The United Nations has launched a major effort to try to fill a key gap in the fight against climate change: standardised, real-time tracking of greenhouse gases.

Better ways of measuring planet-warming pollution are vital to responding to the impact on humanity and should help inform better decision-making.

The UN's World Meteorological Organization brought together more than 250 experts this week in Geneva to start "to assemble the different pieces of the jigsaw puzzle into a single framework".

The effort aims to standardise the way information is produced, fill in the knowledge gaps on where greenhouse gas emissions end up -- and produce much faster and sharper data on how the planet's atmosphere is changing.

"Climate change is the most stressing and long-lasting challenge of our time," Hugo Zunker, from the European Union's Copernicus Earth observation programme, told attendees.

"Without understanding how the climate is changing and which risks these changes bring, we cannot plan for a climate-resilient and sustainable future."

The three major greenhouses gases are carbon dioxide (CO2), methane and nitrous oxide. CO2 accounts for around 66 percent of the warming effect on the climate.

The current Global Atmosphere Watch Programme monitors greenhouse gas concentrations from ground-based stations in pristine locations such as Tasmania, Tenerife and Hawaii.

However, "at present, there is no comprehensive, timely international exchange of surface and space-based greenhouse gas observations", the WMO said.

- Better data -

The agency also said there was doubt surrounding the role played by carbon-absorbing places such as the Amazon rainforest, the ocean and permafrost areas.

WMO chief Petteri Taalas said "big uncertainties" exist regarding CO2 sources and absorption but also about methane.

The WMO's 2021 greenhouse gas bulletin, issued at the COP27 UN climate summit in Egypt in November, showed the biggest annual increase of methane concentration since 1980, "and we don't fully understand the reason behind that", said Taalas.

WMO is therefore developing a concept for an internationally-coordinated Greenhouse Gas Monitoring Infrastructure -- the subject of this week's meeting.

The new framework should facilitate greenhouse gas surface- and space-based observing systems, with common standards and rapid access to its measurements.

The infrastructure should also improve worldwide coordination of modelling and data compilation.

The data generated should deliver solid, detailed information to communities and countries signed up to the Paris climate accords, helping them to tailor their mitigation action.

The 2015 Paris Agreement on climate change saw countries agree to cap global warming at "well below" two degrees Celsius above between 1850 and 1900 -- and 1.5C if possible.

- Carbon tracking -

The proposed monitoring system would improve understanding of the full carbon cycle.

Lars Peter Riishojgaard, who heads the WMO's Integrated Observing System branch, said there was relatively good data on how much CO2 is emitted.

"We know by and large how much coal, oil and gas we dig out. We can assume all of it is burned off," he said.

"Some of it goes into the land surface and some of it goes into the ocean. We understand the sum of these two but not the individual components as well.

"We really need to understand this whole system here quite a bit better than we do."

Some greenhouse gas concentrations, he added, were influenced by natural processes, not just human activity.

Successful mitigation must be based on the whole system, "not just on what we do to it", he said.

Reliable financing is also proving a problem.

Most current greenhouse gas monitoring relies heavily on research capabilities and funding, which is intermittent. Most research funding is subject to competitive allocation, making sustained global monitoring "difficult to achieve", said the WMO.

Proposals emanating from this week's symposium will be submitted to the WMO's executive council meeting in February and then the World Meteorological Congress -- the WMO's supreme decision-making body -- in June 2024.