UN: Greenhouse gas levels in atmosphere hit new high in 2018

GENEVA, Switzerland — Greenhouse gases levels in the atmosphere, the main driver of climate change, hit a record high last year, the UN said Monday, calling for action to safeguard "the future welfare of mankind."

"There is no sign of a slowdown, let alone a decline, in greenhouse gases concentration in the atmosphere despite all the commitments under the Paris Agreement on Climate Change," the head of the World Meteorological Organization Petteri Taalas said in a statement.

The WMO's main annual Greenhouse Gas Bulletin listed the atmospheric concentration of CO2 in 2018 at 407.8 parts per million, up from 405.5 parts per million (ppm) in 2017.

That increase was just above the annual average increase over the past decade. 

Concentrations of the other two main greenhouse gases, methane and nitrous oxide, also hit record levels in 2018, WMO said.

"This continuing long-term trend means that future generations will be confronted with increasingly severe impacts of climate change, including rising temperatures, more extreme weather, water stress, sea level rise and disruption to marine and land ecosystems," WMO said.

Emissions are the main factor that determine the amount of greenhouse gas levels, but concentration rates are a measure of what remains after a series of complex interactions between atmosphere, biosphere, lithosphere, cryosphere and the oceans. 

Roughly 25% of all emissions are currently absorbed by the oceans and biosphere—a term that accounts for all ecosystems on Earth.

The lithosphere is the solid, outer part of the Earth, while the cyrosphere covers that part of the world covered by frozen water.

The UN's Intergovernmental Panel on Climate Change (IPCC) has said that in order to keep warming below 1.5 degrees Celsius, net CO2 emissions must be at net zero, meaning the amount being pumped into the atmosphere must equal the amount being removed, either though natural absorbtion or technological innovation.