Concentration of CO2 in atmosphere hits new high: UN

AFP Yahoo News 24 Oct 16;

Geneva (AFP) - The concentration of carbon dioxide (CO2) in the atmosphere has passed an ominous milestone, ushering the planet into "a new era" of climate change, the UN said Monday.

For the first time on record, the amount of CO2 in the atmosphere averaged 400 parts per million (ppm) in 2015, the World Meteorological Organization (WMO) said in its latest Greenhouse Gas Bulletin.

CO2, the main greenhouse gas driving climate change, has previously passed the 400 ppm threshold on certain months in specific locations but never on a globally averaged basis, WMO said.

The UN agency also reported that CO2 concentration rates had "surged again to new records in 2016" and predicted the annual average would "not dip below (400 ppm) for many generations."

WMO chief Petteri Taalas said "the year 2015 ushered in a new era of optimism and climate action with the Paris climate change agreement.

"But it will also make history as marking a new era of climate change reality with record high greenhouse gas concentrations," he added in a statement.

The CO2 concentration rate for 2014 was 397.2 ppm, just short of the 400 ppm mark that some climate activists once deemed unthinkable.

- El Nino factor -

CO2 concentration rates have spiked in part because of a strong El Nino, the weather phenomenon that occurs every four to five years with a broadly warming effect.

El Nino "triggered droughts in tropical regions and reduced the capacity of 'sinks' like forests, vegetation and the oceans to absorb CO2," WMO said.

But Taalas, warned against complacency just because El Nino has subsided for now.

"The El Nino event has disappeared. Climate change has not," added the Finnish national, who was named WHO chief earlier this year.

Taalas applauded the landmark deal reached in Rwanda's capital Kigali earlier this month to phase out hydrofluorocarbons (HFCs), a category of dangerous greenhouse gases widely used in refrigerators and air conditioners.

The Kigali pact has been heralded as a major step towards curbing global warming, but Taalas cautioned that in working to cap HFC emissions the world could not afford to take its focus off CO2.

"The real elephant in the room is carbon dioxide, which remains in the atmosphere for thousands of years and in the oceans even longer," he said.

The WMO's annual Greenhouse Gas Bulletin tracks concentrations of gasses in the atmosphere, rather than emissions with data compiled from a monitoring station in Mauna Loa, Hawaii.

Aside from CO2, the report monitors concentration rates of other major greenhouse gasses like methane, which in 2015 hit 1845 parts per billion, or more than 256 percent above pre-industrial levels.

Globally averaged concentrations of nitrous oxide, another climate change actor, were 121 percent above pre-industrial levels, according to WMO's 2015 data.

The agency estimates that roughly half of greenhouse gas emissions end up in the atmosphere, as about a quarter is taken up by the ocean and another quarter taken up by the biosphere.


CO2 levels mark 'new era' in the world's changing climate
Matt McGrath BBC 24 Oct 16;

Levels of CO2 in the atmosphere have surged past an important threshold and may not dip below it for "many generations".

The 400 parts per million benchmark was broken globally for the first time in recorded history in 2015.

But according to the World Meteorological Organisation (WMO), 2016 will likely be the first full year to exceed the mark.

The high levels can be partly attributed to a strong El Niño event.

Gas spike

While human emissions of CO2 remained fairly static between 2014 and 2015, the onset of a strong El Niño weather phenomenon caused a spike in levels of the gas in the atmosphere.

That's because the drought conditions in tropical regions produced by El Niño meant that vegetation was less able to absorb CO2. There were also extra emissions from fires, sparked by the drier conditions.

In its annual Greenhouse Gas Bulletin, the World Meteorological Organisation says the conditions helped push the growth in the levels of CO2 in the atmosphere above the average for the last ten years.

At the atmospheric monitoring station in Mauna Loa, Hawaii, levels of CO2 broke through 400 parts per million (ppm), meaning 400 molecules of CO2 for every one million molecules in the atmosphere.

The last time CO2 was regularly above 400ppm was three to five million years ago, say experts.

Prior to 1800 atmospheric levels were around 280ppm, according to the US National Oceanic And Atmospheric Administration (Noaa).

The WMO says that the rise through the 400ppm barrier has persisted and it's likely that 2016 will be the first full year when the measurements show CO2 above that benchmark, and "hence for many generations".

While the El Niño factor has now disappeared, the human impact on climate change has not, the WMO argues.

"The year 2015 ushered in a new era of optimism and climate action with the Paris climate change agreement," said WMO Secretary-General Petteri Taalas.

"But it will also make history as marking a new era of climate change reality with record high greenhouse gas concentrations."

The report also details the growth in other greenhouse gases, including methane and nitrous oxide.

In 2015, levels of methane were 2.5 times greater than in the pre-industrial era, while nitrous oxide was 1.2 times above the historic measure.

The study also points to the impact of these increased concentrations of warming gases on the world's climate.

Between 1990 and 2015 there was a 37% increase in radiative forcing or warming effect, caused by a build up of these substances, from industrial, agricultural and domestic activities.

While welcoming new initiatives like the global agreement to phase out HFC gases agreed recently in Rwanda, the WMO argues that nations must retain their focus on cutting CO2.

"Without tackling CO2 emissions, we cannot tackle climate change and keep temperature increases to below 2 degrees C above the pre-industrial era," said Petteri Taalas.

"It is therefore of the utmost importance that the Paris Agreement does indeed enter into force well ahead of schedule on 4 November and that we fast-track its implementation."

Around 200 nations who signed the Paris climate agreement will meet in Morocco in November to decide on the next steps forward.

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