New paper finds global carbon cycle datasets may be biased

A paper published today in Global Biogeochemical Cycles finds prior calculations of the global carbon cycle may be erroneous because such calculations are based upon partial pressures of CO2 from several meters below the ocean surface instead of CO2 levels at the ocean surface ["the boundary layer"] where CO2 is actually exchanged between the atmosphere and ocean. The authors find a "strong" CO2 variability between the global datasets measured from several meters below the surface in comparison to the ocean surface that cannot be explained by Henry's Law alone, and are primarily due to variations in biological activity between these layers. The paper finds higher levels of CO2 in the boundary layer than in the 5 meter deep global datasets, which would suggest that either the oceans are less of a sink for CO2 or a larger source of CO2 to the atmosphere than previously assumed. The authors recommend, "Observations of pCO2 just beneath the air-sea boundary layer should be further investigated in order to estimate possible biases in calculating global air-sea CO2 fluxes."


Prevalence of strong vertical CO2 and O2 variability in the top meters of the ocean

Maria Ll. Calleja et al

Abstract: The gradient in the partial pressure of carbon dioxide (pCO2) across the air-sea boundary layer is the main driving force for the air-sea CO2 flux. Global data-bases for surface seawater pCO2 are actually based on pCO2 measurements from several meters below the sea surface, assuming a homogeneous distribution between the diffusive boundary layer and the upper top meters of the ocean. Compiling vertical profiles of pCO2, Temperature and dissolved oxygen in the upper 5-8 meters of the ocean from different biogeographical areas, we detected a mean difference between the boundary layer and 5 [meters below the surface] pCO2 of 13 ± 1 µatm. Temperature gradients accounted for only 11 % of this pCO2 gradient in the top meters of the ocean, thus, pointing to a heterogeneous biological activity underneath the air-sea boundary layer as the main factor controlling the top meters pCO2 variability. Observations of pCO2 just beneath the air-sea boundary layer should be further investigated in order to estimate possible biases in calculating global air-sea CO2 fluxes.

Related: 

New paper finds ocean along N. California coast is a net source of CO2 to the atmosphere

New paper finds ocean along Baja California coast is a net source of CO2 to the atmosphere

New paper finds the oceans are a net source of CO2

Henry's law - Wikipedia, the free encyclopedia

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Review paper finds the so-called unprecedented warmth of the late 20th century is simply a myth

A new paper from SPPI and CO2 Science reviews the scientific literature on historical temperature trends in China and concludes, "the results of these several studies demonstrate that the so-called unprecedented warmth of the late 20th century is simply a myth, as far as China is concerned. The apparent great warmth of this period in this particular part of the world appears to have been but a common manifestation of naturally-induced and regularly-recurring conditions similar to those that have been experienced in prior millennia. These results also serve as a testimony against those who would deny the existence of an extensive (hemispheric or global) Medieval Warm Period and Little Ice Age, as well as an extensive Roman Warm Period and Dark Ages Cold Period, and cyclical climate changes in general."

For the Full Report in PDF Form, please click here.

[Illustrations, footnotes and references available in PDF version]

Excerpts:



Controversy abounds over the temperature history of the earth, particularly that of the past one to two millennia. The original debate was sparked by the papers of Mann et al. (1998, 1999), which challenged the long-accepted view that there was nothing unusual about earth's climatic history subsequent to the inception of the Industrial Revolution; and it prompted the Intergovernmental Panel on Climate Change (IPCC) to disavow their original representation of the temperature history of the Holocene (Houghton et al., 1990), where several periods of time prior to the inception of the Industrial Revolution were depicted as having experienced temperatures that were higher than those of the latter part of the 20th century.

For a considerable amount of time during the Medieval Warm Period, this large chunk of China enjoyed greater warmth than has yet to be experienced in modern times during the winter season.

The cyclical nature of the millennial-scale oscillation of climate that is evident in both climate records further suggests that there is no need to invoke rising atmospheric CO2 concentrations as a cause of the development of the Modern Warm Period.

From 1890 to 1950, another warm and dry period held sway, followed by a cooling since the end of the 1940s, which is at odds with the hockeystick temperature history of Mann et al. (1998, 1999).

In conclusion, the results of these several studies demonstrate that the so-called unprecedented warmth of the late 20th century is simply a myth, as far as China is concerned. The apparent great warmth of this period in this particular part of the world appears to have been but a common manifestation of naturally-induced and regularly-recurring conditions similar to those that have been experienced in prior millennia. These results also serve as a testimony against those who would deny the existence of an extensive (hemispheric or global) Medieval Warm Period and Little Ice Age, as well as an extensive Roman Warm Period and Dark Ages Cold Period, and cyclical climate changes in general. Clearly, it's time for everyone to wake up! ... and to recognize the dynamic nature of real-world climate change!

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NASA finds a Grand Canyon hidden under a mile of Greenland ice; formerly a large river system

NASA Data Reveals Mega-Canyon Under Greenland Ice Sheet

Aug. 29, 2013 — Data from a NASA airborne science mission reveals evidence of a large and previously unknown canyon hidden under a mile of Greenland ice.


The canyon has the characteristics of a winding river channel and is at least 460 miles (750 kilometers) long, making it longer than the Grand Canyon. In some places, it is as deep as 2,600 feet (800 meters), on scale with segments of the Grand Canyon. This immense feature is thought to predate the ice sheet that has covered Greenland for the last few million years.

"One might assume that the landscape of the Earth has been fully explored and mapped," said Jonathan Bamber, professor of physical geography at the University of Bristol in the United Kingdom, and lead author of the study. "Our research shows there's still a lot left to discover."

Bamber's team published its findings Thursday in the journal Science.

Hidden for all of human history, a 460 mile long canyon has been discovered below Greenland's ice sheet. Using radar data from NASA's Operation IceBridg, scientists found the canyon runs from near the center of the island northward to the fjord of the Petermann Glacier. (Credit: Image courtesy of NASA)

The scientists used thousands of miles of airborne radar data, collected by NASA and researchers from the United Kingdom and Germany over several decades, to piece together the landscape lying beneath the Greenland ice sheet.

A large portion of this data was collected from 2009 through 2012 by NASA's Operation IceBridge, an airborne science campaign that studies polar ice. One of IceBridge's scientific instruments, the Multichannel Coherent Radar Depth Sounder, can see through vast layers of ice to measure its thickness and the shape of bedrock below.

In their analysis of the radar data, the team discovered a continuous bedrock canyon that extends from almost the center of the island and ends beneath the Petermann Glacier fjord in northern Greenland.

At certain frequencies, radio waves can travel through the ice and bounce off the bedrock underneath. The amount of times the radio waves took to bounce back helped researchers determine the depth of the canyon. The longer it took, the deeper the bedrock feature.

"Two things helped lead to this discovery," said Michael Studinger, IceBridge project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "It was the enormous amount of data collected by IceBridge and the work of combining it with other datasets into a Greenland-wide compilation of all existing data that makes this feature appear in front of our eyes."

The researchers believe the canyon plays an important role in transporting sub-glacial meltwater from the interior of Greenland to the edge of the ice sheet into the ocean. Evidence suggests that before the presence of the ice sheet, as much as 4 million years ago, water flowed in the canyon from the interior to the coast and was a major river system.

"It is quite remarkable that a channel the size of the Grand Canyon is discovered in the 21st century below the Greenland ice sheet," said Studinger. "It shows how little we still know about the bedrock below large continental ice sheets."

The IceBridge campaign will return to Greenland in March 2014 to continue collecting data on land and sea ice in the Arctic using a suite of instruments that includes ice-penetrating radar.

Journal Reference:

Jonathan L. Bamber, Martin J. Siegert, Jennifer A. Griggs, Shawn J. Marshall, and Giorgio Spada. Paleofluvial Mega-Canyon Beneath the Central Greenland Ice Sheet.Science, 2013; 341 (6149): 997-999 DOI:10.1126/science.1239794

Related: 

New paper finds Greenland melt 'strongly influenced' by natural geothermal heating

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New paper finds low estimate of climate sensitivity to CO2 of 1.16C

A paper in press for the journal Tellus finds the "best estimate" of climate sensitivity to CO2 is about 33% less than estimated by the IPCC. According to the authors, the best estimate of transient climate sensitivity is 1.5C for a doubling of CO2 levels, and equilibrium climate sensitivity [after hundreds of years] about 2C. The paper finds a lower bound on equilibrium climate sensitivity of 1.16C per doubling of CO2. The paper adds to many recent peer-reviewed papers finding climate sensitivity to CO2 is significantly less than claimed by the IPCC. 



Determination of a lower bound on Earth’s climate sensitivity



Lennart Bengtsson 1, Stephen E. Schwartz 2



1 Environmental Systems Science Centre, University of Reading, UK; 

2 Atmospheric Sciences Division, Brookhaven National Laboratory, Upton NY 11973, USA



Submitted to Tellus, October 23, 2012

Accepted, August 14, 2013 Revised, May 20, 2013; July 27, 2013; August 15, 2013



ABSTRACT: Transient and equilibrium sensitivity or Earth's climate have been calculated using global temperature, forcing, and heating rate data for the period 1970-2010. We have assumed increased long wave radiative forcing in the period due to the increase of the long-lived greenhouse gases. By assuming that the change in aerosol forcing in the period to be zero we calculate what we consider to be lower bounds to these sensitivities, as the magnitude of the negative aerosol forcing is unlikely to have diminished in this period. The radiation imbalance necessary to calculate equilibrium sensitivity is estimated from the rate of ocean heat accumulation as 0.37 ± 0.03 W m-2 (all uncertainty estimates are 1-σ). With these data we obtain best estimates for transient climate sensitivity 0.39 ± 0.07 K (W m-2)-1 and equilibrium climate sensitivity 0.54 ± 0.14 K (W m-2)-1, equivalent to 1.5 ± 0.3 and 2.0 ± 0.5 K (3.7 W m-2)-1, respectively. The latter quantity is equal to the lower bound of the "likely" range for this quantity given by the 2007 IPCC Assessment report. The uncertainty attached to the lower-bound equilibrium sensitivity permits us to state, within the assumptions of this analysis, that the equilibrium sensitivity is greater than 0.31 K (W m-2)-1, equivalent to 1.16 K (3.7 W m-2)-1, at the 95% confidence level.



Related: Why climate sensitivity is even less than these new estimates

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Global Warmists Might Explain Why No Hurricanes Midway Through 2013 Season

Global Warmists Might Explain Why No Hurricanes Midway Through 2013 Season

By James Taylor, Forbes, 8/29/13
This week marks the halfway point of the 2013 Atlantic hurricane season, yet not a single hurricane has formed anywhere in the Atlantic. This year’s lack of hurricanes continues an ongoing, beneficial trend of fewer hurricanes coinciding with moderately warming temperatures as the planet continues its recovery from the Little Ice Age. The decline in hurricanes also coincides with global warming alarmists ramping up a deceptive public relations campaign designed to convince the public that global warming skeptics are causing more hurricanes.

The lack of hurricanes so far in 2013 is remarkable in several particulars.

First, as mentioned, hurricanes have posted a giant goose egg so far on the 2013 hurricane scoreboard. This isn’t just hurricane strikes in the United States; this is hurricane formation anywhere in the Atlantic. Halfway through the entire 2013 hurricane season, an Atlantic-wide hurricane goose egg is quite remarkable.
Second, this year’s hurricane inactivity continues what was already a record lack of recent hurricanes. Although President Obama is well into his fifth year in office, the Obama administration is tied for the fewest number of U.S. hurricane strikes for any one or two term presidency in history.

Third, the silent 2013 hurricane season extends an amazing record regarding major hurricane strikes of Category 3 or higher. The United States is currently undergoing its longest period in history without a major strike. Major hurricane strikes are particularly important because they are the ones that inflict the most death and damage. It has been nearly 2,900 days (7 years, 10 months) since a major hurricane struck the United States. This easily smashes the previous record of 2,250 days (6 years, 2 months).

Fourth, the record lack of major hurricane strikes continues a longer-term decline. During the past five decades, an average of 5.6 major hurricanes struck the United States per decade. During the preceding five decades, and average of 8.4 major hurricanes struck the United States. Major hurricane strikes occurred 50 percent more often 50-100 years ago than they have during the past 50 years. ()

Fifth, a fairly typical number of small tropical storms continue to form in 2013, but the tropical storms are not growing into hurricanes. Six tropical storms have formed so far in 2013, which is pretty close to average for the midway point of hurricane season. The only one of the six to make landfall in the United States, Tropical Storm Andrea, brought welcome rains to much of the southeastern United States at the beginning of the summer growing season.
Sixth, the silent 2013 Atlantic hurricane season continues a longer-term decline in global hurricane activity. The global number of tropical storms and hurricanes has been in slow but steady decline since at least 1970, bringing 40-plus years of relief from the planet’s most devastating storms.
All of these developments illustrate an important difference between global warming alarmists and global warming skeptics. Alarmists present all sorts of frightening speculation while skeptics present objective facts. Regarding hurricanes, for example, alarmists frequently point out that hurricanes require warm ocean water and then make the logical leap that global warming will increase ocean temperatures and therefore will cause more frequent and severe hurricanes. In the real world, however, global warming causes more upper-level wind shear, which in turn breaks apart tropical storms before they can become hurricanes. The objective data validate that hurricanes are becoming less frequent and severe as the planet continues its modest warming. Nevertheless, alarmists double down on their simplistic and erroneous hurricane speculation, all the while engaging in name-calling and personal attacks against the “deniers” who defer to objective facts and real-world hurricane data.
The 350 Action group garnered substantial media attention this week by engaging in just such misleading and personal attacks. The global warming activist group released a video proposing to name hurricanes after prominent legislators who “deny” that global warming causes more hurricanes.

Mock news coverage in the video included the following gems:
“Senator Marco Rubio is expected to pound the eastern seaboard early tonight. Windows are being boarded up and grocery stores are virtually empty as Marco Rubio threatens everything in his path.”

“Congresswoman Michele Bachmann is incredibly dangerous. If you value your life, please seek shelter from Michele Bachmann.”

“Senator David Vitter is turning out to be one of the hugest and costliest disasters in American history.”

“Local animal shelters are under pressure as thousands of animals have been displaced or killed by Governor Rick Perry.”

The Christian Science Monitor, Seattle Post-Intelligencer, Huffington Post, Salon, Grist and others gave fawning coverage to the ridiculous 350 Action claims without pointing out the long-term decline in hurricanes, the lack of any Atlantic hurricanes this year, and the current record lack of major hurricane strikes.

There is an important lesson to learn from the alarmists’ attempt to smear people who defer to objective evidence and factual data rather than misguided speculation and alarmism. The lesson is the “denier” label applies most fittingly to global warming activists rather than skeptics.
Prior posts on hurricanes and cyclones

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New paper finds another non-hockey-stick in China

A new paper published in Quaternary Science Reviews reconstructs the mean annual temperature in the Pearl River Basin, China over the past ~6,300 years and finds another non-hockey-stick with the modern mean annual temperature of ~15.4C exceeded many times in the past including during the Medieval, Roman, Minoan, and Egyptian Warming Periods, and by the Holocene Climate Optimum. 

Horizontal axis is years before the present. Modern mean annual temperature is ~15.4 C.

A new regional, mid-Holocene palaeoprecipitation signal of the Asian Summer Monsoon

• D. Strong^a, b, 


• R. Flecker^a, , , 


• P.J. Valdes^a, 


• I.P. Wilkinson^c, 


• J.G. Rees^c, 


• K. Michaelides^a, 


• Y.Q. Zong^d,


• J.M. Lloyd^e, 


• F.L. Yu^f, 


• R.D. Pancost^b

• ^a School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK


• ^b Organic Geochemistry Unit, The Cabot Institute, School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, UK


• ^c British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK


• ^d Department of Earth Sciences, University of Hong Kong, James Lee Sciences Building, Pokfulam Road, Hong Kong, China


• ^e Department of Geography, University of Durham, South Road, Durham DH1 3LE, UK


• ^f Earth Observatory of Singapore, Nanyang Technological University, 50 Nanyang Avenue, Block N2-01a-15, 639798, Singapore

---

Highlights

•

The Dongge speleothem δ¹⁸O record mirrors the Pearl River Estuary BIT record.

•

This suggests both are driven by regional precipitation (Asian Summer Monsoon).

•

Leaf wax δ¹³C values reflect the initiation of anthropogenic cultivation ∼2 ka.

•

Scale-equivalent comparison with climate model-data is possible for the first time.

---

Abstract

The Dongge Cave speleothem δ¹⁸O record, which lies in the Pearl River basin (China), has been interpreted as recording a regional decline in Asian Summer Monsoon precipitation over the last 6.5 ka. The same overall trend is seen in the bulk sedimentary organic δ¹³C_org record from a core in the Pearl River Estuary. However, the two records differ in detail and the regional nature of the Dongge palaeoprecipitation signal has therefore been questioned. Our study re-evaluates both records by constructing, for the same estuarine core, biomarker and compound-specific δ¹³C records, which have better constrained terrestrial and marine end members than δ¹³C_org, providing additional insights into the evolution of the Asian Summer Monsoon.

The Branched Isoprenoidal Tetraether (BIT) index reflects the ratio of soil versus marine organic matter. The BIT record from the estuarine core co-varies with the Dongge Cave δ¹⁸O record suggesting the two share a common control which is likely to be driven by regional climate. By contrast, the sterols, n-alcohols and n-fatty acid ratios show the same overall trend as Dongge, but parallel the δ¹³C_org record's variability between 6.5 and 2 ka indicating a partial decoupling between soil and land-plant organic matter fluxes in the Pearl River Basin. There is clear divergence between the biomarker and ¹³C_org records from 2 ka to present. Analysis of the leaf wax δ¹³C suggests that this results from an abrupt change in vegetation probably resulting from local, anthropogenic cultivation two thousand years ago.

The basin scale of these estuarine records equates to up to 15 grid cells in typical Earth System Models used for simulating global climate. This permits comparison of Palaeoclimate Model Intercomparison Project simulations of the mid-Holocene with spatially equivalent data relating to the Summer Asian Monsoon, for the first time.

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New paper finds a long-term decrease in fire activity

A new paper published in Quaternary Research reconstructs fire activity in Israel and finds, "a long-term decline in fire activity over the past 3070 years, from high biomass burning ~ 3070–1750 years before the present to significantly lower levels after ~ 1750 years before the present." The paper corroborates several other peer-reviewed papers demonstrating a long-term decrease in fire activity and that current levels of fire activity are not unusual or unprecedented. 

Fire activity is shown in graphs f and g, demonstrating a long-term decrease in fire activity over the past 3070 years. The Medieval Warming Period is labeled as "MCA" and Little Ice Age as "LIA". Graph b is a proxy of temperature and precipitation, which was higher during the MCA, Roman, and Minoan Warming Periods. Horizontal axis is years before the present.

Climatic and human controls on the late Holocene fire history of northern Israel

• Nadine B. Quintana Krupinski^a, , , 


• Jennifer R. Marlon^b, 


• Ami Nishri^c, 


• Joseph H. Street^d, 


• Adina Paytan^d

• ^a Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA


• ^b Yale School of Forestry & Environmental Studies, New Haven, CT 06511, USA


• ^c Yigal Allon Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, P.O. Box 345, Tiberias N/A 14102, Israel


• ^d Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA

---

Abstract

Long-term fire histories provide insight into the effects of climate, ecology and humans on fire activity; they can be generated using accumulation rates of charcoal and soot black carbon in lacustrine sediments. This study uses both charcoal and black carbon, and other paleoclimate indicators from Lake Kinneret (Sea of Galilee), Israel, to reconstruct late Holocene variations in biomass burning and aridity. We compare the fire history data with a regional biomass-burning reconstruction from 18 different charcoal records and with pollen, climate, and population data to decipher the relative impacts of regional climate, vegetation changes, and human activity on fire. We show a long-term decline in fire activity over the past 3070 years, from high biomass burning ~ 3070–1750 cal yr BP [before the present] to significantly lower levels after ~ 1750 cal yr BP [before the present]. Human modification of the landscape (e.g., forest clearing, agriculture, settlement expansion and early industry) in periods of low to moderate precipitation appears to have been the greatest cause of high biomass burning during the late Holocene in southern Levant, while wetter climate apparently reduced fire activity during periods of both low and high human activity.

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