Carbon monitoring as part of greenhouse gas monitoring refers to tracking how much carbon dioxide or methane is produced by a particular activity at a particular time. For example, it may refer to tracking methane emissions from agriculture, or carbon dioxide emissions from land use changes, such as deforestation, or from burning fossil fuels, whether in a power plant, automobile, or other device. Because carbon dioxide is the greenhouse gas emitted in the largest quantities, and methane is an even more potent greenhouse gas, monitoring carbon emissions is widely seen as crucial to any effort to reduce emissions and thereby slow climate change.
Monitoring carbon emissions is key to the cap-and-trade program currently being used in Europe, as well as the one in California, and will be necessary for any such program in the future, like the Paris Agreement. The lack of reliable sources of consistent data on carbon emissions is a significant barrier to efforts to reduce emissions. [1]
Sources of such emissions data include:
Carbon Monitoring for Action (CARMA) [2] – An online database provided by the Center for Global Development, that includes plant-level emissions for more than 50,000 power plants and 4,000 power companies around the world, as well as the total emissions from power generation of countries, provinces (or states), and localities. Carbon emissions from power generation account for about 25 percent of global CO2 emissions. [3]
ETSWAP – An emissions monitoring and reporting system currently in use in the UK and Ireland, which enables relevant organizations to monitor, verify and report carbon emissions, as is required by the EU ETS (European Union Emissions Trading Scheme). [4]
FMS – A system used in Germany to record and calculate annual emission reports for plant operators subject to the EU ETS. [5]
Carbon emissions are also monitored on a global scale (with data for countries, sectors, companies, activities, etc).
Several organisations provide annual updates to the remaining carbon budget, including the Global Carbon Project, the Mercator Research Institute on Global Commons and Climate Change (MCC) [8] and the CONSTRAIN project. [9] In March 2022, before formal publication of the "Global Carbon Budget 2021" preprint, [7] scientists reported, based on Carbon Monitor [10] (CM) data, that after COVID-19-pandemic-caused record-level declines in 2020, global CO2 emissions rebounded sharply by 4.8% in 2021, indicating that at the current trajectory, the carbon budget for a ⅔ likelihood for limiting warming to 1.5 °C would be used up within 9.5 years. [11]
In April 2022, the now reviewed and officially published The Global Carbon Budget 2021 concluded that fossil CO2 emissions rebounded [12] from pandemic levels by around +4.8% relative to 2020 emissions – returning to 2019 levels.
It identifies three major issues for improving reliable accuracy of monitoring, shows that China and India surpassed 2019 levels (by 5.7% and 3.2%) while the EU and the US stayed beneath 2019 levels (by 5.3% and 4.5%), quantifies various changes and trends, for the first time provides models' estimates that are linked to the official country GHG inventories reporting, and suggests that the remaining carbon budget at 1. Jan 2022 for a 50% likelihood to limit global warming to 1.5 °C (albeit a temporary exceedence is to be expected) is 120 GtC (420 GtCO2) – or 11 years of 2021 emissions levels. [7]
This does not mean that likely 11 years remain to cut emissions but that if emissions stayed the same, instead of increasing like in 2021, 11 years of constant GHG emissions would be left in the hypothetical scenario that all emissions suddenly ceased in the 12th year. (The 50% likelihood may be describable as a kind of minimum plausible deniability requirement as lower likelihoods would make the 1.5 °C goal "unlikely".) Moreover, other trackers show (or highlight) different amounts of carbon budget left, such as the MCC, which as of May 2022 shows "7 years 1 month left" [8] and different likelihoods have different carbon budgets: a 83% likelihood would mean 6.6 ±0.1 years left (ending in 2028) according to CM data. [11]
In October 2023 a group of researchers updated the carbon budget including the CO2 emitted at 2020-2022 and new findings about the role of reduced presence of polluting particles in the atmosphere. [13] They found we can emit 250 GtCO2 or 6 years of emissions at current level starting from January 2023, for having a 50% chance to stay below 1.5 degrees. For reaching this target humanity will need to zero CO2 emissions by the year 2034. To have a 50% chance of staying below 2 degrees humanity can emit 1220 GtCO2 or 30 years of emissions at current level. [14] [15]Almost all climate change regulations in the US have stipulations to reduce carbon dioxide and methane emissions by economic sector, so being able to accurately monitor and assess these emissions is crucial to being able to assess compliance with these regulations. [16] Emissions estimates at the national level have been shown to be fairly accurate, but at the state level there is still much uncertainty. [16] As part of the Paris Agreement, the US pledged to "decrease its GHG emissions by 26–28 % relative to 2005 levels by 2025 as part of the Paris Agreement negotiated at COP21. [17] To comply with these regulations, it is necessary to quantify emissions from specific source sectors. [16] A source sector is a sector of the economy that emits a particular greenhouse gas, i.e. methane emissions from the oil and gas industry, which the US has pledged to decrease by 40–45 % relative to 2012 levels by 2025 [18] as a more specific action towards achieving its Paris Agreement contribution.
Currently, most governments, including the US government, estimate carbon emissions with a "bottom-up" approach, using emission factors which give the rate of carbon emissions per unit of a certain activity, and data on how much of that activity has taken place. [16] For example an emission factor can be determined for the amount of carbon dioxide emitted per gallon of gasoline burned, and this can be combined with data on gasoline sales to get an estimate of carbon emissions from light duty vehicles. [19] Other examples include determining the number of cows in various locations, or the mass of coal burned at power plants, and combining these data with the appropriate emissions factors to estimate methane or carbon dioxide emissions. Sometimes "top-down" methods are used to monitor carbon emissions. These involve measuring the concentration of a greenhouse gas in the atmosphere and using these measurements to determine the distribution of emissions which caused the resulting concentrations. [16]
Accounting by sector can be complicated when there is a chance of double counting. For example, when coal is gasified to produce synthetic natural gas, which is then mixed with natural gas and burned at a natural gas powered power plant, if accounted for as part of the natural gas sector, this activity must be subtracted from the coal sector and added to the natural gas sector in order to be properly accounted for. [16]
NASA Carbon Monitoring System (CMS) is a climate research program [20] created by a congressional order in 2010 that provides grants of about $500,000 a year for climate research that measure carbon dioxide and methane emissions. [20] Using instruments in satellites and airplanes CMS funded research projects provide data to the United States and other countries that help track progress of individual nations regarding their Paris climate emission cuts agreements. For example, CMS projects measured carbon emissions from deforestation and forest degradation. CMS "stitch[ed] together observations of sources and sinks into high-resolution models of the planet's flows of carbon." [21] The 2019 federal budget specifically assured funding for CMS, [20] after the Trump administration proposed to end funding. [21] [22]
As part of the European Union Emission Trading Scheme (EU-ETS), [23] carbon monitoring is necessary in order to ensure compliance with the cap-and-trade program. This carbon monitoring program has three main components: atmospheric carbon dioxide measurements, bottom-up carbon dioxide emissions maps, and an operational data-assimilation system to synthesize the information from the first two components. [24]
The top-down, atmospheric measurement approach involves satellite data and in-situ measurements of carbon dioxide concentrations, as well as atmospheric models that model atmospheric transport of carbon dioxide. These have limited ability to determine carbon dioxide emissions at highly resolved spatial scales and can typically not represent finer scales than a 1 km grid. The models also must resolve the fluxes of carbon dioxide from anthropogenic sources like fossil fuel burning, and from natural interactions like terrestrial ecosystems and the ocean. [24] Due to the complexities and limitations of the top-down approach, the EU combines this method with a bottom-up approach.
The current bottom-up data are based on information that is self-reported by emitters in the trading scheme. However, the EU is trying to improve this information source and has proposed plans for improved bottom-up emissions maps, which will have greatly improved spatial resolution and near real-time updates. [24]
An operational data system to combine the information gathered from the two aforementioned sources is also planned. [25] [26] The EU hopes that by the 2030s, this will be operational and enable a highly sophisticated carbon monitoring program across the European Union. [24]
Satellites can be used to monitor carbon dioxide concentrations from orbit. [27] NASA currently operates a satellite named the Orbiting Carbon Observatory-2 (OCO-2), and Japan operates their own satellite, the Greenhouse Gases Observing Satellite (GOSAT). [27] These satellites can provide valuable information to fill in data gaps from emission inventories. The OCO-2 measured a strong flux of carbon dioxide over the Middle East, which had not been represented in emissions inventories, indicating that important sources were being neglected in bottom-up estimates of emissions. [28] These satellites currently have errors of about 0.5% in their measurements, but the American and Japanese teams hope to reduce the errors to 0.25%. China recently launched their own satellite to monitor greenhouse gas concentrations on Earth, the TanSat, in December 2016. [29] It currently has a three-year mission planned and will take readings of carbon dioxide concentrations every 16 days. [29]
An emission intensity is the emission rate of a given pollutant relative to the intensity of a specific activity, or an industrial production process; for example grams of carbon dioxide released per megajoule of energy produced, or the ratio of greenhouse gas emissions produced to gross domestic product (GDP). Emission intensities are used to derive estimates of air pollutant or greenhouse gas emissions based on the amount of fuel combusted, the number of animals in animal husbandry, on industrial production levels, distances traveled or similar activity data. Emission intensities may also be used to compare the environmental impact of different fuels or activities. In some case the related terms emission factor and carbon intensity are used interchangeably. The jargon used can be different, for different fields/industrial sectors; normally the term "carbon" excludes other pollutants, such as particulate emissions. One commonly used figure is carbon intensity per kilowatt-hour (CIPK), which is used to compare emissions from different sources of electrical power.
Climate change mitigation (or decarbonisation) is action to limit the greenhouse gases in the atmosphere that cause climate change. Climate change mitigation actions include conserving energy and replacing fossil fuels with clean energy sources. Secondary mitigation strategies include changes to land use and removing carbon dioxide (CO2) from the atmosphere. Current climate change mitigation policies are insufficient as they would still result in global warming of about 2.7 °C by 2100, significantly above the 2015 Paris Agreement's goal of limiting global warming to below 2 °C.
A carbon footprint (or greenhouse gas footprint) is a calculated value or index that makes it possible to compare the total amount of greenhouse gases that an activity, product, company or country adds to the atmosphere. Carbon footprints are usually reported in tonnes of emissions (CO2-equivalent) per unit of comparison. Such units can be for example tonnes CO2-eq per year, per kilogram of protein for consumption, per kilometer travelled, per piece of clothing and so forth. A product's carbon footprint includes the emissions for the entire life cycle. These run from the production along the supply chain to its final consumption and disposal.
Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide, from burning fossil fuels such as coal, oil, and natural gas, is one of the most important factors in causing climate change. The largest emitters are China followed by the United States. The United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies. Emissions from human activities have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but have been consistent among all greenhouse gases. Emissions in the 2010s averaged 56 billion tons a year, higher than any decade before. Total cumulative emissions from 1870 to 2022 were 703 GtC, of which 484±20 GtC from fossil fuels and industry, and 219±60 GtC from land use change. Land-use change, such as deforestation, caused about 31% of cumulative emissions over 1870–2022, coal 32%, oil 24%, and gas 10%.
Carbon pricing is a method for governments to mitigate climate change, in which a monetary cost is applied to greenhouse gas emissions. This is done to encourage polluters to reduce fossil fuel combustion, the main driver of climate change. A carbon price usually takes the form of a carbon tax, or an emissions trading scheme (ETS) that requires firms to purchase allowances to emit. The method is widely agreed to be an efficient policy for reducing greenhouse gas emissions. Carbon pricing seeks to address the economic problem that emissions of CO2 and other greenhouse gases are a negative externality – a detrimental product that is not charged for by any market.
In Earth's atmosphere, carbon dioxide is a trace gas that plays an integral part in the greenhouse effect, carbon cycle, photosynthesis and oceanic carbon cycle. It is one of three main greenhouse gases in the atmosphere of Earth. The concentration of carbon dioxide in the atmosphere reach 427 ppm (0.04%) in 2024. This is an increase of 50% since the start of the Industrial Revolution, up from 280 ppm during the 10,000 years prior to the mid-18th century. The increase is due to human activity.
The United States produced 5.2 billion metric tons of carbon dioxide equivalent greenhouse gas (GHG) emissions in 2020, the second largest in the world after greenhouse gas emissions by China and among the countries with the highest greenhouse gas emissions per person. In 2019 China is estimated to have emitted 27% of world GHG, followed by the United States with 11%, then India with 6.6%. In total the United States has emitted a quarter of world GHG, more than any other country. Annual emissions are over 15 tons per person and, amongst the top eight emitters, is the highest country by greenhouse gas emissions per person.
Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. What distinguishes them from other gases is that they absorb the wavelengths of radiation that a planet emits, resulting in the greenhouse effect. The Earth is warmed by sunlight, causing its surface to radiate heat, which is then mostly absorbed by greenhouse gases. Without greenhouse gases in the atmosphere, the average temperature of Earth's surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F).
Atmospheric methane is the methane present in Earth's atmosphere. The concentration of atmospheric methane is increasing due to methane emissions, and is causing climate change. Methane is one of the most potent greenhouse gases. Methane's radiative forcing (RF) of climate is direct, and it is the second largest contributor to human-caused climate forcing in the historical period. Methane is a major source of water vapour in the stratosphere through oxidation; and water vapour adds about 15% to methane's radiative forcing effect. The global warming potential (GWP) for methane is about 84 in terms of its impact over a 20-year timeframe, and 28 in terms of its impact over a 100-year timeframe.
Greenhouse gas monitoring is the direct measurement of greenhouse gas emissions and levels. There are several different methods of measuring carbon dioxide concentrations in the atmosphere, including infrared analyzing and manometry. Methane and nitrous oxide are measured by other instruments. Greenhouse gases are measured from space such as by the Orbiting Carbon Observatory and networks of ground stations such as the Integrated Carbon Observation System.
In 2021, net greenhouse gas (GHG) emissions in the United Kingdom (UK) were 427 million tonnes (Mt) carbon dioxide equivalent, 80% of which was carbon dioxide itself. Emissions increased by 5% in 2021 with the easing of COVID-19 restrictions, primarily due to the extra road transport. The UK has over time emitted about 3% of the world total human caused CO2, with a current rate under 1%, although the population is less than 1%.
The atmospheric carbon cycle accounts for the exchange of gaseous carbon compounds, primarily carbon dioxide, between Earth's atmosphere, the oceans, and the terrestrial biosphere. It is one of the faster components of the planet's overall carbon cycle, supporting the exchange of more than 200 billion tons of carbon in and out of the atmosphere throughout the course of each year. Atmospheric concentrations of CO2 remain stable over longer timescales only when there exists a balance between these two flows. Methane, Carbon monoxide (CO), and other human-made compounds are present in smaller concentrations and are also part of the atmospheric carbon cycle.
Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% of methane released globally was from human activities, while natural sources contributed about 40%. Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.
A carbon budget is a concept used in climate policy to help set emissions reduction targets in a fair and effective way. It examines the maximum amount of carbon dioxide emissions that would result in limiting global warming to a given level". It can be expressed relative to the pre-industrial period. In this case, it is the total carbon budget. Or it can be expressed from a recent specified date onwards. In that case it is the remaining carbon budget.
The amount of greenhouse gas emissions from agriculture is significant: The agriculture, forestry and land use sectors contribute between 13% and 21% of global greenhouse gas emissions. Emissions come from direct greenhouse gas emissions. And from indirect emissions. With regards to direct emissions, nitrous oxide and methane makeup over half of total greenhouse gas emissions from agriculture. Indirect emissions on the other hand come from the conversion of non-agricultural land such as forests into agricultural land. Furthermore, there is also fossil fuel consumption for transport and fertilizer production. For example, the manufacture and use of nitrogen fertilizer contributes around 5% of all global greenhouse gas emissions. Livestock farming is a major source of greenhouse gas emissions. At the same time, livestock farming is affected by climate change.
China's total greenhouse gas emissions are the world's highest of any country, accounting for 35% of the world's total according to the International Energy Agency. The country's per capita greenhouse gas emissions are the 34th highest of any country, as of 2023.
Greenhouse gas emissionsbyRussia are mostly from fossil gas, oil and coal. Russia emits 2 or 3 billion tonnes CO2eq of greenhouse gases each year; about 4% of world emissions. Annual carbon dioxide emissions alone are about 12 tons per person, more than double the world average. Cutting greenhouse gas emissions, and therefore air pollution in Russia, would have health benefits greater than the cost. The country is the world's biggest methane emitter, and 4 billion dollars worth of methane was estimated to leak in 2019/20.
The cumulative contributions to the global carbon budget from 1850. The carbon imbalance represents the gap in our current understanding of sources & sinks. ... Source: Friedlingstein et al 2021; Global Carbon Project 2021