by Chad Bishop
If you have lived in San Diego for more than ten minutes, you have probably heard three things. The weather is perfect. The housing prices are not. And the sky occasionally features suspiciously straight white stripes that make you wonder whether someone is doodling above Mission Bay. Those streaks are regular aircraft contrails created when hot engine exhaust meets cold upper atmosphere air. NASA has extensive atmospheric data explaining how humidity, temperature, and pressure can make these icy trails linger or spread. Despite all of this well documented science, many locals still joke that it is the government testing early access climate engineering over La Jolla. If that were true, I wish they would turn the knob up during heatwaves.
What Is Climate Engineering Really
Climate engineering, also known as geoengineering, refers to deliberate, large scale interventions in Earth’s climate system intended to reduce the effects of global warming. This concept is not fringe. The National Academies of Sciences released a comprehensive report in 2021 encouraging expanded research to understand benefits, risks, and ethical considerations. The two main categories of climate engineering are Solar Radiation Management and Carbon Dioxide Removal.
Solar Radiation Management
Solar Radiation Management focuses on reflecting a small portion of sunlight back into space. Harvard’s Solar Geoengineering Program has models showing that even a one percent reduction in incoming sunlight could reduce global temperatures significantly. Examples include stratospheric aerosol injection, inspired by natural events. When Mount Pinatubo erupted in 1991, global temperatures cooled by roughly half a degree Celsius for about a year. Another method is marine cloud brightening, which involves increasing the reflectivity of low clouds. Researchers at the Scripps Institution of Oceanography at UC San Diego have studied how this technique could cool coastal regions without seriously altering inland weather.
This is the category that inspires many of the chemtrail jokes around San Diego. Crisscrossing flight paths above Kearny Mesa make it easy for the imagination to wander. True stratospheric aerosol injection, however, would require coordinated international monitoring, satellite observation, and precise atmospheric measurements. In other words, a lot more than ordinary commercial flights creating neat little patterns over the 805.
Carbon Dioxide Removal
Carbon Dioxide Removal aims to reduce the amount of CO₂ already in the atmosphere. According to the Intergovernmental Panel on Climate Change, large scale carbon removal will almost certainly be needed to meet global climate goals. Current approaches include direct air capture facilities like those developed by Climeworks, supported by the United States Department of Energy. Other methods include reforestation, which is effective but limited by available land, and experimental ideas such as ocean fertilization. Research from the Monterey Bay Aquarium Research Institute shows that while ocean fertilization may increase phytoplankton growth, it could also create ecological consequences that are not yet fully understood.
Why Climate Engineering Matters Especially in San Diego
San Diego is already experiencing intensified climate impacts. Heatwaves are more frequent, wildfire risk is increasing, coastal bluffs are eroding, and atmospheric rivers bring stronger flooding events. Scripps Oceanography has documented that the waters off San Diego’s coast are warming at a rate faster than the global average. The warm water stresses ecosystems including the kelp forests near La Jolla Shores. These trends push researchers and policymakers to consider every available tool. Climate engineering is not meant to replace emissions reduction but may serve as a supplemental measure if warming accelerates beyond current expectations.
Should We Actually Use Climate Engineering
The answer is complicated. Solar Radiation Management has the potential to cool global temperatures within months. The Geoengineering Model Intercomparison Project shows that carefully applied sunlight reflection could reduce heat related deaths and protect crops during extreme warming. The financial cost would be surprisingly low compared to the cost of climate damages each year.
The risks are significant. Regional rainfall patterns could shift. Questions of global governance arise regarding who sets the thermostat. And the most concerning issue is termination shock. If the world relied on Solar Radiation Management for many years and suddenly stopped, temperatures could rise dramatically in a short period of time. Most scientific leaders, including those at UC San Diego, agree that Solar Radiation Management cannot be treated as a standalone answer. It can only be considered as part of a broader strategy.
Carbon Dioxide Removal avoids many of these governance issues and addresses the core problem of greenhouse gas concentration. The challenge is scale. To meaningfully alter atmospheric CO₂ levels, enormous investment and infrastructure development would be required for decades.
And Now The Obligatory Chemtrails Section
Contrails form when water vapor in jet exhaust freezes into tiny crystals in cold upper atmosphere air. NASA, NOAA, the Federal Aviation Administration, and the American Meteorological Society have all published extensive explanations of the science behind contrails. Still, the sky over North Park sometimes looks like the world’s largest dry erase board, so the jokes persist. True climate engineering would involve transparent monitoring, international cooperation, and consistent atmospheric signatures. Random crossing contrails above Pacific Beach simply reflect busy flight schedules.
Final Thoughts
Climate engineering is not a quick fix, but it may become part of the global climate toolkit if warming continues at its current pace. San Diego, with its strong research community and its habit of suspiciously staring at the sky whenever a JetBlue flight passes overhead, is likely to play a major role in the research and policy conversation.
Whether this future includes marine cloud brightening experiments off Point Loma or carbon removal hubs in Otay Mesa, the decisions ahead require scientific rigor and global cooperation. Not panic and definitely not viral TikTok videos about secret programs hiding in plain sight over La Jolla.
Until then, we will keep glancing upward at the crossing contrails, wondering whether San Diego is simply experiencing heavy air traffic or getting a sneak preview of Earth’s next climate PowerPoint slide.
Chad Bishop 