A study published in Science Advances by an international team of scientists provides clear evidence that marine phytoplankton are much more resilient to future climate change than previously thought.
Photosynthesizing algae play an important role in marine life. According to new computer model simulations, a metabolic hack makes phytoplankton more resilient to 21st century climate change than previously thought. Credit: Institute for Basic Science Combining data from the long-term Hawai'i Ocean Time-series program with new climate model simulations conducted on one of South Korea's fastest supercomputers, the scientists revealed that a mechanism, known as nutrient uptake plasticity, allows marine algae to adapt and cope with nutrient-poor ocean conditions expected to occur over the next decades in response to global warming of the upper ocean. Phytoplankton are tiny algae which drift at the ocean's surface and form the basis of the marine food web. While photosynthesizing, these algae absorb nutrients (e.g., phosphate, nitrate), take up dissolved carbon dioxide and release oxygen, which makes up for about 50% of the oxygen that we breathe. Knowing how marine algae will respond to global warming and to associated decline of nutrients in upper ocean waters is therefore crucial for understanding the long-term habitability of our planet. How the annual phytoplankton production rate will change globally over the next 80 years remains highly uncertain. The latest report of the Intergovernmental Panel on Climate Change (IPCC) states an uncertainty of -20% to +20%, which implies an uncertainty as to whether phytoplankton will increase or decrease in future. Global warming affects the upper layers of the ocean more than the deeper layers. Warmer water is lighter and hence the upper ocean will become more stratified in future, which reduces mixing of nutrients from the subsurface into the sun-lit layer, where phytoplankton reside. Earlier studies suggested that the expected future depletion of nutrients near the surface would lead to a substantial reduction of ocean's…