Soot from burned wood and diesel exhausts may have twice the impact on global warming than previously thought, according to a new study published on Tuesday.

The "black carbon" is said to be the second most important man-made agent of climate change.

The findings, published in the Journal of Geophysical Research Atmospheres, suggest there may be untapped potential to curb global warming by reducing soot emissions.

Countries in the Middle East and north Africa will be among those hardest hit by global warming, unless the upward trend for greenhouse gas emissions can be checked, the World Bank warned last month at the Doha climate change conference.

There will be lower rainfall, higher temperatures and continuing desertification, said Rachel Kyte, World Bank vice-president for sustainable development, during her presentation of the report on Adaptation to a Changing Climate in the Arab Countries.

According to the forecasts, average temperatures could rise by 3C between now and 2050. But night temperatures in city centres could increase by double that figure. The report notes that over the last three decades 50 million people have been affected by climate disasters. Severe flooding is now a recurrent event. But the increasing scarcity of water resources is the biggest challenge for countries in the region, which already have some of the lowest per capita reserves in the world.

Two aircraft have flown over an oil drilling ship that ran aground in a severe Alaskan storm and saw no sign that the vessel was leaking fuel or that its hull had been breached.

The Royal Dutch Shell ship, the Kulluk, which was used in the Arctic last summer, ran aground on Monday on a sand and gravel shore off an uninhabited island near Kodiak Island in the Gulf of Alaska. The ship appeared stable, according to US federal on-scene response co-ordinator Captain Paul Mehler.

Hours of rain continued across much of the country on New Year's Eve, from downpours in some parts to the merely miserable, meaning that as 2012 ended, Britain was on course for the wettest year since records began.

The Met Office said just 46mm (1.8in) of rain by midnight would make this year the wettest – and six steady hours of rain in some places should have ensured that. England, which had drought orders in place in many areas in the spring, has already set a record, with 1,095.8mm of rain between 1 January and Boxing Day.

Parts of upland Cumbria, south Wales and south-west England saw torrential overnight rain, raising the likelihood of further flooding. Hundreds of Environment Agency flood alerts and warnings remain in place, and the Met Office has issued yellow warnings of more heavy rain and gales in many parts of Scotland, the north-east of England, London and the south-east, and Wales.