KUALA LUMPUR, July 1 ― According to the US National Aeronautics and Space Administration’s (NASA) latest temperature increase update, 2015 is expected to be the hottest year in 100 years.

The January-May period this year has been 0.77°C (1.4°F) warmer than in the same period over the 29 years between 1951 and 1980.

This beats last year’s differential of 0.68°C (1.2°F) by 0.9 C (0.2).

The report said these record high temperatures had occurred even before a substantial El Niño had yet to take full effect.

Taking the pre-industrial temperature as the baseline (instead of 1951-1980) and projecting a future trend, the world is on course for a 1°C (1.8°F) rise by the early 2020s.

According to the report, one degree of warming might not sound like much, but the energy required to heat the entire surface and lower atmosphere of a planet to reach this temperature is equivalent to four Hiroshima atomic bombs detonating every second.

GISTEMP is one of the most widely-cited datasets for the measuring of global temperatures and is based on publicly available data from 6,300 meteorological stations around the world, from ship-based and satellite observations of sea surface temperatures and from Antarctic research stations.

These three data sets are combined and adjusted to account for breaks in station records, the effects of urban heating, and the distribution of stations across the landscape.

Apart from NASA’s Goddard Institute of Space Studies, the two main agencies that track global temperature concurred that 2015 has so far been the warmest year in more than a century.

According to data released by the US National Oceanic and Atmospheric Administration, March was the warmest March in their 136-year archive, and the past five months were the warmest start to a year on record. The global average temperature for the month was 1.53°F above the 20th century average and beat the previous record holder (March 2010) by almost a tenth of a degree.

It was a continuation of trends that made 2014 the most blistering year for the surface of the planet, in records going back to 1880.

The Japan Meteorological Agency also ranked March as the hottest in its records, while NASA put it in third place, behind 2010 and 2002.

Each agency handles temperature data in slightly different ways, which can lead to slight variations in rankings for months and years, though there is broad agreement among all three on the overall warming trend.