The Linnean Society was pleased to welcome Nigel Hepper FLS at an evening meeting on Thursday 9 October 2008 when he spoke about “Phenology and Climate Change”.
Throughout his career as a Systematic Botanist at Kew Herbarium Nigel has used his “spare time” during lunchtimes and after work to note the first flowering dates of species within Kew Gardens and in his own garden. Subsequent graphical analysis of the dates has enabled him to follow changes in climate trends.
He began by outlining the structure of his talk which would focus on the broad issue of climate change, the collection of phenological data and then he would draw the two strands together and finally assess the impact of climate change/global warming on agriculture and horticulture.
In introducing the concept of climate change, Nigel referred to recent and devastating climatic events such as Hurricane Katrina which had itself been attributed to climate change. Careful monitoring of the atmosphere by meteorologists has shown that CO2 levels have increased and that Earth’s temperature is rising at a rate of a quarter degree C every 10 years. This is directly attributable to industrial and over-population atmospheric pollution.
Nigel then outlined his interest in phenology – the study of recurring natural phenomena. He emphasised that the recording of biological events had started in the eighteenth century by notable naturalists such as Gilbert White and Robert Marsham, but it seems that the nearest Linnaeus got to phenology was his floral clock which showed the times of flower opening. Nigel had begun recording flowering dates in his family garden in Leeds while still a student in the 1940s, then continued at Kew and Richmond from the 1950s to the present. Some 6,000 species with one or more annual dates are in the database; for example in 1985 he noted 1,954 species – though most years fewer than that.
Analysis by graphs and average dates shows that such species as wood anemone, crocus, daffodil and bluebells are flowering significantly earlier. These changes in flowering times could be correlated with increase in temperature and further comparative study by meteorologists is promised. There is renewed interest in British phenology through the UK Phenology Network with its numerous recorders, and by other people at home and abroad, such as US scientists in Washington who also concluded that spring is several days earlier than formerly.
All of Nigel’s records have been incorporated into Kew’s computerised ‘historical phenology database’. Since his retirement the “Kew 100” – with 100 selected species flowering through the year – has been officially established for monitoring in perpetuity.
The speaker concluded by assessing the probable impact of climate change on agriculture and gardens. He emphasised that agriculture is vital for food production all over the world, but changes in the climate can be better adapted to in the wealthier countries than in the poorer ones. Sadly, it is the latter with underdeveloped agriculture that will suffer most from climatic change. Dry lands, for example, cover a total of 40% of the total land area of the world and carry 1/5 of the population. If climate change deprives these lands of rainfall a significant area would become unproductive desert, thus depriving the inhabitants of both food and income. Annual crops can be more easily adapted to climate change than slow-growing fruit trees. There are implications for biodiversity, too, and nature conservation. There is a climate crisis and concern for the environment is urgent. Phenology can play a part in monitoring the changes for better or for worse.
See www.kew.org (Conservation & wildlife - phenology database)