A collaboration of coast and countryside organisations on The Lizard Peninsula

Sun settiing on the Lizard

New climate study reveals that parts of Lizard have officially become subtropical

In 1966, the geographer Glenn Thomas Trewartha, of Cornish-American descent, developed the world famous classification system for grouping climates into polar, boreal, temperate, subtropical and tropical. Using this system, regions in which temperatures are 10ºC or greater for 4-7 months of the year are considered temperate, and those with temperatures of 10ºC or greater for more than 7 months of the year are considered subtropical. At that time the system was developed, despite popular belief, all parts of Cornwall lay firmly in the temperate zone.
Temperature change map of the LizardResearchers from the Environment and Sustainability Institute in Penryn, Cornwall, have developed new techniques for modelling local microclimates.

The model captures the effects of terrain, sea temperatures, altitude and soil properties to predict local temperatures, which can differ greatly from those measured at weather stations. Using these models, they have been able to track how the climate has changed across the Lizard Peninsula over the last 40 years at a spatial resolution hitherto not possible. These models show that parts of the Lizard, since the turn of the millennium, have officially become subtropical. Walk along the coast path or visit some of the sheltered valleys, and technically speaking, the climate you experience has more in common with that of Florida or southern Brazil than it does with the rest of the UK.

However, the research was done for a more serious purpose. Over the course of this century, climate change is likely to become the greatest threat to biodiversity in many regions of the world. As temperatures continue to warm it is thought that locations with suitable climate will soon lie beyond the dispersal range of many species. However, this new fine-scale model offers hope. It reveals that some parts of landscape have experienced less warming. These variations, though quite small, have profound knock-on effects on the aspects of our climate that are meaningful for species, such as exposure to high temperatures or the length of frost-free season, which in some places has shortened slightly, but in others has lengthened by almost two months.

Lizard warming between 1977-2014    Changes in the length of frost free period
Total warming between 1977 and 2014. While all parts of the landscape have warmed to some extent, some parts have experienced more warming than others.   Change in the length of the frost-free season. Some parts of the landscape have experienced very little change, whereas others a lengthening by almost two months.

These variations are important. Some of the species found on the Lizard, such as the sandwort shown here, are typically found in cooler climates Sandwortand one might expect them to struggle to survive as temperatures increase. However, it is likely that they will cling on at the locations that experience the least warming.

Indeed, the rich history of botanical recording on the Lizard has allowed us to test whether this might be the case. Comparing the flora at locations 40 years ago with flora now shows that little change in the areas experiencing the least warming, whereas in other areas, species associated with cooler and damper conditions have been lost.


Further details of the work can be found in several scientific papers:
Maclean IMD, Suggitt AJ, Wilson RJ, Duffy JP, Bennie JJ (2016) Fine‐scale climate change: modelling spatial variation in biologically meaningful rates of warming. Global Change Biology, in press.
Greenwood O, Mossman HL, Suggitt AJ, Curtis RJ, Maclean IMD (2016) Using in situ management to conserve biodiversity under climate change. Journal of Applied Ecology, 53: 885–894.
Maclean IMD, Hopkins JJ, Bennie JJ, Lawson CR, Wilson RJ (2015) Microclimates buffer the responses of plant communities to climate change. Global Ecology and Biogeography, 24: 1340-1350.

Published: Sept 2017
Author:  Ilya Maclean (Senior Lecturer in Natural Environment, Exeter University)