Greenhouse gases (GHGs) are vital components of Earth's atmosphere that regulate the planet's temperature by trapping heat — a phenomenon known as the greenhouse effect. They function much like a thermal blanket, maintaining the warmth necessary to sustain life on Earth. However, human activities have significantly increased the concentrations of these gases, leading to global warming and climate change.

The main greenhouse gases

Several types of greenhouse gases contribute to the greenhouse effect, each originating from different sources and possessing unique properties.

Carbon dioxide (CO₂)

Carbon dioxide is the most prevalent greenhouse gas produced by human activities. It is primarily released through the burning of fossil fuels such as coal, oil, and natural gas for energy and transportation. Since the Industrial Revolution, atmospheric CO₂ concentrations have risen by about 50%, increasing from approximately 280 parts per million (ppm) in pre-industrial times to over 419 ppm as of 2021. This unprecedented rise is a significant driver of current climate change.

Methane (CH₄)

Methane is a potent greenhouse gas with a global warming potential more than 25 times that of CO₂ over a 100-year period. It is primarily produced through agricultural activities such as livestock farming and rice cultivation, as well as from the decomposition of organic waste in landfills and emissions from oil and gas extraction. Methane concentrations have more than doubled since pre-industrial times, contributing significantly to climate warming.

Nitrous oxide (N₂O)

Nitrous oxide is mainly emitted from agricultural practices, especially the use of synthetic and organic fertilizers that enhance nitrogen availability in soils. It is also released during industrial processes and combustion of fossil fuels and biomass. N₂O has a global warming potential approximately 298 times that of CO₂ over a 100-year period, making it a significant contributor despite its lower concentration.

Water vapor (H₂O)

Water vapor is the most abundant greenhouse gas in the atmosphere, though it is not directly emitted by human activities. Its concentration increases as the atmosphere warms because warmer air can hold more moisture. This creates a positive feedback loop: as temperatures rise due to other greenhouse gases, water vapor levels increase, which in turn amplifies the warming effect.

How greenhouse gases work

The greenhouse effect involves the absorption and re-emission of infrared radiation by greenhouse gases, leading to the warming of the Earth's surface and lower atmosphere.

The basic mechanism

Solar radiation from the Sun, primarily in the form of visible light and ultraviolet radiation, passes through the Earth's atmosphere and reaches the surface. The Earth's surface absorbs this energy, warming up in the process, and then re-emits it as longwave infrared radiation. Greenhouse gases in the atmosphere absorb some of this infrared radiation and re-emit it in all directions, including back toward the surface. This process traps heat in the lower atmosphere, raising the planet's average temperature. Without this natural greenhouse effect, Earth's average temperature would be about –18°C (0°F) instead of the current average of approximately 15°C (59°F).

Specific mechanisms of different greenhouse gases

Each greenhouse gas absorbs infrared radiation at specific wavelengths, contributing differently to the greenhouse effect.

• Carbon dioxide (CO₂) absorbs infrared radiation at wavelengths around 15 micrometers and can remain in the atmosphere for centuries, making it a significant long-term driver of climate change.

• Methane (CH₄) absorbs infrared radiation at wavelengths near 7.66 micrometers. Although methane has a shorter atmospheric lifetime — about 12 years — it is over 80 times more effective than CO₂ at trapping heat over a 20-year period.

• Nitrous oxide (N₂O) absorbs infrared radiation at wavelengths around 7.8 micrometers. With an atmospheric lifetime of about 114 years, it has a long-term impact on warming.

• Water vapor (H₂O) absorbs infrared radiation across a wide range of wavelengths. Its concentration is directly related to temperature, leading to a feedback loop that amplifies warming caused by other greenhouse gases.

The enhanced greenhouse effect

Human activities have intensified the natural greenhouse effect by increasing greenhouse gas concentrations in the atmosphere.

Increased concentrations: Since the Industrial Revolution, atmospheric concentrations of CO₂, methane, and nitrous oxide have risen sharply due to activities such as fossil fuel combustion, deforestation, and industrial processes. For instance, CO₂ levels have increased from about 280 ppm in the pre-industrial era to over 419 ppm in 2021.

Positive feedback loops: Warming temperatures can trigger processes that release additional greenhouse gases, creating positive feedback loops. For example, thawing permafrost in Arctic regions releases methane and CO₂ previously trapped in frozen soils, further enhancing warming.

Climate sensitivity: Climate sensitivity refers to the amount of global temperature increase expected from a doubling of CO₂ concentrations compared to pre-industrial levels. Current estimates suggest a likely range of 2.5°C to 4°C, with a best estimate of around 3°C. Understanding climate sensitivity is crucial for predicting future climate impacts and informing policy decisions.

Measuring and monitoring

Scientists use various methods to measure greenhouse gases and assess their impact on the climate. Understanding the mechanisms and impacts of greenhouse gases is essential for developing effective strategies to mitigate climate change.

Direct atmospheric measurements: Monitoring stations worldwide, such as the Mauna Loa Observatory in Hawaii, continuously measure atmospheric concentrations of greenhouse gases. These measurements provide critical data on how concentrations change over time.

Satellite observations: Satellites equipped with spectrometers measure the Earth's energy balance and the distribution of greenhouse gases in the atmosphere. They can detect changes in outgoing longwave radiation, offering insights into how the greenhouse effect is altering.

Ice core analysis: By examining air bubbles trapped in ice cores from Antarctica and Greenland, scientists reconstruct past atmospheric compositions, extending back hundreds of thousands of years. This information helps contextualize current greenhouse gas levels within historical variations.

Spectroscopy: Spectroscopic techniques identify specific greenhouse gases by their unique absorption spectra, enabling precise measurements of atmospheric composition and the study of gas interactions with radiation.

Kazakhstan: a case study in greenhouse gas emissions

Kazakhstan offers a compelling example of the challenges and efforts associated with greenhouse gas emissions in a developing economy.

Emissions profile

In 2021, Kazakhstan's total greenhouse gas emissions were approximately 338 million metric tons of CO₂ equivalent, marking an increase from previous years. The energy sector is the largest contributor, accounting for about 82% of the country's total emissions in 2015. This high percentage reflects Kazakhstan's heavy reliance on fossil fuels, particularly coal, for electricity generation and industrial processes.

Per capita, Kazakhstan's emissions are relatively high, standing at around 17.3 metric tons of CO₂ equivalent per person as of 2022. This ranks the country among the top emitters on a per capita basis, highlighting its energy-intensive economy.

Kazakhstan contributes approximately 0.6% of global greenhouse gas emissions, making it one of the top 30 emitters worldwide. While this may seem small in global terms, it is significant for a nation with a population of about 19 million.

Climate change impacts in Kazakhstan

The effects of increased greenhouse gas emissions are already apparent in Kazakhstan.

Rising temperatures: Between 1941 and 2020, the average annual temperature in Kazakhstan increased by about 2°C, exceeding the global average temperature rise. This warming trend affects agriculture, water resources, and ecosystems, potentially threatening food security and livelihoods.

Extreme weather events: Kazakhstan has experienced an increase in extreme weather events, including droughts, floods, and heatwaves. These events have substantial social and economic impacts, damaging infrastructure and affecting public health.

Glacial retreat and water resources: The country's glaciers are retreating, which threatens water supplies for agriculture and human consumption in downstream regions. Reduced glacial meltwater can lead to water shortages during dry seasons.

Desertification: Increasing temperatures and changing precipitation patterns contribute to desertification, impacting arable land and biodiversity.

Mitigation efforts

Kazakhstan has implemented several strategies to reduce its greenhouse gas emissions and address climate change.

Emissions trading system: In 2021, Kazakhstan adopted a new Environmental Code that includes an emissions trading system. This market-based approach aims to incentivize emission reductions in the industrial sector by setting caps and allowing trading of emission allowances.

Renewable energy expansion: The country is increasing its share of renewable energy sources. By 2021, Kazakhstan had over 115 renewable energy facilities in operation, including wind, solar, and hydropower plants. The government aims to produce 15% of its electricity from renewable sources by 2030 and 50% by 2050.

Transition to natural gas: Kazakhstan is transitioning from coal to natural gas for electricity generation and heating. Projects like the "Saryarka" gas pipeline are expanding access to natural gas, particularly in regions previously reliant on coal. This shift reduces carbon intensity and improves air quality.

International commitments: Kazakhstan has pledged to achieve carbon neutrality by 2060 as part of its commitment to the Paris Agreement. The country submitted its updated Nationally Determined Contribution (NDC) in 2021, aiming to reduce greenhouse gas emissions by 15% by 2030 compared to 1990 levels.

Energy efficiency initiatives: Efforts are underway to improve energy efficiency across various sectors, including industry, transportation, and buildings. This includes adopting new technologies, enhancing regulations, and promoting public awareness to reduce energy consumption.

As global efforts to combat climate change intensify, countries like Kazakhstan will play a crucial role. Their ability to transition to cleaner energy sources and implement effective climate policies is vital in the global fight against climate change. Continued international cooperation, technological innovation, and investment in sustainable practices are essential to support these transitions.