It was 1.68ºC warmer than at the end of the 19th century, the basis used for temperatures before the burning of fossil fuels began to increase rapidly.

Since last June, the globe has been breaking heat records every month, contributing to maritime heat waves in vast ocean areas.

Scientists said the record heat recorded during this period was not a surprise due to a strong El Nino, a climate condition that warms the central Pacific and changes global weather patterns.

"But the combination of this and unnatural marine heat waves made these records breathtaking," said Woodwell Climate Research Center scientist Jennifer Francis.

As El Nino slows, the margins by which global average temperatures are exceeded each month are expected to shrink, Francis added.

Climate scientists have attributed most of the heat records to man-made climate change, due to emissions of carbon dioxide and methane produced by burning coal, oil, and natural gas.

"The trajectory will not change until the concentrations of greenhouse gases in the atmosphere stop increasing," noted Francis.

Under the 2015 Paris Agreement, the world set the goal of keeping warming at or below 1.5ºC since pre-industrial times.

Copernicus temperature data is monthly and uses a slightly different measurement system than the Paris threshold, which is averaged over two or three decades.

Copernicus deputy director Samantha Burgess said March's temperature record was not as exceptional as other months last year, which broke records by wider margins.

"We had record-breaking months that were even more unusual," Burgess said, pointing to February and September last year. But the "trajectory is not in the right direction," she added.

The globe has already recorded 12 months with average monthly temperatures 1.58°C above the Paris value, according to Copernicus data.

In March, the global average sea surface temperature was 21.07°C, the highest monthly value on record and slightly higher than in February.