Archive · 24 Sep 2026
Rain May Boost Ocean Carbon Absorption by 13.6 Percent
Rain may help the ocean take in more carbon dioxide from the air.
Raindrops collect some carbon dioxide as they fall through the atmosphere.
They also make the salty ocean surface fresher, which helps it hold more gas.
Rain hitting the water creates movement that helps carbon dioxide enter the ocean.
This can create a thin freshwater layer on top of the sea.
Scientists estimate that rainfall could increase ocean carbon absorption by as much as 13.6 percent.
However, the effect is not the same everywhere.
In warm places, the freshwater layer can heat up and absorb less carbon dioxide.
Researchers say more measurements are needed to understand the effect in different seasons and regions.
A University of Notre Dame study found rainfall may increase ocean carbon dioxide absorption by up to 13.6 percent.
Rain dilutes salty surface water, creates turbulence, and carries dissolved carbon dioxide into the ocean.
Rainwater can form a 1-to-3-meter freshwater layer that remains separate from deeper ocean water for hours or days.
Sambuddha Misra cautioned that higher rainfall does not automatically mean greater carbon absorption, especially in warm tropical waters.
Researchers said global carbon calculations may underestimate rain-driven ocean absorption by 5 to 15 percent.
- Who
- Researchers led by the University of Notre Dame, with comments from chemical oceanographer Sambuddha Misra of the Indian Institute of Science.
- What
- A study found that rainfall may increase ocean absorption of atmospheric carbon dioxide by up to 13.6 percent.
- When
- The finding comes from a recent study; the articles do not provide a publication date.
- Where
- The process occurs at ocean surfaces worldwide, with examples discussed for the Bay of Bengal and other regions.
- Why
- Rain dilutes salty surface water, carries dissolved carbon dioxide, and creates turbulence that increases gas exchange between air and water.
Rainfall Has a Larger Carbon Role
The Effect Varies by Region
Overall carbon absorption
Rainfall Has a Larger Carbon Role
The University of Notre Dame-led researchers found that rainfall can increase ocean carbon dioxide absorption by up to 13.6 percent, and said current calculations may underestimate the effect.
The Effect Varies by Region
Sambuddha Misra cautioned that the finding should not be simplified to mean that more rain always produces more carbon absorption.
Tropical versus higher-latitude waters
Rainfall Has a Larger Carbon Role
Rain-driven dilution and turbulence can make surface waters absorb more carbon dioxide.
The Effect Varies by Region
Misra said the effect may be weaker in the tropics because freshwater layers heat up, while the process may be more efficient at higher latitudes.
Confidence in global estimates
Rainfall Has a Larger Carbon Role
The researchers said rainfall effects should be included in calculations of carbon exchange between the ocean and atmosphere.
The Effect Varies by Region
Misra said more in-situ, regional, and seasonal measurements are needed before the effect can be fully assessed.
- Potential increase
- Up to 13.6 percent more ocean carbon dioxide absorption
- Estimated undercount
- Global carbon calculations may underestimate rain-driven absorption by 5 to 15 percent
- Freshwater layer depth
- Typically about 1 to 3 meters
- Layer duration
- The freshwater layer can remain isolated for hours or sometimes days
- Main mechanisms
- Dilution, turbulence, and carbon dioxide carried by raindrops
- Important limitation
- Warm tropical waters may reduce the effect as the freshwater layer heats up
- Needed research
- In-situ measurements and regional and seasonal studies