New temperature record confirms world HAS warmed 0.75C since 1900 - as Nasa 'potato' image shows how planet's gravity is changing as ice melts

World has warmed by less than a degree centigrade between 1900 and 2012
2010 is now hottest year on record
'Virtually all' data behind new study to be published - in contrast to earlier 'Climategate' scandal
Nasa image shows how gravity has changed due to melting ice

PUBLISHED: 12:17 EST, 19 March 2012 | UPDATED: 20:01 EST, 19 March 2012

Updated records of global temperatures stretching back more than 160 years confirm the world has warmed by 0.75 celsius since 1900, scientists said today. The new version of a Met Office 'temperature series' dating back to 1850 adds information from weather stations in Africa and from Canada and Russia, where the Arctic is warming more quickly. The full data behind the study is to be available, to prevent a repeat of the 'Climategate' scandal in which scientists were accused of 'editing' climate data to suit their theories of global warming.

The report comes in the wake of a release from Nasa's GRACE gravity-measuring satellite which shows the 'deforming' effect melting ice has had on Earth's gravity.

Data from Nasa's twin gravity-sensing Grail satellites was used to asssemble a 3D map of how melting ice has changed the gravity of Earth

HOW MELTING ICE HAS 'WARPED' GRAVITY ON EARTH

Nasa's twin Grace satellites were able to measure the melting of glaciers in Greenland with high accuracy from space.

The twin satellites measure changes in their flight path as they orbit - and thus capture tiny changes in Earth's gravity due to the 'lost weight' of melting ice.

The Greenland ice shield had to cope with up to 240 gigatons of mass loss between 2002 and 2011. This corresponds to a sea level rise of about 0.7 mm per year.

‘When the mass of the Greenland ice sheet changes, so does the gravity there,’ explains Dr. Frank Flechtner from the GFZ German Research Centre for Geosciences. ‘The GRACE gravity field measurements therefore give us information on mass changes, including climate-related ones.’

The new record also addresses differences in the way sea surface temperature

measurements have been made in the past, for example water temperatures taken from buckets hauled on board ship or made from engine rooms of ships.

Colin Morice, climate monitoring research scientist at the Met Office, said: ‘The new study brings together our latest and most comprehensive databases of land and marine temperature observations, along with recent advances in our understanding of how measurements were made at sea.

‘These have been combined to give us a clearer a picture of what the historical record can tell us about global climate change over the past 161 years.‘Updates have resulted in some changes to individual years in the nominal global mean temperature record, but have not changed the overall warming signal of about 0.75C since 1900.’ The latest study suggests that 2010 and 2005 were the warmest years on record, slightly warmer than 1998 - which the Met Office and UEA’s Climatic Research Unit (CRU) had previously put as the hottest year.

But the margin of error in the results means the years were all similarly warmer than average global temperatures. All of the 10 warmest years in the record occurred in the past 14 years.

A Nasa image showing the very different gravity on Earth in 1995, before melting ice around the world reshaped the map

Slight increases in the temperatures for recent years is due to inclusion of more data from the rapidly-warming Arctic.

Professor Phil Jones, director of CRU, said the temperature series may not have been fully capturing changes in the Arctic because of a lack of data from the area.

‘For the latest version we have included observations from more than 400 stations across the Arctic, Russia and Canada. This has led to better representation of what’s going on in the large geographical region.’

Previous analysis of temperature records came under fire at the height of the ‘climategate’ scandal, in which researchers were accused of manipulating data to support a theory of global warming.

Scientists were criticised for not publishing the data behind the temperatures series, and today Prof Jones said virtually all the data for the records underpinning the latest analysis would be publicly available.