MOST electricity in poverty-stricken Malawi comes from renewable sources. Solar panels on some school roofs are a prime example. They have improved students’ results as well as providing income by charging villagers’ phones and batteries for a fee. What little central generation takes place in this corner of Africa is mainly hydropower.

This all sounds relatively green, until you realise the country has . Trees are often felled to for cooking. Fewer trees means less ability to absorb carbon dioxide and it exposes soil, which means it also releases CO₂. This is Malawi’s biggest contribution to climate change by far.

Denuded land means rain runs off rapidly. Aquifers don’t get replenished; instead rivers swell and burst their banks. The run-off takes with it silt and debris that can block the intakes of hydropower plants, adding to supply problems already caused by . Black-outs are common for the of Malawi’s 17 million people and businesses connected to the grid.

So what is the country’s answer? Plans for two coal-fired power stations, which will ensure a more constant supply to an increased number of people and businesses.

The government realises that this will raise carbon emissions, but it says Malawi needs this kind of low-cost, reliable power supply for development.

So while energy sector emissions would rise, it aims to do its bit by addressing the worse problem of deforestation. This is the basis of its ahead of the UN’s Paris climate summit.

Part of that pledge is to have 2 million more efficient stoves in operation by 2030, each estimated to use less than half as much wood as a traditional open fire. As part of the Paris deal, Malawi is asking for international help to promote these stoves and to increase tree planting.

It all sounds encouraging. But unless there’s a miraculous turnaround, the of more than five children per woman, which could mean , will undermine gains from more efficient stoves.

Observers have concluded that drivers of climate change cannot be easily tackled in such countries where largely rural populations are forced to degrade the land to meet their needs.

The , they say, is to create densely packed cities with public transport, powered by renewables – Malawi has excellent potential for solar power. Experts in Malawi say the government, , is in no state to fulfil that mission.

It’s nice to think that there are simple fixes to global warming. The reality, as Malawi illustrates, is a lot more complex.

(Image: Andrzej Krauze)

This article appeared in print under the headline “Up in flames”

In Papua New Guinea, the Ring of Fire has bestowed a unique gift on science – an underwater vent of pure carbon dioxide.

Normally researchers projecting the effect of rising CO₂ must rely on computer models. But here they can observe it for real as the CO₂ bubbles dissolve to form carbonic acid, creating on a small scale the conditions expected globally by the end of the century.

At first it is a beguiling sight through a diver’s mask. The parcels of CO₂ are silvered by the sunlight as they wobble towards the surface. But then the eye wanders to the background. The reef is miserably depleted. Tough boulder corals survive, but the most spectacular branching corals and table corals that provide breeding grounds for fish are missing. Research suggests more than a third of coral species will ultimately be wiped out.

Just a few hundred metres away, an unpolluted reef acts as a scientific control. Adorned by more than 500 species of coral, it is a carnival of life and colour.

This tale of two reefs enables researchers to draw conclusions about which creatures will thrive with the shift in ocean chemistry and which will perish.

Beyond this natural laboratory the full effects of rising CO₂ are still hard to predict. But we do know that the current rate of change in sea chemistry is than the last great acidification event caused by volcanic activity 56 million years ago – an event that appears to have contributed to serious ecological disruption.

“The current rate of change in ocean chemistry is 10 times faster than the last great acidification event”

Some major politicians are waking up to “the other CO₂ problem“. US Secretary of State John Kerry will make ocean acidification a key theme of his in Washington DC next week. He is likely to offer funds for a monitoring network to track the rate of acidification.

But the proposed carbon cuts from power stations announced by President Obama won’t be enough to prevent severe acidification, even if China and other nations play their part.

The future lies beneath the waves in Papua New Guinea, if anyone cares to look.

This article appeared in print under the headline “Sea change”

The reliability of weather forecasts is surprisingly hard to measure. The BBC’s Weather Test will make amends

DO I need an umbrella today? When can I harvest my crops? When shall we display the winter clothing range? Is it safe to put up that offshore wind turbine? Can we set sail for France? Shall we go abroad for a holiday or stay at home? Do we need to grit the roads tonight?

Even in 2011, with most people sheltered in cities, weather forecasts still matter. The weather influences our happiness, health and safety, and is also important for the economy. But how confident can we be in the forecasts on which our decisions are based, whether over the next 24 hours or the months ahead? If the forecast says tomorrow will be fine, can you really leave your coat at home?

Long-range forecasts in particular are notoriously tricky. Some forecasters make extravagant claims about their ability to project a season ahead, but it’s not clear whether forecasting the weather for the next season is really any better than guesswork. And is one forecaster’s prognosis really better than another’s?

You might have thought that answers would be readily available. Sadly they are not. Companies whose profits depend on the weather make their own private comparisons of rival weather forecasts – but these analyses are not ours to see.

So, at BBC News, we are aiming to fill the gap. In collaboration with the Royal Meteorological Society, the Royal Statistical Society, the Royal Astronomical Society and various independent academics and forecasters, our t will compare forecasts from different organisations over ranges from a day to a season. The aim is to discover which forecasters and which methods are the most accurate and useful.

This may sound simple but in fact it’s extremely difficult, with many factors in play. Since I first floated the idea it has taken more than a year to get agreement on the rules under which forecasts will be tested.

For example, we plan to ask participating forecasters to produce specific forecasts for a number of weather stations around the UK, but there has been great debate about which stations to include. We originally selected the weather station at London’s Heathrow Airport as one testing point, partly because forecasts there help to determine prices on the gas market. But we abandoned Heathrow after critics complained that its weather was overly influenced by concrete and aircraft.

Another issue has been exactly how to measure rain. Would it be enough to forecast some rain at a given location on a given day, or would we expect forecasters to predict exactly how much rain would fall and when. Which would be more useful?

The draft protocol for the test is available on the Weather Club website (). If all goes to plan, we will launch in the next few months and deliver results over the next four years, starting with 24-hour forecasts and leaving the seasonal ones until last. The project will be funded by BBC News and the data crunched at the University of Leeds, UK.

So who will take part? Obviously the – the UK’s National Weather Service and provider of forecasts to the BBC – is in the frame. It’s one of the world’s most prestigious forecasters, one of just two that supply weather forecasts for global aviation (the other is in Kansas and is run by the US National Oceanic and Atmospheric Administration). It has been massively influential in the World Meteorological Organization and is one of the leading bodies researching climate change.

So far the Met Office has been largely supportive – I suspect it is confident that it will acquit itself well in short-term forecasting. It has been more ambivalent, though, about seasonal forecasting. The organisation was famously embarrassed by the criticism it received in the UK media for its April 2009 forecast of a “barbecue summer”. The summer was indeed warmer than usual, but the Met failed to predict that it would also be unusually rainy.

The Met Office still produces seasonal forecasts but no longer publishes them. It is studying our protocol and will decide later whether it will allow its seasonal forecasts to be judged.

The pressure is on, though, because maverick independent weather forecaster and climate-change sceptic Piers Corbyn, who runs the company , has publicly volunteered to submit his seasonal forecasts to testing.

Corbyn is secretive about his methods. At a public discussion meeting in the historic Royal Institution theatre in London, just above where John Tyndall performed his seminal experiments on the greenhouse effect, he claimed that anyone betting ÂŁ1 on his 2010 winter forecast for central England would have made ÂŁ14 profit. If we can make the Weather Test work, we will be able to assess his abilities in more conventional terms.

So who else will join? The steering group that I chair – comprising the chief executives of the Royal Meteorological Society and Royal Statistical Society, the independent forecaster Philip Eden and other senior scientists – will invite forecasters employing different methodologies so the results can be of long-term benefit to science as well as the general public. Corbyn, for instance, claims to be able to discern solar and lunar influences on the weather in a way that is not recognised by the Met Office. We’ll be able to put such claims to the test.

We will also leave space for a wild-card entrant: an amateur who scrutinises seaweed, tracks bird movements or traces folk sayings about the weather.

There are still hurdles to overcome. But I am starting to believe that before long we will be able to offer the public the information they really need to judge those who provide them with weather forecasts.