The ozone hole over the Antarctic is likely to begin contracting in the future and may disappear by 2050 because of a reduction in the release of chlorofluorocarbons and other ozone-depleting gases, according to a team of Japanese scientists.
Chlorofluorocarbon levels in the earth’s atmosphere have been declining since the mid-1990s due to international efforts to reduce emissions.
“Acid rain” is a broad term used to describe several ways that acids fall out of the atmosphere.
Scientists discovered, and have confirmed, that sulfur dioxide (SO2) and nitrogen oxides (NOx) are the primary causes of acid rain. In the US, About 2/3 of all SO2 and 1/4 of all NOx comes from electric power generation that relies on burning fossil fuels like coal.
Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. Sunlight increases the rate of most of these reactions. The result is a mild solution of sulfuric acid and nitric acid.
source: Acid Rain | US EPA
Title IV of the Clean Air Act set a goal of reducing annual SO2 emissions by 10 million tons below 1980 levels. To achieve these reductions, the law required a two-phase tightening of the restrictions placed on fossil fuel-fired power plants.
Phase I began in 1995 and affected 263 units at 110 mostly coal-burning electric utility plants located in 21 eastern and midwestern states. An additional 182 units joined Phase I of the program as substitution or compensating units, bringing the total of Phase I affected units to 445. Emissions data indicate that 1995 SO2 emissions at these units nationwide were reduced by almost 40% below their required level.
Phase II, which began in the year 2000, tightened the annual emissions limits imposed on these large, higher emitting plants and also set restrictions on smaller, cleaner plants fired by coal, oil, and gas, encompassing over 2,000 units in all. The program affects existing utility units serving generators with an output capacity of greater than 25 megawatts and all new utility units.
The Act also called for a 2 million ton reduction in NOx emissions by the year 2000. A significant portion of this reduction has been achieved by coal-fired utility boilers that will be required to install low NOx burner technologies and to meet new emissions standards.
Detailed information about emissions reductions is available on the emissions data & compliance page.
Whenever a problem is solved quietly by “men in rooms”, people think the problems never existed. Global warming, admitedly, has been talked about since the 1960’s at least, so it would seem as though it is not a real problem…we’re all alright. However, it is alarming to me how much we have changed the atmosphere.
The long term trend on planet Earth is a gradual reduction of CO2 in the atmosphere. This is because the oceans and plants absorb CO2. This process has occured for the last billion years and has been verified as best science can by looking at ice samples and studying ancient life.
However, the last hundred years has seen a sharp reversal of this trend:
BBC News has learned the latest data shows CO2 levels now stand at 381 parts per million (ppm) - 100ppm above the pre-industrial average.
The research indicates that 2005 saw one of the largest increases on record - a rise of 2.6ppm.
source: BBC NEWS | Science/Nature | Sharp rise in CO2 levels recorded
That level of change concerns me, even if I don’t fully understand the science behind it.
Science is not like other fields. Journalists like to report “balance” in their stories. So, when writing about science, they will express the opionion of one group of scientists and another group that disagrees. Both sides will tend to be reported as being equally valid. This is not true. Science is about verifying data with repeatable experiments, it’s about experimenting to disprove theories. Many things can never be proven to be absolutely true (laws such as gravity, conservation of mass and energy etc.), but it doesn’t mean these theories are on shaky ground (evolution, global warming).
Lastly, I don’t think that humans will do anything about global warming in time. I think it’s time we start looking at the decisions we will have to make in the next environment. Such as, do we want to build a giant levee to protect Florida from disappearing? How about NYC? How will we deal with the desire to immigrate to cooler climates? Will we still produce enough food to feed ourselves? Luckily for Americans, the War Department already started thinking about this: