What will the future hold for plant growth?

Plant responses to climate change can have huge consequences for water supply, pollination, crop production and ecosystem health

Plants are proving to be much more sensitive to the nuances of climate change than scientists expected.

In a major research project conducted at the University of California San Diego, scientists analyzed 50 plant studies that included 1,634 plant species on four continents. They found that shifts in how plants time their flowering and leafing because of warming temperatures seemed to be much greater than previously estimated by their own warming experiments.

The results of the research were published last week in the journal Nature.

The UCSD press release written by Kim McDonald stated that plant responses to climate change can have huge consequences for water supply, pollination, crop production and ecosystem health. The shifts in the timing of seasonal changes, something biologists call phenology, are among the most dependable and visible responses to a change in climate.

“This suggests that predicted ecosystem changes, including continuing advances in the start of spring across much of the globe, may be far greater than current estimates based on data from experiments,” said Dr. Elizabeth Wolkovich who is a Postdoctoral Research Fellow at UBC’s Biodiversity Research Centre. She led an interdisciplinary team of scientists that conducted the study while she was a postdoctoral fellow at the University of California, San Diego.

There’s no doubt the seasons are changing and the warming trend, while persistent around the globe, has local/regional variations. According to NASA, 2011 was the 9th warmest year on record since 1880 and nine of the ten warmest years in the modern meteorological record have occurred since 2000. But, for Chilliwack, 2011 was the coolest year since 1996 mainly due to the coldest February since 1994 and the coolest April to July period since 1964.

The warming trend, though, is shifting back. From December to February, mean temperatures in Chilliwack were slightly above normal at 0.25oC above the 30-year average. According to Roger Pannett, volunteer weather observer for Environment Canada, last month was the warmest April since 2005. Mean temperatures were 0.99oC above normal.

And weather patterns are likely to shift again now that the cool-trend La Nina cycle is over and Pacific Ocean currents are in a neutral pattern.

The biologists in San Diego created new global databases of plants’ sensitivity to temperature and how much they shift their timing of leafing and flowering with the shift in warming. Their calculations were done from experiments and then compared to long-term monitoring records.

But they found that their experiments under-predicted how quickly plants responded to temperature by at least four times compared to long-term records.

Historical records consistently showed that, on average, leafing and flowering advances five to six days per one degree Celsius and it seemed to be consistent across all species of plants and data records.

“These findings have extensive consequences for predictions of species diversity, ecosystem services and global models of future change,” said Elsa Cleland, an assistant professor of biology at UC San Diego and senior author of the study, which involved 22 institutions in Canada, Sweden, Switzerland, the U.K. and the U.S.

Scientists have estimated that the world’s average global temperature has risen by 0.8oC since 1900. It could exceed 2oC this century, a threshold that risks weather extremes that could lead to drought, flood, rising sea levels and crop failures.

The research opens up many questions on the future health of food chains and ecosystems. Will the growth and flowering of plants responding to a warming world be a lot faster than current models might estimate? How will that affect pollination, the health of habitats, and crop growth at a time when we are already worried about the need to increase food production for the world’s rapidly expanding population?