IMPACTS OF CLIMATE CHANGE
ON PLANT DIVERSITY IN SOUTH AFRICA

PLANT PARADISE

Boasting more than 23 000 indigenous species, South Africa truly is a plant paradise. Climate has a lot to do with this rich diversity. Across the country, variations in temperature and rainfall patterns provide very different growing conditions for plants. The semi-desert of the dry west contrasts dramatically with the subtropical vegetation of the east coast, while the fynbos is as unusual in Africa as the winter rainfall that supports it. What will happen to these familiar patterns of vegetation if predictions about global climate change prove to be correct? Researchers from the National Botanical Institute and University of Cape Town have been investigating the possible effects of global climate change on indigenous plant diversity in South Africa. This study is one of the first research programmes in the world to link the issues of climate change and biodiversity conservation, thereby servicing both the United Nations conventions on Biological Diversity and Climate Change. Various research institutes have recently been involved in the South African Country Study on Climate Change. This wide-ranging research programme has investigated the effects of climate change on everything from water provision to plant and animal distributions, agricultural production and the spread of diseases. This report summarises the findings of the Plant Biodiversity study.

IS THE CLIMATE CHANGING?

Our lifespans represent a mere snapshot in time. While we mark the decades, Earth history is measured in thousands to millions of years. So we could be forgiven for thinking that climate change is something new. But it's all happened before. Over the last 500 000 years, the Earth has warmed and cooled at least 20 times, with glaciers retreating and advancing and sea levels rising and falling in response. Sometimes changes have been rapid and extreme, with mean temperatures fluctuating by more than 2°C in 50-100 years.

What is new, however, is that this time people are causing the Earth's climate to change. Recent research shows that temperatures are rising higher and faster than can be explained by natural phenomena such as solar activity Instead, rising temperatures mirror increases in the concentrations of so-called 'greenhouse gases'. Gases like carbon dioxide and methane naturally trap heat in the atmosphere, making the Earth a pleasant place to live. But in the last 150 years, fossil fuels have powered the industrialised world, carbon dioxide levels have increased by more than 35%, and the 'greenhouse effect' has gotten out of hand. We are starting to feel the effects of an atmosphere polluted by the by-products of progress.

So is the climate really changing? Draw your own conclusions:

• Temperature reconstructions since AD 1000 indicate that the 20th Century was unusually warm - and the 1990s was the hottest decade on record.
• Global sea levels rose 10-25 cm in the last century.
• Glaciers in the European Alps have lost half their volume since the 1850s.
• In the Antarctic, the five most northerly ice shelves retreated dramatically between 1945 and 1995.
• The Arctic ice-cap has thinned by 40% since the 1950s.
• The ranges of 63% of non-migratory European butterfly species have shifted northwards by 35-240 km since 1900.