Ocean ecosystems constitute more than 70% of the Earth’s surface area, and these
massive watery habitats are home to some of the smallest organisms on the planet.
These abundant microscopic organisms influence climate through the production
and consumption of greenhouse gases such as carbon dioxide (CO2). Since 1988, the
Hawaii Ocean Time-series (HOT) program has studied the open ocean waters of the
subtropical North Pacific Ocean, one of Earth’s largest ecosystems. More than 25
years of monthly HOT program observations have yielded numerous discoveries on
the importance of microorganisms in sustaining Earth’s habitability, including the
role these organisms play in the production of oxygen and consumption of CO2
through photosynthesis. HOT measurements also highlight steady increases in
ocean CO2 concentrations and seawater acidity in response to human-derived
atmospheric CO2. Such time series observations are necessary for helping to build
understanding of how changes in Earth’s climate are influencing marine life.