01/03/2018

Arctic Warming: Scientists Alarmed By 'Crazy' Temperature Rises

The Guardian - 

‘This is an anomaly among anomalies’: temperatures in parts of the Arctic have recently risen well above average. Photograph: Ralph Lee Hopkins/National Geographic/Getty Creative/Getty Images
An alarming heatwave in the sunless winter Arctic is causing blizzards in Europe and forcing scientists to reconsider even their most pessimistic forecasts of climate change.
Although it could yet prove to be a freak event, the primary concern is that global warming is eroding the polar vortex, the powerful winds that once insulated the frozen north.
The north pole gets no sunlight until March, but an influx of warm air has pushed temperatures in Siberia up by as much as 35C above historical averages this month. Greenland has already experienced 61 hours above freezing in 2018 - more than three times as many hours as in any previous year.
Seasoned observers have described what is happening as “crazy,” “weird,” and “simply shocking”.
“This is an anomaly among anomalies. It is far enough outside the historical range that it is worrying – it is a suggestion that there are further surprises in store as we continue to poke the angry beast that is our climate,” said Michael Mann, director of the Earth System Science Center at Pennsylvania State University. “The Arctic has always been regarded as a bellwether because of the vicious circle that amplify human-caused warming in that particular region. And it is sending out a clear warning.”
Guardian graphic Source: Danish Meteorological Institute. Data recorded north of the 80th northern parallel
Although most of the media headlines in recent days have focused on Europe’s unusually cold weather in a jolly tone, the concern is that this is not so much a reassuring return to winters as normal, but rather a displacement of what ought to be happening farther north.
At the world’s most northerly land weather station - Cape Morris Jesup at the northern tip of Greenland – recent temperatures have been, at times, warmer than London and Zurich, which are thousands of miles to the south. Although the recent peak of 6.1C on Sunday was not quite a record, but on the previous two occasions (2011 and 2017) the highs lasted just a few hours before returning closer to the historical average. Last week there were 10 days above freezing for at least part of the day at this weather station, just 440 miles from the north pole.
“Spikes in temperature are part of the normal weather patterns – what has been unusual about this event is that it has persisted for so long and that it has been so warm,” said Ruth Mottram of the Danish Meteorological Institute. “Going back to the late 1950s at least we have never seen such high temperatures in the high Arctic.”
Melting ice on the Chilkat river near Haines, Alaska, in winter. Photograph: Michele Cornelius/Alamy
The cause and significance of this sharp uptick are now under scrutiny. Temperatures often fluctuate in the Arctic due to the strength or weakness of the polar vortex, the circle of winds – including the jetstream – that help to deflect warmer air masses and keep the region cool. As this natural force field fluctuates, there have been many previous temperature spikes, which make historical charts of Arctic winter weather resemble an electrocardiogram.
But the heat peaks are becoming more frequent and lasting longer – never more so than this year. “In 50 years of Arctic reconstructions, the current warming event is both the most intense and one of the longest-lived warming events ever observed during winter,” said Robert Rohde, lead scientist of Berkeley Earth, a non-profit organisation dedicated to climate science.
The question now is whether this signals a weakening or collapse of the polar vortex, the circle of strong winds that keep the Arctic cold by deflecting other air masses. The vortex depends on the temperature difference between the Arctic and mid-latitudes, but that gap is shrinking because the pole is warming faster than anywhere on Earth. While average temperatures have increased by about 1C, the warming at the pole – closer to 3C – is melting the ice mass. According to Nasa, Arctic sea ice is now declining at a rate of 13.2% per decade, leaving more open water and higher temperatures.
Some scientists speak of a hypothesis known as “warm Arctic, cold continents” as the polar vortex becomes less stable - sucking in more warm air and expelling more cold fronts, such as those currently being experienced in the UK and northern Europe. Rohde notes that this theory remains controversial and is not evident in all climate models, but this year’s temperature patterns have been consistent with that forecast.
Longer term, Rohde expects more variation. “As we rapidly warm the Arctic, we can expect that future years will bring us even more examples of unprecedented weather.”
Sea ice off Russia. Photograph: Alamy Stock Photo
Jesper Theilgaard, a meteorologist with 40 years’ experience and founder of website Climate Dissemination, said the recent trends are outside previous warming events. “No doubt these warming events bring trouble to the people and the nature. Shifting rain and snow – melt and frost make the surface icy and therefore difficult for animals to find anything to eat. Living conditions in such shifting weather types are very difficult.”
Others caution that it is premature to see this as a major shift away from forecasts. “The current excursions of 20C or more above average experienced in the Arctic are almost certainly mostly due to natural variability,” said Zeke Hausfather of Berkeley Earth. “While they have been boosted by the underlying warming trend, we don’t have any strong evidence that the factors driving short-term Arctic variability will increase in a warming world. If anything, climate models suggest the opposite is true, that high-latitude winters will be slightly less variable as the world warms.”
Although it is too soon to know whether overall projections for Arctic warming should be changed, the recent temperatures add to uncertainty and raises the possibility of knock-on effects accelerating climate change.
“This is too short-term an excursion to say whether or not it changes the overall projections for Arctic warming,” says Mann. “But it suggests that we may be underestimating the tendency for short-term extreme warming events in the Arctic. And those initial warming events can trigger even greater warming because of the ‘feedback loops’ associated with the melting of ice and the potential release of methane (a very strong greenhouse gas).”

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Cities Urged To Work With Scientists On Climate Change

ANU - Newsroom

Tianjin, China. Image credit: Jakob Montraslo
An urban environment expert at ANU has warned that city councils acting alone to address climate change, in the absence of an evidence-based systems approach, can have unintended consequences.
Professor Xuemei Bai from ANU and other urban experts from around the world identified six research priorities for cities and climate change in a Nature comment piece.
They also called for a stronger collaboration between scientists, urban policy makers and practitioners, ahead of the Intergovernmental Panel on Climate Change (IPCC) Cities and Climate Change Science Conference in Canada next week. "Cities are open, complex, dynamic systems with a global reach," said Professor Bai, an urban environment and human ecology expert at the ANU Fenner School of Environment and Society.
"Well-intended local actions can displace issues to other sectors or into the future. One city's crack-down on energy-intensive production might shift the problem to less-regulated regions, with no net effect on global emissions."
Well-intended local actions can displace issues to other sectors or into the future.
The Conference aims to develop a shared global research agenda on cities and climate change, bringing together over 700 researchers, policy makers and practitioners from more than 80 countries.
Professor Bai said cities were increasingly feeling the effects of extreme weather.
"Last year, more than 1,000 people died and 45 million people lost homes, livelihoods and services when severe floods hit Southeast Asian cities," she said.
"By 2030, millions of people and trillions of dollars of infrastructure globally will be at risk from flooding, drought, wildfires and other natural disasters."
The coastal city of San Juan in Puerto Rico was flooded after Hurricane Maria hit in September 2017. Credit: Dennis M. Rivera Pichardo/The Washington Post/Getty

Professor Bai said researchers, policymakers and city authorities needed to work more closely together to improve how cities mitigate and adapt to climate change.
"A lack of long-term studies of urban climates and their impacts makes it hard for city officials to plan decades ahead, so science needs to have a stronger role in urban policy and practice," Professor Bai said.
"A systems approach is needed to deliver on global climate change as well as the United Nations' New Urban Agenda and Sustainable Development Goals. More needs to be known about interactions, trade-offs and synergies between urban processes and their impacts elsewhere."
Professor Bai said scientific understanding of interactions between cities and climate needed to be improved.
"Climate processes are complex - more so in cities. Urban air pollution is causing heavier rainfall as fine particles influence clouds that, in turn, exacerbates flooding in cities," she said.
"We need to know how urban physical characteristics, building materials and human activities affect atmospheric circulation, heat and light radiation, urban energy and water budgets." 


Professor Bai said cities were at the forefront of addressing these challenges, with many cities experimenting with innovative measures to mitigate and adapt to climate change.
"Successful practices need to be upscaled. It is important that we identify, analyse and build transferable knowledge that can help cities to learn from the front runners," she said.
Professor Bai and her co-authors recommended that city councils should establish scientific advisory boards, chaired by a chief science adviser.
"These would enhance the profile of science, build capacity and leadership, and provide a point of contact," she said.

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