Fourth National Climate Assessment: A Dire Forecast for US if Action is Not Taken

The Fourth National Climate Assessment (NCA4) report was released rather inauspiciously last week on the day after Thanksgiving – a traditionally slow news day. Nevertheless, the report is out and it clearly states, “the evidence of human-caused climate change is overwhelming and continues to strengthen.”

The massive report, considered volume two of NCA4, builds on the Climate Science Special Report issued last year. It gives a detailed account of what the impacts will be across the country and how the worst effects could be avoided.

The U.S average temperature, according to the report, has increased by 1.8°F since 1901, and is projected to continue rising. Over the next few decades, temperatures are projected to rise another 2.5°F.  By the end of the century, our average temperature could soar by as much as 11.9°F if greenhouse gas emissions continue to increase unchecked.

The report also looks at the long-term economic impacts for the country as the average temperature continues to climb. Costs from rising sea levels could reach as high as $118 billion and the projected total for damaged infrastructure is $32 billion. This is in addition to the reduced agricultural productivity expected from high heat and extended drought events. Overall, the report warns that if significant steps are not taken, climate change could slash the US economy’s GDP by 10% by the end of the century.

Not all doom and gloom, the report’s authors emphasize, “These impacts are projected to intensify—but how much they intensify will depend on actions taken to reduce global greenhouse gas emissions and to adapt to the risks from climate change now and in the coming decades.”

While similar in theme to the IPCC report from the UN, this assessment focuses solely on the United States. Emphasizing the fact that rising temperatures will affect different parts of our vast country in different ways, the NCA breaks the nation down into specific regions. It details the current and future impacts of climate change in each one:

The report also includes a supplemental set of State Climate Summaries that give a clear idea of what to expect in each of the 50 states as well as the US territories.

Mandated by Congress under the Global Change Research Act, this exhaustive 1600 page peer-reviewed report was produced by 300 scientists from 13 different government agencies. Published every four years, it is considered this country’s most authoritative statement on climate change.

Annual average temperatures across the United States are projected to increase over this century, with greater changes at higher latitudes as compared to lower latitudes, and greater changes under a higher scenario (RCP8.5; right) than under a lower one (RCP4.5; left). This figure shows projected differences in annual average temperatures for mid-century (2036–2065; top) and end of century (2071–2100; bottom) relative to the near present (1986–2015). Image credit: Fourth NCA, Vol II, figure 2.4.

Hurricane Michael Devastates Florida Panhandle

Hurricane Michael, the 13th named storm of this Atlantic Hurricane season, made landfall near Mexico Beach, Florida on Wednesday. It was the strongest storm on record to hit the Florida Panhandle.

Coming ashore with sustained winds measured up to 155mph, Michael was classified as a high-end category-four hurricane. Its powerful winds sheared roofs off buildings, uprooted trees, and toppled power lines. Storm surge flooding was also a major force of destruction. The NHC estimates the water reached between nine and fourteen feet above normally dry ground from Mexico Beach eastward through Apalachee Bay.

Fueled by the unseasonably warm waters of the Gulf of Mexico, Michael intensified rapidly as it moved closer to shore. According the NWS, Michael was the strongest hurricane to make landfall in the US since Hurricane Andrew in 1992. It was also the strongest storm to ever hit this country in the month of October.

Moving quickly, the storm traveled across the Florida Panhandle toward the northeast. Its strong winds and heavy rain caused flashing flowing and power outages in several states.

As of Friday, the death toll from this historic storm stands at sixteen. But sadly, officials say that number is expected to rise as search and rescue efforts continue in the hardest hit areas.

Hurricane Michael makes landfall near Mexico Beach, FL. Credit: NOAA

Hurricane Florence Swamps the Carolinas

Hurricane Florence, the 6th named storm of the Atlantic Hurricane season, slammed North and South Carolina this weekend.

Steered across the Atlantic by a strong area of high pressure, Florence made landfall near Wrightsville Beach, NC on Friday morning as a category-1 storm.  It peaked at category-4 strength while still over the ocean, but weakened as it moved closer to the US coast.

Despite this downgrade, Florence still packed a powerful punch. Its strong winds, flooding rains, and storm surge forced people to evacuate their homes and caused significant property damage as well as widespread power outages across the region. In the hard hit city of New Bern, NC, at the mouth of the Neuse River, a storm surge of more than ten feet was reported. Local officials there say upward of 4000 homes and businesses were damaged or destroyed.

Moving as slowly as 2 mph at one point, Florence essentially stalled out over the region, allowing it to unleash massive amounts of precipitation. Preliminary reports show that the storm set new state records for rainfall from a single tropical cyclone in both North and South Carolina. In Elizabethtown, NC, 35.93 inches was reported, crushing the previous record of 24.06 inches set by Hurricane Floyd in 1999. In South Carolina, the town of Loris, about 25 miles north of Myrtle Beach, reported 23.63 inches of rain, eclipsing the old record of 17.45 inches set by Tropical Storm Beryl in 1994.

If these numbers are confirmed by the NWS, that would mean four state tropical cyclone rainfall records were broken in the last thirteen months. The other two being Texas with 60.58 inches of rain from Hurricane Harvey in August 2017 and Hawaii with 52.02 inches from Hurricane Lane just last month.

Measuring 400 miles wide, Florence’s successive bands of heavy rain also caused catastrophic inland flooding as several rivers in the region overflowed their banks and inundated communities. In Fayetteville, NC – nearly 100 miles from the coast – more than 15 inches of rain was reported as of Monday. The Cape Fear River, which runs through the city, is forecast to crest at 61.8 feet on Tuesday, which is more than 25 feet above flood stage.

The death toll from this storm currently stands at 20, with most fatalities being water related. Sadly, as the rivers across the area continue to rise, that number is expected to increase in the coming days.

Hurricane Florence off the coast of the Carolinas. Credit: NOAA

Wind Cave National Park and the Science Behind What Makes the Wind Blow

I recently visited Wind Cave National Park in South Dakota, which protects a beautiful expanse of the Northern Great Plains as well as one of the largest and most complex cave systems in the world. While well known for its geology, the park’s namesake feature is also an excellent example of the science behind a basic weather phenomenon – wind.

Wind, which is air in motion, is the result of differences in atmospheric pressure. These pressure differences are caused by the temperature differences created by the uneven heating of the Earth’s surface by the Sun.  Several factors contribute to this unbalanced process, including cloud cover, large bodies of water, topography, and vegetation.

As the surface warms, air heats and rises, creating an area of low pressure. To fill that void, air from an area of relatively higher-pressure rushes in, creating a flow of air that we recognize as wind. The greater the pressure differences between these two areas, the stronger the breeze.

Atmospheric pressure conditions at the cave entrance during my visit. Credit: Melissa Fleming

At Wind Cave, given its vast size, the air pressure inside the cave is constantly working to equalize with that above ground. Therefore, when there is an area of high pressure at the surface, the wind will blow into the cave. If there is an area of low pressure on the surface, the wind will blow out of the cave. For this reason, the cave is described in the oral histories of the Lakota – a Native American tribe who consider it scared – as “the hole that breathes cool air”.

Park Ranger demonstrates the flow of air coming out of the small cave entrance with a ribbon. Credit:RVDreamLife

While other large cave systems can generate barometric winds, those at Wind Cave are more noticeable because of the small size of its entrance. As the Venturi Effect shows, when space is constricted, air will flow faster. Legend says that the first non-native settlers to discover the cave – two brother named Jesse and Tom Bingham – did so by accident when the wind from its entrance blew the hat off one of their heads in 1881.

According to the NPS, winds at the cave’s natural entrance have reached up to 25-mph.

Wind Cave National Park, SD. Credit: Melissa Fleming

The Continental Divide Determines Where Rain Goes After it Hits the Ground

Most people are familiar with the various types of precipitation that falls from the sky. However, have you ever wondered where all that water goes after it falls or melts? The answer is largely dependent on what side of the continental divide it landed.

A continental divide is a natural boundary that separates the river systems of a continent. They are usually tall mountain ranges that direct the flow of rivers and streams to different oceans. Essentially, any precipitation that falls or melts on one side will flow into one ocean basin and anything that falls or melts on the other side of the divide will flow into another basin.

Sign in Rocky Mountain National Park marks the location of the Continental Divide in CO. Credit: Melissa Fleming

Every continent has at least one and some have multiple. In the United States, the main divide is the Rocky Mountains. It is part of the Great Continental Divide of the Americas, which runs from western Alaska through the Andes Mountains in South America. It separates water that runs into the Atlantic Ocean from water that flows into the Arctic or Pacific Oceans.

In some cases, water finds its way into an endorheic basin with no outlet to an ocean.  Utah’s Great Salt Lake and Oregon’s Crater Lake are well known examples.  Here, the water re-enters the water cycle via evaporation. A small percentage of precipitating water also seeps into the ground where it replenishes soil moisture and underground aquifers. That said, the vast majority of water returns to the world’s oceans where it will eventually be evaporated and fall as precipitation again somewhere on the planet.

North America has several drainage divides, but the Great Divide (red) is the largest. Credit: ContinentalDivide.net

 

Hurricane Lane: The Wettest Tropical System Ever Recorded in Hawaii and the Second Wettest for US

Hurricane Lane, the twelfth named storm of eastern Pacific hurricane season, slammed the state of Hawaii with strong winds and flooding rains over the weekend. It was the wettest tropical cyclone on record in the Aloha state.

The storm, according to the NWS, peaked at category-5 strength, but weakened as it approached Hawaii. While it did not make landfall, its outer rain bands still packed a punch that was felt across the island chain. The Big Island, however, was one of the hardest hit. In the town of Mountain View, about 15 miles southwest of Hilo, 52.02 inches of rain was reported. That is the second highest rainfall total ever recorded from a tropical cyclone in the entire United States. The highest total, 60.58 inches, fell in Nederland, Texas during Hurricane Harvey in 2017.

The slow moving nature of Lane and the orographic lift provide by the mountainous terrain of Hawaii helped push the rainfall total into the record books. Falling in a relatively short period of time, the relentless precipitation caused widespread flooding, mudslides, and road closures. It also forced mass evacuations as well as a number of water rescues.

While the eastern and central Pacific basins produce about 15 named storms a year, they rarely hit Hawaii. This is largely because of the state’s location in the vast Pacific Ocean. Sitting at about 20°N latitude, most storms pass south of the archipelago or dissipate in the relatively cooler waters to its north and east.

The last hurricane to make landfall in Hawaii was Iniki, a category-4 storm, in 1992.

Source: NWS

Wildfires Are Scorching the American West

Summer is wildfire season in the American West and it is off to a blazing start.

As of Monday, according to the National Interagency Fire Center, fifty-nine large wildfires – defined as greater than 100 acres – are currently burning in nearly a dozen states. These include Alaska, California, Colorado, Idaho, New Mexico, Nevada, Oregon, Texas, Utah, Washington, and Wyoming.

One of the newest conflagrations, the Ferguson Fire, is raging just outside of Yosemite National Park in California’s Sierra Nevada mountains. At the height of tourist season, the fire has closed down Highway 140, one of the main entrances to the Park. It has forced the evacuation of several communities along Yosemite’s western edge as well as some hotels inside the Park. Ignited on Friday, the fire has burned more than 9,000 acres and is only 2% contained. Sadly, it has also claimed the life of one firefighter who was battling the flames.

Another hard hit state is Colorado, where seven large fires are burning. The largest is the Spring Creek Fire, which stared at the end of June and has burned more than 108,000 acres in Costilla and Huerfano counties.

These huge fires are being fueled by extremely hot and dry conditions that have left the region’s vegetation susceptible to any type of spark. Just a few days ago, excessive heat advisories were in effect for a large swath of the west as temperatures soared well above average.

Year to date, 3.3 million acres in the US have been charred, which is above average for this point in the season. The country’s worst wildfire year on record was 2015 when more than ten million acres burned.

Ferguson Fire in the Sierra National Forest, outside of Yosemite National Park in California. Credit: InciWeb/BlakeScott

Thomas Jefferson: Founding Father of Weather Observers

As the main author of the Declaration of Independence and the third President of the United States, Thomas Jefferson is regarded as one of this country’s Founding Fathers. He was also an astute and systematic weather observer.

Portrait of Thomas Jefferson by Rembrandt Peale, 1805. Credit: NYHS

In the summer of 1776, Jefferson was in Philadelphia, PA to sign the Declaration of Independence.  While there, he purchased a thermometer and a barometer – new and expensive weather equipment at that time. For the next 50 years, he kept a meticulous weather journal.  He recorded daily temperature data wherever he was – at home in Virginia or while traveling.

On July 4, 1776, Jefferson noted that the weather conditions in Philadelphia were cloudy with a high temperature of 76°F.

In an effort to understand the bigger picture of climate in America, Jefferson established a small network of fellow observers around Virginia as well as contacts in a few other states. According to records at Monticello, his estate in Virginia, he hoped to establish a national network for weather observations. While this plan did not come to fruition during his lifetime, today’s National Weather Service considers him the “father of weather observers.”

Happy Independence Day!

An excerpt from Thomas Jefferson’s Weather Journal, July 1776. Credit: NCDC

Names for the 2018 Atlantic Hurricane Season

Today is the first day of the Atlantic Hurricane Season. Although one named storm, Alberto, already formed this year, the season officially runs from June 1 to November 30.

Since 1950, each tropical storm or hurricane to form in the Atlantic has been given a unique name. They come from a set of six rotating lists produced by the World Meteorological Organization. A name is retired only when a storm was particularly noteworthy – causing a large number of fatalities or an extraordinary amount of damage. Some notable retired Atlantic Basin storm names include: Andrew, Harvey, Irma, Irene, Katrina, Maria, and Sandy. The names for this year’s storms are listed below.

Credit: NOAA

2018 Atlantic Hurricane Season Outlook: Average to Above Average

The number of hurricanes that develop in the Atlantic basin varies from year to year. For 2018, NOAA’s Climate Prediction Center is forecasting an average to above average season.

Tropical cyclones, known as hurricanes in the United States, develop around the globe at different times of the year. In this country, we are most impacted by the Atlantic hurricane season, which affects the North Atlantic Ocean, Caribbean Sea, and the Gulf of Mexico. It runs from June 1 through November 30.

Overall, NOAA predicts a 70% likelihood of ten to sixteen named storms forming this season, of which five to nine could become hurricanes, including one to four major hurricanes. An average season produces twelve named storms, including six hurricanes and three that become major hurricanes. A major hurricane is one that is rated category 3 or higher on the Saffir-Simpson scale.

This outlook, according to NOAA, is based on the possibility of the development of a weak El Niño and near-average sea surface temperatures in the tropical Atlantic. El Niño conditions in the Pacific tend to cause increased wind shear in the Atlantic, which suppresses tropical development in that basin.

Last year, 2017, was the most active Atlantic Hurricane season in more than a decade.  It produced seventeen named storms, including Harvey, Irma, and Maria. But regardless of the number of storms that actually form this year, it is important to remember that it only takes one land-falling system in your community to make it an impactful season.

Source: NOAA