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FOLIA GEOGRAPHICA 2013 (21), LV., pp. 38-47

Globálne Stmievanie ako Nový Klimatický Fenomén

Global Dimming as New Climate Phenomenon

Martin Jedlák A*

Received: October 19, 2012 | Revised: January 17, 2013 | Accepted: March 10, 2013

A* University of Prešov, 17. novembra 1, 080 01 Prešov, Slovakia
martin.jedlak@smail.unipo.sk (corresponding author)

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Abstract

This paper examines the atmospheric phenomenon known as global dimming. The phenomenon was first identified through empirical studies conducted between 1950 and 1980, which revealed a decrease in the amount of solar radiation reaching the Earth’s surface. Although these findings were initially met with skepticism, they were later corroborated by research on the pan evaporation rate, which showed a gradual decline despite global warming. The paper also highlights the INDOEX project, which investigated the impact of aerosols—solid particles in the air—on the amount of solar radiation reaching the Earth’s surface. The final section explores the effects of global dimming on the planet’s climatic conditions.

Key words: Global dimming, global warming, evaporation, aerosols

Summary

Global Dimming as New Climate Phenomenon

One of the most significant human impacts on nature in the modern era is global warming, driven by the uncontrolled production of greenhouse gases from burning fossil fuels, posing a considerable threat to humanity. However, the combustion of fossil fuels has additional consequences beyond greenhouse gas emissions. It also releases large quantities of solid particles, known as aerosols, into the atmosphere. Unlike greenhouse gases, aerosols have a cooling effect by blocking solar rays. When aerosols interact with clouds, they bind to tiny water droplets, transforming clouds into giant mirrors with an extended lifespan, further reflecting sunlight.

Research conducted over the Indian Ocean as part of the INDOEX project revealed that a 3 km thick layer of aerosols reduced the amount of solar radiation reaching the Earth’s surface by 10%. This phenomenon, termed global dimming, results from the residues of fossil fuel combustion causing a loss of sunlight on Earth. Initially, global dimming findings were met with skepticism because the Earth’s temperature continued to rise despite reduced sunlight. However, further studies, particularly in the U.S., demonstrated that global dimming cools the Earth’s atmosphere, partially masking the effects of global warming.

Global dimming peaked between 1960 and 1990. Subsequent measures to reduce aerosol emissions improved air quality and mitigated global dimming. However, this reduction in aerosols also diminished the cooling effect, allowing global warming to intensify, resulting in the hottest decade in modern temperature measurement history. Several studies suggest that addressing greenhouse gas emissions and aerosol production separately is insufficient to maintain the current climatic balance. If aerosol production is reduced without a corresponding decrease in greenhouse gas emissions, global warming will accelerate, leading to rapid temperature increases.

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