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Climate Hustle

New research from last week 21/2012

Posted on 29 May 2012 by Ari Jokimäki

This week we have few paleoclimate studies. There's atmospheric carbon dioxide record from Antarctic ice core, faint young sun problem review, the paper on storegga tsunami and 8.2 ka cold event, and one on the role of methane release in end-Triassic mass extinction. Also archaeology can contribute to modern climate science, but I wonder if climate archaeologists 5000 years from now will have a remarkable event to study?

Another thing I wonder is that will the water stay in Caspian Sea or will it just splash to surrounding land areas one day? And will the cattle in Brazil ever stop their GHG emissions (if that's the correct expression for it)? Did they run out of possible causes for 2010 heat wave as they now have started to look if winter Arctic Oscillation caused summer Arctic Oscillation?

The pets are handling this climate situation quite well, as they are multiplying better then ever. Sorry, did I say pets? I meant pests, of course. Pine beetles are also thriving, at least as long as there are pines left. Tropical cyclones grow intense faster than they did before. Russian glaciers are losing ice and Finnish lake freezes later. But Antarctic ozone is rebounding, so we can soon stop putting sun tan lotion on penguins.


What archaeology can do for climate science?

Prospects and challenges for an archaeology of global climate change - Hudson et al. (2012)

Abstract: "Archaeology has a long history of research in reconstructing past environments and in attempting to understand the interactions between climate and human societies. So far, however, there has been little attempt by archeologists to employ this knowledge in the debate over current global climate change. This paper provides a broad overview of the relevance of archaeology to the problem of global climate change, yet also attempts to consider some of the challenges that require further debate. We propose five areas where archaeology may be able to make significant contributions to global climate change discourse: (1) the study not just of past social ‘collapse’ but of how ancient societies attempted to manage decline and recovery in the face of long-term environmental change; (2) the ability to rethink the nature/culture divide; (3) the use of public archaeology to further education and awareness on environmental links and impacts; (4) the study of social injustice and how it may affect societal responses to the environment; and (5) the building of common ‘intercultural’ responses to climate change. Challenges identified are (1) making clearer in public debate the relevance of archaeology to present and future climate change; (2) the contexts in which people really learn from the past; (3) how different (national) traditions of archeological research may affect our ability to relate archaeology to global climate change; and (4) how human-induced climate change on a global scale alters traditional historical approaches to human agency."

Citation: Mark J. Hudson, Mami Aoyama, Kara C. Hoover, Junzō Uchiyama, Wiley Interdisciplinary Reviews: Climate Change, DOI: 10.1002/wcc.174.


Climate and weather are important for spatial expansion of pine beetle outbreaks

Climate and Weather Influences on Spatial Temporal Patterns of Mountain Pine Beetle Populations in Washington and Oregon - Preisler et al. (2012)

Abstract: "Widespread outbreaks of mountain pine beetle in North America have drawn the attention of scientists, forest managers, and the public. There is strong evidence that climate change has contributed to the extent and severity of recent outbreaks. Scientists are interested in quantifying relationships between bark beetle population dynamics and trends in climate. Process models that simulate climate suitability for mountain pine beetle outbreaks have advanced our understanding of beetle population dynamics; however, there are few studies that have assessed their accuracy across multiple outbreaks or at larger spatial scales. This study used the observed number of trees killed by mountain pine beetles per km2 in Oregon and Washington States over the past three decades to quantify and assess the influence of climate and weather variables on beetle activity over longer time periods and larger scales than previously studied. Influences of temperature and precipitation in addition to process model output variables were assessed at annual and climatological time scales. The statistical analysis showed that new attacks are more likely to occur at locations with climatological mean August temperatures greater than 15oC. After controlling for beetle pressure, the variables with the largest effect on the odds of an outbreak exceeding a certain size were minimum winter temperature (positive relationship) and drought conditions in current and previous years. Precipitation levels in the year prior to the outbreak had a positive effect, possibly an indication of the influence of this driver on brood size. Two-year cumulative precipitation had a negative effect, a possible indication of the influence of drought on tree stress. Among the process model variables, cold tolerance was the strongest indicator of an outbreak becoming epidemic size. A weather suitability index developed from the regression analysis indicated a 2.5 times increase in the odds of outbreak at locations with highly suitable weather versus locations with low suitability. The models were useful for estimating expected amounts of damage (total area with outbreaks) and for quantifying the contribution of climate to total damage. Overall, the results confirm the importance of climate and weather on the spatial expansion of bark beetle outbreaks over time."

Citation: Preisler, Haiganoush Krikorian, Jeffrey Hicke, Alan Ager, and Jane L. Hayes. In press. Climate and Weather Influences on Spatial Temporal Patterns of Mountain Pine Beetle Populations in Washington and Oregon. Ecology. http://dx.doi.org/10.1890/11-1412.1.


Tropical cyclones now intensify 9 hours earlier than they did 25 years ago

Tropical cyclone intensification trends during satellite era (1986–2010) - Kishtawal et al. (2012)

Abstract: "Using International Best Track Archive for Climate Stewardship (IBTrACS, version v03r03) analysis during satellite era (1986–2010) we determined the trends of intensification of tropical cyclones (TC) over all the global basins, except the North Indian Ocean. Over all the basins, the rate of TC intensification from 64 kt to first peak of intensity maxima (global average value = 104 kt) was found to be positive. The above trends were significant for 4 out of 5 basins, except the North West Pacific. The trends indicate that the TCs now intensify from 64 kt to 104 kt nearly 9 hours earlier than they did 25 years back. The maximum reduction in intensification time is noticed over the North Atlantic Ocean where the average time needed for TC to intensify from 64 kt to 112 kt has reduced by nearly 20 hours during the past 25-year period."

Citation: Kishtawal, C. M., N. Jaiswal, R. Singh, and D. Niyogi (2012), Tropical cyclone intensification trends during satellite era (1986–2010), Geophys. Res. Lett., 39, L10810, doi:10.1029/2012GL051700.


High resolution 1000-year ice core record of atmospheric carbon dioxide

Atmospheric CO2 over the last 1000 years: A high-resolution record from the West Antarctic Ice Sheet (WAIS) Divide ice core - Ahn et al. (2012)

Abstract: "We report a decadally resolved record of atmospheric CO2 concentration for the last 1000 years, obtained from the West Antarctic Ice Sheet (WAIS) Divide shallow ice core. The most prominent feature of the pre-industrial period is a rapid ∼7 ppm decrease of CO2 in a span of ∼20–50 years at ∼1600 A.D. This observation confirms the timing of an abrupt atmospheric CO2 decrease of ∼10 ppm observed for that time period in the Law Dome ice core CO2 records, but the true magnitude of the decrease remains unclear. Atmospheric CO2 variations over the time period 1000–1800 A.D. are statistically correlated with northern hemispheric climate and tropical Indo-Pacific sea surface temperature. However, the exact relationship between CO2 and climate remains elusive due to regional climate variations and/or uneven geographical data density of paleoclimate records. We observe small differences of 0 ∼ 2% (0 ∼ 6 ppm) among the high-precision CO2 records from the Law Dome, EPICA Dronning Maud Land and WAIS Divide Antarctic ice cores. However, those records share common trends of CO2 change on centennial to multicentennial time scales, and clearly show that atmospheric CO2 has been increasing above preindustrial levels since ∼1850 A.D."

Citation: Ahn, J., E. J. Brook, L. Mitchell, J. Rosen, J. R. McConnell, K. Taylor, D. Etheridge, and M. Rubino (2012), Atmospheric CO2 over the last 1000 years: A high-resolution record from the West Antarctic Ice Sheet (WAIS) Divide ice core, Global Biogeochem. Cycles, 26, GB2027, doi:10.1029/2011GB004247.


Antarctic ozone shows signs of rebounding over the last decade

Changes of the Antarctic ozone hole: Controlling mechanisms, seasonal predictability, and evolution - Salby et al. (2012)

Abstract: "The ozone hole changes considerably from one year to the next. It varies between conditions in which springtime ozone is strongly depleted to others in which ozone is only weakly depleted. Those changes are shown to closely track anomalous planetary wave forcing of the residual circulation. The strong coherence with planetary wave forcing is consistent with similar coherence of springtime temperature, which modulates Polar Stratospheric Cloud (PSC). By controlling the lifetime of PSC, anomalous wave forcing determines the net activation of chlorine and bromine and, hence, springtime depletion of ozone during individual years. The strong coherence with planetary wave forcing affords long-range predictability. It supports a seasonal forecast of springtime depletion, which, through the ozone mass deficit, perturbs ozone across much of the Southern Hemisphere during subsequent months of summer. Conditioned upon wintertime wave structure, a hindcast of springtime depletion faithfully predicts the anomalous ozone observed. A reliable forecast of tropospheric planetary waves would thus enable springtime depletion to be predicted. The current evolution of Antarctic ozone is dominated by dynamically-induced changes. Representing its climate variability, those large changes obscure the more gradual evolution of springtime depletion, like that associated with the decline of chlorine. The strong dependence on planetary wave forcing, however, enables dynamically-induced changes of ozone to be identified accurately. Removing them unmasks the secular variation of Antarctic ozone, the part coherent over a decade and longer. Independent of dynamically-induced changes, that component discriminates to changes associated with stratospheric composition. It reveals a gradual but systematic rebound over the last decade. The upward trend is shown to be robust, significant at the 99.5% level. Uncertainty in this trend is thus small enough to make the probability of it arising through chance alignment of error less than 0.5%. The discriminated component mirrors the decline of effective stratospheric chlorine, representing a gradual return of springtime ozone toward its level in 1980 of 10–15%. It enables Antarctic ozone to be tracked relative to changes of chlorine, CO2, and other features of climate more reliably than is otherwise possible."

Citation: Salby, M. L., E. A. Titova, and L. Deschamps (2012), Changes of the Antarctic ozone hole: Controlling mechanisms, seasonal predictability, and evolution, J. Geophys. Res., 117, D10111, doi:10.1029/2011JD016285.


Rapid sea level changes of the Caspian sea

Rapid Holocene sea-level changes along the Iranian Caspian coast - Kakroodi et al. (2012)

Abstract: "The Caspian Sea is well-known for its rapid sea-level change. During 1929–1995, a full sea-level cycle was observed. First, the sea level dropped ∼3 m with a lowstand in 1977, followed by a 3 m rise to 1995, after which the sea level has been relatively stable. These oscillations are a specific feature of the Caspian Sea and its sedimentary record. The main purpose of this study is to reconstruct the sea-level curve in the Holocene by using sedimentological and biostratigraphic analysis and radiocarbon dating along the Iranian part of the Caspian shore. Remote sensing images and historical maps show that two lagoons totally emerged, and the Gorgan delta prograded rapidly at a rate of around 160 m y−1 until the 1975 lowstand. Gorgan Bay was reduced in size considerably and the connection to the sea was blocked due to growth of a spit and change in base level. When sea level started to rise again, the coastal morphology rapidly changed and the Gorgan delta retrograded at the rate of around 140 m y−1. These sedimentary dynamics can be recognized in the preserved deposits. In addition to the recent dynamics, core data from the southeastern lowlands show four earlier highstands. Using characteristic barrier-lagoon deposits, early Holocene sea level rose until a highstand was reached of ca. −34 m. This phase was followed by fluvial deposition in the Gorgan delta associated with a base level fall. There is also an evidence of sea-level rise between 5000 and 2300 BP at ca. −27.7 m. On top of these deposits there is evidence of a highstand between 2700 and 2300 BP at ca. −23.5 m. The fourth highstand from the core data is dated to the Little Ice Age at ca. −24 m. Data from these last two highstands correspond well with other observations from the Caspian region."

Citation: A.A. Kakroodi, S.B. Kroonenberg, R.M. Hoogendoorn, H. Mohammd Khani, M. Yamani, M.R. Ghassemi, H.A.K. Lahijani, Quaternary International, Volume 263, 14 June 2012, Pages 93–103, http://dx.doi.org/10.1016/j.quaint.2011.12.021.


Glaciers of Russian High Arctic are losing ice

Recent mass changes of glaciers in the Russian High Arctic - Moholdt et al. (2012)

Abstract: "Glaciers and ice caps are known to contribute significantly to present-day sea level rise, but there are still glaciated regions where little is known about modern changes in glacier mass. One of these regions is the Russian High Arctic archipelagos which has a total glaciated area of 51,500 km2. We have assessed the glacier mass budget of this region for a 6-year period between October 2003 and October 2009 using independent ICESat laser altimetry and GRACE gravimetry. Over this period we found that the archipelagos have lost ice at a rate of −9.1 ± 2.0 Gt a−1, which corresponds to a sea level contribution of 0.025 mm a−1. Approximately 80% of the ice loss came from Novaya Zemlya with the remaining 20% coming from Franz Josef Land and Severnaya Zemlya. Meteorological records of temperature and precipitation for the period 1980–2009 suggest that the recent climatic mass budget is not substantially different from the longer-term trend."

Citation: Moholdt, G., B. Wouters, and A. S. Gardner (2012), Recent mass changes of glaciers in the Russian High Arctic, Geophys. Res. Lett., 39, L10502, doi:10.1029/2012GL051466.


Review of the research on faint young sun problem

The faint young Sun problem - Feulner (2012)

Abstract: "For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the “faint young Sun problem.” For the early Earth, models of stellar evolution predict a solar energy input to the climate system that is about 25% lower than today. This would result in a completely frozen world over the first 2 billion years in the history of our planet if all other parameters controlling Earth's climate had been the same. Yet there is ample evidence for the presence of liquid surface water and even life in the Archean (3.8 to 2.5 billion years before present), so some effect (or effects) must have been compensating for the faint young Sun. A wide range of possible solutions have been suggested and explored during the last four decades, with most studies focusing on higher concentrations of atmospheric greenhouse gases like carbon dioxide, methane, or ammonia. All of these solutions present considerable difficulties, however, so the faint young Sun problem cannot be regarded as solved. Here I review research on the subject, including the latest suggestions for solutions of the faint young Sun problem and recent geochemical constraints on the composition of Earth's early atmosphere. Furthermore, I will outline the most promising directions for future research. In particular I would argue that both improved geochemical constraints on the state of the Archean climate system and numerical experiments with state-of-the-art climate models are required to finally assess what kept the oceans on the Archean Earth from freezing over completely."

Citation: Feulner, G. (2012), The faint young Sun problem, Rev. Geophys., 50, RG2006, doi:10.1029/2011RG000375.


Freeze-up has been significantly delayed in a northern Europe lake

Changes in ice-season characteristics of a European Arctic lake from 1964 to 2008 - Lei et al. (2012)

Abstract: "The long-term ice record (from 1964 to 2008) of an Arctic lake in northern Europe (Lake Kilpisjärvi) reveals the response of lake ice to climate change at local and regional scales. Average freeze-up and ice breakup occurred on 9 November and 19 June, respectively. The freeze-up has been significantly delayed at a rate of 2.3 d per decade from 1964 onward (P < 0.05). No significant change has taken place in ice breakup. Annual average ice thickness has become smaller since the mid-1980s (P < 0.05). Air temperature during the early ice season significantly affected the ice thickness. The freeze-up date exhibits the highest correlation with the 2-month average daily minimum air temperature centered at the end of October, while the ice breakup date exhibits the highest correlation with the 2-month average daily maximal air temperature centered in mid May. A 1°C increase in the surface air temperature corresponds to a freeze-up later by 3.4 days and an ice breakup earlier by 3.6 days. Snow cover is a critical factor in lake-ice climatology. For cumulative November to March precipitation of less than 0.13 m, the insulating effect of the snow dominated, while higher rates of precipitation favored thicker ice due to the formation of snow ice. Variations in ice records of Lake Kilpisjärvi can serve as an indicator of climate variations across the northern Europe. The North Atlantic Oscillation (NAO) does not significantly affect the ice season there, although both the local air temperatures and winter precipitation contain a strong NAO signal."

Citation: Ruibo Lei, Matti Leppäranta, Bin Cheng, Petra Heil and Zhijun Li, Climatic Change, 2012, DOI: 10.1007/s10584-012-0489-2.


Storegga tsunami happened during coldest times of 8.2 ka cold event

Green mosses date the Storegga tsunami to the chilliest decades of the 8.2 ka cold event - Bondevik et al. (2012)

Abstract: "Chlorophyll in dead plants ordinarily decomposes completely before permanent burial through exposure to light, water and oxygen. Here we describe 8000-year-old terrestrial mosses that retain several percent of its original chlorophyll. The mosses were ripped of the land surface, carried 50–100 m off the Norwegian coast of the time, and deposited in depressions on the sea floor by the Storegga tsunami. A little of the chlorophyll survived because, within hours after entraining it, the tsunami buried the mosses in shell-rich sediments. These sediments preserved the chlorophyll by keeping out light and oxygen, and by keeping the pH above 7—three factors known to favour chlorophyll's stability. Because the green mosses were buried alive, their radiocarbon clock started ticking within hours after the Storegga Slide had set off the tsunami. Radiocarbon measurement of the mosses therefore give slide ages of uncommon geological precision, and these, together with a sequence of ages above and below the boundary, date the Storegga Slide to the chilliest decades of the 8.2 ka cold event at 8120–8175 years before AD 1950. North Atlantic coastal- and fjord- climatic records claimed to show evidence of the 8.2 cold event should be carefully examined for possible contamination and disturbance from the Storegga tsunami."

Citation: Stein Bondevik, Svein Kristian Stormo, Gudrun Skjerdal, Quaternary Science Reviews, Volume 45, 29 June 2012, Pages 1–6, http://dx.doi.org/10.1016/j.quascirev.2012.04.020.


Agronomically important pests in California might be making more generations during a year with climate change

Climate Change and Voltinism in Californian Insect Pest Species: Sensitivity to Location, Scenario and Climate Model Choice - Ziter et al. (2012)

Abstract: "Experimental studies of the impact of climatic change are hampered by their inability to consider multiple climate change scenarios, and indeed often consider no more than simple climate sensitivity such as a uniform increase in temperature. Modelling efforts offer the ability to consider a much wider range of realistic climate projections and are therefore useful, in particular, for estimating the sensitivity of impact predictions to differences in geographical location, and choice of climate change scenario and climate model projections. In this study we used well-established degree-day models to predict the voltinism of 13 agronomically important pests in California, USA. We ran these models using the projections from three Atmosphere-Ocean Coupled Global Circulation Models (AOCGCMs or GCMs), in conjunction with the SRES scenarios. We ran these for two locations representing northern and southern California. We did this for both the 2050s and 2090s. We used ANOVA to partition the variation in the resulting voltinism among time period, climate change scenario, GCM, and geographical location. For these 13 pest species, the choice of climate model explained an average of 42% of the total variation in voltinism, far more than did geographical location (33%), time period (17%) or scenario (1%). The remaining 7% of the variation was explained by various interactions, of which the location by GCM interaction was the strongest (5%). Regardless of these sources of uncertainty, a robust conclusion from our work is that all 13 pest species are likely to experience increases in the number of generations that they complete each year. Such increased voltinism is likely to have significant consequences for crop protection and production."

Citation: Carly Ziter, Emily A. Robinson, Jonathan A. Newman, Global Change Biology, DOI: 10.1111/j.1365-2486.2012.02748.x.


Methane release might not have caused end-Triassic mass extinction

No causal link between terrestrial ecosystem change and methane release during the end-Triassic mass extinction - Lindström et al. (2012)

Abstract: "Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated successive carbon cycle perturbations across the Triassic-Jurassic boundary (T-J, 201.3 Ma) have primarily been attributed to volcanic emissions from the Central Atlantic Magmatic Province and/or injection of methane. Here we present a new extended organic carbon isotope record from a cored T-J boundary succession in the Danish Basin, dated by high-resolution palynostratigraphy and supplemented by a marine faunal record. Correlated with reference C-isotope and biotic records from the UK, it provides new evidence that the major biotic changes, both on land and in the oceans, commenced prior to the most prominent negative C-isotope excursion. If massive methane release was involved, it did not trigger the end-Triassic mass extinction. Instead, this negative C-isotope excursion is contemporaneous with the onset of floral recovery on land, whereas marine ecosystems remained perturbed. The decoupling between ecosystem recovery on land and in the sea is more likely explained by long-term flood basalt volcanism releasing both SO2 and CO2 with short- and long-term effects, respectively."

Citation: Sofie Lindström, Bas van de Schootbrugge, Karen Dybkjær, Gunver Krarup Pedersen, Jens Fiebig, Lars Henrik Nielsen and Sylvain Richoz, Geology, v. 40 no. 6 p. 531-534, doi: 10.1130/G32928.1.


GHG emissions from cattle industry might be Brazil’s most important opportunity for emissions mitigation

Estimating greenhouse gas emissions from cattle raising in Brazil - Bustamante et al. (2012)

Abstract: "The study estimated, for the first time, the greenhouse gas emissions associated with cattle raising in Brazil, focusing on the period from 2003 to 2008 and the three principal sources: 1) portion of deforestation resulting in pasture establishment and subsequent burning of felled vegetation; 2) pasture burning; and 3) bovine enteric fermentation. Deforestation for pasture establishment was only considered for the Amazon and Cerrado. Emissions from pasture burning and enteric fermentation were accounted for the entire country. The consolidated emissions estimate lies between approximately 813 Mt CO2eq in 2008 (smallest value) and approximately 1,090 Mt CO2eq in 2003 (greatest value). The total emissions associated with Amazon cattle ranching ranged from 499 to 775 Mt CO2eq, that of the Cerrado from 229 to 231 Mt CO2eq, and that of the rest of the country between 84 and 87 Mt CO2eq. The full set of emissions originating from cattle raising is responsible for approximately half of all Brazilian emissions (estimated to be approximately 1,055 Mt CO2eq in 2005), even without considering cattle related sources not explicitly estimated in this study, such as energy use for transport and refrigeration along the beef and derivatives supply chain. The potential for reduction of greenhouse gas emissions offered by the Brazilian cattle industry is very high and might constitute Brazil’s most important opportunity for emissions mitigation. The study offers a series of policy recommendations for mitigation that can be implemented by public and private administrators at a low cost relative to other greenhouse gas reduction options."

Citation: Mercedes M. C. Bustamante, Carlos A. Nobre, Roberto Smeraldi, Ana P. D. Aguiar, Luis G. Barioni, Laerte G. Ferreira, Karla Longo, Peter May, Alexandre S. Pinto and Jean P. H. B. Ometto, Climatic Change, 2012, DOI: 10.1007/s10584-012-0443-3.


Negative winter Arctic Oscillation might have caused the strongly positive AO during summer of 2010

A possible cause of the AO polarity reversal from winter to summer in 2010 and its relation to hemispheric extreme summer weather - Otomi et al. (2012) [FULL TEXT]

Abstract: "In 2010, the Northern Hemisphere, in particular Russia and Japan, experienced an abnormally hot summer characterized by record-breaking warm temperatures and associated with a strongly positive Arctic Oscillation (AO), that is, low pressure in the Arctic and high pressure in the midlatitudes. In contrast, the AO index the previous winter and spring (2009/2010) was record-breaking negative. The AO polarity reversal that began in summer 2010 can explain the abnormally hot summer. The winter sea surface temperatures (SST) in the North Atlantic Ocean showed a tripolar anomaly pattern—warm SST anomalies over the tropics and high latitudes and cold SST anomalies over the midlatitudes—under the influence of the negative AO. The warm SST anomalies continued into summer 2010 because of the large oceanic heat capacity. A model simulation strongly suggested that the AO-related summertime North Atlantic oceanic warm temperature anomalies remotely caused blocking highs to form over Europe, which amplified the positive summertime AO. Thus, a possible cause of the AO polarity reversal might be the “memory” of the negative winter AO in the North Atlantic Ocean, suggesting an interseasonal linkage of the AO in which the oceanic memory of a wintertime negative AO induces a positive AO in the following summer. Understanding of this interseasonal linkage may aid in the long-term prediction of such abnormal summer events."

Citation: Yuriko Otomi, Yoshihiro Tachibana and Tetsu Nakamura, Climate Dynamics, 2012, DOI: 10.1007/s00382-012-1386-0.


CLASSIC OF THE WEEK: Abbe (1894)

The Total Quantity of Aqueous Vapor in the Atmosphere - Abbe (1894) [FULL TEXT]

Abstract: No abstract.

Citation: Abbe, C., 1894, Mon. Wea. Rev., 22, 539–541. doi: http://dx.doi.org/10.1175/1520-0493(1894)22[539:TTQOAV]2.0.CO;2.

This is a cross-post from AGW Observer. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. At least some of these are also retweeted in Skeptical Science Twitter page. Here's the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

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Comments

Comments 1 to 6:

  1. The drop in CO2 during the 1500 is really a stand out event. There has been a theory that the waves of small pox and death in America after contact with Europe lead to a huge amount of reforestation. This could be a part of that drop in CO2. Coming after the vulcanism that is thought to have triggered the glacier growth that helped bring about the so called "little ice age", its a tantalising suggestion of small amounts of human impact on climate before the industrial era.
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  2. The nicest expression for GHG production by cattle that I'm aware of is "enteric fermentation".
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  3. Re Ahn et al (2012), as per Ruddiman, the ca. 1600 low in CO2 correlates time-wise with the ca. 1500-1600 precipitous drop in indigenous North and South American population after first contact with Europeans and unintentional exposure to their diseases, and the subsequent return of considerable agricultural land and managed forest to scrub and wild forest.
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  4. Dorlomin @1 and Jim Eager @3, it is probably no coincidence that CO2 levels rose circa 1000 AD, and fell circa 1620 AD. The former date coincides approximately with the start of the Medieval Warm Period, while the later, of course, coincides with the Maunder Minimum and the end of the MWP. On that basis, the probable cause of the changes in CO2 levels are simply changes in Sea Surface Temperature.

    On that assumption, and based on a 6.5 degree C difference in Global Mean Temperature from the LGM and Pre-industrial average with an associated 100 ppmv excursion in CO2 concentration, the CO2 record provides an approximate measure of temperature change in the MWP. The glacial benchmark sets an expected change of 15 ppmv per degree C, which means the MWP was 0.5 (WAIS divide) to 0.66 (Law Dome) warmer than the Maunder Minimum and associated LIA. Only a back of the envelope calculation, of course, but a significant reality check to those who claim the MWP was significantly warmer than the end of the 20th century, and of course, to those who claim it is the 20th century warming that has caused the modern rise in CO2 levels.
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  5. Tom Curtis, except for two facts: 1) the Maunder Minimum of ~1645 to ~1715 was neither the end of the MWP nor the start of the LIA; and 2) natural CO2 change in response to a change in temperature is delayed by the thermal inertia of the ocean and by the ocean mixing rate, hence CO2's multi-century lag behind temperature coming out of a glaciation in the ice core record. There simply wasn't enough time for significant natural temperature-driven CO2 reduction, and certainly not in the wake of the Maunder Minimum with respect to the ca. 1600-1620 decline.

    See Mike Mann's RC post Global Temperatures, Volcanic Eruptions, and Trees that Didn’t Bark at http://www.realclimate.org/index.php/archives/2012/02/global-temperatures-volcanic-eruptions-and-trees-that-didnt-bark/ on his paper Underestimation of Volcanic Cooling in Tree-ring-based Reconstructions of Hemispheric Temperatures (Nature Geoscience, 2012) which cites the as yet unidentified 1258-1259 AD eruption as one a number of forcings that initiated the onset of the LIA, reinforced by other eruptions in 1452-1453, 1809 and 1815. Also see Ruddiman regarding the impact of the ~1345-1351 Black Death plague pandemic, which reduced the population of Europe by up to 60% or more in some districts, with the resulting return of considerable agricultural and grazing land to scrub and forest and consequent draw down of CO2.

    The point is the end of the MWP and onset and sustaining of the LIA was due to multiple factors working in concert over an extended time, including but not limited to volcanic eruptions, the Maunder Minimum, rapid and dramatic population decline in Europe and then the Americas, and a very limited response to reduced global temperature from these forcings.
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    Moderator Response: TC: Link connected.
  6. I must say, I am really enjoying the convenience of having these nuggets collated here in one weekly thread, when I spread myself too thin with other things to find such papers for myself. I've thanked you before, but I'll say thanks again.

    On a completely off-topic point, and acknowledging that it is not really a part of SkS's remit, might it be possible to post a small thread about the impending transit of Venus? It'll be the last one that anyone alive today will ever see, and there's a lot of astronomical history attached - I reckon that it would be nice to draw attention to it for people to 'appreciate', in case they'd like to observe the event itself.
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