Greenhouse gas levels in the atmosphere reached a record not seen since sea levels were 10 metres to 20 metres higher than they are now, the World Meteorological Organization said in a report.
Concentrations of carbon dioxide and other Earth-warming gases rose last year and are 41 percent higher than in 1990, driving a long-term increase in the global temperature, the United Nations organization said in its annual assessment of the trend.
The findings add to pressure on envoys from almost 200 nations gathering next month in Poland to discuss ways of reining in climate change. The WMO said higher CO2 concentrations are melting ice caps and leading to more violent weather events, which the Bank of England Wednesday said were responsible for a record $140 billion in insurance losses in 2017.
“The science is clear,” WMO Secretary-General Petteri Taalas said in a statement on Thursday. “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.”
Concentrations of carbon dioxide in the atmosphere rose 0.5 percent from 2016. Among the increased emissions, there has been a resurgence of CFC-11, a supposedly regulated greenhouse gas that depletes ozone.
The last time the Earth had similar concentration of CO2 was 3 million to 5 million years ago, when the temperature was 2-3 degrees Celsius warmer and and sea levels were at least 10 meters higher. A sea level rise of that magnitude would wipe out low-lying island nations and much of Manhattan.
The UN goal is hold the global average temperature increase to well below 2 degrees Celsius (3.6 degrees Fahrenheit), which would still represent the quickest shift in the climate since the last ice age ended some 10,000 years ago. A report earlier this year by Intergovernmental Panel on Climate Change said that net emissions must reach zero by 2050 to keep temperatures increases to 1.5 degrees Celsius, which is the goal of many developing nations.
Carbon dioxide “remains in the atmosphere for hundreds of years and in the oceans for even longer,” WMO Deputy Secretary-General Elena Manaenkova said in a report being presented to the United Nations on Thursday. “Every fraction of a degree of global warming matters, and so does every part per million of greenhouse gases.”