Since the Industrial Revolution, the acidity of our oceans has increased by 30% and the amount of carbon dioxide in our atmosphere has increased by over 35%, primarily from the burning of fossil fuels. Human activities have also introduced higher levels of other greenhouse gases such as methane and nitrous oxides. The result? The “evil twins” of global warming and ocean acidification.
Setting the Stage and Feeling the Heat
Oceans play a fundamental role in shaping our climate. We have the ocean and ocean life to thank for enabling the world as we know it, by setting the concentration of gases within our atmosphere, acting as a climate thermostat and facilitating energy, water and carbon exchange within the climate system.
Scientists say that our ability to understand the history of climate change and predict what might happen to earth’s climate in the future, depends on boosting our understanding of how oceans affect our climate.
The ocean also serves to help mitigate climate change by acting as a sink for a portion of the heat building up in earth’s climate systems and for the increasing levels of carbon dioxide in our atmosphere. Coastal systems such as such as mangroves, salt marshes and seagrass meadows can absorb, or sequester, carbon at rates up to 50 times those of equivalent area of tropical forest.
But the ocean may be bearing more of the burden of climate change than we collectively realize. Our oceans are especially vulnerable to the impacts from human-caused emissions. Growing acidification, sea level rise particularly from polar ice cap melts, and changes in temperature and currents are stressing the health of ocean life and their ecosystems, and threatening our coastal communities.
The challenge for researchers is to understand and model critical aspects of our oceans and the impacts on climate change.
How the ocean affects our climate
The world’s ocean is crucial to keeping our planet comfortably warm to inhabit. The ocean acts like a massive heat-retaining solar panel that absorbs the sun’s radiation, particularly in tropical waters around the equator. Earth’s atmosphere also retains heat and land areas play a supporting role.
The ocean not only stores solar energy, it also helps to distribute heat around the planet through evaporation. Ocean water is constantly evaporating which increases the temperature and humidity of the surrounding air to create rain and storms that are then carried by trade winds. Almost all rain that falls on land comes from the ocean.
Tropical areas are especially rainy and wet due to the higher heat absorption, and ocean evaporation. Elsewhere in temperate areas, ocean currents are the primary drivers of weather patterns. These currents move warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics.
In this way, currents regulate global climate, helping to counteract the unevenly distributed radiation and heat from the sun.
Other processes at work in the ocean impact our weather. The phytoplankton, for example, release large quantities of a sulfurous gas called dimethyl sulfide which changes the way clouds are formed in the atmosphere. Differences in ocean and and air temperature drives regional climate, such as monsoons.
Warmer surface water dissipates more readily into vapor, which can make it easier for small ocean storms to escalate into bigger systems. Many weather experts say we are seeing the effects of higher ocean temperatures in the form of stronger and more frequent tropical storms and hurricanes/cyclones.
Gradually warmer temperatures has started to release another greenhouse gas, methane. Natural “marsh gas” is stored in huge masses as frozen methane hydrate in cold continental shelves. Release of this gas at the ocean’s edge is a serious concern, since methane is a more potent greenhouse gas than carbon dioxide volume for volume, even though it has a shorter life in the atmosphere.