Fears over climate change and the increasing problem of pollution have put public concerns about the environment at an all-time high. Governments have responded to public pressure by introducing legislation to reduce pollution, and at the Kyoto summit last year they agreed to reduce emissions of greenhouse gases by an average of 5.2%. Europe has set the most ambitious targets: last month it was announced that Germany, for example, will cut emissions by 22.5% by 2012.

Most of these measures have a direct impact on industry, which must tread a fine line between short-term economic gains and the long-term effect on the environment. This tension has led to the idea of “sustainable development”, first promoted by the United Nations in 1987. Put simply, this policy encourages economic growth but in a way that does not harm the environment.

A good example of how this can work in practice is developed by a university-industry collaboration in the UK. They have worked with industry to develop an optics-based sensor for monitoring emissions of toxic gases. The instrument was invented by the university team in the early 1990s, and the industrial partners have helped to develop it into a practical and commercial instrument. Full-scale production is expected to start later this year.

But some environmental problems are outside human control. Last year global weather patterns were severely disrupted by El Niño, which causes the tropical Pacific Ocean to become warmer than usual. Researchers are now familiar with the effects of El Niño, and are beginning to understand the mechanisms that cause it. As Ping Chang and David Battisti explain, interactions between the ocean and atmosphere play a crucial role in both initiating and ending El Niño events. Computer models of the coupled ocean-atmosphere system have allowed researchers to predict El Niño events several seasons in advance.

Although El Niño is a natural phenomenon, research by the National Oceanic and Atmospheric Agency in the US indicates that its effects could be exacerbated by global warming. The link between the two is still unclear, but underlines the fact that emissions of greenhouse gases are having a major impact on both the weather today and the climate tomorrow.

So what can be done to reduce emissions? The burning of fossil fuels is the largest source of greenhouse gases, with over 85% of the world’s energy coming from oil, coal and gas. An obvious way forward is to develop renewable energy sources. Nuclear energy and hydroelectric power are already well established, while solar power and wind energy are slowly becoming more popular.

Another possibility is thermophotovoltaics (TPV), suggested in 1956 by Pierre Aigrain of the Massachusetts Institute of Technology in the US. These devices work in a similar way to solar cells, but generate electricity from thermal radiation rather than sunlight. As Timothy Coutts and Mark Fitzgerald explain, TPV systems provide higher efficiencies than solar cells, and could provide power in all parts of the globe – not just those with lots of sunshine. The Swiss and Swedish governments are investigating if TPV generators could be used to heat residential homes, and commercial systems are now becoming available.

But the biggest challenge for renewable energy will be the transport sector. Although conventional engines are now more efficient than ever, traffic pollution will continue to get worse as more cars fill the roads. One of the most promising alternatives is fuel cells, which are more efficient and only produce water as a waste product. As Gregor Hoogers points out, several companies have revealed prototype vehicles powered by fuel cells, and millions of dollars are being invested in improving their performance and reducing manufacturing costs. However, fuel cells will still be more expensive than conventional engines, and government incentives will be needed for them to gain widespread acceptance.

These are just a few examples of how physicists are helping to reduce our impact on our planet. But there is the potential to take an even more active role in making new technologies sustainable. Progress made today will help to safeguard the natural environment for many generations to come.

See the features in the August issue of Physics World magazine