Global warming, a phenomenon of planetary scale, represents one of the most pressing challenges of our time. It refers to the gradual and continuous increase in the Earth's average temperature, primarily due to human activities emitting greenhouse gases into the atmosphere. This climate disruption generates a series of harmful consequences that affect all aspects of life on our planet. See our article on natural consequences. This topic, unavoidable and omnipresent, although it has been popularized and integrated into common language, finds its origin in pure scientific reality. This article approaches global warming from a scientific and biological perspective, thus offering a better understanding of climate issues.
Natural global warming
When we discuss global warming, we refer to a combinatory effect of several natural phenomena, the most important being the radiative effect and the greenhouse effect.
a. The radiative effect
Solar radiation, which is the source of global warming, is electromagnetic waves resulting from nuclear fusion that occurs in the core of the Sun. These waves can be broken down into several wavelengths or spectra. Solar radiation colliding with our planet is either reflected by the atmospheric albedo (clouds, troposphere, ozone layer) and terrestrial albedo (glacier, dense forest, sandy desert) by about 30%, or absorbed by the atmosphere (greenhouse gases) and the earth (terrestrial crust) by about 70%. In response, the Earth emits heat in the form of infrared radiation into space. These infrared rays, passing through the atmosphere again, are partly re-emitted back to Earth (greenhouse effect) or reach space. This naturally balanced process, by emitting the same amount of energy entering and leaving the Earth (balanced radiative budget), creates a climate conducive to life on our planet.
b. The greenhouse effect
The composition of the atmosphere thus plays a multiple role in this radiative budget, both in terms of reflection and absorption of solar radiation. The gases composing it do not all have the same heat absorption capacity depending on their molecular structure. Water vapor is, for example, the most abundant greenhouse gas in the atmosphere and the one most actively involved in the natural greenhouse effect. These gases are called greenhouse gases, and their radiative capacity is measured in carbon dioxide equivalent.
Example of greenhouse gas (source : IPCC)
Disrupting the natural composition of the atmosphere leads to a chain reaction of the greenhouse effect, by absorbing and re-emitting some of the infrared rays back to Earth.
Anthropogenic activity
Natural gas fluxes are exchanges between different systems (lithosphere, biosphere, hydrosphere, atmosphere), which are the cause of natural terrestrial warming. It is estimated at approx. 0.5 gigatons of CO2 emitted into the atmosphere each year. Since the pre-industrial era, human activity has disrupted the radiative effect by creating a radiative forcing by reducing the terrestrial albedo (deforestation, glacier melting, construction) and by disturbing the natural gaseous balance of the atmosphere. It is considered that human activities release approx. 40 gigatons of CO2 per year into the atmosphere, accentuating the greenhouse effect and creating a real radiative forcing. We have written a dedicated article on the carbon cycle.
Consequences and actions
The objectives of decarbonization precisely aim to act on the fluxes resulting from anthropogenic activity towards the atmosphere by reducing greenhouse gas emissions, but also by reducing the greenhouse effect by decreasing the concentration of greenhouse gases in the atmosphere through absorption in the biosphere, hydrosphere, and lithosphere. At Apolownia, we propose concrete, transparent, and impactful actions for companies to reduce these fluxes and absorb greenhouse gases into the atmosphere to limit the climate impact of global warming. The two approaches are complementary and inseparable to maintain the IPCC's objectives of keeping global warming below 1.5 degrees Celsius compared to pre-industrial levels.
ABOUT APOLOWNIA
Apolownia is a mission-driven company committed to making a significant impact in the climate sector.
We support businesses and funds willing to engage in long-term and impactful decarbonization strategies - within and beyond their own value chain - by designing, implementing and monitoring science-based carbon reduction projects that restore natural ecosystems.
Through technology and innovative solutions, we aim at shaping a resilient and environmentally friendly world, by encouraging the decarbonization of the economy and supporting social and environmental initiatives.
You can drive positive change for the climate, biodiversity and local communities.
Contact us to engage or for more information. Find us on www.apolownia.com.
Sources :
Le bilan radiatif de la Terre – ENS Lyon
Comment on Ocean heat content and Earth's radiation imbalance - Dana Nuccitelli, Robert Way, Rob Painting, John Church & John Cook
IPCC, "Climate Change 2013: The Physical Science Basis" - Link
NOAA's Earth System Research Laboratory - Link
FAO Global Forest Resources Assessment 2020 - Link
The Rainforest Alliance - Link
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