Although often confused with each other, global warming and ozone depletion are two separate problems threatening Earth’s ecosystem today. Global warming is caused by the build-up of heattrapping gases in the atmosphere. It was dubbed the “greenhouse effect” because it is similar to a greenhouse in that the sun’s rays are allowed into the greenhouse but the heat from these rays in unable to escape. Ozone depletion, however, is the destruction of the ozone layer. Chemicals such as chlorofluorocarbons and methyl bromide react with ozone, leaving a “hole” in the ozone layer that lets dangerous UV rays through. Both are serious threats to life on Earth. While the greenhouse effect maintains the appropriate temperature for life on Earth, problems are exacerbated when the quantity of greenhouse gases in the Earth’s atmosphere increases drastically. When this occurs, the amount of heat energy that is insulated within the Earth’s atmosphere increases correspondingly and results in a rise in global temperature.
An increase of a mere few degrees Celsius does not appear very threatening. However, numbers can be deceiving. When you consider that the Ice Age resulted from temperatures only slightly cooler than those today, it is obvious that even very subtle temperature changes can significantly impact global climate. Global warming threatens to desecrate the natural habitats of organisms on Earth and disturb the stability of our ecosystem. The climate changes that would result from global warming could trigger droughts, heat waves, floods, and other extreme weather events.
Like most other environmental problems, humans are the cause of global warming. The burning of fossil fuels is largely responsible for the increase in the concentration of carbon dioxide in the atmosphere. Every time someone drives a car or powers their home with energy derived from power plants that use coal, carbon dioxide is released into the atmosphere. The atmospheric concentrations of carbon dioxide and methane have risen meteorically since preindustrial times, mainly due to the contributions of factories, cars, and large-scale agriculture. Even if we immediately stopped emitting greenhouse gases, we would continue to see the effects of global warming for decades because of the damage we have already inflicted.
Despite the pessimistic outlook, there are things that can be done to reduce global warming. Although the problem may seem overwhelming, individuals can make a positive difference in combating global warming. Simple things like driving less, using public transportation, and conserving electricity generated by combustion of fossil fuels can help reduce the emissions of greenhouse gases. It is important to realize that it is not too late to make a difference. If everyone does what they can to reduce their contributions of greenhouse gases to the atmosphere, the efforts of people around the world will act in concert to thwart the progression of global warming. If the effort is not made immediately, the delicate global ecosystem could be thrown irreversibly out of balance, and the future of life on Earth may be jeopardized.
In the above passage the word thwart is used to mean?
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Reference / correct answer:
You can infer the definition from the context clues “the progression of global warming.”
