The one bright note in global warming is seemingly that higher carbon dioxide levels will make food crops grow faster. More crops should equal more food. But, as this feature article emphasises, the story is not that simple.

Initial tests have shown that plants grown in high carbon dioxide environments could be less nutritious — with lower protein levels and a different type of protein produced. Other scientists have found a drop in key micronutrients such as chromium, selenium and zinc in high carbon dioxide environments.

Mitigating these changes can involve increasing nitrogen levels to offset protein deficiency, although not all scientists agree on this.

What is clear is that there is very little research in this area and past studies have only looked at carbon dioxide concentrations of 550 parts per million, which is lower than levels predicted by the end of this century.

Paul Reiter, a researcher on insects and infectious disease at the Institut Pasteur in France, is not convinced that climate change will cause a rise in malaria in tropical regions. In this opinionated review he sets out to dispel widely held "common misconceptions" about the effect of climate variability on future transmission.

To do so, he examines the history of malaria. He finds that in the past, contrary to expectations, climate has often not affected the transmission of the malaria parasite. Researchers claim that the Anopheles mosquito that carries the parasite cannot survive extreme temperatures, yet Reiter cites examples of the mosquito finding ways to adapt. In Sudan, for example, they can survive temperatures of over 55 degrees Celsius by hiding in buildings in daytime and only feeding after midnight.

Reiter's main disagreement with prediction models is that they only look at how one climate variable, temperature, is likely to interact with mosquito populations. Temperature, rainfall and humidity are interconnected and cannot be analysed separately, he says. The ecology of mosquitoes and humans is too complex to predict future malaria prevalence and incidence from temperature alone, he adds.