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Met Office researchers expect to record one of the largest increases in CO2 concentrations in the atmosphere in 2019.
Every year, Earth's natural carbon sinks, such as forests, absorb large amounts of CO2 produced by human activities.
But in years when the tropical Pacific region is warmer than this year, trees and plants grow less and absorb smaller amounts of gas.
As a result, scientists say that 2019 will see a much larger CO2 increase than in 2018.
Since 1958, the Mauna Loa Research Observatory in Hawaii continuously monitors and collects data on the chemical composition of the atmosphere.
In the years following registration, the observatory found a 30% increase in CO2 concentration in the atmosphere due to fossil fuel emissions and deforestation.
Scientists argue that the increase would have been even greater without the ability of forests, lands and seas to absorb about half of the gas emitted by human activities.
This capacity however varies with the seasons.
CO forecast? Mauna Loa concentrations in 2019 (in orange), as well as concentrations for 2016 (in blue), 2017 (in green), 2018 (in pink) and Scripps Institute measurements (in black).
In the summer, CO2 levels in the atmosphere decrease as trees and plants absorb more carbon as they grow. In winter, when they drop their leaves, they absorb less and atmospheric levels rise.
But when temperatures are warmer and drier than normal, trees and plants grow less and absorb less. This natural variation worsens over the years when there is an El Niño event, which causes a rise of Pacific heat in the atmosphere.
"The heat of the sea surface will continue over the next few months and this will cause a response from the vegetation," said Dr. Chris Jones of the Met Office.
"This heat has different impacts around the world, in some places it's warmer and drier and there are more forest fires, for example in a tropical rainforest you reduce the natural growth of vegetation."
According to the Met Office, these limits on CO2 absorption capacity will result in an increase in concentrations of 2.75 parts per million, which is above the 2018 level.
They expect average CO2 concentrations in 2019 to be 411 ppm. The carbon dioxide concentration exceeded 400 ppm for the first time in 2013.
The forecast increase for this year will not be as significant as that of the 2015-16 and 1997-98 El Niño years. However, there have been only similar increases to this year about half a dozen times since records began.
An image showing the 2015 El Niño phenomenon with rising temperatures in the Pacific
Researchers say the long-term trend is only one way.
"The annual increase in CO2 emissions continues to grow throughout the 20th century," said Dr. Jones.
"What we will see next year will be one of the largest ever recorded and will certainly lead to the highest concentration of CO2."
Other researchers say the results of the Met Office are worrisome.
"Increases in CO2 are a function of our continued reliance on fossil fuels," said Dr. Anna Jones of the British Antarctic Survey (BAS).
"The ability of the Earth to absorb CO2 from the atmosphere is partly responsible for slowing the increase, but that can change from year to year, as the weather is noticeable. indicate the forecast of the Met Office.
"However, the bottom line is that the persistent increase in atmospheric CO2 is totally at odds with the ambition to limit global warming to 1.5 ° C. We need to witness a reduction in the rate of CO2 emission, not an increase. "
Scientists at the Met Office say that it does not always follow that a record concentration of CO2 will lead to a record global temperature in 2019, as many natural factors may affect the final figure.
Researchers in this country are pleased that the observations of the past four years show that their model is accurate. They think that this can be used in the future to help countries to accurately attribute increases in emissions to their actions or natural factors.
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