Why CO2 is the primary driver of climate change

CO2 is 1 of the astir important GHGs successful the ambiance and is the superior operator of anthropogenic clime change.

Here is simply a look astatine wherefore CO2 has caused astir of the planetary warming.

But first, what are greenhouse gases?

GHGs are those gases successful the Earth’s ambiance that trap heat. The Sun emits shortwave radiation oregon sunlight that passes done the ambiance and is absorbed by the planet’s aboveground to lukewarm it. However, immoderate of this sunlight is reflected backmost by the aboveground arsenic infrared radiation (heat) which has a longer wavelength.

GHGs specified arsenic CO2 and methane (CH4), which cannot sorb shortwave radiation, trap infrared radiation. That is due to the fact that dissimilar oxygen oregon nitrogen molecules, CO2 and methane are made up of 3 oregon much atoms, which gives them a larger assortment of ways to agelong and crook and twist. This means that they tin sorb a wider scope of wavelengths, including infrared radiation, Jason Smerdon, a clime idiosyncratic astatine Columbia University, told State of the Planet, a quality tract of the Columbia Climate School.

Simply put, GHGs enactment similar a broad that envelopes Earth and insulates it from the acold of space. This process of maintaining a warmer somesthesia is called the greenhouse effect. GHGs similar CO2, CH4, and h2o vapour hap people and are a boon for the satellite arsenic successful their lack determination would not beryllium the greenhouse effect without which determination would not beryllium liquid h2o and immoderate signifier of life.

The contented is not the beingness of GHGs but their attraction levels, meaning their magnitude successful the atmosphere. For astir a 1000 years earlier the Industrial Revolution, the GHG attraction remained comparatively constant. Since then, determination has been a changeless emergence successful the magnitude of immoderate of the GHGs, particularly CO2, owed to quality activities similar burning fossil fuels. As a result, much vigor is getting trapped successful the atmosphere, starring to a emergence successful planetary temperatures.

Why has CO2 caused astir of the planetary warming?

Studies person shown that CO2 has contributed much than immoderate operator to clime change. In fact, CO2 is liable for astir 70% of planetary warming, according to an investigation by Facts connected Climate Change, a Czech Republic-based autarkic deliberation tank.

In 2013, the Intergovernmental Panel connected Climate Change (IPCC) — the United Nations assemblage that advances technological cognition astir clime alteration — compared the “radiative forcing” (RF) oregon heating effect of 3 antithetic clime drivers: GHGs, aerosols, and onshore usage change. It was recovered that betwixt 1750 and 2011, CO2 had the highest affirmative RF, meaning it had the top warming effect connected the planet.

The investigation besides showed that different GHGs specified arsenic CH4 oregon Hydrofluorocarbons (an wholly human-made GHG) which are overmuch much potent — portion CH4 is astir 80 times much almighty than CO2, HFCs tin beryllium thousands of times much almighty — had little heating effect than CO2.

There are 2 reasons for this. One, CO2 is overmuch much abundant successful the ambiance compared to CH4 and HFCs. Since the onset of concern times successful the 18th century, quality activities person raised atmospheric CO2 by 50%, which means the magnitude of CO2 is present 150% of its worth successful 1750 (see chart), according to a study successful the National Aeronautics and Space Administration (NASA).

The graph, based connected the examination of atmospheric samples contained successful crystal cores and much caller nonstop measurements, shows the emergence of atmospheric CO2 since the Industrial Revolution. (Credit: NASA)

Two, CO2 remains successful the ambiance longer than the different large GHGs emitted owed to quality activities. It takes astir a decennary for CH4 emissions to permission the ambiance (it converts into CO2) and astir a period for nitrous oxide (N2O).

“After a pulse of CO2 is emitted into the atmosphere, 40% volition stay successful the ambiance for 100 years and 20% volition reside for 1000 years, portion the last 10% volition instrumentality 10,000 years to crook over,” a study by the Union of Concerned Scientists (UCS), a US-based non-profit organisation, said.

Notably, h2o vapour is the astir abundant GHG successful the atmosphere. However, it has a abbreviated rhythm (10 days connected average) and does not physique up successful the ambiance successful the aforesaid mode arsenic CO2 does. Therefore, h2o vapour does not person overmuch heating effect compared to CO2. But arsenic planetary temperatures proceed to soar, much h2o evaporates into the atmosphere, causing much warming.