Climate change set to bring Western Europe more hurricanes

In January 2009 a cyclone called Klaus, which is shown here and boasted hurricane-force winds, hit France, Spain and Italy. Such conditions could become much more common in Europe by the end of the 21st century, according to Rein Haarsma and his KNMI team. Credit: H de C via Flickr Creative Commons license

In January 2009 a cyclone called Klaus, which is shown here and boasted hurricane-force winds, hit France, Spain and Italy. Such conditions could become much more common in Europe by the end of the 21st century, according to Rein Haarsma and his KNMI team. Credit: H de C via Flickr Creative Commons license

Current once-in-a-century hurricane-force winds may become as much as 25 times as likely in parts of Western Europe at the end of the 21st century. That’s what Rein Haarsma and a team from the Royal Netherlands Meteorological Institute (KNMI) have shown using one of the highest-resolution climate models around today. Their findings spring from a change in where hurricanes will develop that could also affect western North America, though more research is needed to study this. “The statement that the wind climate in Western Europe will not change significantly is questionable,” Rein told me. “Significant changes in wind climate will have consequences for agriculture – the increased winds are during the autumn – infrastructure and coastal defence.”

With Europe so far from the tropical regions where warmth and unstable atmosphere spawns hurricanes, it rarely sees them today. But when hurricane conditions do happen, like the ‘Great Storm’ in 1987, or Hurricane Floyd in 1993, they live long in the memory. The hurricane remnants that sometimes reach Western Europe usually bring a lot of rain, Rein noted, and only occasionally hurricane-force winds.

The warming Arctic is reducing ocean temperature differences that help create Europe’s traditional storms, meaning they pose less of a threat. But recently findings have shown that a warmer atmosphere raises hurricane risks. “Many model simulations suggest that the strength of hurricanes will increase due to climate change,” Rein explains. “The area where hurricanes develop appears to move poleward and the moisture content in a warmer atmosphere will increase. These factors might alter the possibility that these remnants of hurricanes are still strong enough to produce hurricane-force winds.” Read the rest of this entry »

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Altered pressure patterns bring Eurasia intense iciness

People enjoying the winter sun - typical of an anticyclone, or high pressure, weather system - on the frozen Landwehrkanal in Berlin-Kreuzberg, during February 2012, when Berlin set a record for extreme cold. Credit: onnola via Flickr

People enjoying the winter sun – typical of an anticyclone, or high pressure, weather system – on the frozen Landwehrkanal in Berlin-Kreuzberg, during February 2012, when Berlin set a record for extreme cold. Credit: onnola via Flickr

Extreme cold that has left Europe and Asia snowbound, shivering and asking, “What global warming?” in recent years has been driven by intensified high pressure patterns. That’s according to Xiangdong Zhang at the University of Alaska, Fairbanks, who has been studying how such cold snaps fit in with increasing average temperatures worldwide. “Extreme cold weather events can occur in a particular region and short time period in a warming global climate,” Xiangdong pointed out. “This may highly disrupt daily life, damage infrastructure, and impact ecosystems and environment.”

Xiangdong started thinking about extreme cold events because climate studies usually use monthly temperature averages, which overlook them. “This cannot reflect extreme cold temperatures occurring on a particular day because daily temperature changes are filtered out by the average,” he told me. “For example, the monthly averaged temperature in February 2012 was -4.9°C in Berlin. But the coldest daily temperature in the same month at the same location was -19.6°C. We don’t directly feel the monthly average temperature in our daily life. What we feel is day-by-day changes in temperature. But if we can understand mechanisms of daily temperature changes, we would be able to better understand why there is colder or warmer monthly average temperature.”

Outside of tropical areas weather patterns known as cyclones, which would be called low pressure on a weather forecast, and anticyclones, or high pressure, drive those daily temperature changes. Xiangdong had previously been part of a team that adapted an automated cyclone spotting method to look at each one separately. Last year, with researchers from Nanjing University of Information Science and Technology in China, he used that method to study records from across Europe and Asia between 1978-2012. They brought together sea level pressure data recorded every six hours by a global collection network, and daily minimum air temperatures recorded at 1337 meteorological stations.

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2012’s record events put climate in mind

Extent of surface melt over Greenland’s ice sheet on July 8 (left) and July 12 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. The satellites are measuring different physical properties at different scales and are passing over Greenland at different times. As a whole, they provide a picture of an extreme melt event about which scientists are very confident. Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory

Extent of surface melt over Greenland’s ice sheet on July 8 (left) and July 12 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. The satellites are measuring different physical properties at different scales and are passing over Greenland at different times. As a whole, they provide a picture of an extreme melt event about which scientists are very confident. Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory

This has been another year of striking climate events and records – but they seem to be happening so much more often today that their effect on me has weakened. That’s pretty cold-hearted, I admit. ‘Extreme weather’ is having terrible effects on peoples’ lives all around the world. But the truth is that we can only handle so many problems before becoming too numbed and overwhelmed to act. And last year, Stefan Rahmstorf and coworkers at the Potsdam Institute for Climate Impact Research showed temperature records are much more likely today than in a stable climate. “I don’t think many people appreciate how much the odds for such extremes have increased due to global warming,” he told me at the time. “I certainly didn’t until we had performed this study.” So it’s hardly surprising if we begin to get complacent when records are flowing thick and fast. But when I actually faced up to what’s happened in the climate this year, it was intriguing how well you could see global warming’s fingerprint.

Warming’s most dramatic effects have long been obvious in the Arctic, and 2012 was no different. Images from three satellites showed that almost Greenland’s entire ice sheet surface was temporarily melted by July 12. That’s the largest area in over 30 years of satellite observations. Then, on September 16, sea ice in the Arctic reached a record annual minimum area of 1.32 million square miles, approximately half the size of the average annual minimum for 1979 to 2000. Just two weeks later, Antarctic sea ice covered its highest area on record at the peak of winter, at 7.49 million square miles. In case you think that’s a natural balance that shows the planet isn’t warming, it’s worth noticing the scale of the changes. The Antarctic record is 193,000 square miles higher than its average maximum area for the last 30 years. That’s much less than the 1.32 million square miles the Arctic lost compared to its long-term average. Read the rest of this entry »

CO2 casts off shackles to power up Atlantic hurricanes

NOAA's GOES-13 satellite captured this visible image of Hurricane Sandy battering the U.S. East coast on Monday, Oct. 29 at 9:10 am EDT. Sandy's center was about 310 miles south-southeast of New York City. Tropical Storm force winds are about 1,000 miles in diameter, and are set to intensify in the 21st century.  Credit: NASA GOES Project

NOAA’s GOES-13 satellite captured this visible image of Hurricane Sandy battering the U.S. East coast on Monday, Oct. 29 at 9:10 am EDT. Sandy’s center was about 310 miles south-southeast of New York City. Tropical Storm force winds are about 1,000 miles in diameter, and are set to intensify in the 21st century. Credit: NASA GOES Project

Changes in greenhouse gases and other air pollution will likely make Atlantic storms that could hit the Caribbean and Eastern US more intense through this century. That’s according to research from Gabriel Vecchi at the US National Oceanographic and Atmospheric Administration (NOAA) in Princeton, New Jersey, and Gabriele Villarini at the University of Iowa. They’ve found that more greenhouse gases strengthen these storms but other pollutants known as aerosols or particulates, which include soot, do the opposite. Increases in both types of pollution through the 20th century therefore cancelled each other out. But with more recent efforts to limit aerosol pollution succeeding, Atlantic storms now look set to become more destructive. “Both reductions in particulate pollution and increases in greenhouse gases are going to co-operate, we think, to give us more intense hurricanes in the Atlantic,” Gabriel said.

Gabriel has long studied Atlantic storms, and together with Gabriele recently found that how often they happen will likely only increase during the first half of the 21st century. “The number of storms in a season is only part of the story,” Gabriel told me. “A big question for society is the intensity.” So it was natural, he added, to follow on by looking at how strong and long-lasting they are. Scientists have already looked at their intensity for narrow “time-slices”, for example from 1985-2005 and then predicting from 2080 to 2100. “People haven’t explored how we go from the late 20th century to the late 21st century,” Gabriel said.” That’s because to do this research they need complex and very detailed ‘high resolution dynamical’ climate models, which use up scarce time on the world’s most powerful computers. For the same reason, previous studies only look at a few possible scenarios for how much of the greenhouse gas CO2 humans will produce by burning fossil fuels. Read the rest of this entry »

Climate change brings landscapes to their last days

Like icebergs, much of the mass of Arctic ice lies under the surface, making studying its thickness important, as well as the area it covers. Thick, multiyear Arctic sea ice is disappearing, giving way to thin, young ice, according to University of Colorado at Boulder scientists. Credit: James Maslanik, University of Colorado

Like icebergs, much of the mass of Arctic ice lies under the surface, making studying its thickness important, as well as the area it covers. Thick, multiyear Arctic sea ice is disappearing, giving way to thin, young ice, according to University of Colorado at Boulder scientists. Credit: James Maslanik, University of Colorado

Nature’s beauty means different things to each of us – but undoubtedly it burns some images onto our souls. Our favourite scenery is less constant than we sometimes suppose,  changing from day to day and season to season. But the slowest changes can be the most heartbreaking, eventually robbing us of our favourite landscapes.

Some destructive changes you might consider man-made,  for example city sprawl overflowing, and some natural, such as coastal erosion. Landscape losses brought by global warming are a curious mixture of these two – humanity somehow pushing nature into a more savage mood.

In the two and a half years since I started this blog, I’ve often reported on science’s efforts to monitor how climate change is affecting landscapes in different parts of the world.  In this week’s blog entry I’ve decided to bring together pictures indicating what their work has told us – you can click on the pictures to read the original blog posts.

With the Arctic changing most rapidly as the world warms, it’s one of the most studied areas, and so its striking environment features highly. But if you look enough at your favourite landscapes, and at when its more regular changes happen, it’s likely you’ll already be able to see the signs of a slow and potentially troublesome revolution in progress.

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Weather watching hits home with powerful warming warning

UK and Japanese scientists compared climate models to show that greenhouse gas emissions affected flooding in the UK, finding that they "substantially increased the odds of these floods occurring in 2000, with a likely increase of about a doubling or more". Credit: Met Office

UK and Japanese scientists compared climate models to show that greenhouse gas emissions affected flooding in the UK, finding that they “substantially increased the odds of these floods occurring in 2000, with a likely increase of about a doubling or more”. Credit: Met Office

Pictures of people forced from their homes by floods, storms, drought-driven famines or fires are among the most dramatic displays of weather and climate’s power that we see.  Just as the world has steadily warmed in recent decades, these “extreme weather events” have also changed. For example, evidence suggests substantial increases in intensity and duration of tropical storms and hurricanes since the 1970s.  Extreme weather events happen all over the world, and the possibility that they will be more likely to hit our homes perhaps should be the best motivation to cut greenhouse gas emissions.

Since Simple Climate started, I’ve regularly featured extreme weather and its links to man-made climate change. Those links are usually put carefully. Scientists typically can only say whether the greenhouse gases we’ve added to the atmosphere have raised the chances of events happening, or whether they will increase the chances they’ll happen in future.  But recently, they’ve been using powerful computer systems to look at whether specific events have been made more likely by climate change in “attribution studies”.  This week, I’ve brought together a few pictures of events that have been included in such attribution studies, and other research that I’ve covered.  I’ve also included images of how climate is affecting people in different parts of the world. Click on the pictures to read the original blog posts.

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Population and climate raise tropical cyclone risks

A boy at the site of his family's damaged house in the Bangladeshi coastal district Cox’s Bazar that was damaged by a tropical storm. When a tropical storm becomes a hurricane-speed cyclone, such houses are just washed away. Casualties are higher when the population is not aware of the coming of a cyclone. Tropical cyclones are expected to become less frequent but more intense with future climate change. Credit: amioascension/Flickr

A boy at the site of his family's damaged house in the Bangladeshi coastal district Cox’s Bazar that was damaged by a tropical storm. When a tropical storm becomes a hurricane-speed cyclone, such houses are just washed away. Casualties are higher when the population is not aware of the coming of a cyclone. Tropical cyclones are expected to become less frequent but more intense with future climate change. Credit: amioascension/Flickr

The number of people threatened by tropical cyclones and the disasters they can cause will “greatly increase” over the next 20 years. And though climate change is predicted to increase tropical cyclones’ intensity, the world’s rapidly increasing population will play an even larger part in raising that risk. “Higher intensity will increase the number of people exposed,” explained Bruno Chatenoux from the Global Change and Vulnerability Unit at the United Nations Environment Program in Geneva, Switzerland. “However, we also show that the increase in population is the main trigger that will increase exposure. This finding is key because some governments may be tempted to delay actions to protect their population over uncertainties in climate change’s impact on tropical cyclones.”

This message is what Bruno and seven other Europe and US-based scientists have learnt while developing a new approach for determining the risks from such cyclones. Currently that risk is calculated from databases of reported past events in which the number of disasters caused by tropical cyclones has increased steadily over the past 40 years. However, the deaths those disasters cause has fluctuated up and down, falling from 357,000 in the 1970s to 174,000 in the 2000s. Perhaps more common disasters have been balanced out by people becoming much less vulnerable, the scientists suggest in a paper published in research journal Nature Climate Change. Or perhaps the increased number of disasters is just due to better recording, as TV and the internet becomes more widespread. Read the rest of this entry »