Questões de Concurso

(1º§)Volcanoes can impact climate change. During major explosive eruptions huge amounts__volcanic gas, aerosol droplets, and ash are injected into the stratosphere. Injected ash falls rapidly from the stratosphere -- most of it is removed within several days to weeks -- and has little impact on climate change. But volcanic gases like sulfur dioxide can cause global cooling, while volcanic carbon dioxide, a greenhouse gas, has the potential to promote global warming.

(2º§)The most significant climate impacts from volcanic injections into the stratosphere come from the conversion of sulfur dioxide to sulfuric acid, which condenses rapidly in the stratosphere to form fine sulfate aerosols. The aerosols increase the reflection of radiation from the Sun back into space, cooling the Earth's lower atmosphere or troposphere.

(3º§)Several eruptions during the past century have caused a decline in the average temperature at the Earth's surface of up to half a degree (Fahrenheit scale) for periods of one to three years. The climactic eruption of Mount Pinatubo on June 15, 1991, was one of the largest eruptions of the twentieth century and injected a 20-million ton (metric scale) sulfur dioxide cloud into the stratosphere at an altitude of more than 20 miles. The Pinatubo cloud was the largest sulfur dioxide cloud ever observed in the stratosphere since the beginning of such observations by satellites in 1978. It caused what is believed to be the largest aerosol disturbance of the stratosphere in the twentieth century, though probably smaller than the disturbances from eruptions of Krakatau in 1883 and Tambora in 1815. Consequently, it was a standout in its climate impact and cooled the Earth's surface for three years following the eruption, by as much as 1.3 degrees F at the height of the impact.

(4º§)The large 1783-1784 Laki fissure eruption in Iceland released a staggering amount more sulfur dioxide than Pinatubo (approximately 120-million ton vs. 20). Although the two eruptions were significantly different__length and style, the added atmospheric SO2 caused regional cooling of Europe and North America by similar amounts for similar periods of time.

(5º§)Carbon dioxide (CO2) is a greenhouse gas and is the primary gas blamed for climate change. While sulfur dioxide released in contemporary volcanic eruptions has occasionally caused detectable global cooling of the lower atmosphere, the carbon dioxide released in contemporary volcanic eruptions has never caused detectable global warming of the atmosphere. In 2010, human activities were responsible for a projected 35 billion metric tons (gigatons) of CO2 emissions. All studies to date of global volcanic carbon dioxide emissions indicate that present-day subaerial and submarine volcanoes release less than a percent of the carbon dioxide released currently by human activities. While it has been proposed that intense volcanic release of carbon dioxide in the deep geologic past did cause global warming, and possibly some mass extinctions, this is a topic of scientific debate at present.

(6º§)Published scientific estimates of the global CO2 emission rate for all degassing subaerial (on land) and submarine volcanoes lie in a range from 0.13 gigaton to 0.44 gigaton per year. The 35-gigaton projected anthropogenic CO2 emission for 2010 is about 80 to 270 times larger than the respective maximum and minimum annual global volcanic CO2 emission estimates.

(7º§)There is no question that very large volcanic eruptions can inject significant amounts of carbon dioxide into the atmosphere. The 1980 eruption of Mount St. Helens vented approximately 10 million tons of CO2 into the atmosphere in only 9 hours. However, it currently takes humanity only 2.5 hours to put out the same amount. While large explosive eruptions like this are rare and only occur globally every 10 years or so, humanity's emissions are ceaseless and increasing every year.

(8º§)There continues to be efforts to reduce uncertainties and improve estimates of present-day global volcanic CO2 emissions, but there is little doubt among volcanic gas scientists that the anthropogenic CO2 emissions dwarf global volcanic CO2 emissions.

(9º§)For additional information about this subject, please read the American Geophysical Union's Eos article "Volcanic Versus Anthropogenic Carbon Dioxide" written__USGS scientist Terrence M. Gerlach.

https://www.usgs.gov/programs/VHP/

(1º§)Volcanoes can impact climate change. During major explosive eruptions huge amounts__volcanic gas, aerosol droplets, and ash are injected into the stratosphere. Injected ash falls rapidly from the stratosphere -- most of it is removed within several days to weeks -- and has little impact on climate change. But volcanic gases like sulfur dioxide can cause global cooling, while volcanic carbon dioxide, a greenhouse gas, has the potential to promote global warming.

(2º§)The most significant climate impacts from volcanic injections into the stratosphere come from the conversion of sulfur dioxide to sulfuric acid, which condenses rapidly in the stratosphere to form fine sulfate aerosols. The aerosols increase the reflection of radiation from the Sun back into space, cooling the Earth's lower atmosphere or troposphere.

(3º§)Several eruptions during the past century have caused a decline in the average temperature at the Earth's surface of up to half a degree (Fahrenheit scale) for periods of one to three years. The climactic eruption of Mount Pinatubo on June 15, 1991, was one of the largest eruptions of the twentieth century and injected a 20-million ton (metric scale) sulfur dioxide cloud into the stratosphere at an altitude of more than 20 miles. The Pinatubo cloud was the largest sulfur dioxide cloud ever observed in the stratosphere since the beginning of such observations by satellites in 1978. It caused what is believed to be the largest aerosol disturbance of the stratosphere in the twentieth century, though probably smaller than the disturbances from eruptions of Krakatau in 1883 and Tambora in 1815. Consequently, it was a standout in its climate impact and cooled the Earth's surface for three years following the eruption, by as much as 1.3 degrees F at the height of the impact.

(4º§)The large 1783-1784 Laki fissure eruption in Iceland released a staggering amount more sulfur dioxide than Pinatubo (approximately 120-million ton vs. 20). Although the two eruptions were significantly different__length and style, the added atmospheric SO2 caused regional cooling of Europe and North America by similar amounts for similar periods of time.

(5º§)Carbon dioxide (CO2) is a greenhouse gas and is the primary gas blamed for climate change. While sulfur dioxide released in contemporary volcanic eruptions has occasionally caused detectable global cooling of the lower atmosphere, the carbon dioxide released in contemporary volcanic eruptions has never caused detectable global warming of the atmosphere. In 2010, human activities were responsible for a projected 35 billion metric tons (gigatons) of CO2 emissions. All studies to date of global volcanic carbon dioxide emissions indicate that present-day subaerial and submarine volcanoes release less than a percent of the carbon dioxide released currently by human activities. While it has been proposed that intense volcanic release of carbon dioxide in the deep geologic past did cause global warming, and possibly some mass extinctions, this is a topic of scientific debate at present.

(6º§)Published scientific estimates of the global CO2 emission rate for all degassing subaerial (on land) and submarine volcanoes lie in a range from 0.13 gigaton to 0.44 gigaton per year. The 35-gigaton projected anthropogenic CO2 emission for 2010 is about 80 to 270 times larger than the respective maximum and minimum annual global volcanic CO2 emission estimates.

(7º§)There is no question that very large volcanic eruptions can inject significant amounts of carbon dioxide into the atmosphere. The 1980 eruption of Mount St. Helens vented approximately 10 million tons of CO2 into the atmosphere in only 9 hours. However, it currently takes humanity only 2.5 hours to put out the same amount. While large explosive eruptions like this are rare and only occur globally every 10 years or so, humanity's emissions are ceaseless and increasing every year.

(8º§)There continues to be efforts to reduce uncertainties and improve estimates of present-day global volcanic CO2 emissions, but there is little doubt among volcanic gas scientists that the anthropogenic CO2 emissions dwarf global volcanic CO2 emissions.

(9º§)For additional information about this subject, please read the American Geophysical Union's Eos article "Volcanic Versus Anthropogenic Carbon Dioxide" written__USGS scientist Terrence M. Gerlach.

https://www.usgs.gov/programs/VHP/

(1º§)The company - which includes Facebook, Instagram and WhatsApp - will see 13 per cent of its 87,000-person global workforce gone. Zuck, 38, described the painful move as "the most difficult changes we've made in Meta's history". "I know this is tough for everyone, and I'm especially sorry to those impacted," he told staff on Wednesday.

(2º§)Meta has been hit by soaring costs and a weaker advertising market, which it heavily relies on to ake money. The social network has also taken a massive gamble with Zuckerberg's metaverse dream, ploughing billions into the project.

(3º§)It's the first set of broad job cuts in Meta's 18-year history. Other tech giants are going through a similar squeeze, including Twitter which recently let go of around half its 7,500 workforce - as part of Elon Musk's $44billion takeover. Unlike most companies, Facebook was one of the few winners during Covid as the world depended on online platforms.

(4º§)But Zuckerberg admits he was wrong to significantly increase investments, believing Meta's surge during the pandemic would continue. "I got this wrong, and I take responsibility for that," he said. "We've cut costs across our business, including scaling back budgets, reducing perks, and shrinking our real estate footprint.

(5º§)"We're restructuring teams to increase our efficiency. "But these measures alone won't bring our expenses in line with our revenue growth, so I've also made the hard decision to let people go." Most affected staff will be frozen out from Meta's top secret systems today, with the exception of their emails.

saaf/ ://www.thesun.co.uk/tech/20370977/facebook-meta-lay-off-11000-staff/

(1º§)The company - which includes Facebook, Instagram and WhatsApp - will see 13 per cent of its 87,000-person global workforce gone. Zuck, 38, described the painful move as "the most difficult changes we've made in Meta's history". "I know this is tough for everyone, and I'm especially sorry to those impacted," he told staff on Wednesday.

(2º§)Meta has been hit by soaring costs and a weaker advertising market, which it heavily relies on to ake money. The social network has also taken a massive gamble with Zuckerberg's metaverse dream, ploughing billions into the project.

(3º§)It's the first set of broad job cuts in Meta's 18-year history. Other tech giants are going through a similar squeeze, including Twitter which recently let go of around half its 7,500 workforce - as part of Elon Musk's $44billion takeover. Unlike most companies, Facebook was one of the few winners during Covid as the world depended on online platforms.

(4º§)But Zuckerberg admits he was wrong to significantly increase investments, believing Meta's surge during the pandemic would continue. "I got this wrong, and I take responsibility for that," he said. "We've cut costs across our business, including scaling back budgets, reducing perks, and shrinking our real estate footprint.

(5º§)"We're restructuring teams to increase our efficiency. "But these measures alone won't bring our expenses in line with our revenue growth, so I've also made the hard decision to let people go." Most affected staff will be frozen out from Meta's top secret systems today, with the exception of their emails.

saaf/ ://www.thesun.co.uk/tech/20370977/facebook-meta-lay-off-11000-staff/