What is "El Niño" and what are its effects?

The term El Niño (Spanish for 'the Christ Child') refers to a warming of the ocean surface (or above-average sea surface temperatures) in the central and eastern tropical Pacific Ocean. The low-level surface winds, which normally blow from east to west along the equator (“easterly winds”), instead weaken or, in some cases, start blowing the other direction (from west to east or “westerly winds”). El Niño recurs irregularly, from two years to a decade, and no two events are exactly alike. El Niño events can disrupt normal weather patterns in the United States and globally.

Although the USGS doesn’t directly study or forecast the weather (our sister agency, NOAA, and its National Weather Service do), the USGS studies and documents the effects and impacts of long-term climate changes and weather phenomena across the U.S. and globally.

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How can climate change affect natural disasters?

With increasing global surface temperatures the possibility of more droughts and increased intensity of storms will likely occur. As more water vapor is evaporated into the atmosphere it becomes fuel for more powerful storms to develop. More heat in the atmosphere and warmer ocean surface temperatures can lead to increased wind speeds in tropical...

What are some of the signs of climate change?

• Temperatures are rising world-wide due to greenhouse gases trapping more heat in the atmosphere. • Droughts are becoming longer and more extreme around the world. • Tropical storms becoming more severe due to warmer ocean water temperatures. • As temperatures rise there is less snowpack in mountain ranges and polar areas and the snow melts...

What is the difference between weather and climate change?

Weather refers to short term atmospheric conditions while climate is the weather of a specific region averaged over a long period of time. Climate change refers to long-term changes.

Can major landslides and debris flows happen in all areas of the U.S.?

Landslides can and do occur in every state and territory of the U.S.; however, the type, severity and frequency of landslide activity varies from place to place, depending on the terrain, geology, and climate. Major storms have caused major or widespread landslides in Washington state, Oregon, California, Colorado, Idaho, Hawaii, Virginia, Ohio,...

What is a landslide and what causes one?

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further...

What is a 1,000-year flood?

The term “1,000-year flood” means that, statistically speaking, a flood of that magnitude (or greater) has a 1 in 1,000 chance of occurring in any given year. In terms of probability, the 1,000-year flood has a 0.1% chance of happening in any given year. These statistical values are based on observed data.

Does an increase in the 100-year flood estimate originate from climate or land-use change?

Climate variability (dry cycles to wet cycles) and land-use change play a significant role, but there is a large amount of uncertainty around the flood quantile estimates (the value of discharge corresponding to the 100-year flood), particularly if there isn’t a long record of observed data at a stream location. Learn more: Flood recurrence...

How can a 1,000-year rainfall not result in a 1,000-year flood?

It comes down to a number of factors, including the pattern of movement of the rain storm in each particular watershed, the conditions of the soil and plant matter in the watershed, and the timing of the rainstorm in one watershed versus other watersheds. For example, if the ground is already saturated before a rainstorm, much of the rain will run...

How are floods predicted?

Flood predictions require several types of data: The amount of rainfall occurring on a realtime basis. The rate of change in river stage on a realtime basis, which can help indicate the severity and immediacy of the threat. Knowledge about the type of storm producing the moisture, such as duration, intensity and areal extent, which can be valuable...
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Date published: February 14, 2017

Severe West Coast Erosion During 2015-16 El Niño

In a study released today, U.S. Geological Survey scientists and their colleagues document how the 2015-16 winter featured one of the most powerful El Niño climate events of the last 145 years.

Date published: October 21, 2016

New Maps from Old Photos: Measuring Coastal Erosion

U.S. Geological Survey scientists and their coauthors from the California Coastal Records Project have found a way to use historical aerial photographs not just to see evidence of coastal erosion, but to accurately measure how much has occurred over time.

Date published: March 4, 2016

USGS Science for an El Niño Winter

El Niño is a phenomenon that occurs when unusually warm ocean water piles up along the equatorial west coast of South America. When this phenomenon develops, it affects weather patterns around the globe, including the winter weather along the west coast of North America. This unusual pattern of sea surface temperatures occurs in irregular cycles about three to seven years apart.

Date published: September 21, 2015

El Niño and La Niña will Exacerbate Coastal Hazards Across Entire Pacific

SANTA CRUZ, Calif. — The projected upsurge of severe El Niño and La Niña events will cause an increase in storm events leading to extreme coastal flooding and erosion in populated regions across the Pacific Ocean, according to a multi-agency study published today in Nature Geoscience.

Attribution: Natural Hazards
Date published: January 14, 2011

ARkStorm: California’s other "Big One"

For emergency planning purposes, scientists unveiled a hypothetical California scenario that describes a storm that could produce up to 10 feet of rain, cause extensive flooding (in many cases overwhelming the state’s flood-protection system) and result in more than $300 billion in damage.

Date published: May 16, 2007

USGS Analyzes 70 Years of Coastal Cliff Retreat in California

The U.S. Geological Survey (USGS) has released a report analyzing coastal cliff retreat along more than 350 km of the California coast over a period of approximately 70 years. This study is the first comprehensive assessment of the state's historical coastal cliff retreat.

Date published: March 9, 2004

USGS Research Links Long-Term Droughts in U.S. to Ocean Temperature Variations in the North Pacific and North Atlantic

Large-scale, long-lasting droughts in the United States — such as the present one in the West — tend to be linked to warmer than normal sea surface temperatures in the North Atlantic Ocean, and not just cooling in the tropical Pacific, according to a USGS study published today in the Proceedings of the National Academy of Sciences.

Date published: May 15, 2000

Understanding Coastal Hazards— From Coastal Erosion and Storms to Sea-level Rise

U.S. Geological Survey (USGS) Congressional briefing on "Understanding Coastal Hazards" highlights how science is helping fast-growing coastal regions and communities make smart land use decisions, minimize costly losses from coastal hazards, and preserve natural resources and the environment.

Date published: November 4, 1997

From Floods and Landslides to Ecosystems...USGS Scientists Gear Up for El Nino

From the West Coast to South Florida, the U.S. Geological Survey is gearing up as part of the scientific front line in studying and reducing the impact of El Nino.

Date published: October 3, 1997

El Nino May Trigger Landslides... USGS Map Indicates Susceptibility and Incidence of Landslides

Floods, coastal erosion and heavy precipitation aren’t the only predicted consequences of the El Nino phenomena. Landslides and debris flows could happen in areas where intense rainfall occurs.

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Big Sur landslide on May 20, 2017 showing material across Highway 1.
May 27, 2017

Big Sur landslide on May 20, 2017

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

2014 Landslide in Washington State
January 4, 2017

2014 Landslide in Washington State

Oblique aerial photograph of the 2014 landslide in northwest Washington. This image shows the entire extent of the landslide source area and path. This event is commonly named the “Oso Landslide” in many official reports. It is also referred to as the “SR530 Landslide,” as named by Snohomish County and Washington State. Credit: Mark Reid, USGS

El Nino map
April 14, 2016

El Nino map

The reds and orange colors on this world map indicate warmer sea surface temperatures. The large band of warmer waters along the equator west of South America is characteristic of El Niño. Image credit: NOAA

Photograph of bluff erosion in 2010 undermining the Great Highway at the southern end of Ocean Beach, San Francisco.
January 20, 2010

Bluff Erosion From El Nino 2010

Bluff erosion during the 2009–10 El Niño undermined the Great Highway guardrail at the southern end of Ocean Beach, San Francisco, California. The shoreline eroded, on average, 55 meters that winter, leading to lane closures on the highway and an emergency $5-million revetment along the base of this bluff. Photo taken by Jeff Hansen, USGS, 20 January 2010.

Photograph showing bluff erosion during the 2009-10 El Nino, undermining the Great Hwy guardrail at Ocean Beach, San Francisco.
January 20, 2010

Bluff Erosion From El Nino (2009-2010)

Bluff erosion during the 2009–10 El Niño undermined the Great Highway guardrail at Ocean Beach, San Francisco, California. The shoreline eroded, on average, 55 meters that winter, leading to lane closures on the highway and an emergency $5-million revetment along the base of this bluff.

Image: Severe Coastal Erosion During an El Niño Storm
January 19, 2010

Severe Coastal Erosion During an El Niño Storm

Severe coastal bluff erosion, along the southern end of Ocean Beach, San Francisco, California. This storm damage occurred during the 2009-2010 El Niño, which, on average, eroded the shoreline 55 meters that winter.

Image: Severe Coastal Erosion During an El Niño Storm
January 19, 2010

Severe Coastal Erosion During an El Niño Storm

Severe bluff erosion, along the southern end of Ocean Beach, San Francisco, California, including damage to the guard rail of the Great Highway (Calif. Hwy.1). The severe winter erosion led to lane closures of the highway and an emergency, $5 million revetment along the base of this bluff. This storm damage occurred during the 2009-2010 El Niño, which, on average, eroded

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USGS
May 26, 2009

What can I do to be prepared for a landslide?

Listen to hear the answer.

USGS
November 25, 2008

What is "El Nino" and what are its effects?

Listen to hear the answer.

USGS
April 23, 2008

What is a landslide, and what causes them?

Listen to hear the answer.

video thumbnail: (Trailer) Riding the Storm—Landslide Danger in San Francisco Bay Area
November 8, 2007

(Trailer) Riding the Storm—Landslide Danger in San Francisco Bay Area

Video Highlights:

* A catastrophic 1982 rainstorm triggered 18,000 landslides in the Bay Area, claiming 25 lives and causing $66 million in property damage

* The combination of steep slopes, weak rocks, and intense winter storms make Bay Area uplands an ideal setting for landslides

*Landslides include both swift,

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