Greenhouse Gases & Climate Impacts

Greenhouse gases & climate impacts. GHG concentrations are scientifically linked to increasing temperatures, and in turn climate change.

Topics:

Transferring Carbon in Fossil Fuel Reserves to the Atmosphere
Formation of Fossil Fuel Reserves Eons Ago
Increasing Greenhouse Gas (GHG) Emissions
Cumulative Emissions to Date (1850 – 2019)
Increasing CO2 Concentrations
Increasing Global Temperatures
Greenhouse Gases & Climate Impacts

Transferring Carbon in Fossil Fuel Reserves to the Atmosphere

The combustion of fossil fuels along with various industrial activities emit greenhouse gases (GHGs) to the atmosphere.

Formation of Fossil Fuel Reserves Eons Ago

Several billion years ago, the earth’s fossil fuels formed over millions of years.

Under different conditions, the remains of dead plant materials underwent anaerobic digestion. Next these digested materials were exposed to heat and pressure under the Earth’s surface.

And after millions of years these varying conditions resulted in the formation of large reservoirs of coal, oil, and methane deposits.

So, a prime component of fossil fuels is hydrocarbons, along with minor components of sulfur, nitrogen, and other materials.

And since the Industrial revolution, our major energy source has been fossil fuels. So, human activities, have returned a significant amount of carbon back to the atmosphere…

Increasing Greenhouse Gas (GHG) Emissions

Fossil fuels are burned for energy uses (heating, industrial operations, transportation…).

And in the combustion process, the carbon component in these fuels combines with oxygen and forms carbon dioxide – a major heat trapping greenhouse gas.

So, carbon dioxide and other greenhouse gases (GHG) are generated by the combustion of fossil fuels.

And since the industrial revolution, human activities continue to transfer carbon from the earth’s reservoirs to the atmosphere.

However, GHG emissions are also generated by industrial processes, deforestation, and land use change.

The Intergovernmental Panel on Climate Change (IPCC) reported in Fourth Assessment Report (AR4) that agriculture accounts for some 10-12% of total global anthropogenic GHG emissions – responsible for approximately 58% of nitrous oxide emissions and 47% of methane emissions. These values vary somewhat from year to year, with higher percentages in countries where agriculture plays more dominant roles.

And the United Nations advises that the agri-food supply chain from farm to fork accounts for some 29% of global greenhouse gas emissions.

As a result, atmospheric GHG emissions are continuing to increase at an alarming rate. However, a reduction in 2020 emissions was observed during the 2020 Covid-19 pandemic, and future observations will reveal if these reductions in emissions continue. Nevertheless, atmospheric concentrations of GHGs continue to increase, although the rate of increase may be somewhat lower.

And the Global Carbon Project reported that in 2018 emissions from fossil fuels and industry reached 36.6 ± 2 GtCO₂ (Gigatonnes of carbon dioxide).

Further their report indicates that Net CO₂ emissions from deforestation and other land-use change were 5.5 ± 2.7 GtCO₂ on average during 2009-2018.

Also their report indicates that in 2018, combined emissions from fossil fuel and industry emissions, plus land use change, reached 42.1 ± 2.8 GtCO₂.

Cumulative Emissions to Date (1850 - 2019)

In a 2019 report, the Global Carbon Project reported that total cumulative emissions from 1850 to 2019 were estimated at 1649 GtCO₂ from fossil fuels and industry, and 751 GtCO₂ from land use change.

And the combined total of some 2400 ± 238 GtCO₂ of emissions was partitioned among the ocean, the land and the atmosphere. The net amount in the atmosphere being an estimated 953 ± 18 GtCO₂. In addition there were emissions of methane, nitrous oxide and other greenhouse gases. Since the Industrial Revolution, average global temperatures have increased by ~ 1C.

However, there are a range of estimates of how much additional carbon can be added to the atmosphere and continue to keep future temperature increases below 1.5C.

So, estimates of our remaining carbon budget range between a few years to a dozen or so years. These estimates are based on our recent annual greenhouse emissions exceeding some 40 GtCO₂ annually.

Also, data for future carbon budgets are available from the Intergovernmental Panel on Climate Change (IPCC) in their Special Report on Global Warming 1.5^oC (SR15). And more updates will be presented in the upcoming IPCC AR6 Report to be released in ~ 2021.

Increasing CO2 Concentrations

Increasing greenhouse gas emissions result in increasing atmospheric carbon dioxide concentrations.

And since the industrial revolution, atmospheric carbon dioxide concentrations have increased from around 280 parts per million (PPM) to over 400 PPM in recent years.

Therefore, the concentration of atmospheric carbon dioxide (CO₂) and many other greenhouse gases continues to increase at an alarming rate.

Noteworthy, carbon dioxide emissions remain in the atmosphere for a very long-time. Heating will continue long after we reduce our emissions.

Increasing Global Temperatures

Scientists know that increasing atmospheric greenhouse gas concentrations are scientifically linked to increasing global temperatures.

Refer to Temperatures