Within the Life Cycle Assessment (LCA) methodology, 10 environmental indicators are used to evaluate the impact of superyachts, beginning with those related to climate change.
These indicators measure the effect on the climate, specifically the Greenhouse effect, from two different perspectives: one considers the emission of greenhouse gases such as methane, CO2, and nitrous oxide, while the other examines chemical compounds relevant for Ozone layer depletion.
Global Warming Potential
The Earth receives energy from the sun through solar radiation, with about half of this energy being absorbed by the earth’s surface. The other half is reflected back into the atmosphere as infrared radiation or heat. Greenhouse gases (GHGs) trap this radiation in the atmosphere, thereby heating the Earth. Consequently, the more GHGs that are present in the atmosphere, the warmer the Earth’s temperature becomes. This process is known as the greenhouse effect.
In order to make meaningful comparisons between GHGs, scientists have adopted CO2 as the benchmark for measuring their heat-trapping abilities. CO2 is a clear, odourless gas produced during carbon combustion and in the respiration of living organisms. The heat-trapping potential of a gas, measured against CO2 over a fixed period, is known as Global Warming Potential (GWP). CO2 is used as a benchmark to measure the GWP of substances, which is expressed in kg of CO2eq.
Ultimately, GWP evaluates the potential impact of different gaseous emissions on climate change by calculating the radiative force over a 100-year time horizon.
Ozone Depletion Potential
In the stratosphere, an ozone-rich layer called the Ozone layer exists. The formation of the ozone hole is directly linked to the stratosphere’s temperature. Once temperatures drop below -78°C, polar stratospheric clouds tend to form, exacerbating ozone depletion over both of the Earth’s hemispheres.
The Ozone layer acts like sunscreen for all living organisms, shielding the Earth’s surface from most of the sun’s UV light. Its depletion could cause serious damage for humans, animals, plants and materials. Ozone Depletion Potential (ODP) calculates these destructive effectives over a time horizon of 100 years.
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