtuality Spectrum | SpringerLink

This seed of professional vexation has borne fruit, with new data showing that the confidence, intelligence and extroversion that have long propelled ambitious workers into the executive suite are not enough online, because they simply don’t translate into virtual leadership. Instead, workers who are organised, dependable and productive take the reins of virtual teams. Finally, doers lead the pack – at least remotely.

The study shows that, instead of those with the most dynamic voices in the room, virtual teams informally anoint leaders who actually do the work of getting projects done. “They are the individuals who help other team members with tasks, and keep the team on schedule and focused on goals,” says lead author Radostina Purvanova, an associate professor of management and leadership at Drake University in the US state of Iowa.

Source: The surprising traits of good remote leaders