What is the present level of atmospheric carbon dioxide?
On May 9th, 2013, the global atmospheric daily concentration of CO2 crossed 400 ppm level mark. On that day the recorded CO2 Concentration was 400.03 ppm as per the NASA’s Mauna Loa observatory in Hawaii. The observatory has been monitoring the atmospheric concentration since last 57 years.
The crossing of 400 ppm mark made news. The scientists from National Oceanic and Atmospheric Administration (NOAA) and Scripps Institute of Oceanography both in USA confirmed these observations.
The CO2 concentration in the atmosphere does not remain same throughout the year. In fact, it varies with the changing season.
From springs till later part of the year when the plants grow maximim, the rate of photosynthesis is very high. During this time the maximum atmospheric CO2 is taken in by the plants. This also reflects as a dip in the global CO2 level in the atmosphere. Recently again the Mauna Loa observatory announced that the global annual minimum has also crossed 400 ppm level mark for the first time in September 2016. And this again made news.
Why 400 ppm CO2 level in the atmosphere is so important?
The level of CO2 in the atmosphere has direct linkages with the increase in the global temperature and therefore with the climate change.
There are some facts one should keep in mind:
- Since 1961 each successive year the global CO2 concentration in the atmosphere has risen by about 2 ppm.
- Since 1970, each successive decade has seen about 0.17 °C rise in the average global temperature. 2016 has been the warmest year on record. Since 1880 all the 10 warmest years on earth have occurred post 2000 (only exception is 1998).
In order to keep the global temperature rise below 2 °C, it is required to keep the total CO2 concentration in the atmosphere below 450 ppm. The safer would be to aim for keeping the temperature rise below 1.5 °C but for this the CO2 concentration should be brought down below 350 PPM.
The most important global treaty to combat the climate change i.e. the Paris agreement 2015 also aims to limit the global temperature rise in the present century below 2 °C as compared to pre-industrial era. The emphasis is also to drive efforts so that the temperature rise can be limited to 1.5 °C.
It is known that if the global temperature rises beyond 2 °C above the pre-industrial era, the climate change effects would be catastrophic. As we have crossed the 400 ppm mark, it is really challenging to restrain the CO2 concentration from reaching 450 ppm.
Reaching 400 mark also conveys that the world would not be able to limit the global temperature rise below 1.5 °C. In fact the rate at which the CO2 level in the atmosphere is increasing we will be crossing 450 marks much before the 2050.
The 450 ppm CO2 concentration in the atmosphere will have impacts such as global sea level rise, interference in the global climate system, erratic rain fall, drought, melting of the glaciers and acute water crisis to name a few.
Although when consider in terms of percentage the 400 ppm CO2 is only 0.04%, the crossing of 400 ppm mark is a warning signal to alarm the world to speed up the mitigation efforts by limiting the harmful emissions as well as adapt more and more with the changing climatic conditions to efficiently combat the adverse impacts of climate change. If the world fails in this attempt, get ready to face the consequences