Climate Matters•August 14, 2024
Introducing Climate Shift Index: Ocean
KEY CONCEPTS
Ocean warming and extreme ocean heat put people and ecosystems at risk — by fueling stronger hurricanes and increasing the risk of events such as coral bleaching.
Today, Climate Central launches the Climate Shift Index: Ocean (Ocean CSI) — a new system and map tool that quantifies the influence of climate change on sea surface temperatures around the world, every day.
According to the Ocean CSI, human-caused climate change made the warm ocean waters that fueled Hurricane Beryl up to 400 times more likely.
Use Climate Shift Index: Ocean, based on the latest peer-reviewed attribution science, to understand the link between human-caused climate change and ocean temperatures around the world, every day.
Since April 2023, global sea surface temperatures have been continuously hotter than any previous period on record.
The world has been experiencing its fourth global coral bleaching event since April 2024.
Fingerprints of climate change on ocean temperatures — every day
Climate Central’s new Climate Shift Index: Ocean measures the influence of climate change on daily ocean temperatures.
Specifically, the Climate Shift Index: Ocean (also known as the Ocean CSI) quantifies the influence of climate change on the likelihood of sea surface temperatures around the world, every day.
The Climate Shift Index: Ocean can help connect human-caused ocean warming to consequences such as coral bleaching or hurricane rapid intensification.
Case study: Human-caused climate change made the warm waters that fueled Hurricane Beryl up to 400 times more likely
Hurricane Beryl, the first hurricane of the 2024 Atlantic hurricane season, caused an estimated $6 billion in damages and killed at least 37 people in the U.S. since making landfall in Texas on July 8. This doesn’t include damage and fatalities across the Caribbean and Yucatán Peninsula.
Beryl's rapid intensification into the earliest Category 5 Atlantic hurricane on record — which left less time for communities in the storm path to prepare — was fueled in part by exceptionally warm oceans.
Climate Central’s Climate Shift Index: Ocean reveals how human-caused climate change altered the likelihood of these ocean temperatures.
According to Ocean CSI, Hurricane Beryl developed and intensified over unusually warm waters whose temperatures were made up to 400 times more likely by human-caused climate change.
Five ways to use the Climate Shift Index: Ocean
Use the tool. The online map tool allows you to explore data showing which parts of the world are experiencing high Ocean CSI levels — every day.
Share custom maps. Use yellow buttons in the tool’s left panel to share a direct link to a custom map or download the current map view as a PNG file.
Download maps in KML format. The tool’s left panel also includes a link to download daily Ocean CSI maps in KML format for use in TV broadcasts.
Read the FAQs. Review common questions and answers on the science behind the Ocean CSI and expert guidance and caveats on using the tool in climate reporting.
Go deeper: read the peer-reviewed paper. Published by Climate Central scientists in May 2024, this openly accessible peer-reviewed paper presents the science behind the Ocean CSI system.
The interactive Climate Shift Index: Ocean map tool can be used to explore the following at nearly any ocean location for any day from spring 2024 through yesterday:
Sea surface temperature (in either °C or °F)
Sea surface temperature anomaly (difference from 1991-2020 normal)
Ocean CSI level (indicating the change in likelihood of each day’s sea surface temperature in that location due to climate change)
In the map tool, right-click on any ocean location to view detailed data for each of these three conditions.
Record-shattering ocean heat
Since April 2023, global sea surface temperatures have been continuously hotter than any period on record — and by a wide margin.
June 2024 marked 15 consecutive months of record-breaking global sea surface temperatures. Record ocean heat has contributed to NOAA’s outlook for an above-normal 2024 Atlantic hurricane season.
According to NOAA, 36% of the global ocean was experiencing a marine heat wave in June 2024. In the tropical North Atlantic, marine heat wave conditions are forecast to continue through October 2024.
The Climate Shift Index: Ocean provides daily insight into the links between this exceptional ocean heat and human-caused carbon pollution.
Warming oceans put people and ecosystems at risk
We all depend on the ocean. It regulates climate and affects weather on land. It hosts vast biodiversity, provides nutrition for billions, and underpins livelihoods and cultures around the world.
But ocean warming disrupts each of these critical functions. And as the planet has warmed in recent decades, about 90% of the excess heat has gone into the ocean — mostly the surface ocean, which has warmed steadily as a result.
Learn more: Ocean Carbon report and Ocean Warming brief.
Long-term warming and 2023-2024’s exceptional ocean heat have major implications for both tropical cyclones and coral reefs.
Warmer oceans fuel stronger, more costly tropical cyclones
Sea surface temperatures influence the weather we experience on land. Warm water is a necessary ingredient for tropical cyclones, which include hurricanes and tropical storms.
About 80% of major hurricanes (Category 3-5) undergo rapid intensification — defined as an increase in the maximum sustained winds of a tropical cyclone of at least 30 kt (about 35 mph) in a 24-hour period.
And ocean warming contributes to an increased fraction of tropical cyclones that undergo rapid intensification.
Learn more: Extreme Weather Toolkit: Tropical Cyclones
Forecasting rapid intensification can be challenging, which contributes to the high human and economic toll of such storms.
Of the 62 tropical cyclones that have caused at least $1 billion in damage in the U.S. from 1980 to 2023, 69% underwent rapid intensification.
The five most costly hurricanes since 1980 — which caused a combined estimated $680 billion (inflation-adjusted) in damages — all had maximum rapid intensification rates between 40-70 kt in 24 hours.
Climate Shift Index: Ocean can be used to understand the influence of human-caused climate change on unusually warm waters that fuel these impactful events, as demonstrated in Climate Central’s case study on Hurricane Beryl.
Coral reefs: vital, valuable, vulnerable
Coral reefs are the world’s most diverse marine ecosystems. About one-quarter of all marine species depend on corals.
Corals support fisheries that provide nutrition and livelihoods, especially in the tropics. Coral reefs also provide coastal protection during tropical storms. Each year, coral reefs in the U.S. provide $3.4 billion in economic value from fisheries, tourism, and coastal protection.
But these valuable ecosystems are also extremely vulnerable to climate change.
Long-term ocean warming and more frequent marine heatwaves like those currently affecting over one-third of the globe cause heat-stress in corals — which can lead to coral bleaching and death.
In April 2024, NOAA confirmed that the world’s fourth global coral bleaching event — linked to the ongoing record ocean heat streak — had begun, meaning that significant coral bleaching had been reported in every ocean region where warm-water corals live.
During the latest global coral bleaching event (through mid-May 2024), mass coral bleaching has been confirmed in at least 62 countries and territories worldwide.
Climate Shift Index: Ocean can be used to understand the influence of human-caused climate change on unusually warm waters that cause these devastating events.
LOCAL STORY ANGLES
Resources on climate change and tropical cyclones
NOAA regularly updates a comprehensive summary of the science on Global Warming and Hurricanes, and offers a hurricane season Media Resource Guide. Climate Central’s Extreme Weather Toolkit: Tropical Cyclones provides reporting resources and multimedia graphics in English and Spanish.
Official storm forecasts, safety guidance, and risk screening
NOAA’s National Hurricane Center monitors current conditions and provides 2-day and 5-day outlooks for the Atlantic, Eastern Pacific, and Central Pacific. NOAA’s National Hurricane Preparedness site includes safety tips, resources to determine local hurricane risk and evacuation zones, and guidance on insurance checkups. The Ready.Gov hurricanes site provides guidance in 13 languages. NOAA’s National Storm Surge Risk Maps can be used to assess risk in hurricane-prone coastal areas. FEMA’s National Risk Index maps provide hurricane risk levels for counties and census tracts in the contiguous U.S.
How are corals doing across U.S. states and territories?
Use NOAA’s Coral Reef Watch tools and interactive maps to monitor observed and forecasted coral heat stress conditions around the world. NOAA’s Coral Reef Conservation Program monitors and reports on conditions in American Samoa, Commonwealth of the Northern Mariana Islands, Florida, Guam, Hawai’i, Puerto Rico, and the U.S. Virgin Islands.
How does ocean warming affect different U.S. regions?
Check out our Ocean Warming Climate Matters brief for broadcast-ready graphics for 11 major U.S. ocean regions showing long-term sea surface temperature trends and their primary impacts on people and ecosystems in each region.
CONTACT EXPERTS
Andrew Pershing, Ph.D.
VP for Science
Climate Central
Contact: apershing@climatecentral.org
Daniel Gilford, Ph.D.
Climate Scientist
Climate Central
Contact: dgilford@climatecentral.org
FIND EXPERTS
Submit a request to SciLine from the American Association for the Advancement of Science or to the Climate Data Concierge from Columbia University. These free services rapidly connect journalists to relevant scientific experts.
Browse maps of climate experts and services at regional NOAA, USDA, and Department of the Interior offices.
Explore databases such as 500 Women Scientists, BIPOC Climate and Energy Justice PhDs, and Diverse Sources to find and amplify diverse expert voices.
Reach out to your State Climate Office or the nearest Land-Grant University to connect with scientists, educators, and extension staff in your local area.
METHODOLOGY
For detailed information on Climate Shift Index: Ocean calculations, see the FAQs and our peer-reviewed methods paper.