Mitigation – what does it mean?

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Mitigation of climate change – what is it?

The rapid economic development of mankind and population growth has led to higher concentrations of greenhouse gases (GHGs) which in the Earth's atmosphere today is higher than ever before. Water vapour (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and fluorinated gases are what enhance the greenhouse effect and enter the atmosphere in relentless quantities every day. It has been found that the rising levels of CO2 concentrations have the greatest impact on the acceleration of the greenhouse effect, but what are the main sources of greenhouse gases?

GHG characteristics

Water vapour (H2O) is the most abundant gas, accounting for about two-thirds of greenhouse gas emissions. It is formed during the natural evaporation process and is not directly related to human economic activities. In the atmosphere, water molecules absorb the heat radiated by the sun and reflected by the Earth, and gradually release it into the environment. However, as global air temperatures rise, when warmer air can retain increasingly more moisture, the amount of these gases also increases and contributes to climate change in reverse links.

Nevertheless, carbon dioxide (CO2) is a major contributor to the anthropogenic greenhouse effect. It is estimated that its emissions are responsible for about 60% of the greenhouse effect, and in the countries with particularly strong industry, CO2 emissions can be as high as 80% of the GHG emissions. According to data from NASA, the concentration of these gases in the Earth's atmosphere was 413 ppm in March 2020. The concentration of CO2 in the atmosphere increases mostly due to the burning of fossil fuels (coal, oil, natural gas) and certain industrial processes such as chemical, mineral, metal and other industry; deforestation and land use change, which reduce the planet's absorptive potential, further contribute to it.

Methane (CH4) is the second most important greenhouse gas. It has been estimated that its concentration on Earth has increased by about 145% over recent centuries and has contributed to the increase in the greenhouse effect by about 20%. In developed countries, methane emissions average about 15% of all GHG emissions. Methane is released to the atmosphere through the extraction, transportation, processing and combustion of fossil fuels, as well as through livestock farming (ruminants, manure) and rice cultivation (CH4 is produced by decomposing organic matter). Methane is also released in landfills through the decomposition of organic waste and biomass combustion. A significant proportion of methane emissions in the environment occur during the drainage of wetlands or thawing of permafrost. Despite that methane concentrations in the air are much lower than those of CO2 its global warming potential over 100 years is much higher. One tonne of CH4 released into the atmosphere has a 25–36 times greater greenhouse gas impact than one tonne of CO2.

Meanwhile, nitrous oxide (N2O) is characterised by an even greater global warming potential. It is estimated to be 265–298 times higher over a 100-year period than CO2. In developed industrialised countries, N2O accounts for about 6% of total GHG emissions; its concentration has increased by about 15% since the industrial revolution and contributes by 4–6% to the increase in the greenhouse effect. N2O is naturally released in the oceans and rainforests, but the largest amount is from human activities: agriculture (livestock and fertilisers), fossil fuel combustion and industrial production, as well as biomass combustion.

Fluorinated gases are the only GHGs that result solely from human activities. Despite their extremely low concentrations in the Earth's atmosphere, the global warming potential of these gases is even greater and exceeds the CO2 potential by thousands or even tens of thousands of times. Fluorinated GHGs include hydrofluorocarbons (HFCs) used in refrigerators and freezers, air conditioners, fire extinguishers and aerosol dispensers. Perfluorocarbons (PFCs) are released into the environment during the production of aluminium and semiconductors, while sulphur hexafluoride (SF6) is mainly used in the manufacture of electrical appliances.

"Mitigation" and "adaptation" are different concepts

The main cause of climate change is the constant increase of GHG concentrations in the Earth's atmosphere, largely due to human activities. Therefore, to mitigate climate change it is necessary to reduce or prevent GHG emissions. It is these efforts to reduce or stabilise GHG concentrations in the atmosphere that are referred to as mitigation of climate change.

In the context of climate change, two concepts are inevitable and equally important: "climate change mitigation" and "adaptation to climate change"; therefore, they should not be confused or considered as identical.

Climate change mitigation typically defines actions to reduce and/or stabilise the extent of climate change and is directly related to the reduction of GHG emissions in the Earth's atmosphere. The concept of climate change mitigation is also closely linked to the effort to increase the carbon dioxide (CO2) absorption potential, for example by restoring the largest CO2 absorbent, the so-called lungs of the Earth – its forests. This means that climate change mitigation not only encourages the reduction of GHG emissions, but also increases their absorption.

Therefore, one of the most important goals of climate change mitigation is to reduce the negative impact of human activities and to stabilise the amount of GHG emissions in the Earth's atmosphere so that ecosystems can adapt naturally to climate change.

Meanwhile, the concept of adaptation to climate change defines the actions taken to manage the existing (unavoidable part) effects of global warming; for example, the rapid construction of dams, when the sea level has already inevitably risen.

Climate change mitigation is particularly important in the energy, transport, industry, waste management, agriculture and forestry sectors. In the meantime, climate change mitigation actions aimed at reducing the extent of climate change mainly include the use of new innovative technologies and improvement of old technologies, in order to make them more efficient, as well as the use of low carbon or renewable energy sources (RES). Climate change mitigation is not possible without a global change in human behaviour, including through legal and policy measures.

How to achieve the maximum effect of mitigation of climate change

The study "Projection of Economic Impacts of Climate Change in Sectors of the European Union Based on Bottom-up Analysis" coordinated by the European Commission's Joint Research Centre reveals that global GHG concentrations are already close to 394 ppmv CO2 equivalent (CO2e) and increase by approximately 2 ppmv CO2e each year.

Nevertheless, the results of the impact assessment on economic growth show that wider international cooperation makes it possible to reduce global GHG emissions to levels that would not exceed the average air temperature by more than 2 °C. In addition, if the GHG emission concentration is stabilised, for example, at 450 ppmv CO2e, there would be a 50% probability of not exceeding the 2 °C limit.

In order to implement the mitigation of climate change targets set in the National Strategy for Climate Change Management Policy, Lithuania, together with the countries of the European Union, is committed to reducing GHG emissions by at least 40% by 2030 and 60% by 2040, compared to 1990. Meanwhile, long-term goals specify that, by 2050, GHG emissions should be reduced by 80% compared to emissions of 1990.