The debate over acid rain continues to grow. NOVA travels to West Germany, the mid-Atlantic states and New England to examine the controversy surrounding this phenomenon.
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00:00It is the summer of 1984.
00:25A party of American congressmen are flying into Freudenstadt in West Germany.
00:31Herr John, the regional forester, greets his chief from Bonn.
00:38The visitors and the press are here to see an environmental catastrophe in the making.
00:47Freudenstadt lies in the Black Forest, and the Black Forest is dying.
01:03The trees have been killed, it's believed, by the form of air pollution called acid rain.
01:10That's why Congressman Henry Waxman, an air pollution specialist, is here.
01:15Well, it's even worse than I expected to find here.
01:19We're seeing probably what we're going to find in the United States in a few short years
01:24in the northeastern part of the nation particularly, but maybe in other places as well.
01:29We are beginning to find it in the United States, from Mount Mitchell here in North
01:34Carolina, to Camel's Hump in the Green Mountains of Vermont.
01:44We've seen lakes acidify and die because of acid rain.
01:47Now we shall in all probability have to add destruction of forests as another penalty
01:52of widespread air pollution.
01:55For many years, the smokestacks of Europe and North America, spewing sulfur from coal
02:01burning, have been political battlegrounds.
02:04Protest banners mark out these sulfur emitters.
02:08Sulfur reduction proposals abound in the Congress, state legislatures, and European
02:14parliaments.
02:15But this film will show that just cutting sulfur may not stop acid rain.
02:22Lakes and forests may still be at risk.
02:26The protests are daring and spectacular, but the latest research shows they may be aimed
02:35at too simple a target.
02:38The science of acid rain is changing.
02:41As a result, the politics will change, particularly since what's now at stake in Europe and America
02:47is the future of our forests.
02:58The Black Forest, perhaps the most famous forest in the world.
03:03Meticulously cared for, every square meter is familiar to the rangers.
03:09Here, just a few years ago, a most alarming sight began to appear.
03:17The needles on the Norway spruce turn yellow, then they drop, and then the tree dies.
03:25Herr Jung charted the progress of this forest sickness.
03:31By 1982, out of his 50-square-mile area, just a few stands were still marked green
03:37or healthy.
03:39The rest were yellow, orange, and red.
03:42Sick, very sick, and dying.
03:45Or black, dead.
04:01That is the progress in one year, that in one year, so frightening.
04:31The Germans are deeply attached to their forests.
04:38They use them a great deal, and now they are seeing them die.
04:46Blue means dying, red is dead.
04:50The foresters have marked the trees for the hikers.
04:57The signs leave no room for doubt.
05:04A number of air pollutants from cars and industry are involved, they claim.
05:11It's just horrible, what I saw today, it makes me think a lot.
05:16It's horrible, I think.
05:18Because if you touch every single tree, it's somehow sick.
05:22You think of children and children's children, you probably don't have any trees here.
05:28Let's hope it doesn't become like that.
05:30When the children grow up and don't see the forest anymore, they only know the forests
05:34from postcards and calendars.
05:37That's depressing.
05:44Help us.
05:47Hilf uns.
05:49Try the trees.
05:53German prosperity, like our own, is not without cost.
06:18Sweden, an acid lake.
06:21The world contains many national boundaries, but the atmosphere ignores them.
06:34Twenty years ago, a Swedish scientist discovered the significance of that, before nature showed
06:40any damage.
06:42Svante Odin.
06:44You know, at that time, almost nothing could be seen in nature.
06:49You could not see anything in the lakes, nothing in the forest here.
06:53Only these more or less artificial maps told that something was going on.
07:00So then the show started on acid rain.
07:04Mapping the chemistry of Europe's rainfall, Svante Odin picked up a clear change.
07:10A decade from the mid-50s, acidity was going up dramatically, clearly spreading out from
07:16sources in the industrial center.
07:19Then he made a vital connection with events which were just beginning to be noticed.
07:25A fishery inspector called me up and just questioned, is it possible that the fish kill
07:33we have here in western Sweden could be attributed to atmospheric conditions?
07:40So that was a shock to me, equivalent to that of the catastrophe of Titanic.
07:47The idea that rainfall could be acidified by industrial pollutants was at first ridiculed,
07:53but it's been confirmed over and over by atmospheric scientists.
07:59In Virginia, Jim Galloway operates part of a national rain chemistry network.
08:06The simple collector would be triggered by rainfall.
08:10And here in the eastern United States, it always contains acids.
08:15We know without a shadow of a doubt that these acids are indeed from our industrial activities.
08:20In all cases, when you're far away from industrial activities, the acidity of the rain
08:25and the concentrations of sulfuric and nitric acids are about ten times less
08:30than what they are in the eastern United States.
08:33The origin of the acids was at one time a mystery, because no polluter actually emits them.
08:40But it turned out they are formed in the atmosphere itself.
08:45Burning anything, oil or coal, produces nitrogen oxides.
08:51Cars emit traces of unburnt fuel, hydrocarbons, as well as nitrogen oxides.
08:59And coal-fired power plants give off sulfur oxides as well as nitrogen oxides.
09:06Up in the sunlight and moisture of the atmosphere,
09:09this chemical cocktail goes through more than 150 reactions over the course of a day or two.
09:16The result? Three main pollutants.
09:20Ozone, a corrosive gas, and two important acids, nitric and sulfuric.
09:27By the time these reactions are complete, the pollutants may have traveled hundreds of miles.
09:42Western Sweden, one of the areas that's been hardest hit by acid rain.
09:51This lake has been acidified for more than a decade.
09:55The fish have long since gone.
10:06Now, a thick felt-like blanket, it's called filamentous algae, covers everything.
10:21Nature has at least found something to replace the rich community of plants and animals that should exist here.
10:31Another typical symptom.
10:33Sphagnum moss, normally confined to the shore, has invaded the lake.
10:38Biologists like Hans Hulteberg now see these signs of collapsed ecosystems on a massive scale in Sweden.
10:48We have at least 3,000 or 4,000 severe acid lakes like this one,
10:53but we have another about 14,000, 15,000 lakes that are damaged.
10:58So a total of about 18,000, 20,000 lakes out of our 90,000 lakes are affected by acidity.
11:08From Sweden to the Adirondack Mountains in upstate New York.
11:21An area of great natural beauty, it attracts sportsmen and vacationers by the thousand.
11:27And, like Sweden, it's on the receiving end of our air pollution as well.
11:33Bill Marlowe was a forest ranger for 35 years.
11:37He built a cabin up here at Woods Lake, and he's watched the lake die.
11:46He's given up fishing, and he's seen the algae come in, as they have in Sweden.
11:55The last trout was caught in the middle of the lake,
12:00The last trout was caught in here in 1969,
12:04and the shiners went out about three or four years ahead of the trout.
12:09There was a lot of vegetation. All this lower end of the lake here was solid lily pads.
12:15You hear no birds, or these lakes always supported a big population of swallows.
12:21There was one pair here this summer.
12:25Out here in the lily pads, there used to be hundreds and hundreds of bullfrogs.
12:31I used to have a Boy Scout troop, and I'd bring them up here,
12:35and they'd still talk about going to Woods Lake and listening to the bullfrog chorus up there in June.
12:40And there were nights you couldn't sleep because it was so loud,
12:43and the boys would come out here on the dock, and they'd yell,
12:45shut up, at the bullfrogs.
12:49Now there was two here last summer, one on each side of the lake.
13:01Enough young brook trout to bring tears to the eyes of Bill Marlow.
13:07But they will never make it to the end of a fisherman's line.
13:11Instead, they're being brought into this acid lake.
13:17It's an experiment run by Carl Schofield of Cornell University on the right,
13:22one of the world's experts on the effects of acid on fish.
13:28Eventually, their work may lead to the rehabilitation of New York's acid lakes.
13:33But for now, the fish are like the miner's canary in the cage.
13:38They are used to test the condition of the water.
13:42And it's not just the fish.
13:45It's the water.
13:48And it's the fish.
13:52They are used to test the condition of the water.
13:56And it's not just acid that the fish have to withstand.
14:00There is also aluminum, dissolved from the surrounding soil by acid rain.
14:06Lake chemistry is always closely linked to the land.
14:1224 hours have passed.
14:22It was Carl Schofield who discovered the special vulnerability of fish
14:27to a combination of aluminum and acid.
14:31The gills on the right are normal.
14:35The others show erosion and clogging typical of aluminum and acid attack.
14:41Fish without the delicate gill membrane simply suffocate.
14:46Why does a lake acidify?
14:51First, of course, it must be in an area of highly acid rain.
14:55This is the part of the continent that receives rain about ten times more acidic than normal.
15:01Within the area, soil plays a crucial role
15:04because rain must filter through it before reaching the streams and lakes.
15:09All soils have some ability to absorb acid.
15:13How much depends on the soil thickness.
15:15But some soils contain as well a key agent that neutralizes acids and protects the water.
15:22Jim Galloway.
15:24The active agent in the soil that causes that protective mechanism to occur is calcium carbonate.
15:31The limestone soils.
15:33These beakers of soil were gathered in this area.
15:36These soils are acid soils, no naturally occurring calcium carbonate in them.
15:41We're going to make a soil of calcium carbonate using a commercially available form of calcium carbonate.
15:53Now we need an acid.
15:55This lemon contains citric acid, which is not found in rain, but it's about as acidic as rainfall.
16:02Now this is the acid soil that has no calcium carbonate on it.
16:06When you add an acid to it, as so, you can see there's no response.
16:14If this had been acid rain falling on the soil, the acid rain would flow right through into the lake and stream, causing acidification.
16:23The other half of the lemon we're putting into the soil with calcium carbonate.
16:29As you see, there's a chemical reaction occurring.
16:32Bubbles are being produced.
16:34The acid rain is interacting with the calcium carbonate.
16:37This process dissolves the calcium carbonate and neutralizes the acidity of the lemon juice.
16:42And therefore the stream and lake draining from that soil would never have been acidified.
16:52In the most intensive project of its kind, teams from New York State are now visiting many of the 2,500 lakes in the Adirondacks.
17:01And there's a lot they have to take along.
17:10Here there is no protective limestone.
17:13And these high mountain areas have thin soils, so there's very little capacity to absorb acid.
17:19It makes these remote mountain lakes doubly vulnerable.
17:24Nets have been set out to check the health of fish populations.
17:36Watch out.
17:47Water samples will be analyzed later in the lab.
17:51And why the llama?
17:53It's the only pack animal that you don't have to bring food along for.
17:59In the Adirondacks, there are 200 lakes too acid for fish.
18:03About the same number shows some damage.
18:06Canada has about 2,000 fishless lakes.
18:09But for the rest of the acid rain area, we don't know how much damage might have occurred.
18:15Western Sweden.
18:21Like the Adirondacks, here the soils are thin and without limestone.
18:26So man has had to intervene.
18:29Limestone, calcium carbonate, is added directly to the water to neutralize the acids.
18:43The water is so thin that it's impossible to see through it.
18:47The water is so thin that it's impossible to see through it.
18:51The water is so thin that it's impossible to see through it.
18:55The water is so thin that it's impossible to see through it.
19:00Liming in Sweden is now going ahead on a massive scale.
19:07It takes about two and a half tons per acre every year or two,
19:11costing maybe $50,000 a year for one average lake.
19:17Svante Odin.
19:22An expert on the effects of liming is Hans Hulteberg.
19:26The lake he's studying here with Svante Odin is making good progress.
19:31You can see that the plants living in the lake is fairly clean.
19:36We limed the lake in 1982 and since then all the mosses have died off
19:42and the filament has already disappeared and it's all clean on the bottom.
19:47You can see the rocks, you can see the plants, the original plants in the lake.
19:51It's more like a natural lake now.
19:56This limed stream has now been restocked with fish,
20:00as Hans Hulteberg will do next year with his lake.
20:04Surveys show they're starting to reproduce.
20:08Success, but at quite a price,
20:12and the liming must be continued for as long as there's acid in the rain.
20:23Nevertheless, with Sweden's success,
20:26an experimental program is just getting underway in the Adirondacks.
20:38It may be a stopgap measure,
20:41but it is the only way in the short term to bring these lakes back to life.
21:07The city of Cologne, West Germany.
21:13In the shadow of the famous cathedral, you could be back in the Middle Ages.
21:23The stonemasons practiced their ancient skills.
21:27They were trained in the art of carving.
21:32The stonemasons practiced their ancient skills.
21:36But the carving he's measuring has been restored with white plaster.
21:42Then the restored pieces are copied in new stone.
21:54Cologne Cathedral is one of the greatest medieval buildings in Europe,
21:59but much of its fabric, like these carvings, is brand new.
22:04It is becoming a 20th century building.
22:10Gradually, stone by stone, 60 builders are removing the ravages of air pollution.
22:16Acid rain is dissolving the sandstone away.
22:30Sites like these are common throughout Europe,
22:35and not so unusual in America, too.
22:39They're another part of the price we pay for our industry, our electricity, our cars.
22:46ACID RAIN
22:54Recently, the Germans have begun to think seriously about the costs of air pollution.
22:59Emission controls on cars are likely.
23:02Even speed limits on the autobahn have been suggested.
23:06It's because of the new element in the acid rain story, forests.
23:12Professor Zech works on the eastern border of Germany,
23:16on the opposite side of the country from the Black Forest.
23:19Now we are arriving at an elevation of 1,000 meters.
23:24Here is a 1,000 meter stone.
23:27On the left side, you have a lot of dead trees.
23:31And we'll have a look at them.
23:35Now we are at the top of the Schneeberg,
23:39and this is the worst picture we have here in Middle Europe as far as I know.
23:55Like the Black Forest and the Adirondacks, this is a vacation area.
24:02Here, the small villages depend on the forests not just for the timber industry,
24:07but to attract tourists as well.
24:12Again, like the Black Forest, the decline came with ferocious speed.
24:17In the last few years, yellowing symptoms, called chlorosis, have become widespread.
24:23The result is inevitable.
24:25If we have now chlorosis,
24:29the result is that the sugar production, the photosynthesis last but not least, is disturbed.
24:37After the yellowing, this needle after some time will be dropped.
24:42You have a naked branchlet.
24:46And if you have a lot of needle dropping to the soil,
24:51the biomass of the tree capable for photosynthesis is sharply reduced.
24:59The tree has to die.
25:01What's happening in Germany's forests?
25:04Could this be a natural phenomenon?
25:08Unlikely.
25:10Forests throughout the country are damaged,
25:13but natural conditions like soil and climate vary widely.
25:18There is a crucial hint in scenes like this.
25:23The trees are at the top of the mountain.
25:26In fact, wherever forest damage is found in Germany,
25:30the higher the elevation, the worse the damage.
25:34Why should altitude be important?
25:37Flying above the Adirondacks, atmospheric scientist Volker Mohn.
25:42These clouds we are looking at are quite pretty.
25:47It was as a surprise that these clouds that we see out there
25:52are so heavily polluted with sulfate, nitrate, oxidants, etc.
25:58It's not just the clouds here in the Adirondacks,
26:01it's the clouds everywhere in the world,
26:03everywhere where in proximity is to industrial emissions.
26:09We might even say that clouds are the vacuum cleaners of the atmosphere.
26:17Down on Whiteface Mountain, they catch the vacuum cleaners.
26:23There's a front moving in.
26:25They'll be able to catch a cloud event, as they call it.
26:36Soon the summit at 5,000 feet will be in the clouds,
26:40and so will their observatory.
26:48The Adirondacks
26:56Inside this cloud, the winds are up to 50 miles an hour,
27:00but that's ideal conditions for the cloud catcher.
27:18The Adirondacks
27:32Whipping through the strands of the catcher,
27:34the cloud moisture builds up into droplets,
27:37then drains down into the observatory cabin below.
27:43Drop by drop, it's analyzed,
27:46and it's carrying a huge load of acidity.
27:58Volker Mohnen pioneered cloud research here,
28:02and he's made some striking discoveries about what they contain.
28:08The clouds we observe at Whiteface Mountain
28:12show a level of pollution that is typically ten times higher
28:17in concentration than we find in precipitation at the same spot.
28:23That tells us that clouds are great concentrators of pollutant material.
28:31If the clouds simply evaporate,
28:33their pollutant load is dispersed throughout the atmosphere.
28:37But there's another possibility.
28:39If the mountain intercepts prior to evaporation,
28:44then it's the leaves and the needles, the stems,
28:48and eventually the soil that receives this high concentration
28:52of pollutant material with the water, with the cloud water.
28:59The mountaintops, where forest damage is worst,
29:03spend up to 200 days a year bathed in this polluted cloud water.
29:11Just like the Whiteface cloud catcher,
29:13conifer needles efficiently comb out the acid moisture.
29:17What effect could it have?
29:20Here in Essen, Dr. Prince believes he's found one possibility.
29:25He raises trees in mountain conditions using the three main pollutants,
29:30ozone, a trace of which is added to the air in the chambers,
29:34and nitric and sulfuric acids,
29:37contained in simulated cloud water on the needles.
29:42As it drops off, this acid fog, as they call it,
29:46is found to have washed vital nutrients out of the needles,
29:50needles weakened by the corrosive effects of ozone.
29:54It works in such a way that the protection layer of the cells,
30:00or the scientists say the cell membrane system, is weakened.
30:05This system loses its protective function.
30:10If now the acid fog comes to the needles, to the cells,
30:15very important nutrients are washed out, are leached out,
30:19above all magnesium, but some other important nutrients too,
30:24for example, potassium and calcium.
30:28There's no yellowing of the needles,
30:30but the loss of nutrients is still highly significant,
30:33because the pattern of yellow needle tips seen by Professor Zech
30:37is a known symptom of a particular nutrient deficiency disease,
30:42magnesium deficiency.
30:44If you look up in this direction,
30:47you see that whole parts of the forests are completely dead now.
30:52These are not old trees, these are young trees,
30:56they are about, let me say, 30 or 40 years old,
31:00and they have died because of this magnesium deficiency.
31:05Ozone, acid clouds, loss of nutrients.
31:10It's a possible mechanism,
31:14one of many new ideas that scientists on both sides of the Atlantic
31:18are suggesting could be the cause of forest decline.
31:28Another dying German forest? No.
31:36This is Camel's Hump in Vermont,
31:39where it was discovered that America too has a problem with its forests.
31:51The bearer of the tidings was a forestry professor, Tom Sickema,
31:56who has a house at the base of the mountain,
31:58like a doctor at the bedside of a sick patient.
32:03Twenty years ago, Tom Sickema picked Camel's Hump
32:06as a site to study typical mountain forest ecology.
32:10As a graduate student, he walked the trails,
32:13making standard measurements,
32:15like the area of forest floor covered by various species.
32:19In 1979, he did it again.
32:23This is actually the 1964 field book,
32:27and what we found then in comparing the 1964
32:31with the more recent 79 survey,
32:34was that for spruce, that area was reduced by about 50%.
32:38So about half of the spruce in those larger trees
32:42had died in that 15, 17-year time frame.
32:46Red spruce should live for 300 years.
32:49Something had gone wrong.
32:51When we were doing this particular area in the 60s,
32:54this was what we would speak of as sort of a closed canopy forest.
32:58That is, right where we're standing now, looking up,
33:02the forest would essentially have trees
33:05at maybe 100 feet or 70 feet, making a canopy.
33:10And now, looking around, it's a pretty scraggly stand.
33:15Most of those trees, the large ones, have died.
33:18They just die standing.
33:20Needles come off, and eventually they probably break off,
33:23leaving stubs.
33:26The discovery set off a flurry of activity.
33:30Students and professors flocked to the forests.
33:36Trees up and down the East Coast were cored and measured.
33:46Nice one.
33:48Tom Sickum, a former engineer,
33:52Nice one.
33:54Tom Sickum was joined by a colleague, Art Johnson.
34:02Together they made a startling discovery.
34:05This is a section from about a 300-year-old red spruce from Camel's Hump.
34:10And we can see that when it started out growing
34:13and was a rather small tree, perhaps 10 or 12 feet high,
34:16it was growing suppressed within the canopy, where it's rather dark,
34:20and the growth rings are quite narrow.
34:22We see that there's a couple of periods of release
34:25or a couple of periods of better growth
34:27when perhaps a neighbor fell over and the tree had a little bit more light
34:31or some more resources to work with.
34:33Then we find that there's a very interesting event
34:36that occurred about 10 to 15 years ago, which begins right here.
34:40There is a rather abrupt change to extremely narrow increments.
34:44This event is really quite synchronized
34:47from trees that we find growing in Maine to North Carolina.
34:52Sometime after 1960, we find that there was this synchronized change
34:57to very slow growth rates in red spruce.
35:02Red spruce is a major species of mountain forests.
35:06Wherever Art Johnson and his colleagues have looked,
35:09spruce trees are in trouble.
35:11Here in Vermont, in New Hampshire, in the Adirondacks,
35:17and right down the Appalachians to the Smoky Mountains in North Carolina.
35:26At Oak Ridge National Laboratory,
35:2814,000 tree cores from 31 species, high and low altitude,
35:34in 15 eastern states, are now being meticulously studied.
35:39The first results assembled by Sandy McLaughlin have been controversial.
35:44All 31 species are now growing more slowly than in the past, he says.
35:49While some of this is probably natural,
35:52he's also looked to see if the growth slowdown
35:55is greater in areas of high pollution.
35:58Until he reworks the data, he's officially cautious.
36:02If we look at the 31 species which we've studied,
36:07across the region, the growth changes,
36:10and remember I'm saying growth changes and not pollution effects,
36:13but the growth changes are most pronounced on high elevation species,
36:17the ones that occur on the mountaintops,
36:19where, coincidentally or not, pollution levels are typically highest.
36:23But for the five high elevation species,
36:25the growth change in the last 10 years,
36:27compared to this 1930 through 60 reference period, is about 40%.
36:32So the forest industry could have trouble ahead.
36:35If the decline is not just on mountaintops,
36:39and if it's linked to pollution rather than some natural cycle,
36:43the forest acreage owned by companies will steadily lose its value.
36:52The Great Smoky Mountains,
36:54the largest mountain range in the world,
36:58The Great Smoky Mountains in North Carolina,
37:01perhaps the ideal place to see how difficult it is
37:04to answer the questions that hang over our forests.
37:08Forest scientist Bob Brook is driving up to Mount Mitchell.
37:12The summit is in the clouds, like mountains everywhere.
37:16It was just about a year and a half ago
37:18when I first drove this road in anticipation
37:21of seeing, or potentially seeing,
37:24of seeing, or potentially seeing,
37:27symptoms of decline and dieback.
37:30And things have deteriorated quite markedly since that particular time.
37:35Some of the symptoms that we are beginning to observe,
37:38even at this relatively low altitude, are really quite profound.
37:42Coming up on our right here,
37:44we see a tree that is dying back from the top.
37:48In addition, there are numerous dead individuals.
37:59Here at the top of Mount Mitchell,
38:016,500 feet up,
38:03he discovered a devastated forest.
38:12At one time, a drought in the 60s
38:16was used to explain forest destruction further north.
38:20Until Bob Brook found this.
38:23Here in the south, there was no drought.
38:29But there was something else to add to the confusion.
38:32An insect which attacks Frazier fir.
38:35It's always caused some damage.
38:38Here in the center, you can see its telltale woolly covering.
38:42But could it lead to such rapid decline?
38:45The rate in which the deterioration of this boreal ecosystem
38:49has taken place is really quite astounding.
38:51We have photographs taken in the 1970s
38:54showing that the Black Mountain Range,
38:56which Mount Mitchell is a part of here,
38:58was covered with a thick, lush, coniferous ecosystem.
39:02There was only minor damage
39:04that could principally be attributed to the balsam woolly aphid
39:07on Frazier fir populations on this mountain.
39:10And here, a mere 10 to 15 years later,
39:13we are looking at as much as 90 to 95% mortality.
39:19Maybe the aphid caused some of this mortality.
39:23But spruce trees are dying up here too,
39:26and they are immune to aphid attack.
39:31There's also obvious yellowing and loss of needles to be seen.
39:35A confusing picture.
39:37But one that was clarified quite recently by a simple insight.
39:44It was provided not by a forest scientist,
39:48but by an air pollution expert in St. Louis, Missouri.
39:52Rudy Hussar studies trends
39:54in oil production, coal production, industrial activity.
39:58From all these numbers,
40:00he reconstructs how air pollution levels have changed.
40:031887 million.
40:06Coal mining figures lead to sulfur emissions, for example.
40:111881.
40:1320 million.
40:15Region by region, he's worked out the impact over the years.
40:19Sulfur emission in the northeastern part of the country
40:22has not changed substantially since the turn of the century.
40:28On the other hand, the sulfur emissions for the southeast
40:32have been increasing steadily.
40:34What is common for both regions
40:37is the trend of nitrogen oxide emissions.
40:41Automobiles were the reason for this common trend.
40:45Since about 1900, gasoline consumption has risen steadily,
40:49with the sharpest increase, north and south,
40:52in the 50s and 60s.
40:55And the 60s was just the time when trees throughout the east
40:59showed the sharp growth decline.
41:02If biological effects are observed both north and south,
41:07then one likely explanation for that would be
41:12that it is the nitrogen oxide hydrocarbon mix
41:16that is largely responsible for those effects.
41:22So nitrogen emissions, not sulfur, went up as the forests declined.
41:27Art Johnson thinks it makes sense in the field,
41:31and he finds his evidence in the way the spruce needles behave on camels' hump.
41:37Brown needles, killed by the frost, are a common sight here.
41:41When we arrive here in the springtime,
41:43what we typically find is that a substantial proportion
41:47of the needles on these declining trees have turned brown over the winter,
41:51and these then subsequently fall off sometime during the summer.
41:56The needles are abnormally sensitive to frost for a strange reason.
42:01Art Johnson believes the nitrogen part of nitric acid
42:05could be fertilizing the needles so they keep on growing late into the year.
42:10These trees are bathed in cloud moisture for a considerable period of time.
42:15The cloud moisture is quite rich in nitrogen,
42:18and we think there may be substantial uptake of nitrogen into the foliage.
42:24The plant continues to grow late into the fall
42:27and doesn't harden properly for the wintertime,
42:30and therefore nitrogen could possibly be a chronic problem
42:34that would be occurring over a long term,
42:37let's say the length of a growing season.
42:39So although the mountain clouds carry sulfuric and nitric acids,
42:44in this theory it's the fertilizing effect of nitrogen that's important.
42:49It could be killing the trees with kindness.
42:52Germany had the same increase in oil use and emissions as the United States.
42:57When nitrogen and hydrocarbons go up, so does the resulting ozone,
43:02the pollutant which led to nutrient losses from the needles in Dr. Prince's laboratory.
43:07So the nitrogen theory offers consistent explanations.
43:13And remarkably, it's an idea which fits with the lakes as well.
43:18Normally, in summer, nitric acid is taken up as a fertilizer by the vegetation.
43:26Only sulfuric acid reaches the water.
43:33But in winter, when plants are dormant,
43:36both nitric and sulfuric acids are absorbed and stored up by the snowpack.
43:43With spring breakup, a massive pulse of both acids hits the streams,
43:49catching the young fish at their most vulnerable,
43:52an acid shock from which they may never recover.
43:56In this way, nitric acid may contribute to damage here as well.
44:01The idea of acid shock has prompted another new theory of forest decline.
44:07These young pine trees are experiencing a sudden shock of simulated acid rain.
44:15Thin, unhealthy trees are the result,
44:19compared to the normal trees on the left.
44:30The early results of this experiment show that the roots are different.
44:36Normal rain, normal roots.
44:40Acid rain, unhealthy roots.
44:55This particular tree was removed from lower altitude about 5,300 feet earlier today.
45:00And you may notice that the root system is quite vigorous.
45:03It is fibrous. It is light in color.
45:05And the tree appears to be quite normal and healthy.
45:09However, this tree just removed from high altitude on Mount Mitchell,
45:13which as we could see is in a state of decline,
45:15a drop of the needles, appears to be very blackened.
45:20Perhaps one of the major differences in the reaction of these root systems
45:25is their location and the amount of deposition,
45:28which correlates nicely back to our laboratory experiments.
45:31The theory is that up on the mountains, just as in the laboratory,
45:36rain or cloud events lasting hours or days are damaging the root systems.
45:41That makes sense, except for one thing.
45:45This soil has excellent ability to absorb acids.
45:49The roots should be protected even up here at high altitude.
45:53Soil scientist Wayne Robards.
45:55One possibility may be that atmospheric deposition is in fact an event process.
46:00And then over a very short period of times,
46:02occurring perhaps in only the upper layers of the soil,
46:05where in fact the roots are concentrated,
46:07we may have conditions that are detrimental to tree growth.
46:10Then, as that time passes, the soil does overcome those short-term effects
46:16and returns to normal.
46:18It's like the spring shock of sulfuric and nitric acids in the streams.
46:22A transient effect, but with lasting damage.
46:26In forest ecosystems, we don't really have much information
46:30about what happens on an event basis.
46:33But it's conceivable that events might be quite important in the forest as well.
46:39Events of snow melt and water percolating through the soil,
46:43which is extremely acidic or has the contaminants,
46:47the other pollutants that are present in melting snow,
46:51could be stressful to organisms.
46:55But we simply haven't enough information to allow us to say
46:59that short-term events are involved in this particular decline disease.
47:05We feel encouraged that perhaps we have seen a specific effect
47:10of atmospheric deposition on these coniferous roots.
47:14However, to say that this is a cause and effect mechanism or relationship
47:18to the decline of these trees would really not be proper.
47:21Undoubtedly, there are many, many interactions on this mountain
47:24that could be taking place.
47:26The effect of gases, the effect of certain oxidants such as ozone,
47:29which are present in abundance at the top of this mountain,
47:32interacting together holistically and stressing this particular system.
47:37And that is the state of acid rain research today.
47:41There are many theories of forest decline.
47:44Ozone and acid clouds, nitrogen over-fertilization,
47:47acid shock to the roots.
47:50They are all new.
47:51They may all be wrong.
47:53They may all be right.
47:54But significantly, they all involve nitric acid as well as sulfuric.
48:00In the lakes, sulfuric acid without doubt causes acidification.
48:05But spring acid shocks are a way that nitric acid
48:09probably contributes to the damage.
48:12A typically imperfect science,
48:14one familiar to the former administrator of the Environmental Protection Agency,
48:19William Ruckelshaus.
48:21By the very nature of these environmental public health kind of decisions,
48:25we are operating in areas of enormous scientific uncertainty.
48:29The public very poorly understands that.
48:32They think we've got all the scientific information we need
48:35and then we're hiding it somewhere.
48:36We want to give it to them.
48:37Why? It would be very clear what ought to be done.
48:39The truth is there are so many things we don't know in these areas
48:43that it sometimes is very, very unnerving to try to make a decision.
48:47But that doesn't mean you don't have to make decisions
48:49on the basis of the information you do have.
48:52Often you simply have to make as prudent a judgment as you can,
48:55knowing that 50 years from now somebody's going to come back and say,
49:00boy, there was a dumb one.
49:01Look at what we now know.
49:03And on the basis of that, we never had to do the things he recommended.
49:06I'm certain of that.
49:08What could be done?
49:10One option is to do nothing.
49:13Because we already control sulfur emissions on new power plants
49:17and nitrogen emissions on new cars,
49:19those pollutants will at least level off by the end of the century.
49:25It's cheap, but risky.
49:27We just don't know how much additional damage we'll do to the forests and lakes.
49:33A second option is to control nitrogen not just from cars,
49:37but from all burning processes, industry, power plants.
49:42That's expensive and technically difficult,
49:45but likely to help both the lakes and forests.
49:49A third option is to cut more sulfur now.
49:53That's fairly expensive, will help the lakes to some degree,
49:57but probably not the forests.
50:00My personal view is that if sulfur and nitrogen compounds
50:05and those compounds that produce ozone and hydrogen peroxide
50:09are reduced in the air,
50:12that it can only help the environment, it will not hurt.
50:16But to monolithically approach the problem in a hastily way
50:21by simply cutting sulfur and then stepping back
50:26and assuming that the problem is resolved,
50:29this, I believe, is a wrong cause.
50:32I would think a prudent man could now decide,
50:35we know enough to start bringing these levels down.
50:38We know enough to bring them down and get the cheap stuff out first.
50:43We don't know enough to bring them down sharply where the cost just goes straight up.
50:47We can't justify that kind of social expenditure.
50:50We can, on the other hand, justify a sort of an insurance policy
50:54keeping these levels coming down as we research very hard what's going on
50:58and develop the administrative machinery for bringing them down much more sharply
51:02if our research dictates that's what ought to be done.
51:05I think that is a prudent approach.
51:07I also don't think it's imprudent to say,
51:09I need a little more information before I decide to do that.
51:12This is a stand on Mount Mitchell.
51:15Perhaps the most depressing news about acid rain
51:18is that for parts of the environment,
51:21it may already be too late, whatever we do.
51:25One of the most striking things about this particular spot on the mountain
51:29is the fact that as we look around,
51:32we see very few intermediate-sized trees
51:35and even fewer small reproduction-sized trees on the forest floor.
51:41What is to become of the west face of this mountain?
51:44The simple fact is that we are looking at a forest
51:48that is in a state of decline and probably imminent mortality.
51:53If I had to guess, I would say that within 10 years,
51:56the majority of the trees in this stand will in fact be dead.
52:00When they are dead, obviously they will not be reproducing anymore.
52:03And in addition, if there are no intermediate-sized trees,
52:06if there are no small trees on the forest floor,
52:09we may be in for a severe ecological problem.
52:21In Sweden, where it all began,
52:23Hans Hulteberg and Svante Odin,
52:26out on their recently limed and now healthy lake,
52:29are also contemplating the future.
52:51It's increased rapidly in needle decline
52:55during the last four or five years.
52:58And now we have done a survey
53:01by the help of people from Svante's institution,
53:05which says that we have about 50% of the trees severely damaged up here,
53:11with more than 20% needle loss.
53:14And it seems to be getting more and more severe.
53:20So in the near future, I guess we'll have a big problem,
53:26or I think we have the problem here now
53:28with the forest decline here in Sweden.
53:31We are some five, maybe eight years
53:36behind what is in central Europe.
53:39If you come back here in five years,
53:41most of the cover trees here you see here will be dying or being taken away.
53:47How much further this kind of destruction will go, we don't know.
53:52How much further can we allow it to go, we don't know.
53:59We know the environment is very resilient.
54:01We can perturb it to a large degree,
54:03and it will still provide us with oxygen and resources to use for our benefit.
54:09But that resiliency, the depth of that resiliency is unknown.
54:13Another way of saying it is,
54:15we don't know how far we can go in damaging ecosystems
54:18before they lose their structure
54:20and then begin to damage us because of their lack of cohesiveness.
54:24I think we must recognize with time
54:27that acid rain, ozone episodes, high pollution episodes
54:33are a problem of industrialization,
54:38not just in the United States,
54:41but in all of America, in all of Europe,
54:43and pretty soon in all of China and all of Asia, all of Japan.
54:48Well, by that time we are talking about a problem
54:51that involves global habitability.
54:53It really involves a second look at our spaceship Earth
54:57and how we like to see this spaceship Earth develop in the future.
55:18NASA Jet Propulsion Laboratory, California Institute of Technology
55:48NASA Jet Propulsion Laboratory, California Institute of Technology
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