In the midst of news about the extremely cold front affecting various parts of the United States, social networks are questioning about the phenomenon of global warming, which many scientific actors claim to be the cause of the # 39; human action.
"If the world heats up, why is it so cold in the United States?" This is a question that has been asked in particular by people who believe that the concern about the average rise in global temperature, which is attributed to an increase in greenhouse gas production, is exaggerated. or even false.
The President of the United States himself, who removed the country from the Paris Agreement, which provides for measures to reduce emissions, quipped the issue on Twitter.
The term global warming is used to explain the fact that the Earth's average temperature is rising alarmingly – and what many may not be aware of is that it creates favorable conditions. to events. extreme weather conditions, including waves of freezing cold.
Doubts such as that of Trump generally arise because of the confusion between two concepts: climate and weather, which have different meanings in meteorology.
Weather conditions refer to weather conditions recorded over a short period – the strong heat that it does in most of Brazil this week, for example, and the cold in North America. A man protects himself from the cold in Wisconsin during a polar vortex in the United States – Photo: John Ehlke / West Bend Daily News via AP "title = Bend Daily News via AP" src = "data: image / jpeg; base64 , / 9j / 4AAQSkZJRgABAQAAAQABAAD / 2wBDAAMCAgMCAgMDAwMEAwMEBQgFBQQEBQoHBwYIDAoMDAsKCwsNDhIQDQ4RDgsLEBYQERMUFRUVDA8XGBYUGBIUFRT / 2wBDAQMEBAUEBQkFBQkUDQsNFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBT / wgARCAAPABkDASIAAhEBAxEB / 8QAFwABAAMAAAAAAAAAAAAAAAAABwMFCP / EABYBAQEBAAAAAAAAAAAAAAAAAAIDBf / aAAwDAQACEAMQAAABVcf3Mg0XFxAntT // xAAdEAACAQQDAAAAAAAAAAAAAAAEBQMAAQIGBxIU / 9oACAEBAAEFAtqK6QFQy3YcZmZ5j0 / fFMWgTEa + OjmLUzD0R1 // // xAAbEQABBQEBAAAAAAAAAAAAAAACAAQREiEBA aAAgBAwEBPwFvIjYU9sXtJc3F / 8QAFxEAAwEAAAAAAAAAAAAAAAAAAAERAv / aAAgBAgEBPwHbphqSn // EACEQAAICAQQCAwAAAAAAAAAAAAECAxEABBIxQRBRFCKB / 9oACAEBAAY / Ao9NupprP4MkCqWb2OMl02ykQWDdjx86VqZ127F4Wuhh3iiVP1YWMbQASmaRVqZuz6rrOc // xAAeEAACAgICAwAAAAAAAAAAAAABEQAhQXGBkWGh8 P / + aAAgBAQABPyFX4bKpzyR1Hl XYhuyaUPZNAcRVd hLgQh9lZLRnZgVMGPm8sRhpbsEsq5O58AZ / 9oADAMBAAIAAwAAABAV3 // EABgRAAMBAQAAAAAAAAAAAAAAAAERIQBx / 9oACAEDAQE / EAHLXcZCKN1C7 EABcRAAMBAAAAAAAAAAAAAAAAAAABIVH // / // 2gAIAQIBAT8QRIvkP EAB0QAQEAAwACAwAAAAAAAAAAAAERACExQWGBkfD / 2gAIAQEAAT8QNQjDYA1eD5jGNCzPFCOBI7XmbVx / HbfUkJudG5MFDdlCSJXwFeo5u5BEQEJTfD7yqv5 ZtqoAIZFJX3 + / NSA / 9k = "/> <img clbad =" content-media__image picture "itemprop =" contentURL "alt =" The man protects from the cold in Wisconsin during the polar vortex Photo: John Ehlke / West Bend daily newspaper via AP "data-src =" https: /// Photo: John Ehlke / Daily Newspaper from West Bend via AP "title =" Man Protects From Wisconsin Cold During Polar Vortex In The United States /b2.bbbbbb
A Man Protects From The Cold In Wisconsin A polar vortex in the United States – Photo: John Ehlke / West Bend Daily News via AP
By contrast, this is a longer and more comprehensive panorama of the mod temporal. It refers to the conditions prevailing in a region or the entire Earth and can be studied with an badysis of historical trends. The weather varies from day to day.
For example, in Brazil, there are several types of climates: the humid subtropical climate in the São Paulo region, the semi-humid tropical climate in Fortaleza, and so on.
When they talk about the climate of the planet, scientists refer to the situation of the entire planet, over time. Indeed, even though it's colder than average in a given region, the world as a whole is warming up on average – that's hundreds of studies done by scientists around the world whole point over the decades.
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On its website aimed at children, the US Space Agency (NASA) gives a simple example to clarify the diff between the two concepts: a rainy day in the city of Phoenix does not change the fact that The state of Arizona has a dry climate.
NASA also explains that one should expect a cold weather even though temperatures on the planet generally increase. [19659016] "The agency's website features many episodes of extremely hot and extremely cold weather," says the website's Web site.
Indeed, climate change is changing the way ocean currents, strong winds and other phenomena Weather events occur around the world and generate extreme weather events – cold and hot.
The warming of the Arctic, for example, can cause polar ice currents to move southward, causing cold spells in places where they have not yet occurred.
Scientists had already predicted the cold front in the United States, which invoked the warming of the Arctic as a cause.
<img clbad = "image content-media__image" itemprop = "contentUrl" alt = "Chicago , Illinois, was snow-covered Thursday (31) – Photo: Scott Olson / Getty Images North America / AFP "title =" Chicago (Illinois) was snowy Thursday (31) = "https://s2.glbimg.com /ont5sX2Q3cp1ggJD2caWt79E4=/0x0:3000×2000/1008×0/smart/filters:strip_icc(()/i.s3.glbimg.com/v1/AUTH_59edd422c0c0c0c0c Chicago, Illinois was snow-covered Thursday (31) – Photo: Scott Olson / Getty Images North America / AFP
According to them, this warming causes the ocean, released from the ice, to release more heat, but it weakens the circulation of cold air overhead. the Arctic and allows it to escape to the south. "When the Arctic is hot, cold temperatures and heavy snowfall are more common. only when the Arctic is cold, "said a study published in Natures Communications last year.
Chicago images frozen during a polar vortex
"We also found that during the warming period, when the Arctic heat reached the upper troposphere and the lower stratosphere between the mid and late winter, the harsh climate has intensified in the winter. "
Previous studies had previously reported the movement of polar icy air southward, called the polar vortex. "Instead of crossing the northern hemisphere in a steady and predictable trajectory, this high-altitude wind zigzags over the United States, the Atlantic, and Europe," says a study. published in Phys.Org in 2013.
causes of global warming and what they do not cause
The role of global warming in the intensification of heat waves, such as that which hit 'Europe last year has already been confirmed,' says Ben Webber, a climatologist with the Climate Research Unit. from the University of East Anlia, United States.
However, studies are still needed to attribute these cold spells to warming because other forces also generate temporal variability.
"Global warming can increase the intensity of cold spells, but it's a subject that requires further study," Webber told the BBC.
One of the causes of extreme weather events in Brazil, for example, is El Niño (warming waters in the Pacific) and, to our knowledge, is not related to global warming.
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