Last month was the hottest June ever recorded worldwide and the fourth consecutive month that the combined global land and sea temperature records have been broken, according to the US government’s climate data centre.

The figures released last night by the National Oceanic and Atmospheric Administration (NOAA) suggest that 2010 is now on course to be the warmest year since records began in 1880.

The trend to a warmer world is now incontrovertible. According to NOAA, June was the 304th consecutive month with a combined global land and surface temperature above the 20th-century average. The last month with below-average temperatures was February 1985. Each of the 10 warmest average global temperatures recorded since 1880 have occurred in the last 15 years with the previous warmest first half of a year in 1998.

Temperature anomalies included Spain, which experienced its coolest June temperature since 1997, and Guizhou in southern China, which had its coolest June on record. According to Beijing Climate Centre, Inner Mongolia, Heilongjiang, and Jilin experienced their warmest June since their records began in 1951.

Scientists expressed surprise that the June land surface temperature exceeded the previous record by 0.11C (0.20F). “This large difference over land contributed strongly to the overall global land and ocean temperature anomaly,” said John Leslie, a spokesman for NOAA.

Separate satellite data from the US National Snow and Ice Data Centre in Colorado shows that the extent of sea ice in the Arctic was at its lowest for any June since satellite records started in 1979. The icy skin over the Arctic Ocean grows each winter and shrinks in summer, reaching its annual low point in September. The monthly average for June 2010 was 10.87 km sq. The ice was declining an average of 88,000 sq km per day in June.

In a further possible sign of a warming world, the Jakobshavn Isbrae glacier, one of the largest in Greenland, lost a 2.7-square mile chunk of ice and retreated one mile between 6-7 July – one of the largest single losses to a glacier ever recorded.

The glacier, a tongue of the Greenland ice sheet, has retreated six miles since 2000 and more than 27 miles since 1850. It is believed to be the single largest contributor to sea level rise in the northern hemisphere.

Greenland’s ice sheet, a vast body of ancient ice covering 1.7m sq km, is melting today more rapidly than only a few decades ago. Since 2000, the ice sheet is calculated to have lost about 1,500 cubic kilometres of water– enough to raise global sea levels by 5mm . If the entire ice sheet melted, the world’s oceans would rise by over six metres.

Glaciologists expressed surprise at the speed of the break-up of the glacier: “This is unusual because it occurs on the heels of a warm winter that saw no sea ice form in the surrounding bay … it lends credence to the theory that warming of the oceans is responsible for the ice loss observed throughout Greenland and Antarctica,” said Nasa scientist Thomas Wagner.

“These are clear signs of a rapidly warming world and exactly what the climate models have predicted. Thankfully, there is a way out of it if we can get greenhouse gas emissions under control,” said Ben Stewart of Greenpeace.

John Vidal guardian.co.uk