It's virtually impossible that none of it is caused by people, because we know we have increased CO2 in the air from 280 to 380 ppm, and we know CO2 has a warming effect. But there's still a very small chance that the effect is tiny. But there is no evidence that it's tiny.
U.S. Government Position: The Energy Act of 2005 states: "the President shall establish a Committee on Climate Change Technology [which] shall submit to the Secretary and the President a national strategy to promote the deployment and commercialization of greenhouse gas intensity reducing technologies and practices."
History: In 1896 Svante Arrhenius (1903 Nobel Prize in Chemistry) predicted thedecrease in CO2 needed to cause past ice ages. He wasn't far off, and it is not a large decrease. This helped confirm the 1859 prediction that human-producedincreases in CO2 would cause just the reverse: global warming.
What's to be done? A global problem requires a global solution, and that requires countries to cooperate. The science of games and strategies explains what leads to cooperation and what doesn't. The basic situation—what each country does helps that country very little—is a classic game call the prisoner's dilemma. And the prisoners do not cooperate. Unfortunately the Kyoto approach actually makes the problem worse. But a better design leads to cooperation, as explained in the Green Fund Game.
What Causes Global Warming (climate change), human activity or the sun? The final answer is not in, but you can see the results so far. (1) Exhaust is clearly the source of CO2. (2) Everyone now agrees the earth is warming. (3) Decide for yourself if warming is better explained by CO2, or the sun's heat.
The Effects of Global Warming. We can see the long-term effects coming in the melting of polar ice and glaciers. But apowerful trend in Atlantic hurricane data indicates we can already see the impact. Katrina was partly the result of a normal weather cycle, but that cannot explain away stronger hurricanes world wide.
Can we Stop Global Warming?
Environmentalists "know" that we are wrecking the climate, and we are doomed.
The deniers "know" that we are not.
The right answer: We don't know which it will be, but we should not risk the Earth while waiting for the scientists. The U.N. Report disaggree's with both sides. It says there's a 90% change that half of the warming since 1950 was caused by people. That means there's a 10% chance that global warming will be much milder than the environmentalists claim.
My view (11/1/2011), after reading extensively and having some science background, is that it's about as likely to be three times milder than environmentalists claim as to be as bad as they say. I'm a bit of a skeptic. Its not unreasonable to be somewhat more pessimistic or optimistic than the UN report.
So what does all this tell us? Everyone pays good money to buy insurance against things that probable won't happen -- like their house burning down, or running over someone while driving, or a horrible illness. We don't wait and see. You can buy a new house. You can't find a new Earth.
They will claim they don't. But I'm an economist, and I've worked with Environment Canada, The World Bank, the Union of Concerned scientist, and the UK's Dept. of Energy and Climate Change, and I've done lots of research in this area. Believe me, the environmentalist are the worst money wasters this side of crony capitalism. But just because they are stupid about this, does not mean we should risk the Earth. It just means we need better environmentalists.
The extreme weather of 2011 and 2012 has conservatives changing their mind. As one weatherman points out, it could be true, even if Al Gore says it is.
March 22, 2012. Republican scientists supporting global warming include Prof. Kerry Emanuel of MIT who was inundated with hate mail after identifying himself in a video as a conservative and voicing concerns about the GOP denial of climate change. Prof. Barry Bickmore, a Mormon, is a geochemist at Brigham Young University and has represented the GOP in local politics. Prof. Richard Alley is the author of a plethora of peer-reviewed papers on climate change and has offered expert testimony to Congress on several occasions. Prof. Calvin DeWitt, is a co-signer of the Evangelical Climate Initiative, a statement from high-profile evangelicals calling for concerted action to battle global warming. Finally, Prof. Katharine Hayhoe, an atmospheric scientist, is an evangelical married to a pastor. Newt Gingrich notoriously dropped a chapter she wrote from his latest book on the environment after Rush Limbaugh referred to her as a "climate babe."
Full size graph . And here's the image of his comment:
Warmer by +3°C if we double CO2
James Hansen's new book, Storms explains—better than any other non-technical source—how we know that climate change is strong and real. But it's still tricky. So zFacts will simplify it for you here on this page and some sub-pages (for footnotes).
The key climate question is:
"How sensitive is the climate to greenhouse gases?
This is called "climate sensitivity" and it's usually described by how much the Earth will warm if we double the CO2 from what it was in 1750. Hansen's answer is that the Earth would warm 3°C, or 5.4°F. So far we've increased CO2 from 280 to 387 ppm, or 38%, so we should have already warmed 1.1°C, or 2°F. That's a little more than we've seen so far, but that could be because of natural fluctuations or man-made counter-effects, such as small sulfur particles from coal-fired power plants in China—they cool the Earth as volcanoes do.
How does Hansen find the answer?
He looks at what happened as the Earth warmed up from the last ice age.
1. It warmed 5°C from 20,000 years ago (ice age) until 1750.
2. Two things caused that, (1) less ice, and (2) more greenhouse gases (GHGs).
3. Less ice caused 3.5 Watts of "climate forcing" and GHGs caused 3 Watts.
4. So 6.5 Watts causes a 5°C temperature increase, or 3/4° per Watt.
5. Doubling CO2 will cause 4 Watts of forcing, so that's 3°C of warming.
Three Scientific (non-partisan) Books. Fresh, Ultra-Competent and Surprising
Storms of My Grandchildren Hansen's struggle to get the word out on the new climate evidence. He criticizes Republicans for suppressing science and Democrats for blocking the solution. But most important, he explains the new evidence on climate.
Carbonomics Written a year ago, Stoft explains the reasons Copenhagen is failing and prescribes a simple fix. He also explains Hansen's fully refunded carbon tax.
Sustainable Energy—No Hot Air MacKay, a brilliant and humorous physicist, Chief UK Scientific Advisor for Climate Change. As forthright as the other two.
All Three Support Effective Action But Rethink What's Really Needed
Why is Hansen's method believable? These are all the main steps in the calculation, but each one requires several smaller steps to gain a better understanding. These are explained below and on sub-pages. But first, why is this approach (paleoclimate science) better than the huge climate models?
Because it gets the feedbacks right. What are feedbacks? For example, say GHGs warm the Earth by 1°. Warm air holds more water (and cold air less—which is why your lips chap in the winter) so there is more water in the air when temperature increases. Water is a greenhouse gas, so it warms the Earth more, say 1/2°. So the air holds more water. The Earth warms another 1/4°, etc., etc. and the grand total is 2° even though the CO2 only warmed the Earth 1° directly.
Some (positive) feedbacks (like water vapor) amplify the warming while others (negative feedbacks) do the reverse. Some are very tricky—like cloud formation—so the big models cannot get them all calculated right. But when the Earth warmed up in the last 20,000 years all the feedbacks happened and so Hansen's approach takes every feedback into account in exactly the proportion as they actually occurred.
The data are reliable. The required data are tricky, but they are self checking. Scientists have data on the ups and downs of temperature for the last 400,000 years (4 ice ages) from sampling ice that is a couple of miles deep in Antarctica. It's that old at the bottom. And trapped in the ice is a bit of air from that long ago. So they can see what GHGs were in the air.
Now here is the check. They work out (1) how much ice, (2) GHGs, and (3) the Earth's temperature. Then they use a quite-simple formula to predict temperature from ice and GHGs for 400,000 years, and the predicted temperature fits the ups and downs of the measured temperatures amazingly well. You can see for yourself. It's just too amazing to be coincidence.
Under construction Dec. 12, 2009.
Step 1 is simply to measure the Earths warming compared to the last ice age. Part of that was due to the increase in CO2 and the trick will be to find out how much of it.
Temperature over the last 400,000 years has been measured in Antarctica by extracting a core (a cylinder a few inches in diameter) of ice about two miles deep. The ice is made up of year after year of snowfall, so it contains a sample of snow from most of those years.
Snow is water is H20, hydrogen and oxygen. But both H and O come in two varieties, heavy and light. Heavy hydrogen (1 proton and 1 neutron) weighs twice as much as normal hydrogen and it's call deuterium. (Heavy Oxygen has two extra neutrons, but is only 18/16 as heavy as regular Oxygen). In both cases the ratio of heavy to normal atoms in snow varies with temperature. So by looking at (mainly) the ratio of deuterium to normal hydrogen in the ice they can determine the temperature when it snowed.
Since temperature changes most at the poles, the change was actually about 10°C, and Hansen divided that by two to give a rough but decent estimate of the average temperature change of the earth as a whole.
For a possible source of the 10°C value see ORNL which mentions that the overall amplitude of the glacial-interglacial temperature change is ~8°C for atmospheric temperatures above the inversion level and ~12°C for surface temperatures.
Step 2 just says that the warming from the last ice age was caused by two things: less ice and more GHGs. That's not too surprising, since those are about the only things that could do it, but we're all curious about how it worked, so here's the story.
The Amazing History of Global-Warming Science
John Tyndall, an English scientist in the forefront of the ice-age debate of the 1800’s, wondered how the climate could have changed so much. He suspected the atmosphere, which was known to have the ability to trap the sun’s heat. Working in his laboratory, in 1859 he found the most important greenhouse gas was water vapor (H2O), but that carbon dioxide (CO2) was also effective.
In 1896 Arrhenius completed a laborious numerical computation which suggested that cutting the amount of CO2 in the atmosphere by half could lower the temperature in Europe some 4-5°C (roughly 7-9°F) — that is, to an ice age level.
In the 1990’s French and Russian scientists extracted a mile and a half deep ice core from Antarctica. Analysis by an international team found that over the four ice-age cycles in the last 400,000 years, CO2 dropped in step with the temperature but only by about one third, not one half. That could easily be because other greenhouse gases changed with CO2. This is either confirmation of the 1896 prediction, or an amazing coincidence.
That's what the IPCC says (the UN climate scientists). How sure are you that your house is going to burn down this year? 90%? More like 0.1%. So I'm sure you don't buy [#fire insurance] That's the position of climate-change deniers.
Climate Predictions More Uncertain than You Think
By Steven Stoft, January 23, 2009
OK, I can't read your mind. But most people think climate change will definitely bring disaster, or definitely be a nothingburger. As the Washington Post explains, there's even more uncertainty than the UN shows in their graphs—and that's a lot.
Here's the worry I explain in Carbonomics. A lot of global-warming activists say, "Just look, you can see it happening." So they're smarter than a 1000 scientists who still have doubts? Nature plays its tricks—and pretty soon it will play a cooling trick and all those activists who said "just look" will have to eat their words. Better to make the real point. We're all unsure! But if there's a 10% chance of a world catastrophe, it's good to take precautions. Don't be an idiot who says you know we're safe. You don't.
Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences 5/02/06 report
A newly published report from the National Oceanic and Atmospheric Administration finds that there is no discrepancy in global average temperature increase. "This is an important revision to and update of the conclusions of earlier reports from the U.S. National Research Council and the Intergovernmental Panel on Climate Change."
"[R]esearch ... shows clear evidence of human influences on the climate systemdue to changes in greenhouse gases, aerosols, and stratospheric ozone. Also, the observed patterns of change over the past 50 years cannot be explained by natural processes alone, nor by the effects of short-lived atmospheric constituents such as aerosols and tropospheric ozone alone."
The debate has shifted. Global-Warming deniers used to say the earth is not warming; now they look to natural causes for why it's warming. First among these is the sun. (Definition of global warming)
The sun does get warmer and cooler every eleven years with the sun-spot cycle. It's actually hotter when it has more spots even thought the spots are cool. They are accompanied by hot spots which are not as easy to see. But the earth has not been found to warm and cool in step with the sun spot cycle, so deniers are forced to look for cycles of cycles and trends in the cycles. In fact, there is something to this. During the little ice age, back in the 1500's there were very few sun spots. But the bottom line is, the global warming of the last thirty years is not explained by solar warming.
Many have denied big hurricanes are part of global warming, but their arguments carefully miss the point. They say we are in a natural upswing. Yes, but it's much bigger than the last one. They say it's caused by Atlantic currents. Yes, but hurricanes are also stronger in the other five hurricane basins around the world. (Read a translation of a NOAA denial.)
There is a scientific consensus. It is that the last 30 years of global warming is, to a considerable extent, the result of human generated carbon dioxide (CO2) and methane. Even the Pentagon commissioned a report on "Abrupt Climate Change."
|[=fire insurance=] "I don’t want to wait around until the house burns down till I decide whether it’s a serious fire or not." —Oilman T. Boone Pickens on climate change, 2008.|
1. How sure? 90% that humans caused at least half the warming since 1950.
9. The problem? US and China need to cooperate.
10. Why failure? Environmentalists use scare tactics and command & control.
There's a good case that the warming of the last 30 years (about 1°F) is human-caused. Here are the three steps.
Human emissions of CO2 predict the increased atmospheric CO2 almost perfectly for the last 250 years.
Is the earth really getting warmer?Yes, and there is complete agreement among several differnent temperature records that in the last 30 years it has warmed dramatically. (See the oldest record of measured temperatures.)
Did the CO2 cause the global warming?We can't be absolutely sure. Here's the best graph of CO2 and global temperature. The only other known contender is the sun, so check that next.
Is the sun causing it? We now have 27 years of accurate solar temperature data from NASA satellites. Although the sun has changed climate in the past, it looks like it is not the culprit this time.
Linked to Human Activity
What do we know for sure? We know for a fact that CO2 levels are rising and that human activity is the cause.
How do we know this? A simple calculation. Let's start with the year 1750, generally accepted as the beginning of the Industrial Revolution, when the standard measure for CO2 levels was 278ppmv. We'll begin then, add the known level of human-generated CO2 for that year, then subtract 2.84% of the excess CO2 – because that's how fast nature tries to restore the balance. If we do this for 255 years, up to 2005, we get the pink line in the graph below. It fits the black line – the actual CO2 level – like a glove.
How accurate is this fit? Considering the difficulties of gathering data from centuries past, amazingly close. We know, for example, that up until 1950, deforestation was putting about as much CO2 into the atmosphere as were burning fossils, but it's not easy to know how many trees were chopped down in, say, 1850, and how much CO2this put into the air. In spite of imperfect data, the fact that a simple calculation predicts the extraordinary shape of actual CO2 so well is clear evidence this can not be a coincidental convergence. Human CO2 emissions must have caused the upsurge is atmospheric CO2.
So what? The link between human activity and rising CO2 levels is the first step. The next one is between CO2 and global warming. That was predicted over 100 years ago, but the evidence has become convincing only very recently. ZFacts will be adding pages about this during February, 2006.
Fossil Fuel data are from the U.S. DOE, including an estimate that fossil fuel emissions will increase at 1.2% per year until 2030. We assume this rate to 2050. However, the average rate for the last 5 years was about 1.9%, so this may be optimistic. Cement manufacture also releases CO2 from the rocks it processes, so that source is tracked separately.
|More electric power plants run on coal than oil, natural gas or hydro-power, but burning coal produces CO2, one of the gases that cause global warming. New and more expensive technology makes it possible to build coal-burning power plants that could be adapted to "sink" the CO2 underground to keep it out of the atmosphere. Builders of new power plants are divided on using the new technology or just polishing up the old for less money. Proponents of both are pushing for government blessing.more|
Amazing "Synfuel".pdf Gasoline, diesel, jet fuel, and other petroleum products can be made from coal. The conversion process removes greenhouse gases, sulfur, mercury and arsenic; a synfuel plant can generate electricity, make synthetic natural gas and even hydrogen. Ordinary engines can use it. Montana has 120 billion tons of coal which would make the equivalent of one quarter of the oil under the Middle East. Do we need Montana?
Mining Under the Radar.pdf A proposed Canadian mine would endanger Glacier and Waterton Parks, Flathead Lake and that is just a start.
Synthetic Fuel.pdf Dreams of reinventing both small town Montana and the fossil fuel industry.
It's now official, 2005 was the hottest year on record. The National Oceanic and Atmospheric Administration (NOAA.gov) has just updated global temperatures from 1890 to 2005, and 2005 beat out 1998 by a hair. Global-warming skeptics had dismissed 1998 as due to an unusually strong El Niño, but 2005 was not. Moreover, 2005 was the coolest solar year since 1987.
Above. This is a plot of average annual temperatures based on measurements made at the time starting in 1659. The temperatures from 1975--2005 have been corrected for urban warming. The dark line is a smoothed version of the annual data.
Below. "In February, 2006 NCDC/NOAA transitioned to the use of an improved Global Land and Ocean data set." These new global temperatures slightly different from those previously posted. They are freely available at www.ncdc.noaa.gov/ oa/climate/research/anomalies/anomalies.html
carbon dioxide vs global temperature graph
This is not proof of that the CO2 caused the warming. But, if CO2 did not cause it, we have a somewhat unusual coincidence. As seen on the temperature page this thirty-year temperature increase is unusual. There was only one temperature swing of this size in the oldest thermometer record which dates back 350 years, and it was a down swing. Upswings of this magnitude would seem to happen only about once in 700 years, and this one happened right in step with human CO2 production.
Caution: The match of the CO2 and temperature graph above is somewhat deceptive. Since one is temperature and one is CO2 they cannot be graphed on the same axis, so the two axes have been adjusted to align the two. However this process does not change the fact that temperature rose faster from 1975 to now than from 1880 to 1975, and so did CO2. It also cannot change the fact the temperature has been highest recently and so has CO2.
The slight downward trend in temperature from about 1945 until about 1975 is due to the increase in Sulfate Aerosols (SO4), largely produced by burning coal that contains sulfur. These cool the earth, and their increase during these years largely canceled the increase in CO2 during the same period.
The nay-sayers admit the globe has warmed but deny it is the result of human activity. They say it is caused by the sun getting warmer. In fact it is quite likely that changes in the sun's temperature do cause changes in the the Earth's temperature. But that does not prove the current temperature increase is caused by the sun.
Starting in late 1978, NASA began monitoring the sun's power output from space. This increased the accuracy of such measurement by more than 10 times and produce the first accurate record of Total Solar Irradiance (TSI), which is astro-speak for total solar power reaching the earth.
Sun spots, though cool, are indicators of solar storms which have hot spots, so when there are more sun spots the sun is hotter than usual. Sunspots go in 11 year cycle and so does the sun's heat as can be seen above. But since the record began there appears to be no connection between solar heat and global temperature. The swings in solar heat at first appear to keep step with temperature, but the earth's temperature gets ahead of the sun to the point where in 2000, the earth's temperature hits a valley exactly when the sun's temperature reaches a peak. Moreover, the solar ups and downs are huge compared with any possible trend, while the earth's ups and downs are minor compared with its trend.
The consensus among astrophysicists studying this connection is that, while some (but not all) historical climate changes were probably significantly influenced by the sun, the present upswing is due mainly to human activity.
The Increase in Hurricane Strength is World-Wide
Partly it may be bad luck and partly it's a predictable, decades-long Atlantic hurricane cycle. But that does not mean global warming isn't part of it. The recent Sciencearticle found a similar increase in category 4 and 5 hurricanes in all six hurricane basins world wide. That's not from the Atlantic cycle, and it's very unlikely to be just bad luck.
To say how much impact global warming is having, two questions must be answered.
• How much has human activity warmed tropical oceans?
• How much does hurricane destructiveness increase per degree of warming?
Human-Caused Warming Has Been Very Slight
The consensus is that tropical oceans are about 0.5° C (slightly less then 1° F) warmer. This is so little that computer models of hurricanes predict only a very slight increase in hurricane power.
But Hurricanes are Very Sensitive to Tropical Sea Temperature
That’s where Dr. Kerry Emanuel’s Nature article comes in. He did not look for global warming; he just looked at how hurricane power has related to tropical sea temperature for the last 61 years. His data show the computer models are wrong, and a 0.5° C causes a much larger impact.
Global warming is obviously melting glaciers in Montana's Glacier Park and the Canadian Rockies, but the warming is so slow that no major effect has been demonstrated. The consensus is that since 1900, the oceans have warmed by slightly less than 1 degree F and the climate slightly more.
But hurricanes are different. Small changes in tropical sea temperatures shut them off completely every winter. In the 1930s-50s Atlantic hurricanes were intense and then tapered off to a low in the 1970s. The cycle reversed, and by the mid-1990s they were back. Most of this was caused by a natural ocean cycle, a fall and rise in sea temperature of about 1 degree fahrenheit that has been going on for centuries. But this time, it's more intense and the temperature is higher than last time. The difference appears to be caused by a little global warming, but with hurricanes, the consequence is not small.
The multi-decade Atlantic ocean cycle that the goverment likes to blame for all of the change is real. But it can't explain why hurricane intensity has risen even more in five other hurricane basins, two in the Indian Ocean, two in the North Pacific and one in the South Pacific. There's a chance the science is wrong and this is nothing unusual. But there's a better chance we're seeing the first large-scale impact of global warming.
In spite of the natural ocean cycle and global warming, the dramatic increases in US hurricane damage is mainly due to the increases in coastal populations since the 1940s. Because hurricanes are so unpredictable, no specific cost can be attributed to global warming. This means it is just as wrong to say there has been no cost as to say it was 20% or 40% of hurricane damage in recent years. Without global warming, Katrina almost certainly would not have happened, but something else would have, and it might have been worse ... or better. We just don't know.
A new study by scientists at University of Alaska Southeast, compared radar mapping data from a space shuttle mission six years ago with air photos taken between 1948 and 1979, of Alaskan glaciers. Motyka, UAF colleague Chris Larsen and three other scientists pinpointed the extent of the glaciers' volume change. They found that 95 percent of Southeast Alaska's glaciers are thinning. Some glacier surface elevations had dropped as much as 2,100 feet since 1948, such as the Muir Glacier in the popular Glacier Bay National Park and Preserve.
Southeast Alaska's glaciers are very sensitive to climate change because of their large surface areas at low elevations. In Juneau, the winters have been getting warmer and rainier -- 6.8 degrees warmer compared to 50 years ago, according to Laurie Craig, a naturalist for the Tongass National Forest. Those warmer temperatures can disrupt a glacier's surface mass balance, the balance achieved between the melting period of summer and accumulation period of winter.
|Andean glaciers are melting so fast that some are expected to disappear within 15 to 25 years, denying cities' water supplies and putting populations and food supplies at risk in Colombia, Peru, Chile, Venezuela, Ecuador, Argentina, and Bolivia.|
Effects of the more Rapid Melting of the Polar Caps
There are spots in Greenland and Antarctica which are actually gaining ice because of increases in annual snowfall. But, on average, they are melting faster. For a while change will come slowly, but later this century it will speed up. The consequences of this melting include the release of methane (a warming gas) trapped in the tundra, and a slowing of the Atlantic Conveyor, which would cool Europe and warm tropical waters.
Greenland Glaciers Speed Up: Satellite measurments taken by NASA in 1996, 2000 and 2005 show that southern Greenland glaciers are moving into the sea almost twice as fast as 10 years ago. Greenland contains enough ice to raise sea level by 20 feet. But this will not not happen in the next 100 years. 2-17-06
The land is disappearing under residents of the Arctic. In Russian towns built on permafrost, buildings are warping, twisting, crumbling as the land melts below them. The shore line is moving 15-18 feet closer to the oil storage tanks each open water season. The longer season brings more oil and gas drilling to endanger the world's largest stocks of cod and herring.
The melting ice sends cold fresh water into the north Atlantic. This could lead to a reduction in the flow of the Gulf Steam.
Eight countries have Arctic territory and can claim a part of the new sea.
Canada, Denmark (Greenland), Norway, Russia, the United States (Alaska) have arctic coast lines. Iceland, Sweden and Finland have arctic territory but no coast line there. From well outside the Arctic, China and India are interested in helping develop the oil and gas resources exposed by the shrinking ice.
At stake are not only gas and oil, but shipping lanes - the fabled Northwest Passage - and fishing rights and national security.
The rules aren't clear. The Law of the Sea, Article 76 describes how ownership of the Arctic might be settled. The United States has not ratified the Law of the Sea because some senators claim it would infringe on American sovereignty. Proponants of the treaty, including the Pentagon, point out the obvious -- if you don't sign, you can't vote.
Canada and Denmark are disputing the ownership of a 1.3 square kilometer island revealed by the melting Arctic ice.
Scientists Predict Melting of Ice Cap at Pole Alarmed by an accelerating loss of ice in the Arctic Ocean, scientists are striving to understand why the speedup is happening and what it means for humankind. If present trends continue, the sea surrounding the North Pole will be completely free of ice in the summertime within the lifetime of a child born today.
Some researchers fear that the polar region already may have passed a "tipping point" from which it can't recover in the foreseeable future. Others think the Arctic ice pack is nearing a point of no return but hasn't reached it yet.
Slowing the Atlantic Conveyor
The Gulf stream, first mapped by Timothy Folger, Benjamin Franklin's cousin, brings warm water to the north Atlantic and especially to England. That is why London, which is as far north as the southern tip of Hudson's Bay, is warmer than Boston in the winter. It is part of the Atlantic Conveyor shown below. About 10,000 years ago, this shut down and cause a relapse of the last ice age. It is believe that melting polar ice can lead to a shutdown. Not much is know yet about how likely this is, but current models seem to indicate a complete shutdown is quite unlikely this century.
The result would be more or stronger hurricanes caused by the warmer tropical waters. Because hurricane formation is so sensitive to sea temperature (one degree F may nearly double annual hurricane energy) the impact could be significant.
Europe, and especially England, will become cooler if the Gulf Stream shuts down, and the tropical part of the Atlantic warmer because less warm water will be sent north. Increasing flows of cold fresh water from the melting Arctic are thought to block the northern path of the warm Gulf Stream.
What Can We See?
Glaciers are melting faster. In 1996, the amount of water produced by melting ice in Greenland was about 90 times the amount consumed by Los Angeles in a year. Last year, the melted ice amounted to 225 times the volume of water that city uses annually. This cold, fresh water of the melting glaciers blocks the gulf stream.
New measurements by NASA satellites of the Antarctic ice sheet show it losing 36 cubic miles of ice a year. Although minimal in terms of rising sea level, it is not what was predicted by an earlier study. "That's a wake-up call. We better figure out what's going on," one glaciologist said.
'Drift ice', which usually closes ports in northern Japan for several months a year, has shrunk by 40 percent. Masaaki Aota, director of the Okhotsk Sea Ice Museum of Hokkaido, said he believed that the most likely cause was global warming, though he added that there was no conclusive evidence. "I don't think this is a problem particular to this place," he said. NYTimes
What Might Happen?
A slowing of the conveyor currents would the diminish the entire marine food chain. The warm nutrient-rich water encourage plankton production, feeding larger fish. A 20% loss of the humble phytoplankton would have a major repercussions all the way up to the human food supply.
Quite a lot can be done rather cheaply. The trick is good economics:
Command and Control: This means telling people and companies what they can't use and can't do. For example Environment Canada is planning on telling coal plants (and even different parts of a single coal plant) how much power they can produce. But isn't that necessary, if you are going to stop them? Not at all. It's perfectly possible to tell the owner of a group of plants, that it must cut output to you-name-the-target, and then let the owner decide which plant to cut back how much.
That saves a lot of money and works just as well as telling the owner what to do in detail. So why doesn't Environment Canada get this (as of 2011)? A lot of environmentalists do, but quite a few are still back in the stone age economically speaking. I've talked with them about this and they are not that dumb, so it is either politics or a sort of religious feeling about environmentalism. In any case, it's terrible for environmental progress. It just makes enemies needlessly.
That's and extreme case, but there are lots of other cases that are less extreme, but where environmentalist are shooting themselves in the foot because they are still half stuck in the old command and control world .
Even Worse: Perhaps an even worse that command & control is the frequent refusal by environmentalists to do things cheaply. (California: how to waste a lot of money.)
Half Way Right: To avoid using command & control on coal plants, a couple of economists invented cap and trade. Environmentalists like it because it gives them a lot of control, camoflages that with a market. They also like it because it provides a less obvious way to bribe coal plants. Coal plants like it becuase they can make money off of it. Economists bless it because it uses a price that helps minimize the cost of getting the job done.
Pricing Carbon: Cap and trade is not the best way to price carbon, but it's usually good step. It has a couple of problems: (1) The price is very hard to predict and scares people so they make the cap weak. (2) Anyone who does better voluntarily just makes it cheaper for someone to do worse and there's no net benefit. (3) The price risk makes investment cost a lot more, so it wastes money. (4) Internationally it's a disaster -- China is not going to buy credits from the US and India is not going to be capped at our emissions level in 1850.
The Best Incentives: The untax and feebates are the best way to price carbon. They are completely predictable. They work like taxes except the government collects no money. You can read about these here: Amazon and there will be more about them on zFacts in the comming months.
Should We Do Something about Global Warming?
That depends on how costly the problem is and how much it costs to reduce it. Almost always, and this case is no exception, doing a little is worthwhile but the more you do the more costly it becomes to improve things. This means the question should be "how much should we do?" and not "Should we do something?"
The fact that we are not completely sure that global warming is increasing the destructiveness of hurricanes is no reason to do nothing. We are not completely sure that terrorists will again attack the U.S. but none of those who claim that "not knowing" is a good reason to "do nothing" about global warming would follow that logic with terrorists. Taking some precautions is almost always a good idea.
We do not know that our house will burn down. In fact we are quite sure that it will not. Yet we all buy house insurance. We do not wait until the scientist can give us a better prediction of the chance it will burn down in the next 50 years. The bigger the risk and the more likely it looks the more we should do about it. The idea of doing nothing until we are completely sure is almost always a bad idea, and it is silly when dealing with a problem that will take decades to bring under control. We will probably not be 100% sure until it is 20 years too late to avoid what we just became sure of.
This does not mean we have to bankrupt the country. For the cost of Katrina or the Iraq war, we could do a huge amount. Why not budget 20% of that for global warming and to reduce international tensions over oil.