Major players in ozone loss
While industrial products like chlorofluorocarbons are largely responsible for current ozone depletion, a NASA study finds that by the 2030s climate change may surpass chlorofluorocarbons (CFCs) as the main driver of overall ozone loss.
Atmospheric scientists from Columbia University, N.Y., find that greenhouse gases like methane and carbon dioxide are changing the climate in many ways .Some of those effects include water vapor increases and temperature changes in the upper atmosphere, which may delay future ozone recovery over heavily populated areas.
Scientists have expected the ozone layer to recover as a result of international agreements to ban CFCs that destroy ozone. CFCs, ones used in cooling systems and aerosols, can last for decades in the upper atmosphere, where they break down, react with ozone, and destroy it. They remain the major cause of present-day ozone depletion.
Ozone shields the planet’s surface from the Sun’s harmful ultraviolet radiation and makes life on Earth possible. The study examined the ozone layer over heavily populated areas around the equator and mid-latitudes where ozone thinning occurs, excluding the Polar regions, where ‘ozone holes’ form. Ozone thinning can occur when increased emissions of methane get transformed into water in the stratosphere. At high altitudes, water vapor can be broken down into molecules that destroy ozone. Also methane and carbon dioxide change our climate by trapping heat in the atmosphere before it can escape out to space. This greenhouse effect, much like the inside of car with all the windows closed, heats the air within the lowest layer of the atmosphere, called the troposphere. Warming in the troposphere can alter atmospheric circulation and make the air wetter, since warmer air holds more water. Though complex and not well understood, there is evidence that water vapor can get wafted from the troposphere into the stratosphere by shifting air currents caused by climate change. Climate change from greenhouse gases can also affect ozone by heating the lower stratosphere where most of the ozone exists. When the lower stratosphere heats, chemical reactions speed up, and ozone gets depleted.
The chemical and atmospheric processes in the lower stratosphere are complex, quite variable, and not well understood.
Computer model simulations were used to separate the different factors that contribute to ozone changes. According to the models, which contain some uncertainty, ozone levels are expected to reach their lowest point in recorded history by around 2006. Scientists hope that by banning CFCs, ozone will eventually return to healthier levels, like those that existed prior to 1979.
Ex.1. What is the main cause of present-day ozone depletion? Is it possible to recover ozone layer? Give your reasons.
Additional Text B
ECOLOGICAL HOUSES
In November of 1994, residents moved into the first apartment building in the United States constructed and maintained with materials which can be safer for person with Multiple Chemical Sensitivities (MCS). Ecology House planners recognized the often conflicting needs of people suffering with MCS.
Therefore, planers understood that many, but not all, persons with MCS could be helped in a single building.
The success of Ecology House may be measured through occupancy data. Ecology House’s eleven units are currently occupied by eleven residents with MCS, eight of whom moved in immediately after the building was completed in November, 1994. During the first year of occupancy three residents moved out because they could not satisfactory tolerate some of the materials used in their apartments.
Residents seem to tolerate most materials and design techniques used. Some residents report their health has substantially improved by living in a safer environment. However, some residents have had difficulty with the interior wall finish, a hard gypsum plaster with no paint or hermetic.
The benefits of Ecology House must be weighed against its costs. Eleven per cent ($200,000) of the total $1.8 million development coat is attributed to the extra cost of special features to accommodate persons with MCS. This extra eleven percent seems a reasonable cost. As developers gain more experience with non-toxic building, costs for future projects will likely be reduced.
Ecology House planners dreamed of a large site with small cottages. Experience with the occupied building indicates that persons with MCS could be more successfully housed in small cottages. This tiny apartment complex has attracted national media attention.
The primary research used to design the building and select materials was the personal experience of persons with MCS and volunteer consultants. Every building component was discussed. Many alternate materials were analyzed. Some materials were selected for use.
The General Contractors used great care in construction techniques to keep the apartments clean and safe. No smoking was allowed on site any time during construction. Only non-toxic cleaners were used.
Ex.1. Give the summary of the next in 3 or 4 sentences in English.
Problems to discuss: (See Unit VI for additional material)
1. What can be done to reduce energy consumption by residential buildings?
2. “Grey” water recycling systems – dream or reality?
3. New approaches to environmental problems solving.
UNIT VI
SUPPLEMENTARY READING
FAMOUS SCIENTISTS