Worldwide, emissions of carbon dioxide, methane, and nitrous oxide - the main climate-warming greenhouse gases (GhG) -- have all reached record levels, and are on track to warm the world by more than 3°C at the start of the 22nd century.
The 2018 Emissions Gap Report, the flagship annual report from the UN Environment Program, said untrammeled emissions of carbon dioxide (CO2), methane and nitrous oxide are now far above pre-industrial levels and show no signs of a reversal of the upward trend.
This study acts as a report card on how countries are doing on their individual contributions to the Paris Climate Agreement. It also helps determine the gap between expected contributions and what will be necessary to stay within the range of 1.5°C to 2°C over pre-industrial temperatures. Burning fossil fuels for industrial needs lead to major increases in GhG in the atmosphere.
The report said the release rate of carbon emissions in 2017 was "unprecedented' over the past 66 million years. Levels of CO2, the primary greenhouse gas, rose to a global average of 405.5 parts per million (ppm) in the atmosphere in 2017.
This was a level almost 50 percent higher than before the Industrial Revolution, which lasted from 1760 to 1840 and began in Great Britain. Projected emissions of CO2 fall woefully short of the 2°C goal set in the Paris Climate Agreement in 2015.
In 2017, global emissions of CO2 were 53.5 gigatons (a gigaton is 1 billion tons), the largest ever released into the atmosphere. This massive amount is an increase of more than 1% over 2016 emissions.
Global emissions need to be 25 percent lower than this figure by 2030 to limit warming to 2°C and 55 percent lower in order to limit to 1.52°C, according to the report.
Levels of methane, a potent GhG responsible for about 17 percent of global warming, are today 2.5 times higher than pre-Industrial Revolution times because of emissions from cattle (or cattle farts) and oil and gas wells, for example.
Nitrous oxide (N2O), which also warms the Earth and destroys our planet's protective ozone layer, is now over 20 percent higher than pre-Industrial Revolution levels. About 40 percent of N2O comes from human activities including soil degradation, fertilizer use, and industry.
The report states the current emission targets for all countries will result in an average global temperature rise of 3.2°C (5.8 °F) by 2100.
A 3.2°C warmer world by the end of this century will trigger many dire consequences for human health, global economies and sea level rise projected to occur as a result of the "higher-emission" scenarios (or worst-case scenarios).
The last time the Earth experienced a comparable concentration of CO2 was three to five million years ago when the temperature was 2°C to 3°C warmer and sea level was 10 to 20 meters higher than now, said Petteri Taalas, secretary-general of the World Meteorological Organization (WMO).
Taalas said the science is clear that without rapid cuts in CO2 and other GhG, climate change will have increasingly destructive and irreversible impacts on life on Earth. She said the window of opportunity for action is almost gone.
In October, scientists worldwide said global warming or even 1.5°C would have severe consequences for humanity. International climate agreements such as the Paris Accord had for two decades set 2°C as a limit.
Every fraction of a degree of global warming matters, and so does every part per million of greenhouse gases, said WMO deputy secretary general, Elena Manaenkova. She noted that CO2 remains in the atmosphere for hundreds of years and in the oceans for even longer. There is currently no magic wand that can remove all the excess carbon dioxide from the atmosphere.
