- The WMO Greenhouse Gas Bulletin 2018 shows that global concentrations of carbon dioxide (CO2), methane and nitrous oxide have been increasing steadily over the past years. In addition, the report notes a resurgence of a potent greenhouse gas and ozone-depleting substance called CFC-11, which is regulated under an international agreement to protect the ozone layer.
- The WMO Greenhouse Gas Bulletin reports specifically on atmospheric concentrations of greenhouse gases, which are what remains in the atmosphere, following a complex process of emissions and absorptions.
- The latest analysis of observations from the WMO AW Programme shows that globally averaged surface mole fractions calculated from this in situ network for carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) reached new highs in 2017, with CO2 at 405.5 ± 0.1 ppm, CH4 at 1859 ± 2 ppb and N2O at 329.9 ± 0.1 ppb. These values constitute, respectively, 146%, 257% and 122% of pre-industrial (before 1750) levels.
- The increase in CO2 from 2016 to 2017 was smaller than that observed from 2015 to 2016 and practically equal to the average growth rate over the last decade. The influence of the El Niño event that peaked in 2015 and 2016 and contributed to the increased growth rate during that period sharply declined in 2017. For CH4, the increase from 2016 to 2017 was lower than that observed from 2015 to 2016 but practically equal to the average over the last decade.
- For N2O, the increase from 2016 to 2017 was higher than that observed from 2015 to 2016 and practically equal to the average growth rate over the past 10 years. The NOAA Annual Greenhouse Gas Index (AGGI)shows
that from 1990 to 2017 radiative forcing by long-lived GHGs (LLGHGs) increased by 41%, with CO2 accounting
for about 82% of this increase. - “The last time the Earth experienced a comparable concentration of CO2 was 3-5 million years ago, when the temperature was 2-3°C warmer,” Taalas said.
- Since 1990, there has been a 41 per cent increase in the warming effect by the various greenhouse gases on the climate – known as “radioactive forcing.”
- CO2 specifically accounts for about 82 per cent of the increase in radioactive forcing over the past decade, according to figures quoted in the WMO report.
- “The last time the Earth experienced a comparable concentration of CO2 was three to five million years ago, when the temperature was 2 to 3°C warmer and sea level was 10 to 20 meters higher than now,” said World Meteorological Organization (WMO) Secretary-General Petteri Taalas.
- The WMO report comes on top of the evidence presented in the Intergovernmental Panel on Climate Change (IPCC) special report on global warming issued in October, which sounded the alarm on the need to reach zero net emissions of CO2 by mid-century, in order to keep temperature increases to below 1.5°C.
- The report showed how keeping temperature increases below 2°C could reduce the risks for the well-being of the planet and its people.
- “CO2 remains in the atmosphere for hundreds of years and in the oceans for even longer. There is currently no magic wand to remove all the excess CO2 from the atmosphere,” warned WMO Deputy Secretary-General Elena Manaenkova. “Every fraction of a degree of global warming matters, and so does every part per million of greenhouse gases,” she insisted.
- This new report adds yet another building block of scientific evidence to inform decision-making at the upcoming UN climate change conference – the COP 24 – planned from 2 to 14 December in Poland. The key objective of this meeting is to adopt an implementation plan for the 2015 Paris Agreement.
- Against the backdrop of the sobering report, Michelle Bachelet, the UN High Commissioner for Human Rights, has sent a letter to all States, telling them they have legal obligations under international human rights law to prevent climate change and try to mitigate its effects.
- “Human rights are under threat from a force which challenges the foundations of all life, as we know it, on this planet we share,” she said, pointing out that the decisions taken CO P24 will govern climate action under the Paris agreement “for the indefinite future,” and said that “the rights of the millions of people [are] threatened by climate change. (UN)
