SoCal extreme heat conditions in a warming climate

OVERARCHING QUESTION

How does a warming ocean impact heat waves in Southern California?

• Topic: Extreme heat and its impacts in the coastal zone & sustainable adaptation
• 5-year lifespan, ending in 2027
• Funded by NSF Coastlines and People (CoPe) program
• Comprised of a team of 15+ scientists and educators, and a growing group of collaborators

SoCal Heat Hub

Climate Dynamics

Health Impacts

& EJ

Ecohydrology & Greening

How do ocean, atmosphere, and land processes drive and/or modulate extreme heat across varied coastal zone climates, and what changes are expected with climate change?

What are the locally-specific health impacts of extreme heat, and how do they vary according to land use and socioeconomic factors?

What is the locally-specific relationship between temperature and vegetation? Where/how can vegetation be used for heat adaptation, and what are the associated climate/water resource constraints?

Education to Broaden Participation

Community

Engagement

Goal:

Expand the Hub’s impact through extensive education activities that will broaden participation of underrepresented high school and community college students.

Goals:

Enable long-term, equitable engagement with regional government agencies and community partners.

Develop a framework for broad community engagement centering an equity-first approach ensuring the co-production of research and programs.

Overarching Goals

Advance scientific knowledge and fill knowledge gaps in several fields

Provide government agencies, non-governmental groups, and partner organizations with science-based planning information

Aid in the assessment of existing urban planning efforts and future greening efforts with respect to climate change, health, and long-term sustainability

Empower students from the communities most hard-hit by climate change and extreme heat to participate in building solutions

Establish lasting partnerships for proactive and equitable engagement in the region

Serve as a model for other coastal areas facing similar challenges

2023 - HOTTEST YEAR ON RECORD

Shift in mean temperatures corresponds to a shift in extreme temperatures.

BUT IT’S FREEZING COLD!

https://www.axios.com/local/san-antonio/2024/01/10/cold-weather-texas-freezing-arctic-outbreak

https://www.ucsusa.org/resources/does-cold-weather-disprove-climate-change

GLOBAL ATMOSPHERIC CARBON DIOXIDE

CO₂ over three generations:

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1960: 317 ppm

1990: 353 ppm

2022: 418 ppm

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How much has CO₂ increased?

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1960: 104 ppm

1990: 67 ppm

2022: 3 ppm

https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide

EVERY TON OF CO₂ EMISSIONS ADDS TO GLOBAL WARMING

Temperature increase depends on cumulative CO₂ emissions. Once added to the atmosphere, CO₂ remains for 300-1000 years.

https://climate.nasa.gov/news/2915/the-atmosphere-getting-a-handle-on-carbon-dioxide/

GLOBAL WARMING = OCEAN WARMING

https://www2.whoi.edu/site/argo/impacts/warming-ocean/

Argo profiling floats have measured temperature of the global ocean to 1900m depth since 2004.

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Warming trend at all depths indicates storage of heat associated with global warming.

https://www.frontiersin.org/files/Articles/568494/fmars-07-00700-HTML/image_m/fmars-07-00700-g001.jpg

GLOBAL WARMING = MELTING ICE

surface melt

basal melt

iceberg calving

As global air temperatures continue to rise, all of these components – accumulation, melting and flow rates – are expected to increase.

snow accumulation

Antarctica + Greenland = 60 m SLR

mass gain

mass loss

credit: NASA/JPL

credit: NASA/JPL-Catech

http:/www.argo.ucsd.edu

Thompson et al. (2020), in ”State of the Climate in 2019”

https://doi.org/10.1175/BAMS-D-20-0105.1

SEA

LEVEL

OCEAN

MASS

OCEAN

HEAT

GLOBAL SEA LEVEL BUDGET

ARGO FLOATS

GRACE GRAVITY

SATELLITE ALTIMETRY

MARINE HEATWAVES ARE INCREASING AS THE OCEAN WARMS

https://scripps.ucsd.edu/research/climate-change-resources/californias-marine-heatwaves

https://www.climatecentral.org/climate-matters/2020-ocean-heat-waves

MARINE HEATWAVES – ECOSYSTEM IMPACTS

https://scripps.ucsd.edu/research/climate-change-resources/californias-marine-heatwaves

Positively (winners) and negatively (losers) affected organisms in Southern California during the 2014-16 marine heat wave.

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In other regions, affects may include coral bleaching, tropical storm intensification, and toxic algal blooms.

LAND HEATWAVES AND HUMAN HEALTH

Tarik

PROJECTIONS OF AVERAGE SUMMER AFTERNOON TEMPERATURES

Dan Cayan

Julie Kalansky

Dave Pierce

Sasha Gershunov

Under sponsorship of California Energy Commission, NOAA RISA Program, Southwest Climate Science Center

PROJECTIONS OF AVERAGE SUMMER AFTERNOON TEMPERATURES

Dan Cayan

Julie Kalansky

Dave Pierce

Sasha Gershunov

Under sponsorship of California Energy Commission, NOAA RISA Program, Southwest Climate Science Center

MEDITERRANEAN CLIMATE ZONES

Mediterranean climate zones are characterized by warm dry summers and cool wet winters, with large year-to-year variations in rainfall.

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All our influenced by ocean/air/land interactions.

SOUTHERN CALIFORNIA SUMMER-AVERAGED TEMPERATURE

INLAND MODE

COASTAL MODE

% variability

Hale et al. (2024)

What drives year-to-year temperature variations in the Coastal Zone?

“Coastal Zone”

EXTREME HEATING DAYS IN THE COASTAL ZONE

The number of heatwave days tracks the coastal mode temperature variability.

Number of extreme heating days varies with the Coastal Mode

Coastal mode temperature

Number of heatwave days

As the mean summer temperature increases, so do the number of extreme hot days.

THE COASTAL MODE CORRELATES SIGNIFICANTLY WITH…

Sea surface Temp

Coastal Low Clouds

Wind Speed

…and Scripps Pier Temperature (blue)

°C

3-month running mean

WIND RELAXATIONS AND SUMMER HEATING

Coastal Mode regressed on Winds and SST

JAS mean Winds & SST

Wind relaxations lead to mixed layer warming, poleward coastal flows

WIND-DRIVEN HEAT CHANGE IN THE OCEAN SURFACE LAYER NEAR THE COAST

https://scripps.ucsd.edu/research/climate-change-resources/californias-marine-heatwaves

THE CONNECTION BETWEEN LAND AND OCEAN AIR TEMPERATURES

https://www.dtn.com/how-do-sea-breezes-work/

Sea breeze driven by land/ocean temperature difference. Strongest in the summer. The difference between warm and cool summers -> temperature of the marine layer air, not the strength of the sea breeze wind, or the degree of cloudiness over land.

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https://www.seasonsinthesea.com/may/phys.shtml

Hub Overview

PARTNERSHIP WITH SCHOOLS

Slide: Jennifer Vanos

HEAT CHANGE IN THE OCEAN SURFACE LAYER NEAR THE COAST