Climate change: how will it hurt our tiniest life?

Professors Louis Schipper (left) and Vic Arcus (right) from the University of Waikato are looking at whether there's a single theory of temperature dependence that applies to life. Photo / Supplied

Climate change is poised to transform landscapes and coastlines – but what will it mean for those tiniest forms of life?

Kiwi researchers have begun a major study, spread across a range of time scales and global ecosystems, investigating whether there's a single theory of temperature dependence that applies to life.

"What we find can tell us more about how things have evolved through time as temperature has changed, and it will allow us to make better predictions about how the biology of the world is going to change as the world warms up," said one of the project's leaders, Professor Louis Schipper of Waikato University.

The crux of the study, supported with a $3m Marsden Fund grant, comes down to how enzymes - macromolecular biological catalysts that speed up chemical reactions in the body – affect biology at different temperatures.

"Enzymes have a weird response to temperature," explained study co-leader Professor Vic Arcus.

"But if everything biological needs enzymes, then the enzymes' response to temperature determines how biological systems respond to temperature."

That, he said, was fundamentally different to how chemical reactions, without enzymes, responded to temperature.

"It's like baking a cake versus baking bread. When baking a cake, you have chemical reactions that occur as the temperature increases. For example, you add baking soda to the mixture, put it in the oven, and the cake rises.

"When you bake bread, you add yeast which is a micro-organism. The way yeast responds to temperature is fundamentally different to the way a cake responds to temperature.

"If we understand how yeast responds and how enzymes in yeast respond to temperature, then we can understand how biology is going to behave as the temperature changes during the day, or between seasons or in a warming world."

Arcus and Schipper have been looking at the relationship between photosynthesis, or fixing carbon dioxide from the atmosphere and producing oxygen, and plant respiration, the process of plants taking in oxygen and releasing it as carbon dioxide.

"The really significant example we're working on is what's going to happen to the carbon dioxide in the atmosphere as the temperature goes up," Arcus said.

"We're adding all this carbon dioxide from fossil fuel, but biology is responding to that and it's very unclear how biology is going to respond if temperatures continue to rise.

"If you want to know what the whole biosphere is going to do as the temperature goes up, you need to know what photosynthesis and respiration are going to do.

"Where will we need to intervene to sustain food and fibre production and biodiversity as ecosystems come under increasing heat stress?"

Their experiments will range from using computers to model how molecules change their behaviour with changing temperature, making direct measurements of enzyme activity, how carbon cycling in soil, plant photosynthesis, and using global data of decades of how ecosystems have responded to the last two decades of climate change.

If successful, they could answer whether there was a single theory for what was being observed across a range of scientific disciplines.

"Vic came up with this beautiful equation, and beautiful theory, that we are testing," Schipper said.

"We don't yet know if it's absolutely correct, but it comes from really strong theoretical background and it explains what we both observe, and what our other colleagues observe, in our respective scientific fields."