Climate change is causing longer and hotter heat waves that take a toll on public health and on a community’s economy, prompting some local governments to take action.
Heat can be deadly. From 2006-2010, exposure to extreme heat resulted in 3,332 U.S. deaths. The elderly and the poor are among the most vulnerable due to pre-existing health issues and limited access to air conditioning. But young outdoor enthusiasts are also at risk. Five hikers died during a heat wave this summer in Arizona, where it got as hot as 120 degrees F.
Heat waves are not only dangerous, they’re also expensive. Extreme heat can damage crops and livestock, reduce worker productivity, drive up energy costs, and increase demand for water resources. A 2011 heat wave and associated drought in the Southwest and Southern Plains cost $12.7 billion.
A hotter, drier Southwest
While it’s hard to determine how climate change influences individual extreme weather events, we do know climate change exacerbates both their frequency and intensity.
In the Southwest, residents are expected to see an additional 13 to 28 extremely hot days (temperatures of 95F or hotter) by mid-century, and 33 to 70 additional days by the end of the century. Higher temperatures will also exacerbate droughts and fire cycles.
How to prepare
The Southwest region has already taken steps to prepare for the impacts of more extreme heat. This is especially critical for urban areas, where stretches of heat-absorbing concrete and asphalt create a heat island effect, increasing temperatures in some cities by up to 15 degrees above surrounding areas
In Southern California, the city government in Chula Vista is working to implement 11 strategies to help adapt to the impacts of climate change. They include using reflective or “cool” paving and roofing to reduce the urban heat island effect, and amending building codes to incentivize water reuse and lower demand for imported water.
In Arizona, the city of Phoenix’s Water Resource Plan includes short- and long-term strategies to deal with water shortage scenarios, including monitoring supplies and managing demand, developing increased well capacities for water storage, and coordinating with neighboring counties to secure additional water resources.
A council of local governments in Central New Mexico is working to determine the impacts of heat waves on infrastructure, including the role of extreme heat in degrading asphalt and pavement, and what types of pavement materials are most resilient to extreme heat.
Early efforts to improve climate resilience can help a community prepare for costly extreme weather events and more quickly bounce back from them. Local governments like the cities of Phoenix and Chula Vista and those in New Mexico are demonstrating strong leadership that can be an example for others. Coordinating with partners in state government and the business community, including through the C2ES Solutions Forum, can ensure local governments’ resilience plans provide maximum protection against the heat waves of the future.
Key Insights on Collaboration for a Resilient Anchorage
C2ES held a two-day Solutions Forum workshop in March 2016 in Anchorage, Alaska, focusing on opportunities for collaboration in building a climate-resilient Anchorage. About 50 business leaders, city, state, federal and tribal officials, nonprofit organizations, and other experts shared their experiences addressing climate change impacts and enhancing resilience. Discussion focused on the role each stakeholder group can play in planning for resilience. This paper summarizes the key insights of the meeting and areas of focus moving forward.
Scientists have typically been cautious when discussing the link between a single extreme weather event and climate change, preferring to focus on broader trends. Previous work, including a paper I wrote with Jay Gulledge four years ago, described a framework for how to think about the link.
But a new report from the National Academies of Sciences (NAS) is making the connection more clear by defining the relative contributions of climate change and other natural sources to the risk of individual weather events. The NAS report – an exhaustive, systematic examination of the peer-reviewed literature – finds high confidence in attribution studies linking individual extreme heat and cold events and climate change, and a more moderate confidence level for several other types of events.
Climate change is making extreme weather more likely. But individual weather events like heat waves or hurricanes are always the product of several risk factors, such as El Nino, climate change or other natural variability, akin to how a poor diet and smoking increase the risk of poor health later in life.
Extreme event attribution attempts to quantify the influence of climate change in comparison to other factors. Determining to what extent climate change strengthened or weakened the event can further our understanding of how much impact climate change is having on our weather.The NAS report assigns a confidence level to the climate impact for a variety of weather events based on three supporting lines of evidence:
- The physical mechanisms that link climate change to a particular extreme
- The length and quality of the observational record showing the baseline risk level and changes to date
- Computational climate modeling showing an increase in risk for a class of extreme event
The report finds the strongest links to climate change for extreme heat and cold, with the highest level of confidence across all three lines of evidence. Drought and extreme rainfall have medium confidence for physical understanding, observation and modeling. Extreme snowfall has medium conference for two out of three, physical understanding and modeling, while the observational record for snowfall is poor.
Image courtesy NOAA
This visualization from NOAA shows much warmer than average or record warm temperatures across much of the globe in 2015, the warmest year on record.
The data are in, and 2015 was officially the warmest year globally ever recorded. We’ve been keeping temperature records since 1880. The last time the record was broken? 2014.
What’s interesting is just how much warmer 2015 was. The observed annual average surface temperature was more than 1.8° F (1° C) above the 19th century average, according to the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA). That’s already half the warming countries have agreed to as the international limit.
And 2015 was about a quarter of a degree Fahrenheit warmer than 2014. That might seem small, but it’s actually huge when compared to the year-to-year differences observed in the record.
A strong El Niño, when the surface ocean in the Eastern Pacific basin warms, contributed to the record warmth of 2015. But even compared to other El Niño years, 2015 set records. The agencies reporting the data attribute this to the long-term warming trend due to the increase of greenhouse gases in the atmosphere.
As with all climate and weather data, the 2015 data shows some variability. Not all locations set high temperature records, and parts of the North Atlantic Ocean actually set a cold temperature record.
In the contiguous United States, 2015 was the second warmest year on record, with 2012 still holding the top spot. It was the 19th consecutive year that the annual average U.S. temperature was more than the 20th century average.
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:
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.
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).
Photo courtesy NOAA
Tornadoes and Climate Change
Definition of a TornadoTornadoes 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 rotating column of air that we associate with a tornado. Tornadoes that form over water are known as waterspouts.
The link between tornadoes and climate change is currently unclear. One problem is the difficulty in identifying long-term trends in tornado records, which only date back to 1950 in the United States. Also, the population in many areas affected by tornadoes has grown, so it’s possible that tornadoes in the early part of the 20th century occurred without anyone seeing them. Improved technology, such as advanced radar, also helps us “see” tornadoes that may not have been detected decades ago.
Another problem lies with the physics associated with 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. Climate change also could shift the timing of tornadoes or the regions that are most likely to be hit, with less of an impact on the total number of tornadoes.
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 (see here and here) find the conditions that produce the most severe thunderstorms are likely to occur more often 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.
Threats posed by tornadoes
The most significant threats from tornadoes are the dangers posed by strong winds and debris that is caught up in those winds. Although individual tornadoes may affect a relatively small area compared to large tropical storms, they can threaten people, homes, and communities.
NOAA estimates that, on average, about 1,200 tornadoes occur across the country annually, but several hundred more or fewer tornadoes can occur in any given year.
On average, tornadoes in the United States cause 70 deaths and 1,500 injuries per year. The death toll from tornadoes has dropped rapidly because forecasters have more tools to detect dangerous weather and quickly warn people to take shelter.
However, tornadoes still cause billions of dollars a year in property damage. The costliest year on record for tornado damage was 2011, when seven tornado and severe weather outbreaks each caused more than $1 billion in damages, and the total damage for the year was more than $28 billion.
How to Build Resilience
Communities can bolster their resilience and reduce the impacts from tornadoes by:
- Adopting more stringent building codes in tornado-prone areas
- Continuing to support new severe weather research and improvements to forecasts for severe weather
Heeding watches and warnings when they are issued, and ensuring that individuals can be reached by emergency alert systems (for example, through text message, television, and radio, or via tornado sirens)
To Learn More
Last updated July 2016
Extreme Weather Event Map: Click on any circle to learn about one of the billion-dollar weather events, or any state to learn about billion-dollar droughts. All events occurred between 2000 and May 2016.
Floods, Tornadoes, Thunderstorms, Hail, Tropical Storms, Wildfires, and Winter Storms are all shown as circles, with the costs indicated by the area of the circles (see image to the right). The location of the circles correspond to places where impacts were experienced (note: locations are approximate; many of the events actually impacted a large area, beyondThis map shows billion-dollar weather events in the United States since 2000, as identified by the National Oceanic and Atmospheric Administration’s National Climatic Data Center. The Top 10 costliest events are listed at the bottom of this page, along with a description of major U.S. droughts since 2000.
the boundaries of the circle). Droughts are not shown by circles, but by the shading in the states – states with darker colors have experienced more droughts since 2000, while states that are lightly shaded have experienced fewer droughts. No billion dollar events have occurred in Hawaii since 2000; some of the wildfire impacts (e.g., fire seasons in 2006, 2007, and 2008) included damages in Alaska, but the markers appear in the continental United States.
Many of these events, including heat waves and heavy rainfall, are likely to become more frequent and intense as a result of climate change. Climate change can also worsen the impacts of some of these events. For example, sea level rise can increase the impacts of coastal storms and warming can place more stress on water supplies during droughts. But it’s important to note that not ALL of these events will necessarily happen more frequently as a consequence of climate change. The links between climate change and tornadoes, ice storms, and hail are unclear, and represent current areas of research.
These events demonstrate ways our communities and infrastructure are vulnerable to extreme weather, and that the costs associated with impacts can be large.
More Resources on Extreme Weather and Climate Change
Fact Pages: Learn more about the links between climate change and:
Weathering the Next Storm - Extreme weather is costly. The events shown on the map above all cost billions of dollars, and several events had widespread and long-lasting implications.
A 2015 C2ES Report, Weathering the Next Storm: A Closer Look at Business Resilience, examines how companies are preparing for climate risks and what is keeping them from doing more. It also suggests strategies for companies and cities to collaborate to strengthen climate resilience. The report synthesizes public disclosures by S&P Global 100 companies, in-depth interviews and case studies, and workshops. It updates the groundbreaking 2013 report, Weathering the Storm, Building Business Resilience to Climate Change, which provided a baseline for how companies were assessing their climate vulnerabilities.
- Preparing for more summer heat waves (July 2016)
- Drought in California (June 2014)
- Extreme Weather and resilience: Coverage from a Senate hearing on resilience (Feb. 2014)
- The polar vortex (Jan. 2014)
- Some lessons from Hurricane Sandy (Nov. 2013)
- Coastal flood risks (April 2013)
|Event and Date||Cost||Fatalities||Description|
|$148 billion||1,833||The hurricane initially hit as a Category 1 near Miami, FL, then as a stronger Category 3 along the eastern LA-western MS coastlines, resulting in severe storm surge damage (maximum surge probably exceeded 30 feet) along the LA-MS-AL coasts, wind damage, and the failure of parts of the levee system in New Orleans. High winds and some flooding occurred in Ala., Fla., Ga., Ind., Ky., Miss., Ohio and Tenn.|
|$65.7 billion||159||Sandy caused extensive damage across several northeastern states (Conn., Del., Mass., Md., N.J., N.Y., R.I.) due to high wind and coastal storm surge, particularly in N.J. and N.Y. Damage from wind, rain and heavy snow also extended more broadly to other states (N.C., N.H., Ohio, Pa., Va., W.Va.), as Sandy merged with a developing Nor'easter. Sandy interrupted critical water and electrical services in major population centers and caused 159 deaths (72 direct, 87 indirect). Sandy also shut down the New York Stock Exchange for two consecutive business days, which last happened in 1888 due to a major winter storm.|
|$30.0-$30.3 billion||123||The 2012 drought was the most extensive in the U.S. since the 1930s. Moderate to extreme drought conditions affected more than half the country for a majority of 2012. Costly impacts included widespread harvest failure for corn, sorghum and soybean crops, among others. The associated summer heat wave also caused 123 direct deaths, but the excess mortality due to heat stress is still unknown.|
|$29.2 billion||112||Ike made landfall in Texas as a Category 2 hurricane. It was the largest Atlantic hurricane on record by size, causing a considerable storm surge in coastal TX and significant wind and flooding damage in Ark., Ill., Ind., Ky., La., Mich., Mo., Ohio, Pa., Tenn. and Texas. Severe gasoline shortages occurred in the Southeast due to damaged oil platforms, storage tanks, pipelines and refineries.|
|$19 billion||35||The Category 3 hurricane hit SW Florida, resulting in strong damaging winds and major flooding across southeastern Florida. Prior to landfall, Wilma as a Category 5 recorded the lowest pressure (882 mb) ever recorded in the Atlantic basin.|
|$19 billion||119||The Category 3 hurricane hit Texas-Louisiana border coastal region, creating significant storm surge and wind damage along the coast, and some inland flooding in the Fla. panhandle, Ala., Miss., La., Ark., and Texas. Prior to landfall, Rita reached the third lowest pressure (897 mb) ever recorded in the Atlantic basin.|
|$18.5 billion||35||The Category 4 hurricane made landfall in southwest Florida, resulting in major wind and some storm surge damage in FL, along with some damage in the states of S.C. and N.C..|
|$17.2 billion||57||The Category 3 hurricane made landfall on Gulf coast of Ala., with significant wind, storm surge, and flooding damage in coastal Ala. and Fla. panhandle, along with wind/flood damage in the states of Ga., Miss., La., S.C., N.C., Va., W.Va., Md., Tenn., Ky., Ohio, Del., N.J., Pa., and N.Y.|
|$12.0-$12.4 billion||95||In Texas and Oklahoma, a majority of range and pasture lands were classified in "very poor" condition for much of the 2011 growing season.|
|$11.1 billion||48||The Category 2 hurricane made landfall in east-central Fla., causing significant wind, storm surge, and flooding damage in FL, along with considerable flood damage in the states of Ga., N.C., N.Y. and S.C. due to 5-15 inches of rain.|
Table 2: Drought Events since 2000
|2015||$4.5 billion||0||Drought conditions continued to affect California throughout 2015, heavily impacting the agricultural sector. Drought conditions inproved in Texas and Oklahoma due to several major flood events.||Ariz., Calif., Idaho, Mont., Nev., Ore., Utah, Wash.|
|2014||$4 billion||0||Historic drought conditions affected the majority of California for all of 2014, making it the worst drought on record for the state. Surrounding states and parts of Texas, Oklahoma and Kansas also experienced continued severe drought conditions. This is a continuation of dought conditions that have persisted for several years.||Ariz., Calif., Kan., Nev., N.M, Okla., Ore., Texas.|
|2013||$11 billion||53||The 2013 drought slowly dissipated from the historic levels of the 2012 drought, as conditions improved across many Midwestern and Plains states. However, moderate to extreme drought did remain or expand into western states. In comparison to 2011 and 2012 drought conditions the US experienced only moderate crop losses across the central agriculture states.||Ariz., Calif., Colo., Idaho, Kan., Neb., Nev., N.M., Okla., Ore., S.D., Texas, Utah, Wyo.|
|2012||$30.0-$30.3 billion||123||The 2012 drought was the most extensive drought to affect the U.S. since the 1930s. Moderate to extreme drought conditions affected more than half the country for a majority of 2012. Costly drought impacts occurred across the central agriculture states resulting in widespread harvest failure for corn, sorghum and soybean crops, among others. The associated summer heatwave also caused 123 direct deaths, but an estimate of the excess mortality due to heat stress is still unknown.||Ariz., Ark., Calif., Colo., Ga., Idaho, Ill., Ind., Iowa, Kan., Minn., Mo., Mont., Neb., Nev., N.M., N.D., Okla., S.D., Texas, Utah, Wyo.|
|2011||$12.0-$12.4 billion||95||Drought and heat wave conditions created major impacts for affected areas. In Texas and Oklahoma, a majority of range and pastures were classified in "very poor" condition for much of the 2011 crop growing season.||Ariz., Kan., La., N.M., Okla., Texas|
|2009||$5.0-$5.4 billion||0||Drought conditions occurred during much of the year across parts of the Southwest, Great Plains, and southern Texas causing agricultural losses in numerous states. The largest agriculture losses occurred in Texas and California.||Ariz., Calif., Kan., N.M., Okla., Texas|
|2008||$2.0-$2.2 billion||0||Severe drought and heat caused agricultural losses in areas of the South and West. Record low lake levels also occurred in areas of the Southeast.||Calif., Ga., N.C., S.C., Tenn., Texas|
|2007||$5.0-$5.6 billion||15||Severe drought with periods of extreme heat over most of the Southeast and parts of the Great Plains, Ohio Valley, and Great Lakes area reduced crop yields, stream flows and lake levels.||Ala., Ark., Fla., Ga., Ill., Ind., Iowa, Kan., Ky., La., Mich., Minn., Miss., Neb., N.Y., N.C., N.D., Ohio, Okla., Pa., S.C., S.D., Tenn., Texas, Va., W.Va., Wis.|
|2006||$6.0-$6.9 billion||0||Severe drought affected crops in the Great Plains and across portions of the South and far West.||Ala., Ark., Calif., Colo., Fla., Ga., Iowa, Kan., La., Minn., Miss., Mo., Mont., Neb., N.M., N.D., Okla., S.D., Texas, Wyo.|
|2005||$1.0-$1.2 billion||0||Severe localized drought caused significant crop losses, especially for corn and soybeans.||Ark., Ill., Ind., Mo., Ohio, Wis.|
|2002||$10.0-$12.9 billion||0||Moderate to extreme drought was experienced over large portions of 30 states, including the West, Great Plains, and much of the eastern U.S.||Ala., Ariz., Calif., Colo., Conn., Del., Fla., Ga., Idaho, Iowa, Kan., La., Maine, Md., Mich., Miss., Mo., Mont., Neb., Nev., N.J., N.M., N.C., N.D., Ohio, Okla., Ore., Pa., R.I., S.C., S.D., Texas, Utah, Va., Wyo.|
|2000||$4.0-$5.4 billion||140||Severe drought and persistent heat over south-central and southeastern states caused significant losses to agriculture and related industries.||Ala., Ariz., Ark, Calif., Colo., Fla., Ga., Idaho, Iowa, Kan., La., Miss., Mont., Neb., Nev., N.M., N.C., Okla., Ore., S.C., Tenn., Texas, Utah, Wash., Wyo.|
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?