jet-stream | GarryRogers Nature Conservation

GR: Still ringing the alarm, but no one is pouring into the streets. CO2 levels are rising, farms are expanding, forests are disappearing, population is rising, and the oceans–the oceans are getting warmer, deeper, and more acidic. Plants and animals are dying. (Here’s another story on extremes.)

This story focuses on the extremes that are beginning.

“New Delhi [India], Mar. 27 (ANI): The increase of devastating weather extremes in summer is likely linked to human-made climate change, mounting evidence shows.

“Giant airstreams are circling the Earth, waving up and down between the Arctic and the tropics. These planetary waves transport heat and moisture. When these planetary waves stall, droughts or floods can occur.

“Warming caused by greenhouse-gases from fossil fuels creates favorable conditions for such events, an international team of scientists now finds.

“The unprecedented 2016 California drought, the 2011 U.S. heatwave and 2010 Pakistan flood as well as the 2003 European hot spell all belong to a most worrying series of extremes,” says Michael Mann from the Pennsylvania State University in the U.S., lead-author of the study now to be published in Scientific Reports.

“The increased incidence of these events exceeds what we would expect from the direct effects of global warming alone, so there must be an additional climate change effect. In data from computer simulations as well as observations, we identify changes that favor unusually persistent, extreme meanders of the jet stream that support such extreme weather events. Human activity has been suspected of contributing to this pattern before, but now we uncover a clear fingerprint of human activity.”

How sunny days can turn into a serious heat wave: “If the same weather persists for weeks on end in one region, then sunny days can turn into a serious heat wave and drought, or lasting rains can lead to flooding”, explains co-author Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research (PIK) in Germany.” –ANI News (Continue reading: Humans responsible for weather extremes in summer: Study | ANI News.)

GR: Southerly movement of cold air balances northerly movement of warm air. The added warmth is melting polar sea ice, increasing humidity, trapping more heat, and strengthening the incursions of warm air north and cold air south. We expect this positive feedback to grow stronger with each passing year. Periods of record winter freezes alternating with record winter warmth will allow earlier spring blooms and will more often freeze spring flowers. Crops will fail, migrating wildlife will be confused, and nature will lose another step in its battle to survive the onslaught of human impact.

“A surge of warm air and stormy weather has once again invaded the Arctic, sending temperatures soaring and stagnating winter sea ice growth. These repeated incursions have helped keep sea ice area at record low levels for much of the freeze season, and have even contributed to an exceptional cold season retreat.

Sea ice area during the winter freeze-up (in blue) as compared to the long-term average (in gray). Periodic incursions of warm, stormy weather, along with persistent winter warmth, have kept sea ice at record low levels for much of the winter. Credit: NSIDC

“These recent record lows are part of a clear downward spiral of Arctic sea ice caused by regional temperature rise that is happening at twice the global pace, fueled by continued greenhouse gas emissions.2016, the hottest year on record for the planet, was something of an exclamation point on that Arctic trend, with seven months of record low sea ice levels, as well as record high air temperatures in the region.“

“2016 is the most anomalous year we have seen yet and it appears to be continuing,” Julienne Stroeve, of the U.S. National Snow & Ice Data Center and the University College London, said in an email. “This is not going to look good going into the melt season.”

“This decades-long decline in sea ice has repercussions for native communities and for the Arctic ecosystem, of which the sea ice is a vital component. It is also exposing the fragile region to more shipping and other commercial activity and could be altering weather patterns over parts of the Northern Hemisphere.” –Andrea Thompson (Continue reading: Warm Air Invades Arctic Again, Slowing Sea Ice Growth | Climate Central.)