The global temperature record is expected to exceed 1.5 degrees Celsius for the first time this year. This has happened sooner than anticipated. So could life on the planet adapt so quickly?
In our new research, published today in Nature, we explored the ability of tiny marine organisms called plankton to adapt to global warming. Our conclusion: Some plankton are less able to adapt now than in the past.
Plankton live in the top few meters of the ocean. These algae (phytoplankton) and animals (zooplankton) are moved by ocean currents because they do not actively swim.
The frequency of heat waves in the ocean is increasing due to climate change. But predicting the future impacts of climate change is difficult because some projections rely on ocean physics and chemistry, while others consider impacts on ecosystems and their services.
Some data suggest that current climate change has already dramatically altered marine plankton. Models predict both a shift of plankton toward the poles (where ocean temperatures are cooler) and a loss of zooplankton in the tropics, but cannot predict the patterns we observed in the data. Satellite data for plankton biomass are still too short term to determine trends through time.
To overcome these problems, we compared how plankton responded to past environmental changes and modeled how they might respond to future climate changes. As scientist Charles Lyell said, “The past is the key to the present”.
We discovered one of the best fossil records ever from a group of marine plankton with hard shells foraminiferaThis comprehensive database of current and past distribution, compiled by researchers at the University of Bremen, has been collected by hundreds of scientists from sea floors around the world since the 1960s. We compared data from the last Ice Age, about 21,000 years ago, and modern records to see what happened when the world first warmed.
We used computational models to simulate marine ecosystems from the last ice age to the pre-industrial era, linking climate trends with marine plankton characteristics and their effects on marine plankton. Comparing the model with data from the fossil record gives us support that the model simulates the rules governing the evolution and distribution of plankton.
We found that the optimal temperatures for extreme growth and reproduction of some subtropical and tropical species may have been offset by warming seawater in the past, which is supported by both fossil data and models. Cold water species of plankton managed to thrive under more favorable water temperatures.
Our analysis shows that foraminifera Can handle natural climate change, even without the need to adapt through evolution. But can they cope with current temperature increases and future changes in ocean conditions, such as temperatures?
future of the food chain
We used this model to predict the future under four different degrees of warming, from 1.5 to 4 degrees Celsius. Unfortunately, the ability of these types of plankton to cope with climate change is much more limited than during previous warming. Our study highlights the difference between rapid human-induced and slow geological warming for marine plankton. The current climate change is very rapid and the food supply is decreasing due to ocean stratification, making it difficult for plankton to adapt to these times.
Phytoplankton produce about 50% of the world’s oxygen. So every second breath we take comes from seaweed, while the rest comes from plants on land. Some plankton eat other plankton. That in turn is eaten by fish and then marine mammals, so energy is transferred further up the food chain. Because it photosynthesizes, phytoplankton is also a natural carbon fixation machine, storing 45 times more carbon than the atmosphere.
Around the world, many people rely heavily on food derived from the sea as their primary protein source. When climate change threatens marine plankton, it has a huge impact on the rest of the marine food web. Marine mammals like whales that eat plankton will not have enough food to hunt and there will be less fish for predators (and people) to eat. Reducing the intensity of warming and slowing the rate of warming are essential to protect the health of the ocean.
,Author: Rui Ying, Postdoctoral Researcher, Marine Ecology, University of Bristol and Daniela Schmidt, Professor in Palaeobiology, University of Bristol
disclosure statement, Rui Ying received funding from the China Scholarship Council for this study.
Daniela Schmidt received funding from NERC. She is a member of the NERC Science Committee and the Council of the Paleontological Association.)
This article is republished from The Conversation under a Creative Commons license. Read the original article.
