Simulating anthropogenic impacts to bird communities in tropical rain forests

We used an aggregated modelling approach to simulate the impacts ofanthropogenic disturbances on the long-term dynamics of faunal diversityin tropical rain forests. We restricted our study to bird communities eventhough the approach is more general. We developed a model calledBIODIV which simulated the establishment of hypothetical bird speciesin a forest. Our model was based on the results of a simple matrix modelwhich calculated the spatio-temporal dynamics of a tropical rain forest inMalaysia. We analysed the establishment of bird species in a secondaryforest succession and the impacts of 60 different logging scenarios on thediversity of the bird community. Of the three logging parameters(cycle length, method, intensity), logging intensity had the most servereimpact on the bird community. In the worst case the number of bird specieswas reduced to 23% of the species richness found in a primary forest

Simulating atmospheric d13CO2 during the last 740,000 years: Model-based estimates in the context of ice core measurements

The ratio of the stable carbon isotopes of atmospheric CO2 (δ 13 CO2 ) contains valuable information on the processes which are operating on the global carbon cycle. However current δ 13 CO2 ice core records are still limited in both resolution, temporal coverage as well as precision. To make optimal use of the existing and future δ 13 CO2 ice core records an estimate of the expected temporal variability would help to constrain for the acceptable measurement uncertainty and resolution to successfully retrieve the characteristic variability in δ 13 CO2 . In this study we performed simulations with the carbon cycle box model BICYCLE with special emphasis on atmospheric δ 13 CO2, proposing how changes in δ 13 CO2 might have evolved over the last 740,000 years. The overall model dynamic is validated with reconstructions of δ 13 C in benthic foraminifera in thedeep Pacific and with atmospheric CO2 ice core data. On glacial/interglacial timescales lower surface ocean temperature is most important for lower glacial δ 13 CO2 , followed by the release of isotopically lighter terrestrial carbon. In addition, changes in the terrestrial biosphere also dominate deep ocean δ 13 CO2 but have only a limited effect on atmospheric pCO2 . All other oceanic processes lead to higher than present glacial δ 13 CO2 . Taken all processes together the effects nearly cancel each other and there are nearly no glacial/interglacial amplitudes in δ 13 CO2 in line with ice core data. However faster variations of up to 0.3 occur throughout the whole simulation period. Due to our model configuration, terrestrial carbon storage is very sensitive to temperature changes over northern hemispheric lands, which accompany the reorganization of the Atlantic meridional ocean circulation during fast climate fluctuations (Dansgaard/Oeschger events). These fast events intensify the frequency and amplitude in δ 13 CO2 . However, due to ocean uptake of additional carbon as well as the signal attenuation in ice cores, the amplitudes of such events are strongly time scale dependent

Phenology of flight feather moult of Red-Crested Pochards Netta rufina at the Ismaninger reservoir

Kolbenenten sind nach dem simultanen Abwurf der Schwingen über zwei Wochen anhand einer veränderten Rückenpartie rasch als flugunfähig erkennbar. Im letzten Drittel des Federwachstums wird die Schwingenmauser aber nur deutlich, wenn der Flügel beim Putzen geöffnet wird. Ein markiertes Weibchen zog 35 Tage nach Abwurf - dann offenbar gut flugfähig - vom Mauserplatz ab. Mit diesem Wert und mittels einer Zuwachsrate der HS 9 eines gefangenen Männchens von 5,6 mm/Tag (bzw. 5,0 mm/Tag bei Schwingenlängen zwischen 60 und 100 mm) wurden die Daten von Schwingenabwurf und wiedererlangter „guter“ Flugfähigkeit von 80 Kolbenenten kalkuliert, die 1980-1986 am „Ismaninger Speichersee mit Fischteichen“, Oberbayern, während ihrer Mauser gefangen wurden. In den Jahren 2002, 2005, 2006 und 2008 wurde die Phänologie der Schwingenmauser hingegen durch Feldbeobachtung ermittelt (41 Stichproben bei 3477 Männchen bzw. 976 Weibchen). In beiden Zeiträumen gleichen sich die Verläufe der Schwingenmauser hinsichtlich Beginn, Anstieg und Lage der Maxima weitgehend. Männchen warfen die Schwingen frühestens zwischen 15.06. und 20.06. ab. Anfang Juli stiegen die Anteile Mausernder von unter 20 % rasch auf über 80 % Mitte Juli. Gipfelwerte über 90 % lagen übereinstimmend Ende Juli. Ab 25.07. konnten die ersten Männchen wieder gut fliegen, Mitte August schon zwei Drittel, Ende August über 90 %. In den 1980er Jahren mauserten die zentralen zwei Drittel der Männchen ihre Schwingen innerhalb von 7 Wochen zwischen 05.07. und 23.08. Erste Weibchen warfen die Schwingen zwischen 02. und 05.07. ab. Ab Mitte Juli stiegen die Anteile Mausernder von 5-23 % langsam auf über 90 % Mitte August. Die frühesten Weibchen konnten ab dem 06.08. wieder gut fliegen, Ende August waren es schon um 40 %, nach der ersten Septemberwoche zwei Drittel. Die zentralen zwei Drittel der Weibchen mauserten 1980-1986 zwischen 10.07. und 12.09. innerhalb von 9 Wochen. Letzte, isolierte Abwurfdaten waren 16.09. für ein Männchen bzw. 10.10. für ein Weibchen, wieder gut flugfähig waren diese Individuen am 21.10. bzw. 14.11. Die beiden Zeiträume unterscheiden sich erheblich hinsichtlich der Herkunft der Mausergäste. 1980-1986 kamen sie vor allem aus dem südlichen Mitteleuropa, 2002-2008 dominierten neu hinzu gekommene Vögel aus Spanien. Trotz dieser Veränderung ist ein Einfluss auf den zeitlichen Ablauf der Schwingenmauser nicht erkennbar.Red-crested Pochards are readily identified as flightless by the changed shape of their backs. This is visible for two weeks following the simultaneous shedding of the old flight feathers. In the last third of the feather growth period, wing moult is noticeable only if the wing is spread during preening. A tagged female left the moulting site 35 days after starting moult, with flight ability being well developed by then. Using this value, and a growth rate of 5.6 mm per day found in a growing primary (P 9) of a recaptured male, dates of moult and regained good flight were calculated from the lengths of growing P 9 of 80 Redcrested Pochards captured when flightless at ”Ismaninger Speichersee mit Fischteichen”, southern Germany, between 1980 and 1986. In 2002, 2005, 2006, and 2008, the phenology of flight feather moult at Ismaning was recorded in 41 sample counts of 3477 males and 976 females. In both periods surveyed, the progression of flight feather moult was similar in terms of onset, increase, and timing of maxima: The first males shed their wing feathers between 15.06. and 20.06. At the beginning of July, the proportion of moulting birds increased rapidly from less than 20% to more than 80% by mid-July. Maxima of more than 90% of birds moulting occurred at the end of July. The earliest males were able to fly well from 25.07., two thirds of them by mid-August, and more than 90% by the end of August. In the 1980s, the central two thirds of all males completed wing moult within seven weeks, 05.07.-23.08. The first females moulted their wing feathers between 02.-05.07. From mid-July, the proportion of moulting birds increased slowly from 5-23% to approximately 90% in mid-August. The earliest females were able to fly well from 06.08., approximately 40% by the end of August, and more than two thirds after the first week of September. In the 1980s, the central two thirds of all females completed wing moult within nine weeks, 10.07.-12.09. The latest isolated dates of moult were 16.09. (male) and 10.10. (female), with flight being regained by 21.10. and 14.11., respectively. The composition of the populations migrating for flight feather moult to Ismaning differed markedly in the two survey periods. In the1980s, birds were coming from southern parts of central Europe including parts of France. These populations were outnumbered by a majority of birds of Spanish origin in 2002-2008. No impact is to be seen from this change to the phenology of flight feather moult at Ismaning

Interactive comment on “The Plio-Pleistocene climatic evolution as a consequence of orbital forcing on the carbon cycle” by Didier Paillard

The paper of Paillard investigates the Plio-Pleistocene carbon cycle by setting up a conceptual model, consisting of differential equation for the carbon content of the atmosphere-ocean-biosphere C, the alkalinity of the ocean, A, and the stable carbon isotope values of C, d13C. I find the conceptual idea how to understand the observed long-term changes in the carbon cycle very interesting. However, I have some fundamental comments to Equation 3 describing the evolution of the the carbon isotope of the system

Interactive comment on "The Earth's climate system recurrent & multi-scale lagged responses: empirical law, evidence, consequent solar explanation of recent CO2 increases & preliminary analysis" by J. S\'anchez-Sesma

This comment deals only with the atmospheric CO2 data plotted in the discussion paper, an issue which - as far as I was able to follow - has not yet been brought up by the reviews published until today

Anthropogenic CO2 of High Emission Scenario Compensated After 3500 Years of Ocean Alkalinization With an Annually Constant Dissolution of 5 Pg of Olivine

The CO2 removal model inter-comparison (CDRMIP) has been established to approximate the usefulness of climate mitigation by some well-defined negative emission technologies. I here analyze ocean alkalinization in a high CO2 world (emission scenario SSP5-85-EXT++ and CDR-ocean-alk within CDRMIP) for the next millennia using a revised version of the carbon cycle model BICYCLE, whose long-term feedbacks are calculated for the next 1 million years. The applied model version not only captures atmosphere, ocean, and a constant marine and terrestrial biosphere, but also represents solid Earth processes, such as deep ocean CaCO3 accumulation and dissolution, volcanic CO2 outgassing, and continental weathering. In the applied negative emission experiment, 0.14 Pmol/yr of alkalinity—comparable to the dissolution of 5 Pg of olivine per year—is entering the surface ocean starting in year 2020 for either 50 or 5000 years. I find that the cumulative emissions of 6,740 PgC emitted until year 2350 lead to a peak atmospheric CO2 concentration of nearly 2,400 ppm in year 2326, which is reduced by only 200 ppm by the alkalinization experiment. Atmospheric CO2 is brought down to 400 or 300 ppm after 2730 or 3480 years of alkalinization, respectively. Such low CO2 concentrations are reached without ocean alkalinization only after several hundreds of thousands of years, when the feedbacks from weathering and sediments bring the part of the anthropogenic emissions that stays in the atmosphere (the so-called airborne fraction) below 4%. The efficiency of carbon sequestration by this alkalinization approach peaks at 9.7 PgC per Pmol of alkalinity added during times of maximum anthropogenic CO2 emissions and slowly declines to half this value 2000 years later due to the non-linear marine chemistry response and ocean-sediment processes. In other words, ocean alkalinization sequesters carbon only as long as the added alkalinity stays in the ocean. To understand the basic model behavior, I analytically explain why in the simulation results a linear relationship in the transient climate response (TCR) to cumulative emissions is found for low emissions (similarly as for more complex climate models), which evolves for high emissions to a non-linear relation

Climate-Vegetation-Feedbacks as a Mechanism for Accelerated Climate Change: The onset of the African Humid Period

Paleo-environmental records and models indicate that the African Humid Period (AHPabruptly ended about 5000-4000 years before present (BP). Some proxies indicate alsan abrupt onset of the AHP between 14,000 and 11,000 BP. How important are local orbitaforcing, ice-sheet forcing, greenhouse gas forcing, and the reorganization of the AtlantiMeridional Overturning Circulation (AMOC) for changes in the African Monsoon/vegetatiosystem? Here we use transient simulations with climate-vegetation models of differencomplexity to identify the factors that control the onset of the African Monsoon/VegetationWe test the following hypothesis:(1) There is no indication for insolation-thresholds for the onset/break of the AHP.(2) Forcing from CO2/ice-sheets significantly controls the climate of North Africa.(3) CO2 fertilization contributes to the vegetation changes over North Africa.(4) A shutdown of the AMOC is as important as orbital insolation for the African Monsoon