Is Humanity’s Impact on Climate Irreversible?

The damage to the earth’s climate and carbon cycle from human activity will take a lot of work to be reversed, according to The Economist article, “Humanity’s immense impact on Earth’s climate and carbon cycle.”

The modern industrial economy is built from fossil fuels, consisting of the top three sources of energy: oil at 34%, coal at 27%, and gas at 24%. All the renewables combined account for 15%.

Our annual use of fossil fuels extracts 9.5 billion tonnes of carbon from the ground and puts it back into the atmosphere. In the past or before the 18th century, atmospheric carbon dioxide levels were pretty stable.

The amounts of carbon dioxide that microbes and animals release through respiration are used again by plants, algae, and bacteria through photosynthesis.  The flow of carbon into the atmosphere is also balanced. Land and water sinks absorb the CO2 released into the atmosphere; thus,

However, the carbon cycle is not quite perfect, and some surpluses of carbon dioxide that sink fail to dissolve or be used up through photosynthesis and are buried in sediments. Over many years, these CO2 surpluses have been deposited into the earth’s crust and have built up significantly.

Fast-forward to the beginning of the 18th century and up to the present, and there is heavy use of fossil fuels. The carbon that was stashed away for several thousands of years is coming back into the carbon cycle in just a matter of two centuries, intensifying the carbon cycle.

Some positive consequences are greening some parts of the globe and the rapid growth of plants. Unfortunately, most outcomes are harmful and may be irreversible, such as a rise in global temperatures and their effect on crops, ice caps, ocean acidification, etc.

Low-carbon, negative emissions, and even carbon capture technologies exist, but these must be done at a scale to make a difference, and the same is true with the expansion of carbon sinks. The article says that achieving a carbon cycle equilibrium similar to the pre-industrial period will take a lot of effort and even time of up to a thousand years.

If carbon dioxide emissions continue unrestrained and damage to the earth’s climate is done, these will have severe implications on climate mitigation and adaptation measures for addressing climate change consequences.

PHOTO CREDIT: Diagram adapted from U.S. DOE, Biological and Environmental Research Information System., Public domain, via Wikimedia Commons