Hydroclimate: Understanding rainfall extremes

Warming induced by greenhouse gases will increase the amount of moisture in the atmosphere, causing heavier rainfall events. Changing atmospheric circulation dynamics are now shown to either amplify or weaken regional increases, contributing to uncertainty in future precipitation extremes.

Nature Climate Change doi: 10.1038/nclimate3305

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Australian climate extremes at 1.5 °C and 2 °C of global warming

Limiting warming to 1.5 °C is expected to lessen the risk of extreme events, relative to 2 °C. Considering Australia, this work shows a decrease of about 25% in the likelihood of record heat, both air and sea surface, if warming is limited to 1.5 °C.

Nature Climate Change doi: 10.1038/nclimate3296

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Early benefits of mitigation in risk of regional climate extremes

It is unclear when the risk reduction benefits of mitigation will be detectable. This study shows for many regions a 50% reduction in the probability of extreme warm periods could be seen in 20 years, indicating near-term benefits of early mitigation.

Nature Climate Change doi: 10.1038/nclimate3259

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The future intensification of hourly precipitation extremes

Climate change is causing increases in extreme rainfall across the United States. This study uses observations and high-resolution modelling to show that rainfall changes related to rising temperatures depend on the available atmospheric moisture.

Nature Climate Change doi: 10.1038/nclimate3168

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How fish adapt to warmer waters but not to extremes

Fish can adjust to warmer ocean temperatures, but heat waves can still kill them, a team of researchers from Sweden, Norway and Australia reports in an article published this week in Nature Communications. 

“A species might adapt and grow well (in warmer waters) but once you get strong heat spells, the water temperature might reach lethal temperatures and kill them,” said Fredrik Jutfelt, an associate professor in biology at the Norwegian University of Science and Technology who was senior author of the study.

Jutfelt and his colleagues studied European perch that live in a unique enclosed basin of warm water off the Swedish coast. The man-made basin, called the Forsmark Biotest Enclosure, was created three decades ago as a 1-km2 open-air laboratory by piping warm water from the nearby Forsmark nuclear power plant into an enclosed basin. 

ENN: Top Stories

Climate data since Vikings cast doubt on more wet, dry extremes

OSLO (Reuters) – Climate records back to Viking times show the 20th century was unexceptional for rainfall and droughts despite assumptions that global warming would trigger more wet and dry extremes, a study showed on Wednesday.

Reuters: Environment

After Mass Extinction: Just Animals at Extremes

As human civilization drives more animals to extinction, extreme sizes will likely become the new norm.
Discovery News

Climate extremes: The worst heat waves to come

The combination of high temperatures and humidity could, within just a century, result in extreme conditions around the Persian Gulf that are intolerable to humans, if climate change continues unabated.

Nature Climate Change doi: 10.1038/nclimate2864

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Cooling of US Midwest summer temperature extremes from cropland intensification

Increases in temperature extremes are of major concern for agricultural production. However, this study identifies a connection between agricultural intensification and less extreme summer temperatures over the agriculturally dominated US Midwest.

Nature Climate Change doi: 10.1038/nclimate2825

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Ocean Warming Leads To Stronger Precipitation Extremes

Simulated precipitation (over 24 hours from 6 to 7 July 2012) of a model run using observed sea surface temperature (a) and (b) using a colder SST representative of the early 1980s). The black cross marks the town of Krymsk, the thin black lines are height contours with a distance of 150 metres. (Credit: GEOMAR)

(Click to enlarge) Simulated precipitation (over 24 hours from 6 to 7 July 2012) of a model run using observed sea surface temperature (a) and (b) using a colder SST representative of the early 1980s). The black cross marks the town of Krymsk, the thin black lines are height contours with a distance of 150 metres. (Credit: GEOMAR)

That the temperatures on our planet are rising is clear. In particular, the increasing emissions of greenhouse gases such as carbon dioxide continue to warm the atmosphere. The effects of global warming on the hydrological cycle, however, are still not fully understood.

(From ScienceDaily) — Particularly uncertain is how the strength of extreme summertime thunderstorms have changed, and how it may change in the future. In coastal regions neighboring warm seas, the sea surface temperature can play a crucial role in the intensity of convective storms.

The Black Sea and eastern Mediterranean have warmed by about 2 degrees Celsius since the early 1980s. Russian and German scientists investigated what impact this warming may have had on extreme precipitation in the region.

“Our showcase example was a heavy precipitation event from July 2012 that took place in Krymsk (Russia), near the Black Sea coast, resulting in a catastrophic flash food with 172 deaths,” said Edmund Meredith, lead author of the study. “We carried out a number of very-high-resolution simulations with an atmospheric model to investigate the impact of rising sea surface temperatures on the formation of intense convective storms, which are often associated with extreme rainfall,” Meredith continued.

Simulations of the event with observed sea surface temperatures showed an increase in precipitation intensity of over 300%, compared to comparable simulations using sea surface temperatures representative of the early 1980s. “We were able to identify a very distinct change, which demonstrates that convective precipitation responds with a strong, non-linear signal to the temperature forcing,” Prof. Douglas Maraun, co-author of the study added.

At the end of June 2015, the nearby Olympic city of Sochi experienced an unusually intense precipitation event. Over 175 mm of rain was recorded in 12 hours, showing the relevance of the scientists work. “Due to ocean warming, the lower atmosphere has become more unstable over the Black Sea and eastern Mediterranean. We therefore expect that events like those in Krymsk or Sochi will become more frequent in the future,” added the Kiel-based climate scientist.

Read the full article here: http://www.sciencedaily.com/releases/2015/07/150713113349.htm

Consortium for Ocean Leadership