Global warming helped make last year the hottest since records began, according to a US government report.

It marks the third year in a row of record highs for both land and sea surface temperatures.

The report from the National Oceanic and Atmospheric Administration said a strong El Nino cycle was also a factor in the record heat.

The report, based on the work of over 450 scientists in nearly 60 countries, also warned that greenhouse gases are now at the highest level ever documented.

Graphic: National Oceanic and Atmospheric Administration

River flooding

It comes as a new study by international and Irish scientists found that global warming is affecting the timing of river floods in Ireland and across Europe.

The scientists said that floods in parts of the west of the country now tend to occur two weeks later than they did 20 years ago.

It's the opposite in Sweden, Finland and the Baltic States - where areas are experiencing floods a month earlier.

It is claimed the changes could have a significant impact on crop yields, water supplies and other infrastructure.

A 2015 UN report on disaster risk reduction warned that river flooding costs the world an estimated €88.5bn every year.

State of the Climate 2016

Global average carbon dioxide concentrations exceeded 400 parts per million for the first time in at least 800,000 years. 

Graphic: National Oceanic and Atmospheric Administration

The global average sea level also reached a new record high and was approximately 3.25 inches higher than in 1993 – when the satellite altimeter record began.

The average Arctic land temperature is now 3.5C warmer than it was in 1900 while Arctic sea ice coverage equalled previous record lows.

Antarctic sea ice coverage meanwhile reached record lows with significantly less ice than the 1981 to 2010 average.