First Half of 2016 the Warmest Half-Year on Record, Says Nasa

Each of the first six months of 2016 set a record as the warmest respective month globally in the modern temperature record, which dates to 1880, according to scientists at Nasa's Goddard Institute for Space Studies (GISS) in New York.

Analysing ground-based observations and satellite data, the scientists found that two key climate change indicators - global surface temperatures and Arctic sea ice extent - had broken numerous records through the first half of 2016.

While these two key climate indicators have broken records in 2016, Nasa scientists said it is more significant that global temperature and Arctic sea ice are continuing their decades-long trends of change.

Both trends are driven by rising concentrations of heat-trapping carbon dioxide and other greenhouse gases in the atmosphere, the scientists said.

"While the El Nino event in the tropical Pacific this winter gave a boost to global temperatures from October onwards, it is the underlying trend which is producing these record numbers," Gavin Schmidt, Director, Goddard Institute for Space Studies, said in a statement.

Previous El Nino events have driven temperatures to what were then record levels, such as in 1998.

But in 2016, even as the effects of the recent El Nino taper off, global temperatures have risen well beyond those of 18 years ago because of the overall warming that has taken place in that time.

The global trend in rising temperatures is outpaced by the regional warming in the Arctic, said Walt Meier, a sea ice scientist at Nasa Goddard.

"It has been a record year so far for global temperatures, but the record high temperatures in the Arctic over the past six months have been even more extreme," Meier said.

"This warmth as well as unusual weather patterns have led to the record low sea ice extents so far this year," Meier noted.

The extent of Arctic sea ice at the peak of the summer melt season now typically covers 40 percent less area than it did in the late 1970s and early 1980s, the scientists said.

Nasa tracks temperature and sea ice as part of its effort to understand the Earth as a system and to understand how Earth is changing.

In addition to maintaining 19 Earth-observing space missions, Nasa also sends researchers around the globe to investigate different facets of the planet at closer range.

Nasa researchers are currently working across the Arctic to better understand both the processes driving increased sea ice melt and the impacts of rising temperatures on Arctic ecosystems.