Blog Archive

Thursday, July 31, 2008

"The Final Countdown" and "100 months (or less) to stop emissions"

The Final Countdown

Time is fast running out to stop irreversible climate change, a group of global warming experts warns today. We have only 100 months to avoid disaster. Andrew Simms explains why we must act now - and where to begin.

by Andrew Simms, The Guardian, August 1, 2008


If you shout "fire" in a crowded theatre, when there is none, you understand that you might be arrested for irresponsible behaviour and breach of the peace. But from today, I smell smoke, I see flames and I think it is time to shout. I don't want you to panic, but I do think it would be a good idea to form an orderly queue to leave the building.Because in just 100 months' time, if we are lucky, and based on a quite conservative estimate, we could reach a tipping point for the beginnings of runaway climate change.

. . .

So, how exactly do we arrive at the ticking clock of 100 months? It's possible to estimate the length of time it will take to reach a tipping point. To do so you combine current greenhouse gas concentrations with the best estimates for the rates at which emissions are growing, the maximum concentration of greenhouse gases allowable to forestall potentially irreversible changes to the climate system, and the effect of those environmental feedbacks. We followed the latest data and trends for carbon dioxide, then made allowances for all human interferences that influence temperatures, both those with warming and cooling effects. We followed the judgments of the mainstream climate science community, represented by the Intergovernmental Panel on Climate Change (IPCC), on what it will take to retain a good chance of not crossing the critical threshold of the Earth's average surface temperature rising by 2C above pre-industrial levels. We were cautious in several ways, optimistic even, and perhaps too much so. A rise of 2C may mask big problems that begin at a lower level of warming. For example, collapse of the Greenland ice sheet is more than likely to be triggered by a local warming of 2.7C, which could correspond to a global mean temperature increase of 2C or less. The disintegration of the Greenland ice sheet could correspond to a sea-level rise of up to 7 metres.

In arriving at our timescale, we also used the lower end of threats in assessing the impact of vanishing ice cover and other carbon-cycle feedbacks (those wanting more can download a note on method from But the result is worrying enough.

We found that, given all of the above, 100 months from today we will reach a concentration of greenhouse gases at which it is no longer "likely" that we will stay below the 2C temperature rise threshold. "Likely" in this context refers to the definition of risk used by the IPCC. But, even just before that point, there is still a one third chance of crossing the line. . .

Link to article:

'100 months' to stop overheating

by Ian Sample, science correspondent, The Guardian, August 1, 2008

Rising greenhouse gas emissions could pass a critical tipping point and trigger runaway global warming within the next 100 months, according to a report today.

The estimate from the New Economics Foundation is based on when emissions will reach such high levels that it "is no longer likely" the world will be able to avoid a 2 C rise in average temperatures. "We know climate change is a huge problem, but there's a missing ingredient of urgency," said Andrew Simms, policy director at the foundation.

According to the UN's experts, greenhouse gas levels in the atmosphere, which are at around 430 ppm, would have to be stabilised at 450 ppm to avoid a rise of more than 2 C.

Simms and Victoria Johnson made a conservative estimate of future emissions based on six greenhouse gases and other pollutants, such as aerosols, which have a cooling effect. They predict that 100 months from today emissions will rise above the critical 450ppm threshold.

According to the government's 2006 report on climate change by Nicholas Stern, a 2 C rise could release vast quantities of carbon stored in soils and permafrost, see 15%-40% of land species threatened with extinction, and up to 4 billion people experiencing water shortages.


Arthur Smith's 'deconstruction" of Monckton's seminal work on climate sensitivity

A detailed list of the errors in Monckton's July 2008 Physics and Society article

by Arthur Smith

See this webpage:

For another discussion of this paper and its "rigorous arithmetic" (as it was put), see RealClimate:

Truffer et al., 2008: Velocity measurements on and near Ilulissat (Jakobshavn) Glacier, Greenland

Geophysical Research Abstracts,
Vol. 10, EGU2008-A-07161, 2008
SRef-ID: 1607-7962/gra/EGU2008-A-07161
EGU General Assembly 2008
© Author(s) 2008


Velocity measurements on and near Ilulissat (Jakobshavn) Glacier, Greenland

M. Truffer (1,2), J. Amundson (1), M. Fahnestock (3), M. Luethi (2), R. Motyka (1),
J. Brown (2)

(1) Geophysical Institute, University of Alaska Fairbanks (, (2) VAW
Glaciology, ETH Zurich, (3) Institute for the Study of Earth, Oceans and Space, University of
New Hampshire

Ilulissat Glacier has been thinning, accelerating and retreating since 1998. Terminus
velocities reached 13 km/yr, essentially doubling the 6-7 km/yr measured between
1985 and 1995 (Joughin et al., 2004). Since the summer of 2006 we have recorded
velocities on and near the glacier using dual frequency GPS receivers, which were
kinematically processed using a nearby GPS base station on bedrock. The 2007 summer
velocities indicate that the lower 25 km of the glacier have reached their maximum
velocity and perhaps even slowed down somewhat. Velocities measured farther
upstream continue to increase. The inland ice on either side of the ice stream shows
increased rates of convergence, even at 50 km from the ice front. Velocities have not
only increased in magnitude since 1985, but they have also changed direction towards
the ice stream, indicating the effect of draw-down from the ice stream acceleration on
the surrounding ice. All targets show events of variable velocity with amplitudes of up
to 10% of the background, but no sudden slip-events could be recorded.

Joughin, I.R., W. Abdalati, and M. Fahnestock. 2004. Large fluctuations in speed on
Greenland’s Jakobshavn Isbræ glacier. Nature, 432, 608-610.

Link to abstract:

Western Greenland, 28 and 30 July 2008

Joughin et al.: Seasonal Speedup Along the Western Flank of the Greenland Ice Sheet

Originally published in Science Express on 17 April 2008
Science 9 May 2008:
Vol. 320, No. 5877, pp. 781-783
DOI: 10.1126/science.1153288


Seasonal Speedup Along the Western Flank of the Greenland Ice Sheet

Ian Joughin,1* Sarah B. Das,2 Matt A. King,3 Ben E. Smith,1 Ian M. Howat,1{dagger} Twila Moon1

It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching the ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled a data set that provides a synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which to evaluate this hypothesis. On the ice sheet, these data reveal summer speedups (50 to 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup of outlet glaciers, however, is far smaller (<15%).> seasonal influence on Jakobshavn Isbrae's flow is the calving front's annual advance and retreat. With other effects producing outlet-glacier speedups an order of magnitude larger, seasonal melt's influence on ice flow is likely confined to those regions dominated by ice-sheet flow.

1 Polar Science Center, Applied Physics Lab, University of Washington, 1013 NE 40th Street, Seattle, WA 98105–6698, USA.
2 Department of Geology and Geophysics, Woods Hole Oceanographic Institute, Woods Hole, MA02543, USA.
3 School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.

{dagger} Present address: The Ohio State University, 1090 Carmack Road, Columbus, OH 43210–1002, USA.

* To whom correspondence should be addressed. E-mail:
Link to abstract:

Wednesday, July 30, 2008

Ward Hunt Ice Shelf loses another chunk

Yahoo! News, July 30, 2008

EDMONTON, Alberta - A chunk of ice spreading across seven square miles has broken off a Canadian ice shelf in the Arctic, scientists said Tuesday.

Derek Mueller, a research at Trent University, was careful not to blame global warming, but said it the event was consistent with the theory that the current Arctic climate isn't rebuilding ice sheets.

"We're in a different climate now," he said. "It's not conducive to regrowing them. It's a one-way process."

Mueller said the sheet broke away last week from the Ward Hunt Ice Shelf off the north coast of Ellesmere Island in Canada's far north. He said a crack in the shelf was first spotted in 2002 and a survey this spring found a network of fissures.

The sheet is the biggest piece shed by one of Canada's six ice shelves since the Ayles shelf broke loose in 2005 from the coast of Ellesmere, about 500 miles from the North Pole.

Formed by accumulating snow and freezing meltwater, ice shelves are large platforms of thick, ancient sea ice that float on the ocean's surface. Ellesmere Island was once entirely ringed by a single enormous ice shelf that broke up in the early 1900s.

At 170 square miles and 130-feet thick, the Ward Hunt shelf is the largest of those remnants. Mueller said it has been steadily declining since the 1930s.

Gary Stern, co-leader of an international research program on sea ice, said it's the same story all around the Arctic.

Speaking from the Coast Guard icebreaker Amundsen in Canada's north, Stern said He hadn't seen any ice in weeks. Plans to set up an ice camp last February had to be abandoned when usually dependable ice didn't form for the second year in a row, he said.

"Nobody on the ship is surprised anymore," Stern said. "We've been trying to get the word out for the longest time now that things are happening fast and they're going to continue to happen fast."

Link to article:

Senators Boxer, Whitehouse, and Klobuchar call for EPA administrator Johnson to resign

by Deborah Zabarenko, Environment Correspondent, Reuters, July 29, 2008

WASHINGTON (Reuters) - Democratic senators called on Tuesday for the resignation of Stephen Johnson, head of the U.S. Environmental Protection Agency, saying he sided with polluters instead of fighting global warming and other ecological problems.

The three senators, all active in the climate change debate, also asked the U.S. attorney general to investigate whether Johnson has made false or misleading statements in sworn testimony before the Senate's Environment and Public Works Committee.

Boxer, who heads the environment committee, said Johnson had made damaging decisions on mercury, lead, toxic chemicals, drinking water standards, ozone air pollution and global warming.

She said these decisions were "harmful to the American people."

Boxer noted that last year, Johnson denied California's request for federal permission -- known as a waiver -- to impose tough new limits on climate-warming carbon dioxide emissions from cars and light trucks. That decision effectively blocked as many as 18 other states from doing the same.

Boxer, Sen. Sheldon Whitehouse of Rhode Island and Sen. Amy Klobuchar of Minnesota wrote to Attorney General Michael Mukasey, asking him to investigate Johnson, specifically noting the California waiver decision.

"False testimony by any witness is serious and undermines our ability to fulfill our constitutional duties on behalf of the American people," the senators wrote. "Our concern is heightened because this decision by the EPA administrator affects the health and well-being of the American people."

White House spokesman Tony Fratto dismissed the allegations against Johnson, saying Boxer has "no standing" to question Johnson's integrity.

"Administrator Johnson is an honorable, experienced, career scientist and everything he has done at the EPA has been with the interests of protecting the American people and our environment," Fratto said.

(Editing by Eric Walsh)

Link to article:

Tuesday, July 29, 2008

NASA: The Earth's Temperature Tracker

BLOGGER'S NOTE: I have a terrible memory, and I often want to refresh it with regard to the way in which GISS temperatures are calculated. The Earth Observatory website is often inaccessible, so I have saved this article, here, for my own benefit and the benefit of anyone who is interested. Many denialists take potshots at the methodology, accusing the scientists of intentional manipulation of the data to show warmer temperatures. Note that GISS-TEMP extrapolates to include the Poles and other temperature trackers do not. As the Arctic is warming faster than any other region of the planet, this would naturally mean that GISS-TEMPs will be slightly warmer, but they still show no significant difference in the trend when compared to the other temperature trackers. Occasionally, GISS-TEMPs are even lower than the other trackers. The second link below is to a more lengthy discussion of the history of the methodology and the changes that have been made over the years. Due to the fact that occasionally I cannot open the NASA page, I will also post the contents of that page, later.

Link to NASA's Earth Observatory:

Link to GISS temperature analysis and history:
Earth's Temperature Tracker

by David Herring • design by Robert Simmon • November 5, 2007

Gazing up at the patch of night sky where the moon had shone just minutes earlier, young James Hansen had a flash of insight that changed the course of his career. It was December 1963 and Hansen, a senior in college, had gathered with fellow students at a small observatory just outside of Iowa City to observe a lunar eclipse. As the moon entered Earth’s shadow, Hansen expected the lunar disk to grow dark but he didn’t expect it to completely disappear from view. At first the moon’s disappearance puzzled Hansen, but then it dawned on him that it must have something to do with the recent eruption of Mount Agung, in Indonesia. Agung Volcano erupted with such force on March 17, 1963, it injected gases and debris particles high into the atmosphere, above where rain clouds form. Over a span of weeks the volcanic particles spread around the upper atmosphere where they scattered and absorbed incoming light, slightly darkening Earth’s surface.

“Normally you can see the moon during an eclipse from the sunlight beams refracted into Earth’s shadow,” Hansen explained, referring to the way in which the atmosphere bends light beams. “But on that night the atmosphere was so filled with volcanic aerosols that the sunlight beams that usually bent into the moon’s shadow region couldn’t penetrate Earth’s atmosphere well. So it appeared to us as a remarkably dark eclipse.”

During a lunar eclipse the moon usually remains visible, dimly lit by sunlight refracted through Earth’s atmosphere. In December of 1963, however, particles in the atmosphere from the eruption of Mount Agung blocked enough sunlight to make the eclipsed moon almost invisible. (Photograph ©2007 Johannes Schedler.)

Hansen marveled at the power of these airborne particles, known as aerosols. If aerosols can reflect and absorb incoming sunlight, what effect could events like Agung's eruption have on Earth’s surface temperature? To find out, he plugged what was known at the time about aerosols, greenhouse gases, and how Earth absorbs and radiates energy into some physics equations. His results suggested that the aerosols should slightly cool the planet.

It was one thing to estimate the impact of volcanic eruptions on global temperature using math and physics. It was quite another thing to compare such estimates to real-world data. The problem was that there were no real-world, global-scale data sets of temperature in the late 1960s to which he could compare his estimates. Murray Mitchell, in the NOAA Weather Bureau’s Office of Climatology, collected the most complete data set at the time. But Mitchell’s data set only included stations in the Northern Hemisphere. Thus Hansen’s goal of comparing his estimates to the real world was put on hold.

A catastrophic eruption of Mount Agung in March 1963 killed over 1,000 Indonesians on the island of Bali. The eruption covered the nearby area with ash and injected sulfur compounds into the stratosphere. The particles remained aloft for several years, absorbing and scattering light and slightly cooling Earth’s surface. (Photograph ©2006 Jesse Wagstaff.)

He continued working on planetary-scale science problems throughout his graduate and post-graduate studies. The United States had become a space-faring nation and the allure of the unknown called many planetary physicists’ attention to worlds beyond Earth’s atmosphere. What were conditions on the other planets like, and could they support life as we know it? Hansen wrote his doctoral thesis on the atmosphere of Earth’s nearest neighbor, Venus. Its dense carbon dioxide atmosphere made Venus’ surface hotter than an oven. Years later Hansen’s studies of Venus would contribute to his efforts to track Earth’s temperature.

The dense carbon dioxide atmosphere of Venus shrouds the planet in a thick layer of clouds—and heats the surface to a scorching 460° C (860° F). Jim Hansen’s research on Venus’ greenhouse effect eventually led him to the study of carbon dioxide and the greenhouse effect on Earth. (Image ©2005 Mattias Malmer.)

Earth is Cooling…No It’s Warming

In 1967 Hansen went to work for NASA’s Goddard Institute for Space Studies, in New York City, where he continued his research on planetary problems. Around 1970, some scientists suspected Earth was entering a period of global cooling. Decades prior, the brilliant Serbian mathematician Milutin Milankovitch had explained how our world warms and cools on roughly 100,000-year cycles due to its slowly changing position relative to the Sun. Milankovitch’s theory suggested Earth should be just beginning to head into its next ice age cycle. The surface temperature data gathered by Mitchell seemed to agree; the record showed that Earth experienced a period of cooling (by about 0.3°C) from 1940 through 1970. Of course, Mitchell was only collecting data over a fraction of the Northern Hemisphere—from 20 to 90 degrees North latitude. Still, the result drew public attention and a number of speculative articles about Earth’s coming ice age appeared in newspapers and magazines.

Graph of Northern Hemisphere temperatures, 1860 through 1970

But other scientists forecasted global warming. Russian climatologist Mikhail Budyko had also observed the three-decade cooling trend. Nevertheless, he published a paper in 1967 in which he predicted the cooling would soon switch to warming due to rising human emissions of carbon dioxide. Budyko’s paper and another paper published in 1975 by Veerabhadran Ramanathan caught Hansen’s attention. Ramanathan pointed out that human-made chlorofluorocarbons (or CFCs) are particularly potent greenhouse gases, with as much as 200 times the heat-retaining capacity of carbon dioxide. Because people were adding CFCs to the lower atmosphere at an increasing rate, Ramanathan expressed concern that these new gases would eventually add to Earth’s greenhouse effect and cause our world to warm. (Because CFCs also erode Earth’s protective ozone layer, their use was mostly abolished in 1989 with the signing of the Montreal Protocol.)

The notion that humans could override nature and force the globe to warm intrigued Hansen. “It had been known for more than a century that increasing carbon dioxide could have an effect on global temperature,” Hansen said (referring to the pioneering work of John Tyndall and Svante Arrhenius in the 1800s). But global warming in the near future? That was another matter.

Hansen returned his attention to the physics equations he’d played with almost 10 years earlier. Collaborating with Andy Lacis, a colleague at NASA, he built a simple climate model to simulate how changes in the atmosphere cause Earth’s average temperature to change over time. Hansen and Lacis tweaked the inputs to simulate the cumulative influence of all known human-made greenhouse gases except carbon dioxide (including CFCs, methane, nitrous oxide, and ozone) to see if their net effect could even be felt on a global scale in the climate system. To their surprise, Hansen’s team found that the warming effect of all those gases added together is comparable to the warming effect of carbon dioxide alone.

Initial efforts to observe Earth’s temperature were limited to the Northern Hemisphere, and they showed a cooling trend from 1940 to 1970 (jagged line). Scientists estimated the relative effects of carbon dioxide (warming, top curve) and aerosols (cooling, bottom curve) on climate, but did not have enough data to make precise predictions. (Graph from Mitchell, 1972.)

Graph of early climate model results showing expected warming due to anthropogenic carbon dioxide emissions.

The simple model also allowed Hansen to simulate the climate impact of Mount Agung’s eruption 15 years after the event. The model indicated that loading the atmosphere with volcanic aerosols should have caused a global cooling—a prediction that agreed pretty well with observed temperature data.

The model demonstrated that both human and natural activities could force climate to change. But Hansen knew that natural forcings, like volcanic eruptions or changes in the Sun’s activity, tend to go up and down over a long period of time whereas the human forcing from greenhouse gas emissions was steadily increasing.

“It became clear that human-produced greenhouse gases should become a dominant forcing and even exceed other climate forcings, such as volcanoes or the Sun, at some point in the future,” Hansen observed.

How soon would the human forcing begin to dominate? No one knew.

In 1981, NASA scientists predicted the impact of carbon dioxide emissions on global temperatures between 1950 and 2100 based on different scenarios for energy growth rates and energy source. If energy use stayed constant at 1980 levels (scenario 3, bottom lines), temperatures were predicted to rise just over 1°C. If energy use grew moderately (scenario 2, middle lines), warming would be 1–2.5 °C. Fast growth (scenario 1, top lines) would cause 3–4°C of warming. In each scenario, the warming was predicted to be less if some of the energy was supplied by non-fossil (renewable) fuels instead of coal-based, synthetic fuels (synfuels). (Graph from Hansen et al., 1981.)

Graph of cooling caused by Mount Agung aerosols

To find out, Hansen would need real-world data on a global scale. He requested data tapes from Roy Jenne, of the National Center for Atmospheric Research, who was widely recognized in the 1970s as having the best weather dataset in the world. Of course, there remained the problem that the weather stations supplying Jenne’s dataset were rather sparse compared to the vastness of Earth’s surface.

To test his climate model, Hansen calculated the cooling effect of Mount Agung’s eruption (dotted line) and compared the results with real-world temperature measurements (solid line). Despite its simplicity, the model accurately reflected the dip in tropical temperatures caused by the eruption. (Graph from Hansen et al., 1978.)

Global map of weather stations

“The lack of any global temperature analysis [for Earth] did not seem right to me,” Hansen recalled. Drawing from his previous work in estimating the average planetary surface temperature of Venus, he knew that if scientists had measurements from as many places on another planet as were available from Jenne’s dataset they would not hesitate to estimate Earth’s global temperature. He decided to try.

At the outset Hansen knew that weather fluctuations would introduce short-term temperature anomalies into the weather station dataset that are not the same thing as climate change. But he reasoned that by taking averages over several years, and appropriately “weighting” the weather stations’ data, it should be possible to determine meaningful temperature changes over longer time periods. In the mid-1970s, he hired Jeremy Barberra, a New York University undergraduate student at the time, to automate the processing of Jenne’s dataset.

They decided to process the data to produce average temperature changes, and not absolute temperature. “If you focus your analysis on temperature change, and not on determining absolute temperature values, then the station coverage is adequate,” Hansen explained. “What matters is the long-term mean over large scales, not single measurements from individual stations.”

The success of Hansen’s and Barberra’s approach depended on the principle that temperature anomalies have a much larger scale than absolute temperature. Consider a mountain on which it can be much cooler on one side than the other. This example illustrates how absolute temperature patterns can vary sharply over relatively short distances. On the other hand, temperature anomalies are typically large-scale events driven by Rossby Waves. Rossby Waves are slow-moving waves in the ocean or atmosphere, driven from west to east by the force of Earth spinning. We see such waves in the atmosphere as large-scale meanders of the mid-latitude jet stream.

Weather stations (red dots) are scattered unevenly across the globe. They are especially sparse in Africa and over the oceans. Before scientists could be confident in global temperature records, Hansen needed to demonstrate that widely spaced observations captured global temperature trends accurately. (NASA map by Robert Simmon, based on data from the National Climatic Data Center.)

“If it is an unusually warm winter in New York, it is probably also warm in Washington, D.C., for example,” Hansen explained. “At high- and mid-latitudes Rossby Waves are the dominant cause of short-term temperature variations. And since those are fairly long waves we didn’t think we needed a station at every one degree of separation.”

A station at every 1 degree would mean a station roughly every 80 kilometers (at mid-latitudes). But in a 1987 paper appearing in the Journal of Geophysical Review, Hansen and Sergei Lebedeff demonstrated that the temperature readings of weather stations within 1,000 kilometers (620 miles) of one another are highly correlated. The close correlation meant they could map global temperature changes over time despite the fact that weather stations are widely spaced and located mainly on continents and islands.

Here’s basically how their approach works: For each center point in a global grid of 1-degree boxes they let all weather station data within a 1,200-kilometer radius influence the estimated temperature change at that point. They gave greatest “weight” to the station closest to that point; for all other stations within that radius, they let the weighting fall off linearly with distance, all the way to a weighting of zero for stations 1,200 kilometers away or farther. “Again, our objective was not to determine the precise temperature of individual stations, but to produce a global-scale map of temperature change,” Hansen emphasized. “We were interested in tracking global climate patterns, not local weather variations.”

In their 1981 analysis, published in the journal Science, Hansen’s team reported finding that, overall, Earth’s average temperature rose by about 0.4°C for the period from 1880 to 1978. There was roughly 0.1°C of global cooling from 1940-1970. This cooling was less than what Mitchell had found earlier due to the fact that Hansen’s team was now using global data, and not just data from a swath around the Northern Hemisphere. Just as Budyko had predicted, Hansen found that Earth’s cooling trend swung back in the warming direction around 1970 and has been warming ever since. Moreover, Hansen noted, the warming trend observed in real-world data is consistent with his (and others’) global climate model outputs in their 100-year simulations.

Absolute temperatures can vary a lot even over short distances, but temperature anomalies usually affect a large region. Most week-to-week temperature variability is driven by Rossby Waves. These waves are easy to see in the looping motions of the jet stream. In this animation, Rossby Waves spiral from left to right toward Europe in the Northern Hemisphere and South Africa in the Southern Hemisphere. The scale of these waves is so large that weather stations separated by 1,000 kilometers or more adequately record the temperature anomalies they produce. (Double-click to pause or replay animation.) (NASA animation by Robert Simmon, based on SEVIRI data copyright EUMETSAT.)

High definition animation (23 MB Quicktime)

Graph of global temperature from 1880 to 1980

Since 1978, global warming has become even more apparent. Over the last 30 years, Hansen’s analysis reveals that Earth warmed another 0.5°C, for a total warming of 0.9°C since 1880.

The first reliable global measurements of temperature from NASA, published by Hansen and his colleagues in 1981, showed a modest warming from 1880 to 1980, with only a slight dip in temperatures from 1940 to 1970. (Graph adapted from Hansen et al. 1981.)

Graph of temperature trend, 1880 to 2006

“To questions about whether this warming is natural or just a fluctuation, the answer has become clear: the world is getting warmer,” Hansen stated. “This fact agrees so well with what we calculate with our global climate model that I am confident we are looking at warming that is mainly due to increasing human-made greenhouse gases.”

Since 1980, global surface temperatures have increased sharply, the Earth’s response to increasing concentrations of greenhouse gases such as carbon dioxide. (NASA graph adapted from Goddard Institute for Space Studies data.)

The Data and the Details

Some nagging questions remained for Hansen and his colleagues. Citing issues such as stations located too close to paved surfaces, stations located in urban areas that are known to be warmer than rural regions, and stations located in developing nations where data collection methods may be unreliable, critics argued that any of these problems could throw off an individual station’s temperature readings. Don’t such concerns cast a shadow of doubt on the NOAA weather station data?

Initially, perhaps, but not after the data have been carefully tested in several ways. First, Hansen’s team (and others) finds good agreement of the weather station data with “proxy” data sets that are sensitive to surface temperature changes—such as the rate at which glaciers are receding, or subsurface temperature measurements in boreholes drilled down into the ground. (Scientists can infer surface temperature change from underground temperatures based on equations that describe how heat diffuses through the ground over time.) The results in thousands of remote locations around the world agree well with the surface temperature measurements.

Second, Hansen’s team “cleans” the weather station data by finding and filtering out flawed data entries. Specifically, they apply a computer algorithm that checks each data point for temperature readings that are very significantly higher or lower than average for a given location at that time of year. Whenever such an anomaly is flagged, the algorithm compares those data to data from nearby stations to see if they show a similar anomaly. If so, then the data in question are kept; if not, or if there are no nearby stations for comparison, then the data are thrown away.

Graph of temperature for Linyi, China showing an outlier.

His team also modifies the data from stations located in densely populated areas by removing the long-term bias of these “urban heat islands.” The team uses satellite data to determine if a given station is in an urban or near-urban location. If so, then the team uses the nearest rural stations to determine the long-term trend at the urban site. If there are no rural neighbors, then Hansen’s team throws out the urban station data.

Bad data are cleaned from the NASA global temperature record by first looking for outliers: months when the temperature at a station is much higher or lower than the average for that time of year. The monthly temperature record for Linyi, China, in 1932 (red dots; June data is missing) shows that September was 5.3° C warmer than average. The unusual data point was compared to nearby stations. Since some of those stations were also exceptionally warm, the data point was retained. If nearby stations do not confirm the anomaly, the team does not use the data. (Graph by Robert Simmon, based on data from the GISS Surface Temperature Analysis Station Data.)

Map of urban areas and weather stations in the United States.

One lesson to be learned here is weather science and climate science are quite different: weather is concerned with what conditions are like at a given location and time, whereas climate is concerned with what conditions are like over large regions, or over the entire globe, and for a long period of time. That explains why climate scientists are not as interested in any given reading for an individual station as they are in 5-year and 10-year blocks of time for the entire planet.

Hansen acknowledged there may be flaws in the weather station data. “But that doesn’t mean you give up on the science, and that you can’t draw valid conclusions about the nature of Earth’s temperature change,” he asserted.

Weather stations are screened for potential bias from urban heat islands by comparing station locations with maps of urbanization. Measurements from nearby stations in rural areas (gray) are used to correct urban station data for warming due to the heat island effect. If no rural neighbors are available for comparison, data from urban (dark blue) and peri-urban (blue) stations are left out of the global average calculation. (Map by Robert Simmon, based on data from NOAA.)

From A Dimmer Past to a Brighter Future?

Of greater concern to Hansen than global warming skeptics is the problem of global warming itself. If greenhouse gases are to blame then why did Earth’s average temperature cool from 1940-1970? And why has the rate of global warming accelerated since 1978? Hansen’s answers to these questions brought him full circle to where he began his investigation more than 40 years ago.

“I think the cooling that Earth experienced through the middle of the twentieth century was due in part to natural variability,” he said. “But there’s another factor made by humans which probably contributed, and could even be the dominant cause: aerosols.”

In addition to greenhouse gas emissions, human emissions of particulate matter are another significant influence on global temperature. But whereas greenhouse gases force the climate system in the warming direction, aerosols force the system in the cooling direction because the airborne particles scatter and absorb incoming sunlight. “Both greenhouse gases and aerosols are created by burning fossil fuels,” Hansen said, “but the aerosol effect is complicated because aerosols are distributed inhomogeneously [unevenly] while greenhouse gases are almost uniformly spaced. So you can measure greenhouse gas abundance at one place, but aerosols require measurements at many places to understand their abundance.”

After World War II, the industrial economies of Europe and the United States were revving up to a level of productivity the world had never seen before. To power this large-scale expansion of industry, Europeans and Americans burned an enormous quantity of fossil fuels (coal, oil, and natural gas). In addition to carbon dioxide, burning fossil fuel produces particulate matter—including soot and light-colored sulfate aerosols. Hansen suspects the relatively sudden, massive output of aerosols from industries and power plants contributed to the global cooling trend from 1940-1970.

Pollution from factories, cars, airplanes, home furnaces, and power plants form aerosols—tiny particles suspended in the air. These particles reflect and absorb sunlight, slightly cooling the Earth’s surface. (Photograph ©2007 Señor Codo.)

Graph of sulfur concentration in Greenland ice from 1880 to 2000

“That’s my suggestion, though it’s still not proven,” he said. “There is a nice record of sulfates in Greenland ice cores that shows this type of particle was peaking in the atmosphere around 1970. And then the ice core record shows a rapid decline in sulfates, right about the time nations began regulating their emission.” (Sulfates cause acid rain and other health and environmental problems.)

In 2007, Michael Mischenko, of NASA GISS, published a paper in the journal Science in which he reported tropospheric aerosols have indeed declined slightly over the last 30 years. The net effect is that more sunlight passes through the atmosphere, slightly brightening the surface. This increased exposure to sunlight could partially account for the increase in surface temperature that Mischenko and Hansen observed over the same time span.

Sulfur trapped in the Greenland Ice Sheet records the presence of reflective sulfate aerosols downwind of the United States and Canada. Emissions of the pollutants that form sulfate aerosols rose sharply in the United States and Europe during and after World War II. This rise may be responsible for the Northern Hemisphere cooling from 1940–1970. By the 1980s, oil embargos and environmental controls had reduced sulfate pollution in North America, but carbon dioxide continued to build up in the atmosphere. (Graph by Robert Simmon, based on data from McConnell et al., NOAA/NCDC Paleoclimatology Program.)

Graph of aerosol optical thickness from 1981 to 2005

Over the course of the twentieth century, Hansen and other climate scientists estimate aerosols may have offset global warming by as much as 50 percent by reducing the amount of sunlight reaching the surface. Scientists call this phenomenon “global dimming,” although the change was too gradual and too slight to be perceived by the human eye. (Aerosols’ dimming potential has been observed, of course, after dramatic events like the Agung Volcano eruption that Hansen noticed during the lunar eclipse of December 1963.)

Hansen describes the global dimming effect of human-emitted aerosols as a “Faustian bargain”—a deal with the devil. “Eventually you get to a point where you don’t want aerosols in the atmosphere because they’re harmful to human health, harmful to agriculture, and harmful to natural resources,” he stated. “So in the U.S. and much of Europe, we’ve been reducing aerosol emissions.”

But we haven’t seen a corresponding reduction in greenhouse gas emissions. Indeed, humans’ use of fossil fuels rose rapidly (about 5 percent per year) from the period after World War II until 1973. After the oil embargo and price shock of oil in 1973, annual average consumption continued to increase, but at a slower pace (between 1.5 and 2 percent per year). A byproduct of that rising fossil fuel consumption has been a corresponding rise in carbon dioxide emission. Because greenhouse gases reside in the atmosphere for decades, while aerosols usually wash out over a span of days to weeks, the warming influence of greenhouse gases gradually won out.

“For much of the twentieth century, both types of human emissions were on nearly equal footing, and aerosols were able to compete with greenhouse gases,” Hansen said. But that balance has tilted increasingly in favor of greenhouse gases in the last 30 years. Today, Hansen’s team estimates the human forcing from greenhouse gases to be about 3 watts per square meter (warming) and the forcing from aerosols to be about minus 1.5 watts per square meter (cooling). Hansen sees these trends as very likely to lead to what he calls “dangerous human interference” with the climate system.

“I think action [to reduce greenhouse gas emissions] is needed urgently, because we are on the precipice of a climate system ‘tipping point’,” Hansen concluded. “I believe the evidence shows with reasonable clarity that the level of additional global warming that would put us into dangerous territory is at most 1°C.”

Satellite observations of aerosol optical thickness (how greatly aerosols reduce the intensity of sunlight reaching the surface) show that aerosol concentrations have decreased since 1991 (green line). Prior to that, they had been rising slightly (blue line). In addition to the long-term trends of human-made aerosols, the graph shows the occurrence of large volcanic eruptions like El Chichón in 1982 and Mount Pinatubo in 1991. These natural events produce large spikes in aerosol concentrations, but their impact is short-lived. (Graph adapted from Mishchenko et al., 2007)

Map of 2001 to 2006 global temperature anomaly

If we follow a ‘business-as-usual’ course, Hansen predicts, then at the end of the twenty-first century we will find a planet that is 2-3°C warmer than today, which is a temperature Earth hasn’t experienced since the middle Pliocene Epoch about three million years ago, when sea level was roughly 25 meters higher than it is today.

Monday, July 28, 2008

In situ sediment core analysis on Greenland ice reveals rapid climate changes

by Nora Schultz, NewScientist, June 20, 2008

The most detailed Greenland ice-core analysis yet offers important clues about what caused the climate to change so rapidly at the end of the last ice age.

"We can now read the climate's history at unprecedented resolution, going 15,000 years into the past," says Jim White at the University of Colorado at Boulder, who studied the new ice core as part of an international team.

Around this time, temperatures in Greenland rose by 10 °C in just 50 years. The new ice-core data suggests that this change began with a very rapid retreat of the ice covering the Atlantic. It also shows that it was preceded by dramatic climate change on the other side of the planet.

Damper deserts

White and his colleagues analysed the amount of dust and heavy oxygen and hydrogen isotopes in small sections of the ice core that each represent a few months of climate history.

This approach is only made possible using an automated analysis tool that continuously melts an ice core and measures its composition at the extraction site, not in the lab.

Most of the dust found in Greenland drifts there from China. The core reveals a sharp drop in dust levels at the end of the ice age, suggesting the Asian deserts suddenly became much wetter.

Following this, levels of the heavy hydrogen isotope deuterium indicate that atmospheric circulation in the North probably led to a retreat in the ice covering the Atlantic all the way from Portugal to Iceland over just one to three years. This was followed by a more gradual rise in Greenland temperatures over the next few decades.

Mystery connection

White says that the rapid ice melt was most likely triggered by a sudden recuperation of the warm North Atlantic deep water circulation.

However, he is surprised that the climate changed in Asia just before or at the same time. Although he does not yet know how the two events could be connected, White says the data strongly suggest that we should take a broader view when looking for warning signs of rapid climate change today.

"Otherwise, if we are just staring at the North Atlantic looking for change then we may get smacked in the rear by something that happens on the other side of the world," he says.

Katrin Meissner at the Climate Modelling Lab at the University of Victoria in Canada says the study presents groundbreaking insights into the existence of tipping points in the planet's climate system.

"This knowledge is crucial to understand and predict future climate changes due to man-made perturbations such as greenhouse gas emissions", she says.

Journal Reference: Science Express (DOI: 10.1126/science.1157707)

Link to article:

Western Canada's Glaciers Hit 7000-Year Low

[BLOGGER'S NOTE: Once in a while I like to post an older article, especially if it is still pertinent -- we need to be reminded that there are many, many pieces to this puzzle.]

Overlord Glacier: 7000 years old. Glacier in background.

Tree stumps at the feet of Western Canadian glaciers are providing new insights into the accelerated rates at which the rivers of ice have been shrinking due to human-aided global warming.

Geologist Johannes Koch of The College of Wooster found the deceptively fresh and intact tree stumps beside the retreating glaciers of Garibaldi Provincial Park, about 40 miles (60 km) north of Vancouver, British Columbia. What he wanted to know was how long ago the glaciers made their first forays into a long-lost forest to kill the trees and bury them under ice.

To find out, Koch radiocarbon-dated wood from the stumps to see how long they have been in cold storage. The result was a surprising 7000 years.

"The stumps were in very good condition sometimes with bark preserved," said Koch, who conducted the work as part of his doctoral thesis at Simon Fraser University in Burnaby, British Columbia. Koch will present his results on Wednesday, 31 October 2007, at the Geological Society of America Annual Meeting in Denver.

The pristine condition of the wood, he said, can best be explained by the stumps having spent all of the last seven millennia under tens to hundreds of meters of ice. All stumps were still rooted to their original soil and location.

"Thus they really indicate when the glaciers overrode them, and their kill date gives the age of the glacier advance," Koch explained. They also give us a span of time during which the glaciers have always been larger than they were 7000 years ago — until the recently warming climate released the stumps from their icy tombs.

Koch compared the kill dates of the trees in the southern and northern Coast Mountains of British Columbia and those in the mid- and southern Rocky Mountains in Canada to similar records from the Yukon Territory, the European Alps, New Zealand and South America. He also looked at the age of Oetzi, the prehistoric mummified alpine "Iceman" found at Niederjoch Glacier, and similarly well-preserved wood from glaciers and snowfields in Scandinavia.

The radiocarbon dates seem to be the same around the world, according to Koch. It's important to note that there have been many advances and retreats of these glaciers over the past 7000 years, but no retreats that have pushed them back so far upstream as to expose these trees.

The age of the tree stumps gives new emphasis to the well-documented "before" and "after" photographs of retreating glaciers during the 20th century.

"It seems like an unprecedented change in a short amount of time," Koch said. "From this work and many other studies looking at forcings of the climate system, one has to turn away from natural ones alone to explain this dramatic change of the past 150 years."

Published by on October 30, 2007

Source: Geological Society of America

Link to article:

Sunday, July 27, 2008

Arctic Sea ice well on its way to disappearing this summer? Part III

: This post is an update to the posts of June 1 and July 10, 2008, on the condition of the Arctic Sea ice and Greenland's ice sheet melt.
See here:
And here:


From Polar View at the Technical University of Denmark (
Composite images from July 27, 2008:

From the Cryosphere Today site (run by the Universities of Illinois and Colorado), a comparison of the Arctic on July 9, 2007 and 2008, and July 22, 2007 and 2008:

Go to this link and put in dates for comparison -- the most recent day is usually available before the evening:

The graphics below are from NOAA of global sea surface temperature anomalies on July 10 and 24, 2008.

Link to updated graphics:

The image below is a NOAA graphic of the 500-hPa height anomalies in the Northern Hemisphere on July 2, 2008. Click on the link below the graphic to see the most recent 30-day animation.

Link to past 30-days' animation:

: from Bremen University, a graphic of the Arctic Sea Ice extent, on July 9, 2008 (be sure to click on it in order to see the detail:

BELOW, July 12, 2008:

BELOW, July 27, 2008:

Link to the graphics above (occasionally data are missing and are represented by grey areas -- normally, these areas will be filled in by the morning of the following day):

BELOW: visual ice cover, July 12, 2008 (from Bremen University).

BELOW: visual ice cover, July 27, 2008

Link to updated images:

BELOW: composite satellite photos of Northern Hemisphere high latitudes on July 9 and 26, 2008.

Link to photos (NOTE: to see photos from other days from 2008, change the 191 to the number of the day that you want, e.g., 190 is July 8, and so forth):

BELOW: from the Japanese Space Agency, a graphic of Arctic Sea ice extent for the current and past years:

Link to graphic:

BELOW: National Snow and Ice Data Center graph of Arctic Sea ice extent, July 10, 2008:

Link to graph:

I find the image below fascinating (and it is the scariest of all):

Link to updated TLT channel temperature anomalies graph (NOTE: often due to volume of traffic it is not possible to access the link -- try again later):

And, below, find an animation of global surface temperature anomalies for the past 30 days -- most disturbing are the anomalies occurring at Antarctica many of which are much higher than 20 C.

Link to animation above:

ABOVE: image from August 4th, 2008.

BELOW, temperature map of the Arctic (first click on the link below the picture, then click on the yellow dots to see weather conditions -- some dots are inactive):

Link to map:

Saturday, July 26, 2008

Appealing to Bloggers’ Influence, Gore Asks for Help in Promoting Energy Challenge

AUSTIN, Tex. — Nancy Pelosi, the speaker of the House, was asked a question here at a bloggers conference about energy. Ms. Pelosi glanced at her BlackBerry, noting that she had an e-mail message from a friend on that very subject.

Al Gore and the House speaker, Nancy Pelosi, at the Netroots Nation conference.(Harry Cabluck/Associated Press)

With that, the voice of former Vice President Al Gore came over the public address system, as if reading the e-mail message: “Dear Nancy.” This created a sea of quizzical looks in the audience, then gasps, cheers and a standing ovation as Mr. Gore strode on stage.

The surprise appearance produced the first electric moment at the conference, the Netroots Nation, an ever-widening group of progressive bloggers whose major interests — the war in Iraq, the environment and technology — mesh well with Mr. Gore’s current pursuits. Indeed, many in the crowd of about 3,000, most of whom are supporting Senator Barack Obama, the likely Democratic presidential nominee, were overheard saying they wished Mr. Gore were running for president.

As waves of cheers washed over the cavernous convention center, Mr. Gore said to Ms. Pelosi, “We ought to take that act on the road.”

“We are on the road,” she replied.

“Well, I feel right at home here, I’ll tell you,” he said.

Mr. Gore, later answering questions from the audience, said he would not accept a role in the next administration. The best use of his talent and experience, he said, is “to focus on trying to enlarge the political space” within which politicians can address the climate crisis.

“I have seen firsthand how important it is to have a base of support out in the country for the truly bold changes that have to be made now,” he said, noting that is why he intends to devote his life to bringing about “a sea change in public opinion.”

He repeated the challenge he issued to the country on Thursday to produce 100 percent of its electricity from renewable energy and clean, carbon-free sources within 10 years. And he called on the bloggers to help achieve that goal, saying they were on the leading edge of reclaiming democracy for the grass roots.

As the morning began, Ms. Pelosi, Democrat of California, appeared on stage with Gina Cooper, the moderator and an organizer of the conference. The bloggers had submitted questions in advance and voted on them; the first was why Democratic leaders in the House were reluctant to take up impeachment proceedings against President Bush and Vice President Dick Cheney. Ms. Pelosi said the House was considering contempt resolutions against Karl Rove, the president’s former top adviser.

Ms. Cooper asked Ms. Pelosi whether Mr. Rove, if found in contempt of Congress, would be put “in that little jail cell that’s in the basement of the House.” The audience cheered. Ms. Pelosi replied that Representative John Conyers Jr., the Michigan Democrat who is chairman of the Judiciary Committee, had told her, “Leave it up to me.”

She was next asked about the wiretapping bill, detested by many progressives. She said the House version was better than the Senate’s and blamed Senate Democrats for approving a version that “enabled the Republicans to send that bill to the House.”

Ms. Cooper, who periodically interceded with pointed comments that were much appreciated by the audience, told Ms. Pelosi, “It sounds like your colleagues need to get with the program with the American people.”

Asked if she would redirect money from abstinence-only programs to sex education, Ms. Pelosi said, “Yes,” adding that the current program “caters to a radical right-wing view.”

When Mr. Gore addressed the group, he noted first that the polar ice cap, which is about the size of the continental United States and has been in existence for three million years, had a 75 percent to 80 percent chance of melting in five years.

Mr. Gore also mentioned his energy challenge, which brought another standing ovation. He said he was trying to recruit “an army” of 10 million citizens to build political consensus across party lines for the energy challenge, and directed the audience to, the Web site of his group, the Alliance for Climate Protection.

“I need your help,” Mr. Gore said, a plea that bloggers heard repeatedly throughout their conference, which began Thursday and ends Sunday, as speaker after speaker for various causes took note of their increasing influence within society.

Mr. Gore promised them that the alliance would not turn partisan or take up some other agenda and that he was in it “for the long haul.”

Ms. Pelosi was asked whether Congress would accept Mr. Gore’s energy challenge. “It is absolutely possible to do so,” she said.

She added that without Mr. Gore, “there would be no Netroots Nation; we would simply not have the technology.”

As a reminder of the flap caused years ago — when he got tagged with having said he “invented” the Internet, although he had not used that word and had, in fact, helped legislatively to create it — he smiled at Ms. Pelosi’s comments and said, “I think I’ll refrain from saying it.”

Link to article:

Friday, July 25, 2008

Democrats: White House must publish 'chilling' climate change document

by Elana Schor, The Guardian, July 25, 2008

The row over US inaction on carbon emissions reached new heights yesterday after the White House allowed Congress to look at last year's government proposal to officially deem climate change a threat to public health – a plan that aides to George Bush refused to acknowledge or read.

The climate plan was finished in December by the US Environmental Protection Agency (EPA) in response to a supreme court ruling that required the Bush administration to state whether carbon emissions should be regulated to protect public health.

The EPA concluded that regulation was needed, but whistleblowers have revealed that the White House ordered the agency to scrap its proposal. Democratic attempts to investigate the backroom dealings were stymied until this week, when senators were finally permitted a look at the plan.

The chairman of the Senate environment committee, California Democrat Barbara Boxer, released a summary of the proposal to reporters. Boxer was allowed to take notes on the plan but not given a copy.

"Based on the evidence before him, the [EPA] administrator believes it is reasonable to conclude current and future emissions of greenhouse gases will contribute to future climate change," the proposal stated.

"The US has a long and populous coastline," the EPA continued. "Sea level rise will continue and exacerbate storm surge flooding and coastline erosion … in areas where heat waves already occur, they are expected to be more intense, more frequent, and longer-lasting."

The EPA proposal also predicted that warming temperatures would lead to more wildfires in western US states and "additional strain" on already overtaxed water resources in the dry south-east and western regions.

Democrats asked the EPA administrator, Stephen Johnson, to testify next week at a hearing exploring allegations of White House obstruction on climate change. But Johnson refused, citing executive privilege and forcing the cancellation of the hearing.

"The American people are poorly served by an administration whose head of environmental protection cannot appear before a Senate committee and honestly discuss what he did and why he did it," senior Democrat Patrick Leahy said.

The next step may be holding Johnson in contempt of Congress, which would effectively move the dispute into the judicial system. White House chief of staff Josh Bolten and former Bush counsellor Karl Rove were found in contempt last year after refusing to cooperate with a different investigation, but their case has yet to move forward.

Boxer decried the White House's decision not to release the full EPA proposal to the public.

"It is clear. It is chilling. It is detailed," she said to colleagues yesterday. "That information belongs to the American people and we must get it to them. Then they will decide whether we should act to prevent this coming crisis or sit on our hands."

The EPA attempted to downplay the controversy in a statement to the Washington Post that called the proposal "a pre-decisional draft document" and "nothing new."

Link to article: