Climate Change & the Carbon Cycle

Climate change is a global-scale problem with major implications for human and ecological systems. Earth’s climate has operated for millennium within an equilibrium state between the atmosphere, ocean and terrestrial systems. As the burning of fossil fuels and landscape alterations, such as deforestation and industrial agriculture, mobilize fossil carbon into the atmosphere, the earth’s carbon cycle is pushed out of balance and climate changes.

Human generated climate change is an enormous perturbation in the global carbon cycle. Prior to the modern industrial world, events such as volcanism, sea floor rifting, and meteorite impacts determined the global carbon cycle. Now, human activities dictate much of the movement of carbon around the world. Once released into the atmosphere, greenhouse gases, such as carbon dioxide and methane, can change the thermal conductance of the atmosphere, the chemistry of seawater and the movement of our oceans.

Who drives the global carbon cycle: the ocean or the atmosphere? To answer this question, we have to look at the mass balance of carbon in both the atmosphere and ocean. In preindustrial times, the atmosphere contained 578 Pg (Pg=Petagrams, 1 Pg=1 billion metric tons) of carbon. The modern atmosphere contains at least 766 Pg of carbon. To compare, the global oceans contain roughly 38,000-40,000 Pg of carbon! The oceans contain roughly 50 times more carbon than the atmosphere, meaning the ocean is the driver of the global carbon cycle, not the atmosphere. This dynamic is important to remember when considering modern climate change. 

Today, the carbon content of the atmosphere is driving changes in the carbon content of the ocean. This is a large role reversal in the way our Earth’s systems naturally operate, and thus modern climate change is an event that has no analogue in the past. The carbon content of our atmosphere is steadily rising and our global ocean is slowly absorbing this abundance of atmospheric carbon. As many scientists say, climate change is a vast global experiment with very uncertain outcomes for human and biological communities. 

To adapt to climate change, our oceans need healthy, resilient ecosystems that can act as refuges in the face of new stresses. Our Global Ocean Refuge System (GLORES) initiative works to unite the marine protection community, recognize lasting marine protections and incentivizing new efforts worldwide. Its goal is to create an urgently-needed worldwide system of strongly protected areas as a strategic way to ensure the future diversity and abundance of marine life. Become an Ocean Guardian or donate to support our work to enhance the ocean’s climate change resiliency.