The Azolla event is a scenario hypothesized to have occurred in the middle Eocene epoch, around 49 million years ago, when blooms of the freshwater fern Azolla are thought to have happened in the Arctic Ocean. As they sank to the stagnant sea floor, they were incorporated into the sediment; the resulting draw-down of carbon dioxide has been speculated to have helped transform the planet from a "greenhouse Earth" state, hot enough for turtles and palm trees to prosper at the poles, to the current icehouse Earth known as the Late Cenozoic Ice Age.
- "Azolla Event" | 2019-07-22 | 104 Upvotes 80 Comments
Kaktovik Iñupiaq numerals are a featural positional numeral system created by Alaskan Iñupiat.
Arabic numeral notation, which was designed for a base-10 numeral system, is inadequate for the Inuit languages, which use a base-20 numeral system. Students from Kaktovik, Alaska invented a base-20 numeral notation in 1994 to rectify this issue, and this system spread among the Alaskan Iñupiat and has been considered in other countries where Inuit languages are spoken.
The image at right shows the digits 0 to 19. Twenty is written as a one and a zero (I0), forty as a two and a zero (V0), four hundred as a one and two zeros (I00), eight hundred as a two and two zeros (V00), etc.
- "Kaktovik Iñupiaq Numerals" | 2020-12-07 | 26 Upvotes 11 Comments
Kaktovik numerals are a featural positional numeral system created by Alaskan Iñupiat.
Arabic numeral notation, which was designed for a base-10 numeral system, is inadequate for the Inuit languages, which use a base-20 numeral system. Students in Kaktovik, Alaska, invented a base-20 numeral notation in 1994 to rectify this issue, and this system spread among the Alaskan Iñupiat and has been considered in other countries where Inuit languages are spoken.
The image at right shows the digits 0 to 19. Twenty is written as a one and a zero (\ɤ), forty as a two and a zero (Vɤ), four hundred as a one and two zeros (\ɤɤ), eight hundred as a two and two zeros (Vɤɤ), etc.
- "Kaktovik numerals – A base-20 number system that is visually easy too" | 2021-03-04 | 39 Upvotes 2 Comments
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.
The largest driver of warming is the emission of gases that create a greenhouse effect, of which more than 90% are carbon dioxide (CO
2) and methane. Fossil fuel burning (coal, oil, and natural gas) for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and manufacturing. The human cause of climate change is not disputed by any scientific body of national or international standing. Temperature rise is accelerated or tempered by climate feedbacks, such as loss of sunlight-reflecting snow and ice cover, increased water vapour (a greenhouse gas itself), and changes to land and ocean carbon sinks.
Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires. Temperature rise is also amplified in the Arctic, where it has contributed to melting permafrost, glacial retreat and sea ice loss. Warmer temperatures are increasing rates of evaporation, causing more intense storms and weather extremes. Impacts on ecosystems include the relocation or extinction of many species as their environment changes, most immediately in coral reefs, mountains, and the Arctic. Climate change threatens people with food insecurity, water scarcity, flooding, infectious diseases, extreme heat, economic losses, and displacement. These impacts have led the World Health Organization to call climate change the greatest threat to global health in the 21st century. Even if efforts to minimise future warming are successful, some effects will continue for centuries, including rising sea levels, rising ocean temperatures, and ocean acidification.
Many of these impacts are already felt at the current level of warming, which is about 1.2 °C (2.2 °F). The Intergovernmental Panel on Climate Change (IPCC) has issued a series of reports that project significant increases in these impacts as warming continues to 1.5 °C (2.7 °F) and beyond. Additional warming also increases the risk of triggering critical thresholds called tipping points. Responding to climate change involves mitigation and adaptation. Mitigation – limiting climate change – consists of reducing greenhouse gas emissions and removing them from the atmosphere; methods include the development and deployment of low-carbon energy sources such as wind and solar, a phase-out of coal, enhanced energy efficiency, reforestation, and forest preservation. Adaptation consists of adjusting to actual or expected climate, such as through improved coastline protection, better disaster management, assisted colonisation, and the development of more resistant crops. Adaptation alone cannot avert the risk of "severe, widespread and irreversible" impacts.
Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2.0 °C (3.6 °F)" through mitigation efforts. However, with pledges made under the Agreement, global warming would still reach about 2.8 °C (5.0 °F) by the end of the century. Limiting warming to 1.5 °C (2.7 °F) would require halving emissions by 2030 and achieving near-zero emissions by 2050.
- "Climate Change" | 2021-07-10 | 14 Upvotes 4 Comments