NOAA Index tracks how greenhouse gas pollution amplified global warming in 2020 – Homeland Security Today


The additional heat trapped in the atmosphere by pollution caused by man-made greenhouse gases continued to exacerbate global warming in 2020, due to historically high levels of emissions that largely did not occur. not affected by the economic slowdown resulting from the pandemic, NOAA scientists reported.

NOAA’s annual greenhouse gas index, known as the AGGI, follows the increasing influence of warming of most heat-trapping gases added to the atmosphere mainly due to human activity, including carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and other chemicals. The top five greenhouse gases account for about 96% of the increase in heat trapped in the atmosphere due to human activity since 1750, the start of the Industrial Revolution. The AGGI also tracks 16 secondary greenhouse gases responsible for the remaining 4 percent of human-induced warming.

The AGGI is based on thousands of air samples collected each year from sites around the world with NOAA. Global Greenhouse Gas Reference Network. The concentrations of these greenhouse gases and other chemicals are determined by analyzing these samples at the NOAA Global Monitoring Laboratory in Boulder, Colorado. Scientists then calculate how much extra heat these gases trap in the Earth’s system as a result of human activity over the past year, and how much that has changed over time.

“This analysis of samples collected by NOAA’s Global Greenhouse Gas Reference Network provides a measure of the excess heat trapped in the atmosphere by greenhouse gas pollution,” said James Butler. , director of the global surveillance laboratory. “The contributions of different greenhouse gases have evolved over time, but the conclusion that humans are almost 100% responsible for their increase is inevitable.

An issue follows the human impact on the climate

NOAA scientists published the first AGGI in 2006 to help policymakers, educators and the public understand the cumulative impact of greenhouse gases on the climate over time. AGGI converts complex scientific calculations of the amount of additional heat trapped in the atmosphere by human-made emissions each year into a unique number that can easily be compared to previous years. The AGGI is updated every spring after nearly all of the air samples taken in the previous year have been obtained and analyzed.

Scientists compared AGGI to the year 1750, the start of the Industrial Revolution, assigning it a value of zero. An AGGI value of 1.0 was assigned to 1990 – the year of the Kyoto Protocol, an international treaty that called on the global community to reduce greenhouse gas pollution. The AGGI is useful for monitoring the relative evolution of heat trapped in the atmosphere by anthropogenic greenhouse gas emissions since the Kyoto Protocol.

In 2020 – AGGI reached a value of 1.47, and the change from 2019 to 2020 was similar to previous years despite an economic slowdown caused by the pandemic. This means that 47% more heat, mainly attributable to human activity, was captured by the Earth’s climate system in 2020 than in 1990.

Analysis of samples collected in 2020 showed that the average global load of methane, the second most abundant anthropogenic greenhouse gas, reached 1,879 parts per billion (ppb), continuing a rapid increase that began in 2007 after a plateau of 10 years. The year-over-year jump was almost 16 ppb, the largest increase detected in observational data from 1984, when the world average was 1645 ppb.

While a given amount of methane is 28 times more effective at trapping heat over 100 years than carbon dioxide (CO2), the influence of methane on global warming is 4 times less than that of CO2 due to its much lower concentrations in the atmosphere.

CO2 is by far the most abundant human-emitted greenhouse gas. About 40 billion metric tons of CO2 are generated each year from transportation, power generation, cement manufacturing, deforestation, agriculture, and many other practices.

NOAA measurements showed the global average level of CO2 in 2020 was 412.5 parts per million (ppm), an increase of 2.6 ppm from 2019. This was the sixth-largest annual increase since 1980, when the first calculation of the global average of NOAA showed the average atmospheric abundance of CO2 to be 338.9 ppm. The 2020 increase could have been the largest on record without the economic downturn induced by the pandemic, NOAA scientists said.

Since 1990, the amount of additional heat trapped in the atmosphere by increases in CO2 alone accounts for 66 percent of the total of all major long-lived greenhouse gases.

The influence on the climate of a powerful set of greenhouse gases – ozone-depleting gases such as chlorofluorocarbons (CFCs) once commonly used as refrigerants and blowing agents – continued to decline in 2020, with largely due to the controls adopted by the Montreal Protocol.

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