Ross Cameron, Professor of Environmental Horticulture at Sheffield University, spoke to us on the implications of climate change, some aspects of which present a science fiction scenario unless the problems are addressed. Global warming is expected to bring – obviously – warmer temperatures, but also greater turbulences with occasion severe hurricanes and deep water freezing.
Bio-geology will reach physical tipping points by 2100 unless steps are taken to slow down the warming. The transition to renewable energy will slow the release of carbon dioxide into the atmosphere. Currently, the temperature is 1.2 degrees centigrade warmer than in the pre-industrial age. We are getting more heat waves, we are getting more extreme rainfall and sea levels are rising. There will be more droughts and inconsistent water supplies, there will be a loss of biodiversity, plant species will move further north, food supplies will become endangered and temperatures could rise by four degrees by the end of the century.
Homeowners will need to rethink what goes into their gardens because, by 2050, there are predictions that London’s temperature will be the same as Barcelona’s is at present. This will affect planting because, already, the soil is drying. By the middle of the century, half of England will have temperatures similar to London’s present climate. Plants cannot cope with the aridity and the flood variability. Atypical seasons will become more common, with floods and cracking soil occurring in the same summer.
Ross did some research with primulas, and how they might cope with atypical summers, using the Primula Vulgaris and three other varieties, Primula Cottage Cream, Primula Alaska and Primula Forza. The potted plants were given a drought and a water-logging four times over a 10-week period. Vulgaris suffered and then bounced back, Cottage Cream didn’t suffer as much, while Forza and Alaska were much more susceptible to the stress.
We can look for species that cope better with drought. Should we stick to native plants, or should we look at Mediterranean varieties or even equatorial plants?
The Royal Horticultural Society is doing more research to check the resilience of different plants. Prof Cameron explained that different areas of England have different problems.
Areas that will have to cope with too much rainfall could divert water into gardens, ponds or storage tanks, mini-dams or ‘green sponge’ wet meadows. Planting trees in in city areas gives a cooling effect and, as trees provide shade and water run-off, flooding is reduced. Planting some plants next to the walls of buildings could give up to 25 degrees of cooling (Ross’s work currently includes supervising PhD projects on improving the thermal performance of buildings through appropriate plant selection, for example on both green walls and green roofs).
In conclusion, Ross told us, we need to move to a carbon-free economy immediately. Floods, fires and droughts, and sea level rises, impact on crop productions which threatens humanity. Identifying plants that can cope with climate oscillations is very challenging and will likely narrow the species we can use, even though plants themselves provide some adaptation.