The distribution and physiology of plants are constantly changing over different time scales as the plants are affected by changes and fluctuations in the environment. Recently, climate change has received much attention, and there is increasing evidence that it is already having an effect on some species, not only on their distribution but also on the timing of key events, such as leafing and flowering. With global temperatures predicted to increase by 1.4–5.8°C (2.5–10.4°F) over the period 1990–2100, and global precipitation predicted to increase (but with regional variation), it is important to assess the implications of such changes and to identify which ecosystems and plants might be particularly vulnerable.