## First Compilation of Tropical Ice Cores Shows Two Rapid Global Climate Shifts: 5,000 Years Ago and Today

##### 28 June 2006
 The locations of ice cores and evidence for abrupt climate change approximately 5,000 years ago discussed in the research are shown, along with areas of large-scale ice retreat. Courtesy of Lonnie Thompson, Ohio State University. Click to enlarge.

Researchers from Ohio State University’s Byrd Polar Research Center and three other universities have combined and analyzed the chronological climate records held in ice cores retrieved from seven remote locations north and south of the equator. The cores drilled through ice caps and glaciers capture a climate history of each region, in some cases, providing annual records and in others decadal averages.

The data suggest a massive climate shift to a cooler regime occurred just over 5,000 years ago, and a more recent reversal to a much warmer world within the last 50 years.

The evidence also suggests that most of the high-altitude glaciers in the planet’s tropical regions will disappear in the near future. Lastly, the research shows that in most of the world, glaciers and ice caps are rapidly retreating, even in areas where precipitation increases are documented. This implicates increasing temperatures and not decreasing precipitation as the most likely culprit.

A paper describing the work is published in the journal Proceedings of the National Academy of Science (PNAS).

This study includes cores taken from the Huascaran and Quelccaya ice caps in Peru; the Sajama ice cap in Bolivia; and the Dunde, Guliya, Puruogangri and Dasuopu ice caps in China.

For each of these cores, the team extracted chronological measurements of the ratio of two oxygen isotopes—18O and 16O—the ratio of which serves as an indicator of air temperature at the time the ice was formed. All seven cores provided clear annual records of the isotope ratios for the last 400 years and decadally averaged records dating back 2,000 years.

Our climate system is sensitive, and it can change abruptly due to either natural or to human forces. If what happened 5,000 years ago were to happen today, it would have far-reaching social and economic implications for the entire planet. The take-home message is that global climate can change abruptly, and with 6.5 billion people inhabiting the planet, that’s serious.

We have a record going back 2,000 years and when you plot it out, you can see the Medieval Warm Period (MWP) and the Little Ice Age (LIA). And in that same record, you can clearly see the 20th Century and the thing that stands out—whether you look at individual cores or the composite of all seven—is how unusually warm the last 50 years have been.

There hasn’t been anything in the record like it—not even the MWP. The fact that the isotope values in the last 50 years have been so unusual means that things are dramatically changing. That’s the real story here.

—Prof. Lonnie Thompson, OSU

While the isotope evidence is clear throughout all of the cores, Thompson says that the more dramatic evidence is the emergence of unfossilized wetland plants around the margin of the Quelccaya ice cap, uncovered as the ice retreated in recent years.

First discovered in 2002, the researchers have since identified 28 separate sites near the margin of the ice cap where these ancient plants have been exposed. Carbon-dating revealed that the plants range in age from 5,000 to 6,500 years old.

This means that the climate at the ice cap hasn’t been warmer than it is today in the last 5,000 years or more. If it had been, then the plants would have decayed.

—Lonnie Thompson

The researchers say a major climate shift around 5,000 years ago in the tropics had to have cooled the region since the ice cap quickly expanded and covered the plants. The fact that they are now being exposed indicates that the opposite has occurred—the region has warmed dramatically, causing the ice cap to quickly melt.

The role of precipitation in the global retreat of alpine glaciers may have been clarified by this study. Some researchers, convinced that a reduction in local precipitation is causing their retreat, have been skeptical about the role of rising temperatures.

While all the glaciers we have measured throughout the tropics are retreating, the local precipitation at all of these sites but one, has increased over the last century. That means that the retreat of the ice is driven mainly by rising temperatures.

—Lonnie Thompson

Working along with Thompson and Ellen Mosley-Thompson on the project were Henry Brecher, Mary Davis, Ping-Nan Lin and Tracy Mashiotta, all with the Byrd Center; Blanca Leon of the University of Texas; Don Les of the University of Connecticut, and Keith Mountain of the University of Louisville.

Support for the research came from the National Science Foundation, the National Oceanic and Atmospheric Administration and Ohio State.

More proof that

(a) the world's climate is a highly non-linear system, subject to fairly rapid transitions between multiple stable states.

(b) these transitions can occur due to natural phenomena alone, or due to anthropogenic changes in atmospheric composition.

(c) we are in the middle of a transition, though it is not certain which stable state (if any) we will reach at the end of it.

Conclusions:
- we need to take heed of scientists' warnings, however inconvenient they may be for our industrial economy. The general public and politicians tend to think in terms of linear systems, so some education is essential here.

- we need to sharply reduce our individual GHG footprints, if only because the "developed" world will number not one but two or three billion people by 2050. Motor vehicles in particular need to become substantially more efficient. That means OECD governments have to make GHG emissions expensive to produce.

Moreover, industrialized nations have a vested interest in making efficient energy-related technology available to emerging economies at a price they can afford, provided they agree to refrain from deploying older, cheaper but more polluting technology.

- we need to assume that significant climate change will happen regardless, simply due to the large time constants of the dynamics of the system. Perhaps we can slow this juggernaut down, but it would be unwise to assume that somehow, magically, we can pull back from the brink. Therefore, regions that are predicted to be subject to increased meteorological risk need to start adapting immediately.

Examples: stop building beachfront property in hurricane zones. Stop growing thristy crops where precipitation rates are likely to fall. Start reserving areas where flooding will become more common for aquaculture (fish, energy algae) rather than agriculture. We have 20-30 years lead time, enough to avoid economic desaster and social conflict if we plan ahead. What we do not have is another decade to merely study the issue.

The coasts are amongst our most rapidly growing areas and will continue to be so, despite the obvious drawbacks.

I am conflicted. An adaptive strategy means that we will give up doing anything about actually slowing down or stopping global warming. Unfortunately, the time for action was 30 years ago. Even if we all conformed to the Kyoto protocol, it would have little impact on global warming. We need to cut our GHG emission by up to 70%. It's not going to happen.

By the time the likes of George Bush wake up, it will truly be too late. Apres moi, le deluge. Scientists say we should be prepared to use geoengineering only in case of emergency. We have reached that state. Start putting those little mirrors in the upper atmosphere.

I try to influence my children because it is their future, not mine. They say there is no point because there is nothing they can do about it. Party on. My guess is that this is the attitude of the vast majority of the population that actually understands that there is a problem.

If we try to solve this problem by tinkering around the edges so that we can perpetuate the automobile's reign, we are screwed. China's increases in auto ownership will dwarf any and all technological changes. In the transportation sector, car free cities are the only answer.

China is building one coal fired plant a week. The U.S. has dozens of plants on the drawing boards. Sequestration is a pipe dream and is not being required for all those new plants. We continue to build monster homes which require massive amounts of heating and cooling. We continue to expand in insane places like Phoenix, which requires massive amounts of water and energy for survival.

And proferred to usher in this great new, green world. Ethanol!! Ethanol is marginal at best and could exacerbate our problems by making us even more complacent, even assuming it has a positive energy balance.

One bright spot, I guess, is that most of those evacuees have had the good sense not to move back to New Orleans.

t, surely both you and I agree that an adaptive strategy does not preclude CO2 reductions. After all, the more CO2 we emit the worse it will be. If we don't reduce CO2 for another 30 years it will be a lot, lot worse.

t -

"In the transportation sector, car free cities are the only answer."

A sgnificant number of European cities actually have extensive pedestrian zones, with parking at the perimeter plus excellent access by public transport. In Vienna (Austria), essentially the entire old town (approx. 1km diameter) is off limits to motor vehicles, except residents, taxis, buses, police, fire brigade, ambulance, garbage trucks and at certain times of day, delivery trucks. Plus, of course, the Fiaker (horse-drawn carriages for tourists and other romantics).

http://www.virtourist.com/europe/vienna/24.htm
http://www.virtourist.com/europe/vienna/30.htm

The reason these zones were established was congestion and local pollution, not global warming. Businesses were initially dead set against these zones, fearing they would lose customers. In truth, the opposite has happened, especially for the many eateries, which can now offer al fresco dining without the noise or pollution. Luxury goods stores, musea, art houses and souvenir shops are all thriving.

So yes, car-free city centers can be very good ideas, though completely car-free cities are a pipedream.
HINT: gasoline, diesel and parking near the city center are all expensive here. Public transport (subway, trams, buses) is completely integrated and cheap.

t, Phoenix uses less energy and is more sustainable than the northern areas, say, all of Canada, because there's virtually zero heating costs and cooling costs aren't bad. Also, Phoenix is ideally situation to take advantage of solar energy.

Total water consumption for the state of Arizona hasn't changed in the last 100 years even though population went from around 50,000 to 5 million. It was mainly used for inefficient agriculture a hundred years ago and homes continue to get more efficient in both water and electrical usage. The whole region from Texas through the southwest and in to California is an ideal zone for habitation, especially if solar power augmentation of homes increases either by mandate or by increasing taxation of electricity on new homes.

Our North American engrained energy guzzling atitude and acquired complacency are two enormities that we, as individuals, will have to address, if we seriously want to reduce GHG and limit climate changes.

We have the choice between 50+ mpg vehicles or 15 mpg gas guzzlers and mass transports.

Since most of us will NOT make the proper choice, cities are fully justified to impose special permits to use down town streets and definately charge much more for gas guzzlers and let the zero or near zero pollution vehicles in free or almost free. The same should apply to parking tariffs on city streets. London City has had sucess with such a program is now increasing the zone and the tariffs to maximize the effects.

In our province, grid electricity tariff goes up with increased consumption instead of down, to discourage over use and to benefit small and conscientious users. Since about 75+% of our residences are heated with electricity, owners of large houses and poorly built (insulated) houses are encouraged to insulate their home, change windows and doors etc through Hydro/government supported programs. Vermont State has a similar program. It is amazing to see how such program can reduce energy waste and be very cost effective at the same time. For those of you with Oil furnaces and electricity from Coal generating plants, a similar program could reduce GHG (created by your residence) by 30% to 40%.

Sid,
COOLING. Have you forgotten Phoenix is in the desert? I do agree about the solar aspect though, but water usage is depleting fossil water resources faster than being its replaced. Furthermore, proper design and construction would reduce energy usage in northern/plains states. Geothermal heating and cooling would be a big part of this, as would proper insulation and windows/eaves/ landscaping/solar for energy/runoff considerations.

Part of the high energy consumption comes from the legacy of European building designs for homes from the 1700- 1800's. Combine that with ample supplies of firewood (Eastern US used to have unbroken multi canopy forests), then coal, then oil; there was not a great push for insulation except for cold winters states, and often it was for around the base of country homes (farms). Only until the asvent of the air conditioner, and the 70's energy crisis did a concerted effort for insulation appear.
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___That is not to say that earlier designs and constructions were inefficient. Many stone and wood homes were well suited for their environs. However, stone was expensive for city construction. Another fact was that the slums and apartments of the late 1800's and early 1900's were built with more people/units for external surface area. Post-WW2 era suburban homes were designed with ample, cheap supplies of fuel in mind. They also had less people per surface area, thus with same insulation, more energy spent per inhabitant.
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___Recently, the large sized homes trend has put some onto the "Me too" mentality to "Keep up with the Jones". This has meant skimping on certain key, but not externally visable aspects in order to add another 100 or 1,000 sq ft. They were lucky winter 05-06, but it may not repeat next winter. They will either close off those rooms, retrofit in the future, or sell the house as the Adjustable Rate Mortgage resets rates, making some unaffordable with heating bills on the horizon.
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___As to making more heating/cooling available at little/no/negative costs ($, GHGs, etc.), Cogenergation of heat, steam and electricity would be a start in urban/high to medium density areas with retrofiting/upgrading existing gas/coal/oil/biomass (incinerator) electric plants. Industrial processes (chemical, paper, etc.) could benefit from nuke plants' waste heat, though psychological and engineering hurdles would be larger. _ ___Finally, modified OTEC, using sea/brackish water and waste heat may be a interesting way to produce freshwater, electrical power, and minerals. Thermal pollution would be put to use. Allen, I've lived in Phoenix over 20 years. Two things here - first, there has been a push for over 20 years to build homes very well insulated to reduce energy costs. I remember even seeing ads on TV when I was a small kid for homebuilders all touting their energy saver certified homes. Second, over two thirds of the housing in the Phoenix area was built after 1980. Some half of it was bult after 1992 or something. Building construction is very modern and designed with both water saving and power saving in mind. EVERYONE who lives here knows we live in a desert, not to mention we're right next door to California who had all their rolling blackouts a couple years ago. That was big news because we're always worried that we're next. A few other factors are that all the newer housing here is pretty high density. Small lots, small homes (my 1350 sq/ft is at the low end of average although a friend of mine just purchased a 990 sq/ft home last year; 2500+ is considered a luxury home) so it's not quite the picture of sprawl that many believe it is. Sure, the affluent neighborhoods all have monster sized quarter acre lots and 3000+ square feet, and true luxury homes have a half acre or so. Generally only older homes built in the mid 90's and earlier will have anything more than a half acre, or else we're talking about$1,000,000+ homes, where of course anything goes, but those represent a tiny, tiny fraction of the market.

As a final point, I actually have every single electric bill since purchasing my current home in February of 2000 in an excel spreadsheet, broken down by the average kw/hour per day. My usage has been pretty consistent over the time I've lived here at around 20-25kwhr/day in the winter and 50-65kwhr/day in the summer. In terms of total usage per year, I know this was less than many folks I compared numbers with who have electric heat in the cold zones of the US. I'm not sure where you would get definitive numbers from, but by all means check your last year or two of bills and see how it compares against others.

While there are always some exceptions that prove the rule, in general people everywhere will only do the (inconvenient) right thing if the alternative is prohibited by law (e.g. to protect public health), becomes too expensive or a mark of shame.

Note that all of these are disincentives for the status quo, sticks if you will. Carrots alone are *not* sufficient to overcome consumer inertia in a reasonable timeframe! Often, they understand and even accept that they ought to change but simply do not want to be goodie two-shoes as long as their neighbor can get a free ride.

E.g. in LDVs, we are seeing all three strategies being applied in different parts of the world: pedestrian zones prohibit car traffic in Europe, US emissions regs effectively prohibit diesl cars, high taxes on initial purchase (Denmark) and fuel (Europe, Japan) encourage frugal fuel use, SUV drivers everywhere are demonized by those that do not own one, Japanese would not be caught dead in a car that gave off puffs of smoke (ever).

Much the same, with a rather less emotion, could be applied to housing. The CO2 footprint due to this sector is both direct (home size, climatization) and indirect (urban sprawl, remote locations in fire-prone woodland areas). Architects have the knowledge to design more energy-efficient buildings, but they cost more up front and are not as easy to furnish.

Sid:
I do agree with
I'm in NYC and spend less than 10 KwH a day year round, mostly in the 6-8 range. As for heating, it is natural gas fired. Due to retrofits (multiset/multiplane windows and blinds/curtains) and a new heater, we don't spend alot on gas ~$600 a year/~$50 a month. Lowered thermostats to 65 F in the winter helps too. The new fridge helped too; cut electric bills 25%+. Need a new AC though, it is 10+ years old.
_A modified swamp cooler, and fans cuts summer costs. It does not evaporate water but uses a heat pump and cold tap water to cool. Water is then used for hot water.

I agree with you that denser development is going up (for me it is right next door), but the exburbs are poping up/moving out too. One of the retiring teachers from my former H.S. has a few acres in the Poconos, Penn. He plans to move there after he moves on (marine facilities, maybe structural engineering) after teaching Civil Engineering, CAD, robotics, and other technical subjects for 20 years. The point is the Burbs are pushing way out, entailng a lengthy commute, and associated fuel costs. It is also costing time (driving a car), and that has societal and health costs. Development also bumps up against water issues too. NYC relies on mountain streams and rivers from Southeast NY. The area surrounding those bodies of water/reservoirs need to be maintained/preserved to ensure the quality of the tap water. In the Southwest, the issue of fossil groundwater may become more problematic with the possible entrance of the West into a long term dry climate period, and possible needs of water for kerogen production from Oil Shale (and subsequent upgrade to syncrude). It may also become problematic if algae biomass/oil production follows a water intensive route.
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___The Sahara was a savanna with wet and dry seasons around 3,500 BC, but changed aboout 5,000 yrs ago. This shift may do wierd things too. The Sahara's development and expansion pushed/concentrated civilization to/in the Nile, Europe, and the Middle East. It separated Europe and the Middle East from tropical Africa. That changed the course of history. The question is if the earth warms, would it revert back to a climate like that of around 4,000 BC, would it turn the Sahara into the Serengeti??? Would it turn North Africa into something that would be agriculturally productive, and would it then cause a population boom? High child mortality and low development makes the child/couple ratio high, in the 4-7 range. Will the new peak signal a new cooling period like after the Midieval maximum, or will it continue upwards, more or less.

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