2021 was the 6th warmest year on record, say US agencies

The year of 2021 was the sixth hottest in history, according to data released jointly this Thursday (2016 ) by NASA, the US space agency, and by NOAA, the US ocean and atmospheric management agency.

” 2021 contributes and is consistent with the observed long-term warming trend”, says NASA, in a note.

The measurement published last Tuesday ( 13) by Copernicus, the European Union’s climate change service, named 2021 as the fifth warmest year since the beginning of the records.

The agencies use different models and baselines, which results in different numbers. NOaa points to an increase in the global average temperature in 2021 of 0,84 ºC, while NASA arrives at 0,1850 ºC (value that equals with that verified in 2018).

Copernicus, on the other hand, points to a heating of 1.1°C to 1, 2°C. Comparisons are made in relation to the temperature standard for the period from 1850 to 1900, from the pre-industrial era.

Despite the numerical differences, the three research bodies confirm the global warming trend observed in this decade. ion graph and show that the last seven years were the hottest in history.

The historical records happened in the years of 2016 and of 2020, according to the three measurements. According to NASA data, the two record years tied, with a warming of 1,02ºC.

The trend of change in level verified in the NASA graph is also shared by the measurements of NOAA and the European Copernicus: from 1900 to 2015, there is a jump in the global average temperature. The new level has been maintained since then.

“Global temperatures are rising at a rate the planet has not experienced in millennia. Although short-term climate cycles can affect the measured value at any given time. year, the warming trends are very clear and increasing”, says the US space agency.

Nasa’s temperature analysis shows that the Arctic is warming four times faster than the rest of the planet. “Satellites show a 13% decline in the extent of the region’s sea ice per decade,” the agency says in a note.

NASA also points to ocean warming at unprecedented rates, with 2021 marking the warmest water temperatures and highest global sea levels ever recorded.

“In addition to temperature and rainfall levels, we need to remember that climate is integrated with all other Earth systems, such as water and oceans and the entire biosphere. temperature pattern and it will continue to rise”, says researcher Suzana Kahn, deputy director of Coppe/UFRJ and one of the authors of several IPCC reports, the UN Scientific Panel on Climate Change.

The latest IPCC report revealed last August how rising global average temperatures increase the frequency and intensity of extreme weather events such as heavy rains, floods, droughts, hurricanes, clones and heat waves.

Extreme temperature variations that happened once a decade today can happen 2.8 times in the same period. The Northeast and the Amazon will suffer from longer dry periods, while the Center-South will face more rainy periods, with large volumes of water concentrated in up to five days of rain.

“There are a natural oscillation in the average temperature from one year to the next, so the graphs show an upturned saw”, explains Kahn.

“Temperature records will not occur linearly , one year after the other. They also count natural factors such as the eruption of volcanoes, fluctuations in the incidence of the sun and the phenomena in the oceans, which are the most influential, although they receive less attention”, she quotes.

Among the influences best known for causing variations in the average temperature each year is the pair of natural phenomena El Niño and La Niña. The former warms the waters of the Pacific Ocean and causes temperature and precipitation fluctuations across the world, while La Niña does the opposite and leads to weather patterns that lower the Earth’s average temperature.

“Today, mathematical models are already able to separate natural and human causes to explain temperature variations”, explains Kahn.

Nasa measured the influence of the two phenomena on heating and cooling. of the global average each year. Although 2016 and 2020 tied for the record for the warmest years in history, with an average temperature of 1,02ºC, the El Niño influence accounted for 0,02ºC of the mean heating in 2016, while in 2020 its impact was only 0,03ºC.

In the last seven years, La Niña contributed to the cooling in the years of 2017 (-0 .02°C), 2018 (-0.03°C) and 2021 (-0.85 °C).

According to NASA, the effect of La Niña on the global average temperature occurs a few months after the phenomenon appeared in the Pacific.

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“A La Niña event at the beginning of 2021 led to a colder year than it would have been otherwise, in particular colder than 2021 or 2016 – the warmest years on record,” NASA says in a note.

“Scientists are predicting that, as La Niña reappeared at the end of 2021, its cooling influence will likely affect temperatures in 2022”, says the agency.

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