Plant responses to climate change: impacts and adaptation

Pre-industrial global atmospheric carbon dioxide (CO2) concentration (Ca), was ca. 280 mu l l(-1), is now 376 mu l l(-1) and may be 700 mu l l(-1) by 2100. Temperature is now ca. 0.6 degrees C greater than pre-industrially, and may be ca. 4 degrees C greater by 2100. Warming is decreasing frost, snow and ice cover. Rain may increase in some areas, particularly high latitudes, but decrease in others. Also cloud, and therefore solar radiation reaching vegetation, will change. Agriculture must adapt to such changes, which affect crop growth, yield, and pests and diseases. Stimulation of yields of cereals, sugar beet, potatoes, pastures and forests by ca. 20-30% is expected with Ca of 700 mu l l(-1). This results from increased photosynthesis. However, heat speeds respiration and crop development, shortening the growing season and thus limiting yield; a 4 degrees C rise decreases dry matter by ca 20-30% in cereals and 20% in sugar beet. Quality of products (N-content, types of proteins in grain, and sugar beet storage tissue) are also affected. The biochemical and physiological mechanisms responsible for these effects are discussed, emphasising crop interaction with environment, including nutrition and water. Rates of environmental change are very rapid, however technology including plant breeding - but probably not current genetic engineering methods - may allow adjustment. Socio-economic pressures (consumer demand, world trade etc) may affect agriculture more than climate change per se. Advanced simulation modelling, linked closely to agronomic and plant research, is required to assess the consequences of putative changes on such complex systems.