********************************************************* GLOBAL WARMING & OZONE ********************************************************* ******************* GLOBAL WARMING ******************* __________ QUESTION: How can you prevent the global warming from increasing the temperature that will melt the Arctic ice? ANSWER from Kathy McNitt on January 24, 1993 The only way I can think of to prevent global warming is to find out what's causing it and to change the way we live so that humans don't spoil the planet for ourselves and other living things. I'm not sure that an increase in temperature will melt the ice caps, though. Can you think of a way that an increase in temperature could actually help the ice caps grow? I'll give you a hint: warmer air can hold more moisture than colder air. Maybe a slightly warmer climate would produce more clouds, dropping more snow onto the ice caps. These are the puzzles we're trying to solve, and it gets confusing! So before we change things too drastically, we have to study the effects those changes might bring. Then again, if we keep waiting to prove what the consequences will be, by the time we Do change the way we live, it may be too late to "fix our mistakes." This is where common sense comes in. What kinds of things can you do at your school to minimize our impact on the planet? __________ QUESTION: Do any of the scientists there believe in the global warming theory, or is it possible that warming/cooling cycles are a natural part of Earth's processes that we have only recently been able to measure? ANSWER from Katy McNitt on February 4, 1995 I think most of us believe in BOTH. That is, the greenhouse effect is a naturally occurring thing, but mankind has dramatically increased the greenhouse effect by pumping greenhouse gases into the atmosphere. If you consider that the world's population has DOUBLED since 1950, and that this trend is continuing, it's hard to believe that humans aren't having some effect on natural cycles. The problem is figuring out what that overall effect is, though, because there are so many things involved, and so many "feedback" variables. For instance, by putting CO2, etc., into the air we cause some warming, but at the same time, our smog pollution blocks sunlight and tends to cool the Earth's surface. We can't just hope that the two will "cancel each other out," though. We have to decide what our priorities are for the future and act accordingly. ********************* GREENHOUSE EFFECT ********************* __________ QUESTION: How does the Greenhouse effect affect the inhabitants of Antarctica? ANSWER from Katy McNitt on February 4, 1995: The greenhouse effect makes it possible for life to exist, not just in Antarctica but all over the world. Without greenhouse gases bouncing long-wave radiation back to the Earth's surface, the whole planet would be 33 degrees C colder, and most of the life as we know it would not be able to exist. ******************************************* OZONE ******************************************** ***************************** OZONE HOLE MEASUREMENT ***************************** __________ QUESTION: How do you measure the ozone layer so that you know if it is getting thinner or thicker? ANSWER from Katy McNitt on December 29, 1994 There are many, many different ways to measure ozone. One way is to compare different wavelengths of light. If you know what kind of light is absorbed by ozone, you can let sunlight into an instrument which compares the amount of that kind of light to a kind which isn't absorbed by ozone. Once you know how much light is "missing" (absorbed), you can figure out how much ozone there is between you and the sun! Can you think of other ways to measure ozone? ************************* SIZE OF THE OZONE HOLE ************************* __________ QUESTION: Currently, how large is the ozone hole above the continent, and are any studies being done on the effect of the UV rays on the species found there? ANSWER from Katy McNitt, LTJG, NOAA, on Jan 3 1995: This year's Antarctic ozone hole has closed up as far as I can tell: usually the hole disappears by mid-November. Can you figure out why? Several science groups are studying the effects of increased UV radiation on Antarctic animals and plants. Most of these scientists do their research from ships or remote field camps near the coast, although we have a UV monitor at the South Pole, too. Right now, U.S. scientists in Antarctica are studying the variability of UV irradiance, photochemistry of the water, and the effects of UV radiation on algae, grasses, and phytoplankton. __________ QUESTION: Is the decrease in the ozone layer continuing? ANSWER from Katy McNitt on December 29, 1994 The ozone in our atmosphere is continuously being created and destroyed, mostly by chemical reactions involving sunlight. How do you suppose the sunlight could be responsible for both the creation and destruction of ozone? Well, it has to do with certain "conditions," and the conditions over Antarctica during the spring happen to be "just right" for ozone destruction. Since scientists are predicting similar conditions for the years to come, you can probably expect to see some sort of ozone "hole" over Antarctica each August-October. ___________ QUESTION: How big is the hole in the ozone layer? Has there been any changes in the size? What is the ozone layer made of? ANSWER from Farzad Mahootian and the students of Gonzaga College High School: The ozone hole isn't really a HOLE, but a large region where the ozone layer gets 2 to 3 time thinner than it ever gets anywhere else on the globe, and it's been getting thinner each year for the last 10-15 years. The ozone layer is made of lots of ozone molecules; each one is made of three oxygen atoms. Ozone is formed by sunlight striking breathable oxygen molecules (O2, made of two oxygen atoms) and starting a reaction that generate ozone (O3). The boundary of the ozone hole is wobbly, so it changes size constantly as it rotates around Antarctica between August and November. It has also been growing each year. The hole has passed over the tip of S. America, (55 degrees S. Latitude). Australia and New Zealand are far outside the hole, although they do experience ozone depletion, more than in the Northern hemisphere. After the 1987 ozone hole broke up in December, ozone levels over Australia and New Zealand were 10% below normal. ___________ QUESTION: I've heard that the ozone layer over Antarctica is almost gone. Is this true? If so, why is this? ANSWER from Diana Freckman It is "gone" or reduced for the year. But, it will take more than one year to determine if it is really gone. One thing about any part of science dealing with the environment is that you need more than one season. For example, you may have a hot summer one year, but it doesn't mean that next year it will also be hot. The same thing is true with the ozone layer. We are collecting data to see the trend over several years. __________ QUESTION: I heard that the biggest hole in the ozone layer is over Antarctica. Why is that? ANSWER from Katy McNitt, LTJG, NOAA, on December 29, 1994: Antarctica has a very unusual climate system, which happens to be perfect for ozone depletion each spring in the southern hemisphere. Look at a globe and compare the North Pole to the South Pole. How are they different? Can you see why the South Pole is colder than the North Pole? Both Poles experience a wintertime wind system called a "polar vortex." This is a strong wind that blows around and around the Poles. The air trapped inside the vortex gets very, very cold; colder at the South Pole than the North Pole. Winter at the Poles means Night. At the South Pole, the sun sets in March and doesn't come up again until September! Just like home, winter is the coldest time of year. Special clouds form over Antarctica from ice crystals in the very cold winter air. Chemicals like CFCs can get into the stratosphere and stick to the ice crystals. In August the sun starts to rise over Antarctica, and when the sunlight hits these ice-crystal-clouds, a chemical reaction takes place, and ozone is destroyed. As the sun rises higher it warms up more air which creates wind. Winds break up the polar vortex and bring in ozone-rich air from the mid latitudes. Why do you suppose there is more ozone over the Equator than there is over the Poles? You'd have to know how ozone is formed to answer this question. ***************************** ADAPTATION TO OZONE LOSS ***************************** __________ QUESTION: Do plants and animals in that area have special adaptations to help them survive with less ozone in the atmosphere? Do the researchers and crew have to take any special precautions? ANSWER: It takes most animals and plants a long time to adapt to changes in the environment. However, there are always adaptations that the animals and plants already have that can protect them. For example, the feathers of a penguin are better protection than human's exposed skin! So no, they haven't (as far as I know) developed special adaptations. We just wear clothes with long sleeves and lots of sun screen, but the algae and mosses and lichens are much more susceptible. They are being harmed by the ozone and UVB. (But once again, we need more than a few seasons to collect data on this!) __________ QUESTION: Is it dangerous to be in Antarctica with the ozone hole right there? ANSWER from Katy McNitt on December 29, 1994 For people working at the South Pole under the ozone hole, we get about the same exposure to sunlight as you would skiing in the Rocky Mountains. Can you guess why? Think about how the Earth moves around the sun, and where the sun would be at noon in Colorado, then try to picture noon at the South Pole. How could we get the same amount of sunlight when there's so much less ozone over Antarctica? Even on the coast of Antarctica where the sun rises higher in the sky, the amount of sunlight getting through is about the same that you'd get lying on the beach at Ocean City next summer! This is okay for people working in Antarctica, because we're usually bundled up to protect us from the cold. But pretend you're a critter living in the Southern Ocean, and you're not used to so much sunlight. The plants and animals around Antarctica have grown and evolved under certain conditions, and if those conditions change, the entire balance of life in the oceans could be upset, which in turn could affect many other things, including the earth's climate, which could be dangerous to humans, too! **************************** SUNBURN AND SUNGLASSES **************************** __________ QUESTION: Does the depleted ozone layer require you to wear suntan lotion? ANSWER from Bryan Schultz on January 26, 1995: Yes, sunscreen would be advised in Antarctica, even though the ultraviolet radiation is weaker at the 77.6 degree S latitude of McMurdo Sound. The McMurdo sunburn time for light untanned skin for today (Jan. 25, 1995) would be about 81 minutes for a relatively weak UVB index of 1.6 (ultraviolet 290-320 nm that most affects human skin). For their summer solstice of Dec. 21, 1994, an expected sunburn time of 55 minutes would correspond to an index of 2.4 at McMurdo. A reading of 0-4 on the new national ultraviolet index is considered lower risk, but we still advise sunscreen and a wide-brimmed hat. Chicago, by contrast at 41.8 degrees N latitude, had a sunburn time for today of 120 minutes and 18 minutes on our summer solstice June 12, 1994 (UV index greater than 8). Snow can reflect 85% of the UVB and thick sea ice 70%. Wind has also been shown to potentiate ultraviolet damage to skin and, as you know, Antarctica can be quite windy. These two factors could cut the 55 and 81 minutes sunburn times in half. Ascending Mt. Erebus would also decrease sunburn times because of stronger ultraviolet in the thinner atmosphere as elevation increases. Each 1000 ft. elevation can increase UVB intensity approximately 4%. We must also consider that the virtual 24 hours of sunlight in mid-summer in Antarctica may encourage some to have more prolonged exposure than might be available with shorter days in the U.S. Terry Triminigham's journal described a 90-minute walk to and from Scott base-- enough time to burn without sunscreen. I might recommend a wide-brimmed hat, however, to avoid the described burning sensation in the eyes from running sunscreen. This also provides the added benefit of protecting the top of the ears that can frequently be missed when applying sunscreen. A stick-type sunscreen is an alternative for the type that won't run, but could aggravate acne in some with continued use. Newer "chemical-free" sunscreens with micro pulverized titanium dioxide would also circumvent the stinging experienced with other sunscreens. The ozone "hole" in Antarctica represents a very dramatic drop in protective stratospheric ozone in their spring, but their sun is not very intense then-- an approximate sunburn time of 700-800 minutes in October. This ozone-poor air does break up and may circulate to lower latitudes though, and is therefore still quite significant for all of us. A similar but less intense hole develops over northern polar regions with potential spreading to lower northern latitudes in our spring. __________ QUESTION: Why do most of the people in the "Live From" program wear sunglasses or goggles? ANSWER from Deane Rink, Live from Antarctica field producer, on December 19, 1994 Most people working in the field in Antarctica wear sunglasses because the snow is very bright and the sun is in the sky here during the summer 24 hours a day. Since the snow is so bright, light reflects off the white snow and bounces back into the eyes, creating a glare problem that only heavy-duty sunglasses help to alleviate. Without them, sunburn of the retina would be a common occurrence, and seeing clearly would be almost impossible with all that glare. All sunglasses down here must contain special ultraviolet filters, since there is a seriously depleted ozone layer over Antarctica. That means more UV gets in from space, which would also burn one's eyes. ******************************************** OZONE'S EFFECT ON CLIMATE AND GEOLOGY ******************************************** __________ QUESTION: Are you noticing climatic changes as a result of ozone depletion? As a result of ozone depletion do you anticipate geologic changes (plate tectonics/glacial melting, etc.)? ANSWER from Katy McNitt on December 29, 1994 The changes associated with climatic and geologic change occur so slowly, and there are so many variables involved, that it will take a long time for us to really understand what's happening. For instance, you mentioned glacial melting. Let's imagine that the Earth's atmosphere suddenly warmed up a degree or two. Would this be enough of a change to actually melt the ice caps? In most of Antarctica the average temperature would still be well below freezing. Or, would a two-degree difference be "just warm enough" to allow the air over Antarctica to hold more moisture, meaning it could snow more and actually increase the size of the ice cap? I don't know the answer to these questions, and I'm not sure that anyone does, yet.