Friday, April 27, 2007

This is TSUNAMI

World Record Tsunami

TsunamisWhoa! You're thinking... what is a tsunami and I don't see a huge wave in the picture, anywhere. Well, a tsunami (it's actually a Japanese word) is a word scientists use to describe an enormous wave (or series of waves) that happens when an enormous amount of energy is released into the waters of the ocean creating a ripple effect, like when you drop something in the bathtub or throw a rock into a lake. Only the "ripples" come from:

1) an earthquake (movement of the sea floor)
2) a volcanic eruption (lava and rock going "kersploosh" into the sea)
3) a huge landslide, as was the case in Lituya Bay

The incredibly massive size of the material 'plopping' into the ocean (or the shifting of the sea floor) creates MAJOR ripples that are so big they are gigantic waves traveling at speeds of up to 200 mph/320kph over really long distances in the open sea. But, when the waves reach the beach they are incredibly high and wash way inland causing major damage and sometimes loss of life.

SO, you're asking, why no wave in the picture? Well, close up shots of tsunamis actually happening are pretty rare and hard to get, as you can imagine. Would YOU stand on the shore with a camera to take a picture of a ten-story high wave coming right at you? Most people turn and run for the hills because their lives are in serious danger.

Enormous Earthquake

What happened at Lituya was movement along the fault that runs from left to right in the above picture. If you pretend you're actually standing on the ridgetop looking out over the Bay (like the view in the above picture) the fault would be in the mountains behind you. The "movement in the fault", of course, is called an earthquake. The magnitude of the quake was about 8.3, although some


This photo shows the damage to the headland; every living thing was completely wiped off where the first major wave struck.

sources say it was a 7.9, on the Richter Scale (a scale for measuring the magnitude, or amount of energy released, from an earthquake). Pretty awesome shaker. Well, shaker it was...it "shook" loose an estimated 40 million cubic yards of dirt and glacier from a mountainside at the head of the Bay, about where you're standing in the above picture. When the stuff went "kersploosh" into the water it created a massive wave that washed 1,720 ft/524m high over the headland in the right side of the above picture. The tsunami inundated approximately 5 square miles of land along the shores of Lityua Bay, sending water as far as 3,600 feet inland, and clearing millions of trees.You can see the damage to the trees that were growing on the headland when the wave washed over the top of it - there were no trees left...wiped 'em clean off. The picture above gives you a closer view of the damage to the headland that the tidal waves caused.

Human Witnesses

There were three fishing boats anchored at the mouth of Lituya Bay on the day the awesome waves


U.S.G.S. Aerial photo of Lituya Bay taken after July 9, 1958 event. Note the extent of the non-forested areas of land lining the shore of the bay, which marks the approximate reach of the tsunami's runup.

happened. That's the main reason we know it happened. There were human witnesses to the catastrophic event. Unfortunately, one of the boats was close to shore and the huge waves overtook it killing the two people on board. Amazingly, the other two boats "rode" the tidal waves as they washed from the source of the landslide and resonated around the bay, like water sloshing in a wash basin. The boaters watched in horror as the first enormous wave engulfed the small fishing boat and wiped everything in its path off the land. If there had been a town or city on the shores of the bay everyone in it would have been killed. Fortunately, because it was an unpopulated area, the loss of life was minimal (although, the family of the victims hardly think that it was good fortune).

How Do They Know?

To measure the height of the biggest wave, all scientists had to do was look for the high water mark - that's the line where the water reached its highest point on the nearby land. It's real easy to find you just look for the uppermost edge of the damaged area (see photo at left).

Then, they measured the elevation of the highest point on the high water mark to get a measurement of 1,720 ft/524 high - the biggest wave ever measured.


The yellow mark illustrates the maximum height the wave reached as it washed over the headland.

Other Big Waves

There are waves out on the ocean all the time, which are created by the friction, or the dragging motion, of the wind over the vast surface of the sea. When big storms develop out at sea creating fast winds it causes really big waves, called storm waves. Ships out at sea during these really big storms have experienced some pretty big waves, some as much as 100 ft/31m high, but that's about as big as storm waves get out on the open sea. Nothing like the "big one" at Lituya Bay.

Here's something to think about...There happened to be people fishing in the Bay the day that the landslide and resulting tidal wave occurred. That part of Alaska is not populated, but people come to that area for many reasons. There are places on this earth that are so inhospitable (really bad) that few people ever visit. For example, the Arctic, or the Antarctic, in winter are some pretty nasty, cold places. Not only are they not fun places to visit, but they're virtually inaccessible to humans in winter. It's totally possible that in early spring, when the ice starts to melt, and glaciers calve into the ocean (break off HUGE chunks) that really big waves occur. Possibly even bigger than the massive one at Lituya Bay! The wave may wash up over ice and ice-covered land, but the evidence melts away so that no human ever knows it happened.

We say that the tsunami at Lituya Bay was the biggest wave ever, but that's just the ones humans have witnessed and have been able to record. There have probably been even BIGGER waves that have happened in the past when human witnesses didn't even exist. And you never know, there may even be a bigger wave to happen yet!


http://www.extremescience.com/BiggestWave.htm

This is TSUNAMI

World Record Tsunami

TsunamisWhoa! You're thinking... what is a tsunami and I don't see a huge wave in the picture, anywhere. Well, a tsunami (it's actually a Japanese word) is a word scientists use to describe an enormous wave (or series of waves) that happens when an enormous amount of energy is released into the waters of the ocean creating a ripple effect, like when you drop something in the bathtub or throw a rock into a lake. Only the "ripples" come from:

1) an earthquake (movement of the sea floor)
2) a volcanic eruption (lava and rock going "kersploosh" into the sea)
3) a huge landslide, as was the case in Lituya Bay

The incredibly massive size of the material 'plopping' into the ocean (or the shifting of the sea floor) creates MAJOR ripples that are so big they are gigantic waves traveling at speeds of up to 200 mph/320kph over really long distances in the open sea. But, when the waves reach the beach they are incredibly high and wash way inland causing major damage and sometimes loss of life.

SO, you're asking, why no wave in the picture? Well, close up shots of tsunamis actually happening are pretty rare and hard to get, as you can imagine. Would YOU stand on the shore with a camera to take a picture of a ten-story high wave coming right at you? Most people turn and run for the hills because their lives are in serious danger.

Enormous Earthquake

What happened at Lituya was movement along the fault that runs from left to right in the above picture. If you pretend you're actually standing on the ridgetop looking out over the Bay (like the view in the above picture) the fault would be in the mountains behind you. The "movement in the fault", of course, is called an earthquake. The magnitude of the quake was about 8.3, although some


This photo shows the damage to the headland; every living thing was completely wiped off where the first major wave struck.

sources say it was a 7.9, on the Richter Scale (a scale for measuring the magnitude, or amount of energy released, from an earthquake). Pretty awesome shaker. Well, shaker it was...it "shook" loose an estimated 40 million cubic yards of dirt and glacier from a mountainside at the head of the Bay, about where you're standing in the above picture. When the stuff went "kersploosh" into the water it created a massive wave that washed 1,720 ft/524m high over the headland in the right side of the above picture. The tsunami inundated approximately 5 square miles of land along the shores of Lityua Bay, sending water as far as 3,600 feet inland, and clearing millions of trees.You can see the damage to the trees that were growing on the headland when the wave washed over the top of it - there were no trees left...wiped 'em clean off. The picture above gives you a closer view of the damage to the headland that the tidal waves caused.

Human Witnesses

There were three fishing boats anchored at the mouth of Lituya Bay on the day the awesome waves


U.S.G.S. Aerial photo of Lituya Bay taken after July 9, 1958 event. Note the extent of the non-forested areas of land lining the shore of the bay, which marks the approximate reach of the tsunami's runup.

happened. That's the main reason we know it happened. There were human witnesses to the catastrophic event. Unfortunately, one of the boats was close to shore and the huge waves overtook it killing the two people on board. Amazingly, the other two boats "rode" the tidal waves as they washed from the source of the landslide and resonated around the bay, like water sloshing in a wash basin. The boaters watched in horror as the first enormous wave engulfed the small fishing boat and wiped everything in its path off the land. If there had been a town or city on the shores of the bay everyone in it would have been killed. Fortunately, because it was an unpopulated area, the loss of life was minimal (although, the family of the victims hardly think that it was good fortune).

How Do They Know?

To measure the height of the biggest wave, all scientists had to do was look for the high water mark - that's the line where the water reached its highest point on the nearby land. It's real easy to find you just look for the uppermost edge of the damaged area (see photo at left).

Then, they measured the elevation of the highest point on the high water mark to get a measurement of 1,720 ft/524 high - the biggest wave ever measured.


The yellow mark illustrates the maximum height the wave reached as it washed over the headland.

Other Big Waves

There are waves out on the ocean all the time, which are created by the friction, or the dragging motion, of the wind over the vast surface of the sea. When big storms develop out at sea creating fast winds it causes really big waves, called storm waves. Ships out at sea during these really big storms have experienced some pretty big waves, some as much as 100 ft/31m high, but that's about as big as storm waves get out on the open sea. Nothing like the "big one" at Lituya Bay.

Here's something to think about...There happened to be people fishing in the Bay the day that the landslide and resulting tidal wave occurred. That part of Alaska is not populated, but people come to that area for many reasons. There are places on this earth that are so inhospitable (really bad) that few people ever visit. For example, the Arctic, or the Antarctic, in winter are some pretty nasty, cold places. Not only are they not fun places to visit, but they're virtually inaccessible to humans in winter. It's totally possible that in early spring, when the ice starts to melt, and glaciers calve into the ocean (break off HUGE chunks) that really big waves occur. Possibly even bigger than the massive one at Lituya Bay! The wave may wash up over ice and ice-covered land, but the evidence melts away so that no human ever knows it happened.

We say that the tsunami at Lituya Bay was the biggest wave ever, but that's just the ones humans have witnessed and have been able to record. There have probably been even BIGGER waves that have happened in the past when human witnesses didn't even exist. And you never know, there may even be a bigger wave to happen yet!

ozone

Chemistry

Ozone is a powerful oxidizing agent. It is also unstable at high concentrations, decaying to ordinary diatomic oxygen:

2 O3 → 3 O2.

This reaction proceeds more rapidly with increasing temperature and decreasing pressure. Ozone will oxidize metals (except gold, platinum, and iridium) to oxides of the metals in their highest oxidation state:

2 Cu2+ + 2 H+ + O3 → 2 Cu3+ + H2O + O2

Ozone converts oxides to peroxides:

SO2 + O3 → SO3 + O2

It also increases the oxidation number of oxides:

NO + O3 → NO2 + O2

The above reaction is accompanied by chemiluminescence. The NO2 can be further oxidized:

NO2 + O3 → NO3 + O2

The NO3 formed can react with NO2 to form N2O5:

NO2 + NO3 → N2O5

Ozone reacts with carbon to form carbon dioxide, even at room temperature:

C + 2 O3 → CO2 + 2 O2

Ozone does not react with ammonium salts but it reacts with ammonia to form ammonium nitrate:

2 NH3 + 4 O3 → NH4NO3 + 4 O2 + H2O

Ozone reacts with sulfides to make sulfates:

PbS + 4 O3 → PbSO4 + 4 O2

Sulfuric acid can be produced from ozone, either starting from elemental sulfur or from sulfur dioxide:

S + H2O + O3 → H2SO4
3 SO2 + 3 H2O + O3 → 3 H2SO4

All three atoms of ozone may also react, as in the reaction with tin(II) chloride and hydrochloric acid:

3 SnCl2 + 6 HCl + O3 → 3 SnCl4 + 3 H2O

In the gas phase, ozone reacts with hydrogen sulfide to form sulfur dioxide:

H2S + O3 → SO2 + H2O

In an aqueous solution, however, two competing simultaneous reactions occur, one to produce elemental sulfur, and one to produce sulfuric acid:

H2S + O3 → S + O2 + H2O
3 H2S + 4 O3 → 3 H2SO4

Iodine perchlorate can be made by treating iodine dissolved in cold anhydrous perchloric acid with ozone:

I2 + 6 HClO4 + O3 → 2 I(ClO4)3 + 3 H2O

Solid nitryl perchlorate can be made from NO2, ClO2, and O3 gases:

2 NO2 + 2 ClO2 + 2 O3 → 2 NO2ClO4 + O2

Ozone can be used for combustion reactions and combusting gases in ozone provides higher temperatures than combusting in dioxygen (O2). Following is a reaction for the combustion of carbon subnitride:

3 C4N2 + 4 O3 → 12 CO + 3 N2

Ozone can react at cryogenic temperatures. At 77 K (-196 °C), atomic hydrogen reacts with liquid ozone to form a hydrogen superoxide radical, which dimerizes:[9]

H + O3 → HO2 + O
2 HO2 → H2O4

Ozonides can be formed, which contain the ozonide anion, O3-. These compounds are explosive and must be stored at cryogenic temperatures. Ozonides for all the alkali metals are known. KO3, RbO3, and CsO3 can be prepared from their respective superoxides:

KO2 + O3 → KO3 + O2

Although KO3 can be formed as above, it can also be formed from potassium hydroxide and ozone:[10]

2 KOH + 5 O3 → 2 KO3 + 5 O2 + H2O

NaO3 and LiO3 must be prepared by action of CsO3 in liquid NH3 on an ion exchange resin containing Na+ or Li+ ions:[11]

CsO3 + Na+ → Cs+ + NaO3

Treatment with ozone of calcium dissolved in ammonia leads to ammonium ozonide and not calcium ozonide:[12]

3 Ca + 10 NH3 + 6 O3 → Ca•6NH3 + Ca(OH)2 + Ca(NO3)2 + 2 NH4O3 + 2 O2 + H2

Ozone can be used to remove manganese from the water, forming a precipitate which can be filtered:

2 Mn2+ + 2 O3 + 4 H2O → 2 MnO(OH)2 (s) + 2 O2 + 4 H+

Ozone will also turn cyanides to the one thousand times less toxic cyanates:

CN- + O3 → CNO- + O2

Finally, ozone will also completely decompose urea:[13]

(NH2)2CO + O3 → N2 + CO2 + 2 H2O

Ozone in Earth's atmosphere

Concentration of ozone as measured by the Nimbus-7 satellite.
Concentration of ozone as measured by the Nimbus-7 satellite.

The standard way to express total ozone levels (the volume of ozone in a vertical column) in the atmosphere is by using Dobson units. Concentrations at a point are measured in parts per billion (ppb) or in μg/m³.

[ Ozone layer

Main article: Ozone layer
Total ozone concentration in June 2000 as measured by EP-TOMS satellite instrument.
Total ozone concentration in June 2000 as measured by EP-TOMS satellite instrument.

The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 km and 50 km above the surface (or between 6.21 and 31.1 miles). Here it filters out the shorter wavelengths (less than 320 nm) of ultraviolet light (270 to 400 nm) from the Sun that would be harmful to most forms of life in large doses. These same wavelengths are also among those responsible for the production of vitamin D, which is essential for human health. Ozone in the stratosphere is mostly produced from ultraviolet rays reacting with oxygen:

O2 + (radiation <>
O + O2 → O3

It is destroyed by the reaction with atomic oxygen:

O3 + O → 2 O2

(See Ozone-oxygen cycle for more detail.)

The latter reaction is catalysed by the presence of certain free radicals, of which the most important are hydroxyl (OH), nitric oxide (NO) and atomic chlorine (Cl) and bromine (Br). In recent decades the amount of ozone in the stratosphere has been declining mostly due to emissions of CFCs and similar chlorinated and brominated organic molecules, which have increased the concentration of ozone-depleting catalysts above the natural background. See ozone depletion for more information. For more information on stratospheric ozone see Seinfeld and Pandis (1999).

Low level ozone

Low level ozone (or tropospheric ozone) is regarded as a pollutant by the World Health Organization.[14] It is not emitted directly by car engines or by industrial operations. It is formed by the reaction of sunlight on air containing hydrocarbons and nitrogen oxides that react to form ozone directly at the source of the pollution or many kilometers down wind. For more details of the complex chemical reactions that produce low level ozone see tropospheric ozone or Seinfled and Pandis (1998).

Ozone reacts directly with some hydrocarbons such as aldehydes and thus begins their removal from the air, but the products are themselves key components of smog. Ozone photolysis by UV light leads to production of the hydroxyl radical and this plays a part in the removal of hydrocarbons from the air, but is also the first step in the creation of components of smog such as peroxyacyl nitrates which can be powerful eye irritants. The atmospheric lifetime of tropospheric ozone is about 22 days and its main removal mechanisms are being deposited to the ground, the above mentioned reaction giving OH, and by reactions with OH and the peroxy radical HO2· (Stevenson et al, 2006).[15]

As well as having an impact on human health (see below) there is also evidence of significant reduction in agricultural yields due to increased ground-level ozone and pollution which interferes with photosynthesis and stunts overall growth of some plant species.[16][17]

Ozone as a greenhouse gas

Although ozone was present at ground level before the industrial revolution, peak concentrations are far higher than the pre-industrial levels and even background concentrations well away from sources of pollution are substantially higher.[18][19] This increase in ozone is of further concern as ozone present in the upper troposphere acts as a greenhouse gas, absorbing some of the infrared energy emitted by the earth. Quantifying the greenhouse gas potency of ozone is difficult as it is not present in uniform concentrations across the globe. However, the most recent scientific review on the climate change (the IPCC Third Assessment Report[20]) suggests that the radiative forcing of tropospheric ozone is about 25% that of carbon dioxide


http://en.wikipedia.org/wiki/Ozone

Ocean become angry

Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earth's stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole.

The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine.[1] The main source of these halogen atoms in the stratosphere is photodissociation of chlorofluorocarbon (CFC) compounds, commonly called freons, and of bromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface. Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased.

CFCs, halons and other contributory substances are commonly referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (270–315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol banning the production of CFCs and halons as well as related ozone depleting chemicals such as carbon tetrachloride and trichloroethane (also known as methyl chloroform). It is suspected that a variety of biological consequences such as increases in skin cancer, damage to plants, and reduction of plankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.

another kind of disaster

Ocean acidification

Main article: Ocean acidification

Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans.[47] Carbon dioxide gas dissolved in the ocean reacts with water to form carbonic acid resulting in ocean acidification. Ocean surface pH is estimated to have decreased from approximately 8.25 to 8.14 since the beginning of the industrial era,[48] and it is estimated that it will drop by a further 0.3 to 0.4 units by 2100 as the ocean absorbs more anthropogenic CO2.[49] Since organisms and ecosystems are adapted to a narrow range of pH, this is a serious concern directly driven by increased atmospheric CO2.

Global dimming

Main article: Global dimming

Scientists have stated with 66–90% confidence that the effects of volcanic and human-caused aerosols have offset some of global warming, and that greenhouse gases would have resulted in more warming than observed if not for this effect.[1]

Ozone

Main article: Ozone depletion

Although global warming and ozone depletion often are linked in the media, the relationship between the two is not strong.

Causing global warmin

Causes

Carbon dioxide during the last 400,000 years and the rapid rise since the Industrial Revolution; changes in the Earth's orbit around the Sun, known as Milankovitch cycles, are believed to be the pacemaker of the 100,000 year ice age cycle.
Carbon dioxide during the last 400,000 years and the rapid rise since the Industrial Revolution; changes in the Earth's orbit around the Sun, known as Milankovitch cycles, are believed to be the pacemaker of the 100,000 year ice age cycle.

The climate system varies through natural, internal processes and in response to variations in external forcing factors including solar activity, volcanic emissions, variations in the earth's orbit (orbital forcing) and greenhouse gases. The detailed causes of the recent warming remain an active field of research, but the scientific consensus[7][8] identifies increased levels of greenhouse gases due to human activity as the main influence. This attribution is clearest for the most recent 50 years, for which the most detailed data are available. Contrasting with this view, other hypotheses have been proposed to explain some of the observed increase in global temperatures, including: the warming is within the range of natural variation; the warming is a consequence of coming out of a prior cool period, namely the Little Ice Age; or the warming is primarily a result of variances in solar radiation.

None of the effects of forcing are instantaneous. Due to the thermal inertia of the Earth's oceans and slow responses of other indirect effects, the Earth's current climate is not in equilibrium with the forcing imposed. Climate commitment studies indicate that, even if greenhouse gases were stabilized at present day levels, a further warming of about 0.5 °C (0.9 °F) would still occur.[9]

Greenhouse gases in the atmosphere

Main article: Greenhouse effect
Recent increases in atmospheric CO2. The monthly CO2 measurements display small seasonal oscillations in an overall yearly uptrend; each year's maximum is reached during the northern hemisphere's late spring, and declines during the northern hemisphere growing season as plants remove some CO2 from the atmosphere.
Recent increases in atmospheric CO2. The monthly CO2 measurements display small seasonal oscillations in an overall yearly uptrend; each year's maximum is reached during the northern hemisphere's late spring, and declines during the northern hemisphere growing season as plants remove some CO2 from the atmosphere.

The greenhouse effect was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warms a planet's atmosphere and surface.

Greenhouse gases create a natural greenhouse effect without which mean temperatures on Earth would be an estimated 33 °C (59 °F) lower, so that Earth would be uninhabitable.[10] It is therefore not correct to say that there is a debate between those who "believe in" and "oppose" the greenhouse effect as such. Rather, the debate concerns the net effect of the addition of greenhouse gases while allowing for associated positive and negative feedback mechanisms.

On Earth, the major natural greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect (not including clouds); carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone, which causes 3–7%. The atmospheric concentrations of CO2 and CH4 have increased by 31% and 149% respectively above pre-industrial levels since 1750. This is considerably higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores. From less direct geological evidence it is believed that CO2 values this high were last attained 20 million years ago.[11] "About three-quarters of the anthropogenic [man-made] emissions of CO2 to the atmosphere during the past 20 years are due to fossil fuel burning. The rest of the anthropogenic emissions are predominantly due to land-use change, especially deforestation."[12]

The present atmospheric concentration of CO2 is about 383 parts per million (ppm) by volume.[13] Future CO2 levels are expected to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological, natural developments, but may be ultimately limited by the availability of fossil fuels. The IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100.[14] Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100, if coal, tar sands or methane clathrates are extensively used.[15]

Positive feedback effects such as the expected release of CH4 from the melting of permafrost peat bogs in Siberia (possibly up to 70,000 million tonnes) may lead to significant additional sources of greenhouse gas emissions[16] not included in IPCC's climate models.[1]

Feedbacks

The effects of forcing agents on the climate are complicated by various feedback processes.

One of the most pronounced feedback effects relates to the evaporation of water. CO2 injected into the atmosphere causes a warming of the atmosphere and the earth's surface. The warming causes more water to be evaporated into the atmosphere. Since water vapor itself acts as a greenhouse gas, this causes still more warming; the warming causes more water vapor to be evaporated, and so forth until a new dynamic equilibrium concentration of water vapor is reached at a slightly higher humidity and with a much larger greenhouse effect than that due to CO2 alone.[17] This feedback effect is reversed only as the CO2 is slowly removed from the atmosphere.

Another important feedback process is ice-albedo feedback.[18] The increased CO2 in the atmosphere warms the Earth's surface and leads to melting of ice near the poles. As the ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice, and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continues.

Feedback effects due to clouds are an area of ongoing research and debate. Seen from below, clouds absorb infrared radiation and so exert a warming effect. Seen from above, the same clouds reflect sunlight and so exert a cooling effect. Increased global water vapor concentration may or may not cause an increase in global average cloud cover. The net effect of clouds thus has not been well modeled. Positive feedback due to release of CO2 and CH4 from thawing permafrost is an additional mechanism contributing to warming. Possible positive feedback due to CH4 release from melting seabed ices is a further mechanism to be considered.

Solar variation

Solar variation over the last 30 years
Solar variation over the last 30 years
Main article: Solar variation

Variations in solar output, possibly amplified by cloud feedbacks, have been suggested as a possible cause of recent warming.[19] A difference between this mechanism and greenhouse warming is that an increase in solar activity should produce a warming of the stratosphere while greenhouse warming should produce a cooling of the stratosphere. Stratospheric warming has not been observed.[20]

Solar variation has probably had a relatively small effect on recent global warming, compared with anthropogenic effects.[1] However, some research has suggested that the Sun's contribution may have been underestimated. Researchers at Duke University have estimated that the Sun may have minimally contributed about 10–30% of the global surface temperature warming over the period 1980–2002.[21] Similarly, Stott et al. estimate in 2003 that climate models overestimate the relative effect of greenhouse gases compared to solar forcing but also that the cooling effect of volcanic dust and sulfate aerosols has been underestimated.[22] They conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming during the latest decades is attributable to the increases in greenhouse gases.

History

Sign in this wolrd

The impact of global warming in North America

Click on the numbered icons below for more information.
Global Warming Hotspots Map

The vast North American continent ranges from the lush sub-tropical climate of Florida to the frozen ice and tundra of the Arctic. Within these extremes are two wealthy industrialized countries with diverse ecosystems at risk. Yet the United States and Canada are two of the largest global emitters of the greenhouse gases that contribute to a warming climate. Examples of all 10 of the "hotspot" categories can be found in this region, including changes such as polar warming in Alaska, coral reef bleaching in Florida, animal range shifts in California, glaciers melting in Montana, and marsh loss in the Chesapeake Bay.

For North America we have many more hotspots than for some other regions of the world, although impact studies have been emerging in larger numbers in recent years from previously under-studied regions. This higher density of early warning signs in the US and Canada is due in part to the fact that these regions have more readily accessible climatic data and more comprehensive programs to monitor and study environmental change, in part to the disproportionate warming that has been observed over the mid-to-high-latitude continents compared to other regions during the last century, and in part to capture the attention of North Americans who need to take action now to reduce greenhouse gas emissions.

Fingerprints

4. Edmonton, Canada -- Warmest summer on record, 1998. Temperatures were more than 5.4�F (3�C) higher than the 116-year average.

7. Glasgow, Montana -- No sub-zero days, 1997. For the first time ever, temperatures remained above 0�F (-17.8�C) in December. The average temperature was 10.9�F (6�C) above normal.

8. Little Rock, Arkansas -- Hottest May on record, 1998.

9. Texas -- Deadly heat wave, summer 1998. Heat claimed more than 100 lives in the region. Dallas temperatures were over 100�F (37.8�C) for 15 straight days.

10. Florida -- June heat wave, 1998. Melbourne endured 24 days above 95�F (35�C); nighttime temperatures in Tampa remained above 80�F (26.6�C) for 12 days.

11. USA -- Late fall heat wave 1998. An unprecedented autumn heat wave from mid-November to early December broke or tied more than 700 daily-high temperature records from the Rockies to the East Coast. Temperatures rose into the 70�F (20�C) as far north as South Dakota and Maine.

12. Eastern USA -- July heat wave, 1999. More than 250 people died as a result of a heat wave that gripped much of the eastern two-thirds of the country. Heat indices of over 100�F (37.8�C) were common across the southern and central plains, reaching a record 119�F (48.3�C) in Chicago.

13. New York City -- Record heat, July 1999. New York City had its warmest and driest July on record, with temperatures climbing above 95�F (35�C) for 11 days -- the most ever in a single month.

39. Chesapeake Bay -- Marsh and island loss. The current rate of a sea-level rise is three times the historical rate and appears to be accelerating. Since 1938, about one-third of the marsh at Blackwater National Wildlife Refuge has been submerged.

40. Bermuda -- Dying mangroves. Rising sea level is leading to saltwater inundation of coastal mangrove forests.

42. Hawaii -- Beach loss. Sea-level rise at Waimea Bay, along with coastal development, has contributed to considerable beach loss over the past 90 years.

65. Glacier National Park, Montana -- All glaciers in the park will be gone by 2070 if retreat continues at its current rate.

68. Interior Alaska -- Permafrost thawing. Permafrost thawing is causing the ground to subside 16-33 feet (4.9-10 m) in parts of interior Alaska. The permafrost surface has warmed by about 3.5�F (1.9�C) since the 1960's.

69. Barrow, Alaska -- Less snow in summer. Summer days without snow have increased from fewer than 80 in the 1950's to more than 100 in the 1990's.

71. Bering Sea -- Reduced sea ice. Sea-ice extent has shrunk by about 5 percent over the past 40 years.

72. Arctic Ocean -- Shrinking sea ice. The area covered by sea ice declined by about 6 percent from 1978 to 1995.

135. Canadian Rockies - Disappearing glaciers. The Athabasca Glacier has retreated one-third of a mile (0.5 km) in the last 60 years and has thinned dramatically since the 1950s-60s. In British Columbia the Wedgemont Glacier has retreated hundreds of meters since 1979, as the climate has warmed at a rate of 2�F (1.1�C) per century, twice the global average.

136. Alaska - Increasing rate of retreat. A study of 67 glaciers shows that between the mid-1950s and mid-1990s the glaciers thinned by an average of about 1.6 feet (0.5 m) per year. Repeat measurements on 28 of those glaciers show that from the mid-1990s to 2000-2001 the rate of thinning had increased to nearly 6 feet (1.8 m) per year. Alaska has experienced a rapid warming since the 1960s. Annual average temperatures have warmed up to 1.8�F (1�C) per decade over the last three decades, and winter warming has been as high as 3�F (2�C) per decade.


Harbingers

16. Mexico -- Dengue fever spreads to higher elevations. Dengue fever has spread above its former elevation limit of 3,300 feet (1,006 m) and has appeared at 5,600 feet (1,707 m).

19. Central America -- Dengue fever spreads to higher elevations. Dengue fever is spreading above its former limit of 3,300 feet (1,006 m) and has been reported above 4,000 feet (1,219 m).

23. Lake Mendota, Wisconsin -- Fewer days of ice cover. The number of days per year with ice cover has decreased by 22 percent since the mid-1800s.

24. Mirror Lake, New Hampshire -- Earlier spring ice-out. The ice-covered period has declined by about half a day per year during the past 30 years.

25. Nenana, Alaska -- Early river thaw. During 82 years on record, four out of the five earliest thaws on the Tanana River occurred in the 1990's.

26. Washington, D.C. -- Cherry trees blossoming earlier. Average peak bloom from 1970-1999 came April 3, compared to April 5 from 1921-1970.

28. California -- Butterfly range shift. Edith's Checkerspot Butterfly has been disappearing from the lower elevations and southern limits of its range.

31. Olympic Mountains, Washington -- Forest invasion of alpine meadow. Sub-alpine forest has invaded higher-elevation alpine meadows, partly in response to warmer temperatures.

33. Alaska -- Sea bird population decline. The black guillemot population is declining from 1990 levels because melting sea ice has increased the distance the birds must fly to forage for food and reduced the number of resting sites available.

34. Canadian Arctic -- Caribou die-offs. Peary caribou have declined from 24,000 in 1961 to perhaps as few as 1,100 in 1997, mostly because of major die-offs that have occurred in recent years after heavy snowfalls and freezing rain covered the animals' food supply.

35. Monterey Bay , California -- Shoreline sea life shifting northwards. Changes in invertebrate species such as limpets, snails, and sea stars in the 60-year period between 1931-1933 and 1993-1994 indicate that species' ranges are shifting northwards, probably in response to warmer ocean and air temperatures.

36. Monteverde Cloud Forest, Costa Rica -- Disappearing frogs and toads. A reduction in dry-seson mists due to warmer Pacific ocean temperatures has beenlinked to disappearances of 20 species of frogs and toads, upward shifts in the ranges of mountain birds, and declines in lizard populations.

38. U.S. West Coast -- Sea bird population decline. A decline of about 90 percent in sooty shearwaters from 1987 to 1994 corresponds to a warming of the California Current of about 1.4�F (0.78�C).

46. Pacific Ocean, Mexico -- Coral reef bleaching.

53. Caribbean -- Coral reeef bleaching.

54. Florida Keys and Bahamas -- Coral reef bleaching.

55. Bermuda -- Coral reef bleaching.

76. New England -- Double normal rainfall, June 1998. Rainfall in Boston on June 13-14 broke a 117-year-old record, closing Logan Airport and two interstate roads. Vermont, New Hampshire, Rhode Island, and Massachusetts each received more than double their normal monthly rainfall.

78. Black Hills, South Dakota -- Record snowfall, 1998. At the end of February, the Black Hills received 102.4 inches (260 cm) of snow in five days, almost twice as much snow as the previous single-storm record for the state.

79. Texas -- Record downpours, 1998. Severe flooding in southeast Texas from two heavy rain storms with 10-20 inch (25.4-50.8 cm) rainfall totals caused $1 billion in damage and 31 deaths.

80. Santa Barbara, California -- Wettest month on record, 1998. 21.74 inches (55.22 cm) of rain fell in February, the most rain in a month since record keeping began.

81. Mount Baker, Washington -- World record snowfall, 1999. 1,140 inches (2,896 cm) of snow fell between November 1998 and the end of June 1999, a world record for most snowfall in a single winter season.

82. Florida -- Worst wildfires in 50 years, 1998. Fires burned 485,000 acres (196,272 hectares) and destroyed more than 300 homes and structures.

84. Florida, Texas, Louisiana -- Driest period in 104 years, April-June 1998. San Antonio received only 8 percent of its normal rainfall in May. New Orleans suffered its driest and hottest May in history.

85. Mexico -- Worst fire season ever, 1998. 1.25 million acres burned during a severe drought. Smoke reaching Texas triggered a statewide health alert.

86. Nicaragua -- 2.2 million acres (890,308 hectares) burned, 1998. Over 15,000 fires burned in 1998, and the blazing acreage included protected lands in the Bosawas Biosphere Reserve.

89. Eastern USA -- Driest growing season on record, 1999. The period from April-July 1999 was the driest in 105 years of record-keeping in New Jersey, Delaware, Maryland, and Rhode Island. Agricultural disaster areas were declared in fifteen states, with losses in West Virginia alone expected to exceed $80 million.

102. North America - Genetic adaptation to global warming in mosquito. Ecologists have identified the first genetic adaptation to global warming in the North American mosquito Wyeomyia smithii. Modern mosquitoes wait nine days more than their ancestors did 30 years ago before they begin their winter dormancy, with warmer autumns being the most likely cause. Higher temperatures, enhancing mosquito survival rates, population growth and biting rates, can increase the risk of disease transmission.

109. Colorado - Earlier emergence from hibernation. Marmots are emerging from hibernation on average 23 days earlier than 23 years ago. This coincides with an increase in average May temperatures of about 1.8�F (1�C) over the same time period.

110. Southeast Arizona - Earlier egg-laying. Mexican jays are laying eggs 10 days earlier than in 1971. The earlier breeding coincides with a nearly 5�F (2.8�C) increase in average nighttime temperatures from 1971 to 1998.

114. Alaska - Changing vegetation patterns. Comparison of photographs taken in 1948-50 to those taken in 1999-2000 of the area between the Brooks Range and the Arctic coast show an increase in shrub abundance in tundra areas, and an increase in the extent and density of spruce forest along the treeline. The increased vegetation growth is attributed to increasing air temperatures in Alaska, on average 1.8�F (1�C) per decade over the last three decades.

115. Western Hudson Bay, Canada - Stressed Polar Bears. Decreased weight in adult polar bears and a decline in birthrate since the early 1980s has been attributed to the earlier spring breakup of sea ice. Rising spring temperatures have shortened the spring hunting season by two weeks over the last two decades.

116. Banks Island, Canada - Expanded Ranges. The Inuit now regularly see species common much further south that previously were never seen on the island, such as robins and barn swallows. Thunder and lightning, never before recorded in Inuit oral history, have also been reported.


The following organizations produced GLOBAL WARMING: Early Warning Signs:
Environmental Defense
Natural Resources Defense Council
Sierra Club
Union of Concerned Scientists
U.S. Public Interest Research Group
World Resources Institute
World Wildlife Fund

http://www.climatehotmap.org