Tornados Attacking in Swarms. Is Climate Change to Blame?
Tornados are among the most frightening storms, in part because of their destructive power but also because of their unpredictability. You can track and prepare for a hurricane, but tornados strike quickly and with little warning. And unlike hurricanes, tornados have no specific season.
Photo credit: Shutterstock
And if it seems to you that tornado incidents have been bigger and scarier recently, you're right, says a team of researchers in a new study published today in Science. While it found that tornados haven't increased in number and, in fact, the number of days on which tornados are occurring has decreased, the appearance of tornados in clusters has risen. That means if one tornado touches down, more are likely to occur in quick succession in the same geographic area. And scientists are asking if climate change is to blame.
"When people ask, 'Are we getting more tornadoes, are we getting fewer tornadoes, are they later, are they earlier?'—the answer to everything is yes," said lead study author Harold Brooks, senior scientist at the National Oceanic and Atmospheric Administration's Severe Storms Laboratory in Norman, Oklahoma.
An earlier study by Florida State University professor James Elsner, released in August, found a similar change in tornado patterns.
"We may be less threatened by tornadoes on a day-to-day basis, but when they do come, they come like there's no tomorrow," said Elsner.
The new study found that while the number of days with tornados stronger than F-1 on the Fujita scale for ranking tornado power decreased, the odds of having a day with 32 tornados has doubled. Prior to 1990, most years had no such days. Since 2001, every year has had one day with 32 or more tornados. A three-day period in April 2011 produced 355 tornados across the southern and eastern U.S. with 211 touching down in a 24-hour period on April 27, primarily in Alabama and Mississippi, killing more than 300 people in six states.
The study's summary says, "Whether or not climate change has had an impact on the occurrence of tornadoes in the United States has become a question of high public and scientific interest, but changes in how tornadoes are reported have made it difficult to answer it convincingly. We show that, excluding the weakest tornadoes, the mean annual number of tornadoes has remained relatively constant, but their variability of occurrence has increased since the 1970s. This is due to a decrease in the number of days per year with tornadoes combined with an increase in days with many tornadoes, leading to greater variability on annual and monthly time scales and changes in the timing of the start of the tornado season."
Photo credit: Shutterstock
While the study only hinted a link to climate change, Brooks said it's a preliminary step in investigating how global warming might be connected to changes in the patterns of tornado activity. Brooks told Live Science "Obviously, we've had a change in the frequency of the number of days of tornadoes, and in some sense that's a reflection of the climate being different than it was. But we don't have the primary cause and effect yet."
Tornados develop when warm, moist weather fuels thunderstorms that create changing wind directions (wind shear) that rotates the winds. While global warming creates fertile conditions for thunderstorms, studies have disagreed on whether it strengthens or weakens wind shear.
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By 2030, almost a third of all the energy consumed in the European Union must come from renewable sources, according to binding targets agreed in 2018. Sweden is helping lead the way.
Sweden is a world leader in renewable energy consumption. Swedish Institute/World Bank
Naturally Warm<p>54% of Sweden's power comes from renewables, and is helped by its geography. With plenty of moving water and 63% forest cover, it's no surprise the <a href="https://sweden.se/nature/energy-use-in-sweden/#" target="_blank">two largest renewable power sources</a> are hydropower and biomass. And that biomass is helping support a local energy boom.</p><p>Heating is a key use of energy in a cold country like Sweden. In recent decades, as fuel oil taxes have increased, the country's power companies have turned to renewables, like biomass, to fuel local 'district heating' plants.</p><p>In Sweden these trace their <a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140#fig3" target="_blank">origins back to 1948</a>, when a power station's excess heat was first used to heat nearby buildings: steam is <a href="https://www.sciencedirect.com/topics/engineering/district-heating-system" target="_blank">forced along a network of pipes</a> to wherever it's needed. Today, there are around 500 district heating systems across the country, from major cities to small villages, providing heat to homes and businesses.</p><p>District heating used to be fueled mainly from the <a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140" target="_blank">by-products of power plants</a>, waste-to-energy plants and industrial processes. These days, however, Sweden is bringing more renewable sources into the mix. And as a result of competition, this localized form of power is now the country's<a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140#fig3" target="_blank" rel="noopener noreferrer"> home-heating market leader.</a></p>
Sweden is using smart grids to turn buildings into energy producers. Huang et al/Elsevier
Energy ‘Prosumers’<p>But Sweden doesn't stop at village-level heating solutions. Its new breed of energy-generation takes hyper-local to the next level.</p><p>One example is in the city of Ludivika where 1970s flats <a href="https://www.buildup.eu/sites/default/files/content/transforming-a-residential-building-cluster-into-electricity-prosumers-in-sweden.pdf" target="_blank">have recently been retrofitted with the latest smart energy technology</a>.</p><p>48 family apartments spread across 3 buildings have been given photovoltaic solar panels, thermal energy storage and heat pump systems. A micro energy grid connects it all, and helps charge electric cars overnight.</p><p>The result is a cluster of 'prosumer' buildings, producing rather than consuming enough power for 77% of residents' needs. With <a href="http://www.diva-portal.org/smash/get/diva2:1232060/FULLTEXT01.pdf" target="_blank" rel="noopener noreferrer">high levels of smart meter usage</a>, it's a model that looks set to spread across Sweden.</p>
<div id="d7bf9" class="rm-shortcode" data-rm-shortcode-id="8757b138d5570bec9d6aad18074a429a"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1273556364263071744" data-partner="rebelmouse"><div style="margin:1em 0">Read more about Western Harbour and book a visit: https://t.co/ujSmVs9rNK 🏡🌳🌊 https://t.co/C5PuPziqIM</div> — Smart City Sweden (@Smart City Sweden)<a href="https://twitter.com/SmartCitySweden/statuses/1273556364263071744">1592474473.0</a></blockquote></div>
Scaling Up<p>A recent development by E.ON in Hyllie, a district on the outskirts of Malmö, southern Sweden, <a href="https://www.eonenergy.com/blog/2019/February/sweden-smart-city" target="_blank">has scaled up the smart grid principle</a>. Energy generation comes from local wind, solar, biomass and waste sources.</p><p>Smart grids then balance the power, react to the weather, deploying extra power when it's colder or putting excess into battery storage when it's warm. The system is not only more efficient, but bills have fallen.</p><p>Smart energy developments like those in Hyllie, Ludivika, and renewable-driven district heating, offer a radical alternative to the centralized energy systems many countries rely on today.</p><p>The EU's leaders have a challenge: how to generate 32% of energy from renewables by 2030. Sweden offers a vision of how technology and local solutions can turn a goal into a reality.</p>
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