How a warming planet is threatening ocean cycles that fuel our atmosphere, food chain, and weather patterns.

The ocean’s phytoplankton, also known as marine algae, is the planet’s most important organism. They generate at least half of the oxygen we breathe, and are a vital component in the ocean’s food chain.

So when researchers find trouble among phytoplankton, which has dramatic implications for the marine food web and the world’s carbon cycle, we should pay attention.

According to researchers at Canada’s Dalhousie University, phytoplankton populations have dropped 40 per cent since 1950.

Recently published studies have shown that these populations are continuing to fall. Scientists interviewed by Al Jazeera are concerned that our world’s oceans are growing increasingly instable and unhealthy.

Global warming’s effects on marine cycles and ocean chemistry are going to be hot topics at the upcoming Rio+20 United Nations Conference on Sustainability next month in Brazil.

Al Jazeera’s investigation has revealed serious warning signs.

Phytoplankton

Phytoplankton, which are microscopic single-celled organisms, absorb carbon dioxide in order to produce 50 per cent of the world’s oxygen, an amount equivalent to that of all the trees and plants on land.

Alarmingly, there has been an annual drop of about one per cent of the average plankton population between 1899 and 2008, and scientists like Dr Michael Latz with the Scripps Institute of Oceanography believe that rising sea surface temperatures are to blame.

Latz, a marine biologist, specialises in bioluminescent phytoplankton, which produce light through photosynthesis. Latz believes that by monitoring these organisms’ bioluminescence, it is possible to assess the health of the oceans.

“As global warming changes ocean flows, these micro-organisms are increasingly at risk,” he said. “Changes in phytoplankton will impact all of the food chain.”

Read the full story at Al Jazeera English.