The world faces record-breaking temperatures as the sun’s activity increases, leading the planet to heat up significantly faster than scientists had predicted for the next five years, according to a study.

The hottest year on record was 1998, and the relatively cool years since have led to some global warming sceptics claiming that temperatures have levelled off or started to decline. But new research firmly rejects that argument.

The research, to be published in Geophysical Research Letters, was carried out by Judith Lean, of the US Naval Research Laboratory, and David Rind, of Nasa’s Goddard Institute for Space Studies.

The work is the first to assess the combined impact on global temperature of four factors: human influences such as CO₂ and aerosol emissions; heating from the sun; volcanic activity and the El Niño southern oscillation, the phenomenon by which the Pacific Ocean flips between warmer and cooler states every few years.

The analysis shows the relative stability in global temperatures in the last seven years is explained primarily by the decline in incoming sunlight associated with the downward phase of the 11-year solar cycle, together with a lack of strong El Niño events. These trends have masked the warming caused by CO₂ and other greenhouse gases.

As solar activity picks up again in the coming years, the research suggests, temperatures will shoot up at 150% of the rate predicted by the UN’s Intergovernmental Panel on Climate Change. Lean and Rind’s research also sheds light on the extreme average temperature in 1998. The paper confirms that the temperature spike that year was caused primarily by a very strong El Niño episode. A future episode could be expected to create a spike of equivalent magnitude on top of an even higher baseline, thus shattering the 1998 record.

The study comes within days of announcements from climatologists that the world is entering a new El Niño warm spell. This suggests that temperature rises in the next year could be even more marked than Lean and Rind’s paper suggests. A particularly hot autumn and winter could add to the pressure on policy makers to reach a meaningful deal at December’s climate-change negotiations in Copenhagen.

Bob Henson, of the National Centre for Atmospheric Research in Colorado, said: “To claim that global temperatures have cooled since 1998 and therefore that man-made climate change isn’t happening is a bit like saying spring has gone away when you have a mild week after a scorching Easter.” Temperature highs and lows

Hottest year of the millennium

Caused by a major El Niño event. The climate phenomenon results from warming of the tropical Pacific and causes heatwaves, droughts and flooding around the world. The 1998 event caused 16% of the world’s coral reefs to die.

Most sunspots in a year since 1778

The sun’s activity waxes and wanes on an 11-year cycle. The late 1950s saw a peak in activity and were relatively warm years for the period.

Coldest year of the millennium

Ash from the huge eruption the previous year of a Peruvian volcano called Huaynaputina blocked out the sun. The volcanic winter caused Russia’s worst famine, with a third of the population dying, and disrupted agriculture from China to France.

The release of America’s spy satellite images of Arctic sea ice provides unexpected, dramatic new evidence about the dangers of global warming.

These visions of dwindling ice cover confirm that changes in climate in the planet’s high latitudes are progressing much faster than originally expected. And what happens there is bound to have an impact elsewhere on our overheating world, in particular to its rising sea levels.

It is not the actual loss of Arctic sea ice that is the danger, of course. Its melting will add nothing, directly, to rises in sea levels. But its dwindling will almost certainly have a profound knock-on effect – mainly on the great ice sheets that cover Greenland and Antarctica. Without sea ice to prop them up at their edges, these sheets will break apart at faster and faster rates and tip more and more ice into the oceans. And once changes have been triggered at their edges, these will be transmitted into the hearts of these great glaciers at remarkably fast rates, scientists predict.

And here lies the threat to Earth. The destruction of the ice sheets of Antarctica and Greenland will feed vast amounts of meltwater into the oceans, far more than has been calculated until very recently. For example, the last report of the Intergovernmental Panel on Climate Change contained little input from melting ice sheets in its estimates and concluded, instead, that sea-level rises would be constrained to around 20 to 60 centimetres by the end of the century.

That figure now looks uncomfortably optimistic and current estimates put the likely rise at one metre or more by 2100 – a figure backed by the US Geological Survey, which this year warned that rises could reach as much as 1.5 metres. As a result, low-lying areas, including Bangladesh, Florida, the Maldives and the Netherlands, will undergo catastrophic flooding, while in Britain large areas of the Norfolk Broads and the Thames estuary could disappear. In addition, cities including London, Hull and Portsmouth will need new flood defences.

And that is just the beginning. No matter what we do about carbon dioxide emissions – the key cause of this heating and melting – the world will continue to warm and its sea levels to rise beyond 2100. Reversing global warming will be a very long process. However, we have, if nothing else, been warned.