Natural and human CO2 emissions: natural carbon cycle
Any emanation discharged by the human or nature falls under this general definition of emissions. However, while natural emissions are difficult to measure accurately, human emissions can be easily accounted for through industry and fossil fuel combustion data. If we classified this emission concept by the negative impact on our environment, we would find that, except for natural events such as the volcanic eruption of La Palma in 2021, human influence is behind most of the current emissions. Carbon dioxide (CO2) is one of the gases that most contributes to global warming, so knowing how much is being emitted by human activities into the Earth atmosphere is vital to curb global warming.
Atmospheric CO2 concentrations have varied naturally and constantly over millions of years of the planet history, within the natural carbon cycle. The CO2 emitted by nature from the oceans and vegetation is offset by natural uptakes from the same oceanic and forest environments (the carbon stores and drains), playing a crucial role in climate regulation and preservation of life on earth. While the oceans and vegetation are able to absorb a portion of human emissions, drains are unable to counteract the accelerating rate of emissions. Accurate assessment of anthropogenic CO2 emissions and their redistribution between the atmosphere, ocean and terrestrial biosphere in an increasingly changing climate is essential to understand better the global carbon cycle, support the development of appropriate climate policies and project future climate change.
Picture 1. The carbon cycle. Source: Global Carbon Budget 2022
Historically, emissions were never viewed negatively because of their temporary or small-scale impact, but since industrialization began in the late 19th century, the rapid increase has become a problem that affects our life-style today and, above all, the future of our planet. In the 1930s-1980s, the drive for large-scale industrialisation led to a global increase in pollutant emissions.
Despite the implementation of commitments such as the Kyoto Protocol or the recent Paris Agreement to reduce CO2 and other greenhouse gas (GHG) emissions, when looking at atmospheric CO2 concentration related to fossil energy and industry, global CO2 emissions rebounded in 2022 to their highest level in history, at 37.5 billion metric tons. The global economy had to recover strongly after the COVID-19 crisis and relied heavily on fossil fuels for that purpose.
One of the main reasons of the global emissions increase has been the economic development of countries around the world, especially in Asia. For example, between 1990 and 2021, CO₂ the emissions in China increased by more than 400 per cent. Emissions in India experienced a similar growth rate during this period.
Figure 1. Global CO2 emissions from 1940-2022. Source: Global Carbon Project 2022
CO2 Emissions in Spain
If we focus on our country, since 1970, emissions have not stopped growing due to the increase in the capacity of the different sectors involved in these emissions, mainly CO2. We can distinguish two main stages with a different growth rate. The first stage, from 1970 to the mid90s, emissions increased from 121 million metric tons to 226 million metric tons. The main reason is the increase in living standards, with an accelerated industrialization and the opening up of European and world markets, also driven by an improvement in the transport infrastructures.
The second stage, driven by the previous sectors and the liberalization of the electricity system, had a greater impact, increasing from 226 M mt to 380.5 Mt in 2007. This increase of more than 160 Mt in just 12 years was halted in its tracks by two main reasons: the global economic crisis and the implementation of national and international policies at the level of awareness of the impact on these emissions.
The Kyoto protocols of 2008 and the European involvement in the reduction of greenhouse gases marked a turning point, with emissions starting to decrease after a year thanks to European initiatives and a series of clear objectives towards decarbonization, where renewable energies began to play a key role in the economy and the industrial sector. The same as the rest of the world, Spain’s CO2 emissions rebounded after the COVID-19 health crisis, returning to a downward trend in 2022.
Figure 2. Annual CO2 emissions from 1970-2022 in Spain Source: Energy report 2022 KPMG
The sectors with the highest CO2 emissions in Spain
If we analyse who is creating the emissions in Spain, we see that the main sectors are transport, industry and agriculture, accounting for almost 64% of the total emitted in 2021. The transport industry, with a 29.6% of the total, is the main source of polluting emissions, mainly due to the fossil nature of most of the fuels used (combustion of petrol and diesel). Despite the promotion of non-polluting transport and the progressive change towards electrification, in Spain we are still a long way from sustainable mobility based on renewable electricity. The need for new electric vehicle charging infrastructures and the development of an industry that lowers the costs of acquiring this technology are the main causes of this low momentum. Despite this, the transport and urban mobility sector is one of the key objectives of sustainable development, where decarbonization is most reinforced, with policies to promote new vehicles and the limitation of high polluting vehicles. An example of that, is the access limitation in certain cities according to the DGT category given to some vehicles, or speed limits if certain pollution levels are exceeded.
In 2021, annual greenhouse gas emissions from the transport sector in Spain increased by 11.6 million tonnes of CO2 equivalent (+15.7 per cent) from 2020. In total, annual greenhouse gas emissions from the transport sector amounted to 85.5 million tonnes of CO2 equivalent in 2021.
Industry in Spain is responsible of the 22,4% total emissions; however, the progressive implementation of renewable energy and emissions policy draw a promising future towards decarbonization.
The amount of annual greenhouse effect gases in the manufacturing field have increased 3,1 tons of CO2 equivalent (+7,11 per cent) in 2021. In total, the annual emissions of greenhouse effect gases increased 46,7 million tons of CO2 equivalent in 2021. This rise was preceded after diminishing greenhouse effect gases in this industry.
We should mention agriculture, with a global emission of 12%. The same with transport, most of the vehicles and machinery used in the collection and primary transformation of the good is working with fossil fuels, and as the related industry involved is less powerful than traditional transportation, changes in technology is more complex linked to expensive cost, what makes any change into electromobility slower. Besides, this changes in costs will affect to the competitivity of the goods prices, aggravated by our export activity in the European Common market.
As the agricultural sector is one of the most vulnerable regarding global warming and climate change effects (desertification and insufficient rainfall), it becomes a challenge for all sectors in Spain including agri-food industry, to stablish new sustainable technological developments with solutions based on their operations decarbonization.
Contrary what happens in other fields as chemical, petrochemical and steelmaker industry, we cannot observe any descent tendency in their emissions, quite the opposite CO2 emissions in agriculture increased between 2012-2021 with a maximum value of 34,7 M Tm C02 in 2020. In 2021 Agriculture emissions reached approximately 34,4 million tons equivalent of CO2.
Figure 3. Emissions distribution of CO2 by sector in 2021 in Spain. Source: MITECO
The fourth sector with the greatest impact in terms of CO2 emissions is the energy industry, with a 10.8% of the total emitted. The liberalization of the energy sector in the 1990s, with a marked impact on the increase in cogeneration and combined cycle plants based on natural gas and fossil fuels, meant that in the mid2000s there was a growing problem in terms of emissions and a strong dependence on external fuels (gas and coal). So at this level in industry, we can differenciate between thermal and electrical generation. At the thermal level, substitution is more complex, as electrification is a costly process and industries are subject to investment cycles and profitability of the technology implemented. At the electricity production level, the factor of change towards energy production with lower emissions is where most progress has been made in recent years. The increase in renewable technologies and the legislative drive towards their development has made it possible to achieve a more sustainable energy sector with less environmental impact.
The main source of greenhouse gas emissions from electricity generation in Spain is combined cycle power plants, which emitted 26.2 million metric tonnes of carbon dioxide equivalent (MtCO₂e) in 2022 and followed by coal-fired power generation, with an additional 7.49 MtCO₂e. Overall, combined cycle power plants account for more than half of Spain’s electricity emissions.
Figure 4. CO2 emissions in electricity generation in 2022 in Spain by technology. Source: MITECO
Comparison of CO2 emissions between Spain and the rest of Europe
Focusing our vision on the European panorama, we can see that Spain is the country that has grown the most in emissions since 1970, but since 21st century it has begun to stabilize its emissions in relation to the rest of the European countries. From 2005, when we saw a peak of 374.9 million tonnes of CO₂, annual greenhouse gas emissions in Spain have fallen by 114 million tonnes of CO₂ equivalent (-30.4 per cent).
Although emissions in Germany have decreased considerably in recent decades, the country still has by far the highest CO₂ emissions in the EU. Germany produced 634.9 million metric tons of carbon dioxide emissions (M Tm CO₂) in 2022.
Although the transition to cleaner energy sources has helped Germany to reduce its carbon footprint, it still relies heavily on coal. Coal is the most polluting fossil fuel and one of the main reasons for Germany’s high emissions level. It is also the case of Poland, where almost 70 percent of the country’s electricity generation is coal-fired. The most polluting of all power plants is the Bełchatów lignite-fired power plant in Poland.
In 2022, Germany produced more than twice the emissions by the following most polluting member states: Italy, Poland, France and Spain. In comparison, we can see how from 2015 onwards, emissions in these countries remain stable, at around 250-300 M Tm CO₂, with Germany’s role as a higher European industry standing out as having higher associated emissions than the rest, but with a favourable decline since its peak in the 1980s, with 1077.8 M Tm CO₂. Compared to 1990, Germany’s annual greenhouse gas emissions decreased by 372.7 million tonnes of CO₂ equivalent (-36.7 per cent).
Figure 5. CO2 emissions 1970-2022, European comparison. Source: Energy Report KPMG
Evolution of CO2 emissions in Spain
Greenhouse gas (GHG) emissions in Spain have been consistently higher between 1995 and 2005, compared to 1990 levels, due to the increase of industrialization in our country and the marked impact of combined cycles based on natural gas and fossil fuels. The highest increase was observed in 2005, when GHG emissions in our country were about 52.5% higher than in 1990.
2020 was the first year that emissions dropped compared to 1990, with levels dropping by about 5.4 per cent. It was mainly due to the Coronavirus pandemic and the restrictions imposed. However, one year later, Spain’s emissions had again risen above 1990 levels. Overall, annual GHG emissions in Spain have followed a mostly downward trend since 2007.
Figure 6. Percentage change in greenhouse gas (GHG) emissions in Spain from 1995 to 2021, relative to 1990 levels. Source: MITECO
According to the latest summary report of the national inventory of atmospheric emissions (March 2023) by MITECO, gross greenhouse gas (GHG) emissions at the national level are estimated for 2021 at 288.8 million tonnes of CO₂-eq, what represents an increase in emissions of 6.1 % compared to the previous year, and a reduction of 6.4 % compared to 2019, in a framework of recovery from the crisis originating from the COVID-19 pandemic.
The total emission level represents an increase of 0.4% compared to 1990 and a decrease of 34.2% compared to 2005.
Comparison of CO2 emissions between Europe and the rest of the world: future developments
If we study in more detail a future analysis of emissions, with the neutrality objectives foreseen for Europe in 2050, we can see globally, that emissions will not stop growing until they reach their maximum in 2025 with 36,000 M tm of CO2. Countries with a huge production capacity, such as China (with an industry based on coal consumption) of 31% of the total in 2021, or emerging countries such as India do not have the same sensitivity to change in their production models and technologies with a focus on combating climate change.
This trend will change in the future, as the progressive depletion of fossil fuels and cheaper technology will lead us to a scenario in 2050 with global emissions levels estimated at around 22,000 M tm of CO2, below the level in 2000, with around 25,500 M tm. A feeling of hope at the end of the tunnel.
Figure 7. Global CO2 emissions in 2000 and estimate to 2050. Regional breakdown. Source: Enerdata
Challenges for the future: Emission neutrality towards 2050
As part of the Paris Agreement, 195 countries have committed to reduce their greenhouse gas (GHG) emissions. In the European Union, there is a firm commitment to reduce GHG emissions by 80% to 95% of 1990 levels by 2050. To learn more about global initiatives to achieve these decarbonisation goals, I recommend reading the article by our colleague Javier Taibo Pose on the Norvento ´s blog. https://www.norvento.com/blog/objetivos-de-descarbonizacion/
Scientific challenges: CO2 monitoring through remote sensing
The Copernicus Project is one of the most innovative Earth Observation (EO) programmes. This initiative between the European Commission and the European Space Agency (ESA) currently has a fleet of satellites called Sentinel (Sentinel 1, Sentinel 2, Sentinel 3, and Sentinel 5P) that operate around the Earth recording environmental information and, above all, data linked to the effects of climate change. Sentinel 5P allows atmospheric monitoring of the Earth, with indicators of the concentration and distribution of pollutants in the atmosphere such as CO, SO2, N02 or CH4, among others.
Sentinel 2 provides a high-resolution satellite imagery. They are used to monitor the Earth’s surface in order to keep track of vegetation cover, water bodies and coastal areas.
Sentinel satellites began work in mid2014. Since then, multiple Sentinel variants have been launched to date to perform different functions. In 2026, ESA Copernicus is expected to launch the Sentinel 7 mission into space, which will be able to differentiate man-made CO2 emissions from nature’s emissions, a major progress to face climate change crisis.
This European CO2 monitoring mission will be the first satellite mission capable to measure anthropogenic emissions as distinct from natural carbon cycle emissions, monitoring not only its concentration in the atmosphere but also the sources of emissions.
Picture 2. Sentinel 2 satellite image of the 2021 La Palma volcanic eruption. Source: ESA Copernicus