From RESEARCH ORGANIZATION OF INFORMATION AND SYSTEMS and the “goodbye climate disruption” department, comes this study that might very well explain why we have less landfalling U.S. hurricanes, less tornadoes, and extreme weather of all kinds seems to be waning.

Climate instability over the past 720,000 years
Ice core analysis from Dome Fuji, Antarctica and climate simulation

A research group formed by 64 researchers from the National Institute of Polar Research, the University of Tokyo, and other organizations analyzed atmospheric temperatures and dust for the past 720,000 years using an ice core obtained at Dome Fuji in Antarctica. Results indicate that when intermediate temperatures occurred within a glacial period, the climate was highly unstable and fluctuated. A climate simulation was also performed based on the Coupled Atmosphere-Ocean General Circulation Model, which revealed that the major cause of the observed climate instability was global cooling by a decline in the greenhouse effect.

Climate instability severely impacts both the Earth’s natural environment and human society. In the continued effort for understanding how global warming could affect climate instability, it is important to identify periods in the past that experienced climate instability. These periods need to be studied and modeled to clarify any potential causes of the observed instability. However, little progress has been made in improving our documenting and understanding of climate instability prior to the last glacial period.

The research groups of Dr. Kenji Kawamura and Dr. Hideaki Motoyama (National Institute of Polar Research) analyzed the Second Dome Fuji ice core (Fig. 1, left) that were obtained as part of the Japanese Antarctic Research Expedition (JARE) between 2003 and 2007. Their team reproduced fluctuations in the air temperature and dust (solid particulate matter carried by the atmosphere) in the Antarctic for the past 720,000 years (Fig. 1, right).

Figure 1 – Left: Ice Core from the Dome Fuji station. Right: Oxygen isotope ratio (an indicator of air temperature) and dust flux (an indicator of atmospheric particle concentrations) during the past 720,000 years obtained from the Antarctic Dome Fuji ice cores. The triangles at the bottom of the chart indicate the locations of warming peaks in the Antarctic as abstracted by this study. CREDIT Dome Fuji Ice Core Project

They combined this with data from the Dome C ice core drilled by a European team to obtain highly robust paleoclimate data. They examined these data, discovering that for the past 720,000 years, the intermediate climate within glacial periods was marked by frequent climate fluctuations (Fig. 2).

Figure 2 – Relationship between the frequency of climate fluctuations with temperatures in the Antarctic during the past 720,000 years obtained from analysis of Antarctic ice cores (black spots), as well as results for the final glacial period based on ice cores from Greenland (red squares). During the warm interglacial periods, and the coldest portion of a glacial period, the frequency of climate fluctuations was low, but during periods of intermediate temperatures within a glacial period, climate fluctuations occurred frequently and the climate was unstable. CREDIT Dome Fuji Ice Core Project

This raised a question: Why does the most instability occur when there is an intermediate climate during a glacial period, rather than during an interglacial period, such as we are currently experiencing, or during the coldest part of a glacial period? The research group of Dr. Ayako Abe-Ouchi (University of Tokyo) used a climate model (MIROC) to first reproduce three types of background climate conditions–the interglacial period, intermediate climate within a glacial period, and the coldest part of a glacial period. They then performed a simulation that added the same quantity of fresh water to the northern part of the North Atlantic Ocean in each of the three climate conditions. This simulation was performed using the Earth Simulator supercomputer at the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). The simulation results indicated that the response to freshwater inflow is maximized during the intermediate climate that occurs within glacial periods, causing the climate to become unstable (Fig. 3 A-C).

Figure 3 – Temperature deviations following the continuous addition of fresh water to the northern part of the North Atlantic for 500 years as simulated by the Coupled Atmosphere-Ocean Global Climate Model (MIROC), which was used to reproduce the atmospheric carbon dioxide concentrations and ice cover corresponding to three different climate conditions (A: an interglacial period, B: intermediate climate within a glacial period, and C: the coldest part of a glacial period). During the intermediate climate within glacial periods, the response was dramatic, with the Northern Hemisphere cooling and the southern hemisphere warming. Sensitivity tests using artificial conditions were also performed (D, E) in which the atmospheric carbon dioxide concentrations and ice-sheet coverage in the Northern Hemisphere from the interglacial periods were switched with those from the intermediate climate within glacial periods. The atmospheric carbon dioxide concentration appears to play a major role in increasing climate instability. CREDIT Dome Fuji Ice Core Project

An important factor affecting climate instability is the vulnerability of Atlantic deep water circulation during global cooling resulting from a decrease in the atmospheric carbon dioxide concentration (Fig. 3 D-E). Until now, the primary factor for climatic instability was thought to be the existence and instability of continental ice sheets in the Northern Hemisphere, but this experiment has revealed that carbon dioxide is another important factor, determining not only the average state of the climate, but also the long-term stability of the climate. These results also suggest that future stability in the present interglacial period, which has continued for more than 10,000 years, is not guaranteed. Indeed, if significant melting of the Greenland ice sheet occurs due to anthropogenic warming, it might destabilize the climate.

According to Dr. Kawamura, “Due to anthropogenic emissions, the atmospheric greenhouse gas concentrations have reached a level not seen over the past million years. Large climate components, such as ice sheets and the oceans that have vast size and longtime scales for variations, will undoubtedly change. It will become even more important to combine the climate reconstructions and numerical simulations for the periods when the global environment was much different than it is today, to understand the Earth system by verifying its mechanisms.”

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The study results have been published in the on-line journal, Science Advances.

Full study, open access is here: http://ift.tt/2pUewPg

WCS coral expert finds that some reefs were less sensitive to warming water over time

NEW YORK (May 2, 2017) – A new WCS study reveals evidence that some corals are adapting to warming ocean waters – potentially good news in the face of recent reports of global coral die offs due to extreme warm temperatures in 2016. The study appears in the latest issue of Marine Ecology Progress Series.

The study looked at responses to extreme temperature exposures in the same reefs over time, and found less coral bleaching in 11 of the 21 coral species studied. WCS Senior Conservation Zoologist Tim McClanahan, who has been studying coral responses to climate change since the extreme temperatures of the1998 El Nino, authored the study.

The study took place in two marine national parks of Kenya. Looking at two similarly severe warming events in 1998 and 2016, McClanahan found that the number of pale and bleached coral colonies declined from 73 to 27 percent, and 96 to 60 percent in the two parks with different background temperatures. Most of this change was due to about half of the most common species that did not bleach strongly in 2016. One rare species was, however, more sensitive than in 1998.

Bleaching takes place when stressed corals discharge beneficial algae that supply energy to corals causing them to turn pale or white and often starve. Worldwide, an estimated 60 percent of corals and 90 percent of coral species experienced bleaching due to unusually warm ocean water in 2016.

McClanahan says: “This was a rare chance to study bleaching responses during two separate times with very similar conditions. Adaptation is evident for some of the more important reef building corals but, sadly, many species are not adapting, so this is a good news-bad news story.”

But McClanahan warns: “Evidence for adaptation in the past is not evidence for adaptation in the future. Nevertheless, I suspect this adaptation to hot water started before my 1998 work and could have begun during the 1983 and 1988 El Niños, when coral bleaching was first observed in the region.”

Said Tim McClanahan: “Despite the many caveats and interpretation of these results, this study provides one of the first response-rate estimates for many common corals at the population level. It therefore provides a basis for future studies and improving model predictions and the types of evaluations needed to address the future health of coral reefs.”

Global awareness continues to grow about the immediate threats facing coral reef ecosystems, and a global commitment to address those threats. In February, at the Economist World Ocean Summit in Bali, Indonesia, the ’50 Reefs’ initiative was launched by the Global Change Institute of the University of Queensland and the Ocean Agency. The initiative brings together leading ocean, climate and marine scientists to develop a list of the 50 most critical coral reefs to protect, while leading conservation practitioners are working together to establish the best practices to protect these reefs.

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