Daily Archives: May 20, 2013

Decreased cloud cover primary cause of 2007 Arctic summer sea ice anomaly

Jennifer E. Kay, Tristan L’Ecuyer. Observational constraints on Arctic Ocean clouds and radiative fluxesduring the early 21st century. Journal of Geophysical Research: Atmospheres. DOI: 10.1002/jgrd.50489

Arctic Ocean observations are combined to create a cloud and radiation climatology for the early 21st century (March 2000 – February 2011). Data sources include: observed top-of-atmosphere (TOA) radiative fluxes (CERES-EBAF), active (CloudSat, CALIPSO) and passive (MODIS) satellite cloud fraction observations, and observationally constrained radiative flux and cloud forcing calculations (CERES-EBAF, 2B-FLXHR-LIDAR).Uncertainty in flux calculations is dominated by cloud uncertainty, not surface albedo uncertainty. The climatology exposes large geographic, seasonal, and inter-annual variability in the influence of clouds on radiative fluxes but, on average, Arctic Ocean clouds warm the surface (+10 Wm-2, 2B-FLXHR-LIDAR) and cool the TOA (−12 Wm-2, CERES-EBAF, 2B-FLXHR-LIDAR).Shortwave TOA cloud cooling and longwave TOA cloud warming are stronger in 2B-FLXHR-LIDAR than in CERES-EBAF, but these two differences compensate each other yielding similar net TOA values. During the early 21st century, summer TOA albedo decreases are consistent with sea ice loss, but are unrelated to summer cloud trends that are statistically insignificant. In contrast, both sea ice variability and cloud variability contribute to inter-annual variability in summer shortwave radiative fluxes. Summer 2007 had the largest persistent cloud, radiation, and sea ice anomalies in the climatology. During that summer, positive net shortwave radiation anomalies exceeded 20 Wm-2 over much of Arctic Ocean. This enhanced shortwave absorption resulted primarily from cloud reductions during early summer, and sea ice loss during late summer. In summary, the observations show that while cloud variability influences absorbed shortwave radiation variability, there is no summer cloud trend affecting summer absorbed shortwave radiation.

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Acidification increases coral reef fish reproduction

Gabrielle M. Miller, Sue-Ann Watson, Mark I. McCormick, Philip L. Munday. Increased CO2 stimulates reproduction in a coral reef fish. Global Change Biology. DOI: 10.1111/gcb.12259

Ocean acidification is predicted to negatively impact the reproduction of many marine species, either by reducing fertilization success or diverting energy from reproductive effort. While recent studies have demonstrated how ocean acidification will affect larval and juvenile fishes, little is known about how increasing partial pressure of carbon dioxide (pCO2) and decreasing pH might affect reproduction in adult fishes. We investigated the effects of near-future levels of pCO2 on the reproductive performance of the cinnamon anemonefish, Amphiprion melanopus, from the Great Barrier Reef, Australia. Breeding pairs were held under three CO2 treatments (Current-day Control (430μatm), Moderate (584μatm) and High (1032μatm)) for a 9-month period that included the summer breeding season. Unexpectedly, increased CO2 dramatically stimulated breeding activity in this species of fish. Over twice as many pairs bred in the Moderate (67% of pairs) and High (55%) compared to the Control (27%) CO2 treatment. Pairs in the High CO2 group produced double the number of clutches per pair and 67% more eggs per clutch compared to the Moderate and Control groups. As a result, reproductive output in the High group was 82% higher than the Control group and 50% higher than the Moderate group. Despite the increase in reproductive activity, there was no difference in adult body condition between the three treatment groups. There was no significant difference in hatchling length between the treatment groups, but larvae from the High CO2 group had smaller yolks than Controls. This study provides the first evidence of the potential effects of ocean acidification on key reproductive attributes of marine fishes and, contrary to expectations, demonstrates an initially stimulatory (hormetic) effect in response to increased pCO2. However, any long-term consequences of increased reproductive effort on individuals or populations remains to be determined.

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Do climate models incorporate lightening strikes?

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Near Grand Canyon south rim. US Dept of Interior.

So, how do the climate models account for this energy transfer?