“Every year we report a new record in greenhouse gas concentrations … Every year we say that time is running out”
Atmospheric concentrations of heat-trapping carbon dioxide will soon stay above the symbolic 400 parts per million mark permanently, the World Meteorological Organization said this week in its annual report on the state of the global atmosphere.Unsurprisingly, the organization reported that CO2 reached another record level in 2014, reaching 397.7 ppm after relentlessly rising the past few decades. Altogether, CO2, methane and nitrous oxide from industrial, agricultural and domestic sources have increased radiative forcing by 36 percent since 1990. according to the WMO’s Greenhouse Gas Bulletin.
“Every year we report a new record in greenhouse gas concentrations,” said WMO secretary-general Michel Jarraud. “Every year we say that time is running out. We have to act NOW to slash greenhouse gas emissions if we are to have a chance to keep the increase in temperatures to manageable levels.”
This year’s report also explains the connection between increasing CO2 and water vapor, considered to be a short-lived greenhouse gas. Higher levels of CO2 mean warmer temps, which leads to more water vapor, intensifying the greenhouse effect.
This year, CO2 spiked above 400 ppm during the northern hemisphere spring, and by next year, the concentration may stay above that level permanently, especially because of the strong El Niño conditions, which tend to shift rainfall away from tropical land masses, out over the ocean. That slows the growth of tropical forests, which are key to removing CO2 from the atmosphere, as explained in this post from the Scripps Institution of Oceanography.
“We can’t see CO2. It is an invisible threat, but a very real one. It means hotter global temperatures, more extreme weather events like heatwaves and floods, melting ice, rising sea levels and increased acidity of the oceans. This is happening now and we are moving into uncharted territory at a frightening speed,” Jarraud said.
“Carbon dioxide remains in the atmosphere for hundreds of years and in the ocean for even longer. Past, present and future emissions will have a cumulative impact on both global warming and ocean acidification. The laws of physics are non-negotiable,” he added.
According to the report, CO2 accounted for about 83 percent of the total increase in radiative forcing by long-lived greenhouse gases over the past decade.
The pre-industrial level of about 278 ppm represented a balance between the atmosphere, the oceans and the biosphere. Human activities such as the burning of fossil fuels has altered the natural balance and in 2014, globally averaged levels were 143 percent of pre-industrial levels.
Methane is the second most important long-lived greenhouse gas. Approximately 40 percent of methane is emitted into the atmosphere by natural sources (e.g., wetlands and termites), and about 60 percent comes from human activities like cattle breeding, rice agriculture, fossil fuel exploitation, landfills and biomass burning. Atmospheric methane reached a new high of about 1833 parts per billion in 2014 and is now 254 percent of the pre-industrial level.
Nitrous oxide is emitted into the atmosphere from both natural (about 60 percent) and anthropogenic sources (approximately 40 percent), including oceans, soil, biomass burning, fertilizer use, and various industrial processes. Its atmospheric concentration in 2014 was about 327.1 parts per billion. This is 121 percent of pre-industrial levels. It also plays an important role in the destruction of the stratospheric ozone layer which protects us from the harmful ultraviolet rays of the sun.
Water vapor and CO2 are the two major greenhouse gases. But it is CO2 which is the main driver of climate change. Water vapor changes are the so-called feedback mechanisms and happen as a response to the change in CO2.
If CO2 doubles from pre-industrial levels, scientists estimate that water vapor and clouds globally would lead to an increase in atmopsheric warming that is about three times that of long-lived greenhouse gases.