WASHINGTON • For the second year in a row, atmospheric carbon dioxide concentrations have climbed at a record pace.
According to data from the US National Oceanic and Atmospheric Administration (NOAA), carbon dioxide levels jumped by three parts per million in 2015 and last year, and now rest at about 405 parts per million.
It is the biggest jump ever observed at the agency's Mauna Loa Baseline Atmospheric Observatory in Hawaii, where the measurements were recorded.
Similar observations have been recorded at stations all over the world, said Dr Pieter Tans, who leads the Carbon Cycle Greenhouse Gases group at NOAA's Greenhouse Gas Reference Network.
"Over the last decade, a more average rate is about 2.4 parts per million per year," he added.
In March 2015, NOAA scientists found that the monthly global average concentration of carbon dioxide exceeded 400 parts per million for the first time.
The level is a symbolic threshold set by scientists as a milestone to show the remarkable human-caused growth of greenhouse gases in the atmosphere.
The levels of atmospheric carbon dioxide averaged about 280 parts per million up until the industrial revolution.
Since then, all signs have suggested that we are now living in a permanently post-400 parts per million world. Last September, the time of year when atmospheric carbon dioxide levels are usually at their lowest, scientists observed that the monthly average concentration still remained above this threshold.
And now, the new NOAA measurements indicate that carbon dioxide levels are continuing to grow - at breakneck speed.
It may be a little confusing to consider this news alongside others which suggest that global carbon emissions caused by human activity have actually remained fairly flat for the past three years.
But even if emissions have remained pretty stable in recent years, humans are still pouring billions of tonnes of greenhouse gases into the air each year.
And even if these emission levels are starting to plateau, they are still evening out at an all-time high, after decades of climbing.