The amount of carbon dioxide in the Earth’s atmosphere is approaching a level not seen in 15m years and perhaps never previously experienced by a hominoid.
As a United Nations agency released new climate projections showing that the world is on track in the next five years to hit or surpass a key limit of the Paris agreement, authors of a new study warned Thursday 09/07/2020 that increasing carbon dioxide in the atmosphere is nearing a level not seen in 15 million years.
For the study, published in the journal Scientific Reports, researchers at the University of Southampton in the United Kingdom examined CO2 levels during the Late Pliocene about three million years ago “to search for modern and near future-like climate states,” co-author Thomas Chalk explained in Figure 1.
Dr Thomas Chalk added: “Focussing on a past warm interval when the incoming insolation from the Sun was the same as today gives us a way to study how Earth responds to CO2 forcing. A striking result we’ve found is that the warmest part of the Pliocene had between 380 and 420 parts per million CO2 in the atmosphere. This is similar to today’s value of around 415 parts per million, showing that we are already at levels that in the past were associated with temperature and sea-level significantly higher than today. Currently, our CO2 levels are rising at about 2.5 ppm per year, meaning that by 2025 we will have exceeded anything seen in the last 3.3 million years.”
Also, the WMO report projects that the annual global temperature is likely to be at least 1°C warmer than pre-industrial levels in each of the next five years. Although it is “extremely unlikely” the average temperature for 2020–2024 will be 1.5°C warmer than pre-industrial levels, WMO warned certain periods could hit that temperature.
Specifically, there is about a 70% chance that one or more months during those five years will be at least 1.5°C hotter than pre-industrial levels and about a 20% chance that one of the next five years will be at least that warm, according to WMO’s Global Annual to Decadal Climate Update, led by the United Kingdom’s Met Office.
“WMO has repeatedly stressed that the industrial and economic slowdown from Covid-19 is not a substitute for sustained and coordinated climate action,” Taalas said. “Due to the very long lifetime of CO2 in the atmosphere, the impact of the drop in emissions this year is not expected to lead to a reduction of CO2 atmospheric concentrations which are driving global temperature increases.”
“Whilst Covid-19 has caused severe international health and economic crisis, failure to tackle climate change may threaten human well-being, ecosystems, and economies for centuries,” he continued. Governments should use the opportunity to embrace climate action as part of the recovery program and ensure that we grow back better.