First author

Variations in the Sun's total energy output (luminosity) have been implicated in global warming. Peter Foukal, from Heliophysics in Nahant, Massachusetts, and his collaborators reviewed the literature on the possible effects of variations in solar luminosity on global climate (see page 161). These depend mainly on changes in bright and dark magnetic structures — known as faculae and sunspots — on the Sun's surface. The energy output of these variations is too small to have accelerated global warming during the past 30 years, but a different ratio of sunspots to faculae might have contributed to higher solar-irradiance levels in past millennia. Nature caught up with Foukal to discuss the political and scientific impact of his work.

Why are you fascinated by the Sun?

The Sun's constantly changing atmospheric structure has fascinated me ever since I first saw it through a telescope as a graduate student. Forty years later, the field still has much unexplored territory.

How does it feel, dealing with so much energy?

Victorian astronomers were the first to measure the Sun's output, and they were impressed by the amount of energy it emits. Now, we take this huge output for granted and are more excited by the power produced by extra-galactic objects such as quasars.

Do you believe that the causes of global warming are solely anthropogenic in nature?

The climate record shows variation across Earth's life time, extending well before any conceivable human impact. But the rapid increases in global temperature and carbon dioxide levels during the past 30 years are difficult to explain by natural variation alone.

Is there a political lesson to be learnt from global warming?

There are many. One scientists are reluctant to admit is that science itself has become big business. The scientific community has developed its own agenda, which can hinder efficient problem-solving.

How do you think this work will affect the debate about the causes and extent of global warming?

Climate simulations continue to be published that use solar brightening during the past few centuries as a much greater factor in global warming than can be justified by current data or theories. We hope that our review clearly presents the arguments against such unreasonable solar driving, and that this will help research into the true causes of global warming.