Monthly Archives: June 2017

Surface-Warming Hiatus Attributable to Internal Variability

Christopher Hedemann, Thorsten Mauritsen, Johann Jungclaus1 and Jochem Marotzke. The subtle origins of surface-warming hiatuses. Nature Climate Change, 7:336-339 (2017). doi:10.1038/nclimate3274 

During the first decade of the twenty-first century, the Earth’s surface warmed more slowly than climate models simulated1 . This surface-warming hiatus is attributed by some studies to model errors in external forcing2–4 , while others point to heat rearrangements in the ocean5–10 caused by internal variability, the timing of which cannot be predicted by the models1 . However, observational analyses disagree about which ocean region is responsible11–16. Here we show that the hiatus could also have been caused by internal variability in the top-of-atmosphere energy imbalance. Energy budgeting for the ocean surface layer over a 100-member historical ensemble reveals that hiatuses are caused by energy-flux deviations as small as 0.08 W m−2 , which can originate at the top of the atmosphere, in the ocean, or both. Budgeting with existing observations cannot constrain the origin of the recent hiatus, because the uncertainty in observations dwarfs the small flux deviations that could cause a hiatus. The sensitivity of these flux deviations to the observational dataset and to energy budget choices helps explain why previous studies conflict, and suggests that the origin of the recent hiatus may never be identified.

Arctic Sea Ice to Increase Towards 2020

“In a paper by Marius Årthun et al appearing in Nature Communication titled: Skillful prediction of northern climate provided by the ocean, researchers checked whether anomalous heat in the Gulf Stream’s northern extension provided predictability of northwestern European and Arctic climate.” click here for the NoTricksZone.

South China Sea coral confirm Little Ice Age, Medieval Warming

Wenfeng Deng, Xi Liu, Xuefei Chen, Gangjian Wei, Ti Zeng, Luhua Xie, Jian-xin Zhao. A comparison of the climates of the Medieval Climate Anomaly, Little Ice Age, and Current Warm Period reconstructed using coral records from the northern South China Sea. Journal of Geophysical Research: Oceans 122(1):264-275 DOI:10.1002/2016jC012458

For the global oceans, the characteristics of high-resolution climate changes during the last millennium remain uncertain because of the limited availability of proxy data. This study reconstructs climate conditions using annually resolved coral records from the South China Sea (SCS) to provide new insights into climate change over the last millennium. The results indicate that the climate of the Medieval Climate Anomaly (MCA, AD 900–1300) was similar to that of the Current Warm Period (CWP, AD 1850-present), which contradicts previous studies. The similar warmth levels for the MCA and CWP have also been recorded in the Makassar Strait of Indonesia, which suggests that the MCA was not warmer than the CWP in the western Pacific and that this may not have been a globally uniform change. Hydrological conditions were drier/saltier during the MCA and similar to those of the CWP. The drier/saltier MCA and CWP in the western Pacific may be associated with the reduced precipitation caused by variations in the Pacific Walker Circulation. As for the Little Ice Age (LIA, AD 1550–1850), the results from this study, together with previous data from the Makassar Strait, indicate a cold and wet period compared with the CWP and the MCA in the western Pacific. The cold LIA period agrees with the timing of the Maunder sunspot minimum and is therefore associated with low solar activity. The fresher/wetter LIA in the western Pacific may have been caused by the synchronized retreat of both the East Asian Summer Monsoon and the Australian Monsoon.

Solar activity affects all surface geophysical systems

Yavor Chapanov, Cyril Ron and Jan Vondrak.   Decadal Cycles of Earth Rotation, Mean Sea Level and Climate, Excited by Solar Activity. Acta Geodyn. Geomater., Vol. 14, No. 2 (186), 241–250, 2017  DOI: 10.13168/AGG.2017.0007 

The solar activity affects all surface geosystems, including weather and climate indices, winds, rains, snow covers, mean sea level, river streamflows and other hydrological cycles. The mean sea level and polar ice changes cause common variations of the principal moments of inertia and Earth rotation with decadal, centennial and millennial periods. The mean sea level, Earth rotation
and climate indices have also some oscillations with periods below 40 years, whose origin is not connected with the known tidal and solar effects. The shape of solar cycles is rather different from sinusoidal form, so they affect geosystems by many short-term harmonics. A possible solar origin of decadal variations of Earth rotation, mean sea level and climate indices is investigated by the harmonics of Jose, de Vries and Suess cycles with centennial periods of 178.7, 208 and 231 years. The common decadal cycles of solar-terrestrial influences are investigated by long time series of Length of Day (LOD), Mean Sea Level (MSL) variations at Stockholm, ElNiño/Southern Oscillation (ENSO), temperature and precipitation over Eastern Europe, Total Solar Irradiance (TSI), Wolf’s Numbers Wn and North-South solar asymmetry. A good agreement exists between the decadal cycles of LOD, MSL, climate and solar indices whose periods are between 12-13, 14-16, 16-18 and 28-33 years. The new linear models of the decadal
common Earth and solar cycles may help for long term forecasts of many global and local changes.

Warmer Temperatures Might Actually Enhance Predator Control of Parasites

Spencer R. Hall, Alan J. Tessier, Meghan A. Duffy, Marianne Huebner, and Carla E. Cceres. Warmer Does Not Have to Mean Sicker: Temperature and Predators can Jointly Drive Timing of Epidemics. Ecology, 87(7), 2006, pp. 1684-1695

Ecologists and epidemiologists worry that global warming will increase disease prevalence. These fears arise because several direct and indirect mechanisms link warming to disease, and because parasite outbreaks are increasing in many taxa. However, this outcome is not a foregone conclusion, as physiological and community-interaction-based mechanisms may inhibit epidemics at warmer temperatures. Here, we explore this thermal-community ecology-based mechanism, centering on fish predators that selectively prey upon Daphnia infected with a fungal parasite. We used an interplay between a simple model built around this system’s biology and laboratory experiments designed to parameterize the model. Through this data-model interaction, we found that a given density of predators can inhibit epidemics as temperatures rise when thermal physiology of the predator scales more steeply than that of the host. This case is met in our nsh-Daphnia-iungus system. Furthermore, the combination of steeply scaling parasite physiology and predation-induced mortality can inhibit epidemics at lower temperatures. This effect may terminate fungal epidemics of Daphnia as lakes cool in autumn. Thus, predation and physiology could constrain epidemics to intermediate temperatures (a pattern that we see in our system). More generally, these results accentuate the possibility that warmer temperatures might actually enhance predator control of parasites.

Global Satellite Temperature Products, Methods and Results

Roy W. Spencer, John R. Christy, and William D. Braswell. UAH Version 6 Global Satellite Temperature Products: Methodology and Results. Asia-Pac. J. Atmos. Sci., 53(1), 121-130, 2017  DOI:10.1007/s13143-017-0010-y

Version 6 of the UAH MSU/AMSU global satellite temperature dataset represents an extensive revision of the procedures employed in previous versions of the UAH datasets. The two most significant results from an end-user perspective are (1) a decrease in the global-average lower tropospheric temperature (LT) trend from +0.14o C decade−1 to +0.11o C decade−1 (Jan. 1979 through Dec. 2015); and (2) the geographic distribution of the LT trends, including higher spatial resolution, owing to a new method for computing LT. We describe the major changes in processing strategy, including a new method for monthly gridpoint averaging which uses all of the footprint data yet eliminates the need for limb correction; a new multi-channel (rather than multi-angle) method for computing the lower tropospheric (LT) temperature product which requires an additional tropopause (TP) channel to be used; and a new empirical method for diurnal drift correction. We show results for LT, the midtroposphere (MT, from MSU2/AMSU5), and lower stratosphere (LS, from MSU4/AMSU9). A 0.03o C decade−1 reduction in the global LT trend from the Version 5.6 product is partly due to lesser sensitivity of the new LT to land surface skin temperature (est. 0.01o C decade−1 ), with the remainder of the reduction (0.02o C decade−1 ) due to the new diurnal drift adjustment, the more robust method of LT calculation, and other changes in processing procedures.


Canadian Wind Energy is Unsustainable

“TransAlta Corp. said Tuesday the blades on 57 turbines at its Cowley Ridge facility near Pincher Creek have already been halted and the towers are to be toppled and recycled for scrap metal this spring. The company inherited the now-obsolete facility, built between 1993 and 1994, as part of its $1.6-billion hostile takeover of Calgary-based Canadian Hydro Developers Inc. in 2009.” click here