extreme weather

Extreme Weather and Resilience: An Ounce of Prevention

A recent Senate hearing highlighted some of the progress U.S. communities are making, and the major challenges they face, in better coping with costly extreme weather events — including those, such as heat waves and coastal flooding, whose risks are heightened by climate change.

Sen. Tom Carper, chairman of the Homeland Security and Governmental Affairs Committee, noted that the “frequency and intensity of these extreme weather events are costing our country a lot - not just in lives impacted – but in economic costs, as well.” Nearly 130 weather-related events in 2013 caused more than $20 billion in losses in the United States.

Extreme weather is costly, not only to federal, state, and local governments, but also to businesses and individuals.

Much of the Senate testimony echoed key findings in our report, “Weathering the Storm, Building Business Resilience to Climate Change.”  Three key points made at the hearing were:

The State of the Climate

As President Barack Obama prepares to deliver his State of the Union address, we believe it’s a good time to take a look at the state of our climate: the growing impacts of climate change, recent progress in reducing U.S. emissions, and further steps we can take to protect the climate and ourselves.

The consequences of rising emissions are serious. The U.S. average temperature has increased by about 1.5°F since 1895 with 80 percent of this increase occurring since 1980, according to the draft National Climate Assessment. Greenhouse gases could raise temperatures 2° to 4°F in most areas of the United States over the next few decades, bringing significant changes to local climates and ecosystems.

Chilling out on the Polar Vortex

This week’s brief but bitter cold snap over more than half the country prompted intense discussion about the polar vortex ranging from educational to bombastic.

Figure 1: A depiction of the “average” polar vortex on Jan. 6. The winds of the vortex correspond to the narrow “rainbow” areas. The map is an average of the upper atmosphere’s “topography” (specifically, the 500 millibar height) from all the January 6ths between 1980 and 2010.
Figure 2: The polar vortex on Jan. 6, 2014. The ridge (“R”) and trough (“T”) responsible for relatively warm weather in much of the West and bitterly cold weather in the Midwest and East have been labeled.

So let’s be clear: The cold snap this week was unusual but not entirely unprecedented. A few super-cold days don’t disprove global warming, just like a day of rain doesn’t end a drought. At the same time, we don’t yet know whether climate change will change the odds of future outbreaks of bitter cold. Research is still underway, and as of now, we shouldn’t necessarily expect these events to be more or less frequent in future winters. 
Here’s a Q&A to cut through the hype:

  • What is the polar vortex?  The polar vortex describes the air circulating aloft (thousands of feet above the ground) about the North Pole, and its extent is marked by a ribbon of strong winds that is often called the “jet stream.” (We most commonly focus on the North Pole, but a similar circulation is present around the South Pole, too).
    In the map (Figure 1), which is from the point of view of the North Pole, the vortex corresponds to purple and blue colored areas. The band where the colors change from blue/purple to red/yellow indicates the location of the jet stream, or the outer edge of the vortex. Winds are strongest where this color gradient is tightly packed (e.g., over the Pacific Ocean and North Atlantic Ocean). It tends to be quite cold at the surface below the purple areas, and warmer under the red/yellow areas.

It’s important to note that this figure is an average of many winter days. On any given day, we would see a number of deviations from this average pattern.

  • What happened this week? Comparing this week (Figure 2) to the average picture (Figure 1), we can see that the purple area of the vortex has contorted and moved farther south. Along with this pattern, there are substantial “wiggles” in the jet stream. These deviations in the circulation helped bring cold air into the continental United States that normally stays in northern Canada and the Arctic. Meteorologists look for these wiggles, called “ridges” and “troughs” (“R” and “T” on the map)  when putting together a forecast. While the trough brought notable cold to the Midwest and the East, the ridge has kept parts of the West warmer than average and relatively dry (much to the dismay of skiers).

Tornadoes and Climate Change

What causes a tornado?

Tornadoes are formed by a combination of atmospheric instability and wind shear.  Instability occurs when warm, moist air is wedged under drier, cooler air aloft. This warm air rises, causing the intense updrafts and downdrafts seen in strong thunderstorms — the incubators of tornadoes. Wind shear refers to changes in wind direction and speed at different elevations in the atmosphere. The combination of instability and wind shear forms the circular air flow that generates a tornado.

Why are there so many in the U.S. Midwest?

The Central United States has an abundance of the ingredients necessary for tornado formation. During the spring, warm tropical air masses from the Gulf of Mexico collide with colder, drier air at higher altitudes to spawn intense thunderstorms. Thunderstorms also form into the summer and fall, as the region’s vast plains heat up air near the surface, causing atmospheric instability. These intense thunderstorms act as incubators for tornadoes. Tornadoes occur around the world but are most common in “Tornado Alley” of the Central United States.

Is there a link between climate change and tornadoes?

It is important to keep in mind that climate change has an impact on all weather events.  The effect of the carbon dioxide in our atmosphere cannot be switched off – it influences our seemingly benign “everyday” or “normal” weather as well as the extreme events. 

A specific link between tornadoes and climate change, however, is unclear. It is difficult to identify and diagnose trends in long-term records of tornadoes, since the population in many areas affected by tornadoes has grown (e.g., tornadoes in the early part of the 20th century may have occurred without anyone seeing them) and the technology used to observe tornadoes has improved (e.g., radars help us “see” tornadoes in ways that were not possible many decades ago).

How could climate change affect the frequency or intensity of tornadoes?

Researchers are working to better understand how the building blocks for tornadoes -- atmospheric instability and wind shear -- will respond to global warming. It is likely that a warmer, moister world would allow for more frequent instability. However, it is also likely that a warmer world would lessen chances for wind shear. Recent trends for these quantities in the Midwest during the spring are inconclusive. It is also possible that these changes could shift the timing of tornadoes or regions that are most likely to be hit.

Adding to the difficulty, tornadoes are too geographically small to be well simulated by climate models. Models can simulate some of the conditions that contribute to forming severe thunderstorms that often spawn tornadoes. Multiple studies (e.g., here and here) find the conditions that produce the most severe thunderstorms are likely to occur more often in the in a warmer world, even if the total number of thunderstorms decreases (because of fewer weak storms). However, this work does not conclusively tell us whether tornadoes should follow the same trend as their parent thunderstorms.

Extreme Weather

 

Extreme Weather Event Map: Click on any icon on the map above to see details on the extent of an extreme weather event between 1990 and 2012.

 

Extreme Weather Events Map

The events shown above are examples of four types of extreme weather that scientists say are becoming more frequent and intense because of climate change: extreme heat, drought, wildfires, and heavy precipitation. Individual events cannot be blamed on any single cause.  However, the long-term trends in these types of events demonstrate that extreme weather risk is rising as a result of climate change. Each new event is an opportunity to better understand our vulnerabilities and ways to cope with these rising risks. Examined together, these events also can help us evaluate the benefits of actions and policies aimed at reducing the emissions of heat-trapping gases that are warming the planet and “juicing up the weather”.

Here are two C2ES papers taking a closer look at the trends shown in the map and how we can respond:

 


Scientific American Series on Extreme Weather, Climate Change, and the Risks We Face

Published in three parts in June 2011, this series in Scientific American provides firsthand accounts of record-breaking weather events, insights into their links to climate change, and what can be done to manage the growing risks.  The articles were written by science journalist John Carey with support from C2ES.


 

Additional C2ES Resources

Find answers to some of the most frequently asked climate science questions and learn about the realities and misconceptions of climate change science.

Learn how Hurricane Sandy is a stark reminder of the rising risks of climate change.

See the latest on drought and climate change.

Learn more about extreme heat and climate change.

Keep up to date on current extreme weather events, climate change, and risk management.

On our own?

Spring not only brings us daffodils and cherry blossoms in Washington, D.C., but also occasionally powerful thunderstorms that can knock out power to thousands of homes and businesses.

I live in one of those northern and western suburbs of DC that tend to lose power fairly frequently.

It used to be that one of the few nice things about losing power was the sound of silence. But those days are gone. Now losing power has a new sound: the whirring of the startup of my neighbors’ backup generators.

We need power not only to keep our food from spoiling and protect us from uncomfortable and even dangerous heat, but also to stay connected. As a nation, we are becoming ever more dependent on electronic devices. We cannot survive without our cell phones and computers, let alone our refrigerators and air conditioners. At the same time, climate change threatens the reliability of the grid through more intense heat waves and potentially more powerful storms.

While it’s easy to say we should work to prevent disruption in electricity, how much should we invest to bolster the resilience of the grid? And who should pay?

How climate change amplified Sandy’s impacts

As Hurricane Sandy moves out of the region, people in affected areas are beginning to take stock of the damage. Flooding in parts of New Jersey and New York from the storm surge hit record levels. The 13.8-foot surge measured at Battery Park in Lower Manhattan surpassed the all-time record of 11.2 feet set in 1821, flooding the New York subway system and two major commuter tunnels.  Along the Eastern Seaboard, an estimated 7.5 million people lost power. Farther inland, blizzard conditions dropped as much as 2 feet of snow as Sandy crashed into arctic air over the Midwest. While early estimates indicate direct damages from the hurricane may be as much as $20 billion, the total economic losses, including losses in consumer and business spending, could be more than twice that amount.

A number of climate change-related factors may well have intensified the storm's impact: higher ocean temperatures, higher sea levels, and an atmospheric traffic jam that may be related to Arctic melting.  Hurricane Sandy is also a clear reminder of how vulnerable our homes and infrastructure already are to extreme weather — and this risk is growing.

Increasing extreme weather is costly in many ways

A report released this week by two senior members of Congress notes that the unusual number of extreme weather events in 2012 has cost the country billions of dollars and that the unusual frequency of these events is consistent with what scientists have predicted from climate change.

The staff report, “Going to Extremes: Climate Change and the Increasing Risk of Weather Disasters” is from the offices of Reps. Edward Markey (D-MA) and Henry Waxman (D-CA), the prime movers behind the last attempt at significant climate legislation. It cites information from a variety of sources, including NOAA, the news media and the private sector to show how rising weather risk costs real money.  

Their report comes a week after Congress headed home for the elections having accomplished very little to address climate change. Nearly half the bills introduced by the current Congress would block or hinder climate action, though none of these have been enacted into law.

C2ES Releases New Extreme Weather Map on Eve of Senate Climate Hearing

Press Release
July 31, 2012

Contact: Laura Rehrmann, 703-516-0621, rehrmannl@c2es.org

 
C2ES Releases New Extreme Weather Map on Eve of Senate Climate Hearing

The Center for Climate and Energy Solutions (C2ES) has created a new online map providing an overview of extreme U.S. weather events since 1990. The map highlights examples of extreme heat, heavy precipitation, drought, and wildfire -- four types of events with clear trends connected to climate change.

In a blog post announcing the new map, C2ES science and policy fellow Dan Huber summarizes the recent run of extreme weather:

“Climate change is elevating the risk of extreme weather,” writes Huber. “It’s crucial that we take stock of what each disaster teaches us so that we understand the rising risks and are better prepared for what’s to come.”

The science behind climate change will be the focus of a hearing tomorrow (Wednesday, Aug. 1) before the Senate Environment and Public Works Committee titled “Update on the Latest Climate Change Science and Local Adaptation Measures.” The hearing, set for 10 a.m. in 406 Dirksen, is the Senate’s first in this Congress focusing directly on climate change science.

For more information:

Extreme weather map: http://www.c2es.org/science-impacts/extreme-weather

Climate Compass blog: http://www.c2es.org/climatecompass

Follow @C2ES_org on Twitter or #epwclimatehearing.

Contact Senior Communications Manager Laura Rehrmann at rehrmannl@c2es.org to arrange an interview with a C2ES expert.

About C2ES: The Center for Climate and Energy Solutions (C2ES) is an independent non-profit, non-partisan organization promoting strong policy and action to address the twin challenges of energy and climate change. Launched in November 2011, C2ES is the successor to the Pew Center on Global Climate Change.

Mapping extreme weather across the U.S.

Today we’re updating our online map providing an overview of extreme weather events in the United States since 1990.  The map highlights memorable examples of extreme heat, heavy precipitation, drought, and wildfire, four types of events with clear trends connected to climate change.

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