CONCENTRATION of Carbon dioxide, the most important greenhouse gas reached to 403.3 parts per million this year. According to scientists, this record annual increase of 3.3 ppm was partly due to the strong El Niño this year, which triggered droughts in tropical regions and reduced the capacity of “sinks” like forests, vegetation, and the oceans to absorb CO2. Average global temperature goes parallel with the concentration of CO2.
In mid of 18th-century concentration of CO2 was below 250ppm. The rate of increase of atmospheric CO2 over the past 70 years is nearly 100 times larger than that at the end of the last ice age. As far as direct and proxy observations can tell, such abrupt changes in the atmospheric levels of CO2 have never before been seen.
The major sources of CO2 emissions are burning of fossil fuels in factories, vehicles, ships and planes, deforestation and increase in population. The other two greenhouse gases are methane and nitrous oxide. CH4 is mainly generated by agricultural activities, the production of coal and gas, as well as waste treatment and disposal. Methane (CH4) is the second most important long-lived greenhouse gas and contributes about 17% of radiative forcing. Approximately 40% of methane is emitted into the atmosphere by natural sources (e.g., wetlands and termites), and about 60% comes from human activities like cattle breeding, rice agriculture, fossil fuel exploitation, landﬁlls and biomass burning.
Atmospheric methane reached a new high of about 1 853 parts per billion (ppb) in 2016 and is now 257% of the pre-industrial level. Nitrous oxide (N2O) is emitted into the atmosphere from both natural (about 60%) and anthropogenic sources (approximately 40%), including oceans, soil, biomass burning, fertilizer use, and various industrial processes. N2O is mainly emitted by agricultural soil activities and chemical production. Its atmospheric concentration in 2016 was 328.9 parts per billion. This is 122% 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.
It accounts for about 6% of radiative forcing by long-lived greenhouse gases. The upward trend in CH4 and N2O emissions is also visible in the US, China, Japan, and India which all recorded increasing GHG emissions. In the EU, 60% of the CH4 and N2O emissions are emitted by the top six emitting countries — Germany, UK, France, Poland, Italy and Spain. Concentrations of carbon dioxide in the atmosphere surged at a record-breaking speed in 2016 to the highest level in 800,000 years, according to the World Meteorological Organization’s Greenhouse Gas Bulletin. The abrupt changes in the atmosphere witnessed in the past 70 years are without precedent. Globally averaged concentrations of CO2 reached 403.3 parts per million in 2016, up from 400.00 ppm in 2015 because of a combination of human activities and a strong El Niño event.
Concentrations of CO2 are now 145% of pre-industrial (before 1750) levels, according to the Greenhouse Gas Bulletin. Rapidly increasing atmospheric levels of CO2 and other greenhouse gases have the potential to initiate unprecedented changes in climate systems, leading to “severe ecological and economic disruptions,” said the report. Population growth, intensiﬁed agricultural practices, increases in land use and deforestation, industrialization and associated energy use from fossil fuel sources have all contributed to increases in concentrations of greenhouse gases in the atmosphere since the industrial era, beginning in 1750. “Without rapid cuts in CO2 and other greenhouse gas emissions, we will be heading for dangerous temperature increases by the end of this century, well above the target set by the Paris climate change agreement,” said WMO Secretary-General Petteri Taalas. “Future generations will inherit a much more inhospitable planet, ” he said. “CO2 remains in the atmosphere for hundreds of years and in the oceans for even longer. The laws of physics mean that we face a much hotter, more extreme climate in the future. There is currently no magic wand to remove this CO2 from the atmosphere,” said Mr. Taalas.