22.11.2018
Levels of heat-trapping greenhouse gases in the atmosphere have reached another new record high, according to the World Meteorological Organization (WMO). There is no sign of a reversal in this trend, which is driving long-term climate change, sea level rise, ocean acidification and more extreme weather.
Quelle: WMO, 2018
The WMO Greenhouse Gas Bulletin showed that globally averaged concentrations of carbon dioxide (CO2) reached 405.5 parts per million (ppm) in 2017, up from 403.3 ppm in 2016 and 400.1 ppm in 2015. Concentrations of methane and nitrous oxide also rose, whilst there was 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.
Since 1990, there has been a 41% increase in total radiative forcing – the warming effect on the climate - by long-lived greenhouse gases. CO2 accounts for about 82% of the increase in radiative forcing over the past decade, according to figures from the US National Oceanic and Atmospheric Administration (NOAA) quoted in the WMO Bulletin.
“The science is clear. Without rapid cuts in CO2 and other greenhouse gases, climate change will have increasingly destructive and irreversible impacts on life on Earth. The window of opportunity for action is almost closed,” said WMO Secretary-General Petteri Taalas.
“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 and sea level was 10-20 meters higher than now,” said Mr Taalas.
The WMO Greenhouse Gas Bulletin reports on atmospheric concentrations of greenhouse gases. Emissions represent what goes into the atmosphere. Concentrations represent what remains in the atmosphere after the complex system of interactions between the atmosphere, biosphere, lithosphere, cryosphere and the oceans. About a quarter of the total emissions is absorbed by the oceans and another quarter by the biosphere.
A separate Emissions Gap Report by UN Environment (UNEP), to be released on 27 November, tracks the policy commitments made by countries to reduce greenhouse gas emissions.
The WMO and UNEP reports come on top of the scientific evidence provided by the Intergovernmental Panel on Climate Change (IPCC) Special Report on Global Warming of 1.5°C. This said that net emissions of CO2 must reach zero (the amount of CO2 entering the atmosphere must equal the amount that is removed by sinks, natural and technological) around 2050 in order to keep temperature increases to below 1.5°C. It showed how keeping temperature increases below 2°C would reduce the risks to human well-being, ecosystems and sustainable development.
“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,” said 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 said.
Together, the reports provide a scientific base for decision-making at the UN climate change negotiations, which will be held from 2-14 December in Katowice, Poland. The key objective of the meeting is to adopt the implementation guidelines of the Paris Climate Change Agreement, which aims to hold the global average temperature increase to as close as possible to 1.5°C.
“The new IPCC Special Report on Global Warming of 1.5°C shows that deep and rapid reductions of emissions of carbon dioxide and other greenhouse gases will be needed in all sectors of society and the economy. The WMO Greenhouse Gas Bulletin, showing a continuing rising trend in concentrations of greenhouse gases, underlines just how urgent these emissions reductions are,” said IPCC Chair Hoesung Lee.
Quelle: WMO, 2018
Watch WMO's Video on the Greenhouse Gas Bulletin - November 2018 at YouTube
