Solar radiation and the greenhouse effect: the real driving force of global warming

Solar radiation and the greenhouse effect are an inseparable pair when we talk about global warming and its profound consequences for our planet. These natural phenomena, although they originally made life on Earth possible thanks to the temperate climate they generated, have been abruptly altered in recent decades by human intervention, generating effects that are already evident in our environment and quality of life.

Understanding how solar radiation, greenhouse gases and human activities interact is essential. to address the challenges of climate change, propose real solutions, and anticipate the impacts on various social, economic, and environmental sectors. This article delves thoroughly and comprehensively into all the key aspects of understanding the relationship between solar radiation, the greenhouse effect, and global warming, based on the most relevant and up-to-date information.

Global Warming: Causes, Effects, and Mitigation Measures

Solar radiation: the energy that moves everything

Solar radiation is the energy engine of the Earth and of the entire atmosphere, oceans and biosphere. More than 99,9% of the energy that drives the planet's natural processes comes from the Sun. However, this enormous amount of energy does not reach the Earth's surface unhindered: as it travels through the atmosphere, solar radiation is subjected to various physical phenomena that reduce its intensity and affect the planet's temperature.

Solar radiation attenuation occurs through three main mechanisms:

Dispersion: Solar radiation, when interacting with gas molecules and suspended particles in the atmosphere, is deflected in multiple directions. This phenomenon explains everyday phenomena such as the blue color of the sky and the reddish hues of sunrise and sunset. Furthermore, scattering depends strongly on wavelength, acting most intensely on short wavelengths (blue and violet).
Reflection (Albedo): A fraction of solar radiation is reflected back into space by clouds, land surfaces (especially clear, smooth ones like ice or snow), oceans, and atmospheric particles. The percentage reflected is called albedo, and its global average is around 30%. Areas such as deserts or the poles, with clear or snow-covered surfaces, reflect much more than forests or oceans.
Absorption: Another portion of solar radiation is absorbed by atmospheric gases and suspended particles (aerosols). For example, ozone absorbs ultraviolet radiation, and water vapor and carbon dioxide are strong absorbers of infrared radiation, thus selectively warming the atmosphere.

The energy that finally reaches the Earth's surface is only a part of the total emitted by the Sun: Approximately 50% of the energy reaches the surface after these processes, while the rest is reflected or absorbed before reaching the ground. Of this energy, most heats the surface and the oceans, and drives evaporation, hydrological cycles, and photosynthesis.

Differences between climate change and global warming

The greenhouse effect: the essential thermal blanket for life

The greenhouse effect is a natural physical phenomenon that has allowed the existence of life on Earth. It consists of retaining part of the heat emitted by the Earth's surface, preventing all of that energy from being lost to outer space. This thermal retention is due to the action of the so-called greenhouse gases (GHG), naturally present in the atmosphere:

Carbon dioxide (CO₂): Released by organic processes, volcanic eruptions, and, overwhelmingly today, by the burning of fossil fuels.
Methane (CH₄): Generated by ruminant animals, decomposition of organic matter and agricultural and industrial activities.
Nitrous oxide (N₂EITHER): Natural emissions and, to a large extent, from the use of nitrogen fertilizers in agriculture.
Water steam: The most abundant and efficient greenhouse gas, also acting as a climate feedback factor.
Fluorinated gases: Industrial compounds (hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, among others) that, although less present, have a disproportionately high impact on the thermal balance.

The functioning of the greenhouse effect can be explained in three key phases:

Solar radiation passes through the atmosphere and heats the Earth's surface.
When the Earth's surface heats up, it re-emits part of this energy in the form of infrared radiation (heat).
Greenhouse gases absorb some of this infrared radiation and re-emit it in all directions, trapping heat and keeping the average global temperature at around 15°C. Without this natural "blanket," temperatures would drop by more than 33°C, making life as we know it impossible.

This thermal retention capacity is what keeps the Earth in a zone suitable for life—neither too cold nor too hot—but it is also at the heart of the current problem of global warming.

natural atmospheric particles and global warming

Influence of atmospheric particles on global warming

The imbalance: anthropogenic increase in greenhouse gases

Over the past few decades, human activity has driven greenhouse gas concentrations in the atmosphere to levels never recorded in modern history. This artificial increase has intensified the natural greenhouse effect, preventing some of the Earth's radiation from escaping into space and causing a sustained increase in the average global temperature.

What are the most significant human sources of greenhouse gas emissions?

burning fossil fuels (coal, oil, and natural gas) in electricity generation, heating, and transportation. This sector is primarily responsible for CO emissions₂, covering the majority of global emissions.
Industry and manufacturing processes, which use fossil fuels for both heat and energy production, and also generate fluorinated gases and CO₂ in chemical reactions, such as in the manufacture of cement, steel or chemicals.
Deforestation and land use change, both for agriculture and for pastures. Cutting down or burning forests releases stored carbon and also reduces the planet's ability to absorb CO₂ from the atmosphere, aggravating the problem.
Intensive livestock farming, which produces significant amounts of methane from ruminant metabolism and, to a lesser extent, from manure and agricultural waste management.
The extensive use of nitrogen fertilizers in agriculture, which increases nitrous oxide emissions.
Transport, especially those using petroleum derivatives. Vehicles, ships, and airplanes account for a growing percentage of global emissions, especially carbon dioxide and associated pollutants.
Domestic consumption and lifestyles: Home energy use, the purchase of manufactured goods, urban travel, and waste generation add up to a significant percentage of the global emissions footprint.

Since the Industrial Revolution, CO emissions₂ have grown by around 40%, exceeding values of 414 ppm in 2023, according to atmospheric observatories. Methane and fluorinated gases have followed similar trends, multiplying their presence compared to pre-industrial levels.

Impact of global warming: beyond rising temperatures

The global rise in temperatures caused by the strengthening of the greenhouse effect is only the most visible aspect of a much broader range of consequences. Among the most worrying impacts are:

Accelerated melting of the poles and glaciers: Rising temperatures have caused the ice mass in Greenland, Antarctica, and high mountain areas to retreat at an alarming rate. This directly contributes to rising sea levels.
Rise in mean sea level: Scientific forecasts estimate a rise of between 24 and 63 centimeters by the end of the century, putting coastal cities and low-lying islands at serious risk.
Extreme weather events: More intense storms, heat waves, prolonged droughts, hurricanes, and increasingly frequent torrential rains. Recent examples demonstrate that weather instability is already affecting agricultural production, water availability, and the safety of millions of people.
Alterations in ecosystems and biodiversity: Many animal and plant species are forced to migrate, adapt, or become extinct due to changes in their natural habitat. This leads to biodiversity loss and ecological imbalances that are difficult to reverse.
Impacts on human health: Global warming facilitates the spread of vector-borne diseases (such as dengue and malaria), worsens air quality, exacerbates heat-related epidemics, and puts healthcare systems at risk, especially in vulnerable areas.
Displacement of people (climate migration): Millions of people have already fled their homes due to floods, droughts, or extreme events, a phenomenon that international agencies predict will worsen in the coming decades.

No less relevant is the economic and social impact: The destruction of infrastructure, the loss of crops, the scarcity of resources such as water and fertile soil, and the geopolitical instability resulting from these changes generate multi-billion-dollar costs and exacerbate inequalities between regions and countries.

Clean air and global warming: an interconnected dilemma

Operation of the radiative balance: incoming and outgoing energy

The Earth's radiative balance is the balance between all the energy received by the planet and that returned to space. This balance is what determines the global climate and generates, for example, the variability of temperatures between the equator and the poles.

Every year, the solar energy falling on Earth's atmosphere is equivalent to more than 15,000 times the energy consumed by humanity from fossil and nuclear sources. However, this energy flow undergoes a series of transformations and diversions:

Thirty percent of total solar radiation is reflected back into space due to the albedo of the atmosphere, clouds, ice, and other light-colored surfaces. This does not contribute to global warming.
The remaining 70% is absorbed: 47% warms the surface, oceans, and soil, and 23% is used in water evaporation, which in turn contributes to climate cycles.
The energy absorbed by the Earth's surface is transformed into heat, part of which is transferred to the adjacent air by conduction and convection, contributing to atmospheric dynamics.
Most of the absorbed energy is re-emitted as longwave infrared radiation from the surface, some of which escapes into space and some of which is absorbed and re-emitted by greenhouse gases.

Of the 342 W/m² that enter on average at the top of the atmosphere, only 168 W/m² actually reach the Earth's surface due to the combined effect of reflection and absorption. The difference between the radiation emitted by the Earth and that which escapes into space represents the energy trapped by the greenhouse effect.

The Caspian Sea and Global Warming: An Impending Crisis

Role of economic and social sectors in emissions

Economic activities and development models are directly related to the generation of greenhouse gases. Analyzing the key sectors, it can be observed that:

Energy and industrial sector: Energy production from fossil fuels accounts for the bulk of emissions, followed by industrial activities such as iron and steel, cement, chemical production, and petroleum refining.
Shipping cost: 24% of global COXNUMX emissions₂ Energy-related expenditures come from transport, primarily road transport. Increased motorization and urbanization exacerbate this trend.
Building and urban environments: Both residential and commercial buildings consume more than half of the world's electricity, generating emissions from the use of coal, gas, and other fuels for heating, air conditioning, and equipment.
Agriculture, livestock and deforestation: The conversion of forests to cropland or pasture, the use of fertilizers, and intensive livestock farming not only emit greenhouse gases but also reduce natural carbon sinks. For example, deforestation alone is responsible for a quarter of global greenhouse gas emissions.
Consumption and lifestyles: Everyday actions—such as purchasing goods, waste management, commuting, and energy use at home—add a significant percentage to our personal and collective carbon footprint.

Innovative Icelandic Technology Turns CO2 into Rocks to Combat Global Warming

How the problem is measured and quantified

Today, we have advanced instruments and techniques to measure and monitor greenhouse gas concentrations and emissions. These methods include:

Ground measuring stations: Located at different points around the planet, they constantly capture data on the concentration of greenhouse gases, particulate matter, and other atmospheric parameters.
Satellites: They offer a comprehensive view of atmospheric composition, planetary albedo, energy fluxes, and emissions from space, providing near-complete coverage.
Climate modeling: Mathematical models integrate physical, chemical, and biological data to project future scenarios and analyze the impact of different policies and actions.
National and sectoral inventories: Each country reports and calculates its GHG emissions by economic sector, facilitating comparison and monitoring of international reduction targets.
Industrial metrics: Indicators such as carbon footprint or carbon intensity help companies analyze and reduce their climate impact.

This rigorous monitoring is key to establishing mitigation strategies, ensuring regulatory compliance, and verifying real progress in the fight against climate change.

Natural factors and their role in the climate

While human activities are primarily responsible for global warming since the last century, there are other natural factors that influence the global climate:

Solar cycles: The Sun's activity varies in cycles of about 11 years, causing small fluctuations in the solar radiation reaching Earth. These changes, although measurable, are much less significant today than the increase in greenhouse gases.
Volcanic eruptions: Large eruptions launch particles and aerosols into the atmosphere that can block solar radiation, temporarily cooling global temperatures for months or years.
Ocean oscillations (El Niño/La Niña): Periodic phenomena that alter the temperatures of the Pacific Ocean and affect the climate worldwide, intensifying or mitigating droughts, rainfall, and temperatures.
Changes in the Earth's orbit (Milankovitch cycles): Variations in the Earth's orbit, inclination, and position relative to the Sun over thousands of years, related to ice ages.
Atmosphere-ocean interaction: Ocean currents and wind patterns redistribute heat, generating regional and temporal differences in the global climate.

Although these factors can induce climate variability, the scientific consensus is that the temperature increases observed since the industrial era are due almost exclusively to human action on the greenhouse effect.

Solar energy: the clean alternative to the climate challenge

In the face of the challenge of global warming, solar photovoltaic energy and other renewable sources have emerged as key players in the global energy transition. Technological advances have allowed the cost of solar and wind energy to fall by more than 80% in the last decade, making them competitive, sustainable, and long-term options.

Some of its most notable advantages are:

They do not emit greenhouse gases or air pollutants. during operation, reducing the carbon footprint and improving air quality.
They are inexhaustible and renewable: Solar radiation is virtually unlimited and available throughout the planet.
They do not generate hazardous waste or water pollution, avoiding many of the problems associated with traditional thermal or nuclear power plants.
They are becoming more and more affordable: Lower costs and improved efficiency make it viable on a small and large scale, for both individuals and businesses.

Solutions and paths to sustainability

The fight against global warming is not an individual challenge, but a global undertaking involving governments, businesses, and citizens. Some key strategies include:

Emission reduction: Invest in renewable energy, electrify transportation, improve energy efficiency in buildings and industrial processes, and promote the circular economy.
Carbon capture and storage: Technologies capable of capturing CO₂ from industries and store it safely in deep geological formations, reducing its presence in the atmosphere.
Reforestation and ecosystem protection: Restore and conserve forests, peatlands, and fertile soils that act as natural carbon sinks.
Promotion of sustainable business models: Promote clean technologies, energy-efficient services, and responsible resource management practices.
Mitigation and adaptation: It's not enough to simply mitigate emissions: we must anticipate and adapt to the inevitable effects of climate change, protecting the most vulnerable people and ecosystems.

A challenge and an opportunity for present and future generations

Over the decades, the planet has shown more than evident signs that the alteration of the greenhouse effect due to human actions threatens the climatic balance on which our civilization depends. Mitigating global warming requires structural changes and coordinated international action. However, it also represents a unique opportunity to boost innovation, create green jobs, and improve global well-being.

The role that each person, company, and government adopts in this transformation will be crucial to ensuring that future generations inherit a habitable, resilient, and fairer planet. Solar radiation and the greenhouse effect are no longer just scientific concepts: they are the pillars on which to build a sustainable and secure future for all.

MeteorologíaenRed