The planet has not been only record warm this year, it's been so unusually mild that the temperature records themselves have set records of their own. This is the case with October 2015, according to new preliminary NASA data released Tuesday.

The information shows that October 2015 was by far the warmest October on record, dating back to 1880. Not only that, but October also had the largest temperature departure from average of any month on record.

The scorchingly hot October seals the deal: 2015 is almost certain to become the Earth’s hottest year since instrument records began in 1880. This means the year will beat out 2014, and become yet another data point showing that manmade global warming, plus natural climate variability, is pushing the climate into new territory.

Global average surface temperatures so far this year versus the other warmest years on record. Image: NOAA NCEI

The global average surface temperature came in at 1.04 degrees Celsius above average for the month, which is the biggest warm temperature anomaly in recorded history, the NASA data shows.

Global temperature anomalies for the month of October 2015, according to NASA. Image: NASA GISSTEMP

Importantly, this was also the first time that a single month exceeded the 1-degree Celsius temperature anomaly, surpassing the 0.97 degree Celsius temperature anomaly in January 2007. This is a symbolic milestone, but one that will be broken more frequently as the climate continues to warm due to increasing amounts of greenhouse gases in the air because of human activities.

The NASA data corroborates information released by the Japan Meteorological Agency (JMA) on Monday, also showing that October was the warmest such month on record, as the year heads toward setting a record for the warmest calendar year, beating out 2014 for the top spot.

On Wednesday, the National Oceanic and Atmospheric Administration (NOAA) released its October temperature data, and also found the month was the warmest such month on record, and broke the record for the largest monthly global temperature anomaly in 1,630 months of record-keeping. The agency said the month fell just short of the 1 degree Celsius anomaly, at 0.98 degrees Celsius above average, but nevertheless solidly beat the previous record monthly temperature anomaly, which was set in September.

According to NOAA, 2015 is cruising toward the record for the planet's warmest year since instrument records began.

Parts of South America, the Atlantic Ocean, Indian Ocean, Africa, Europe, Australia, the Pacific Ocean and the western U.S. were all record warm in October, according to the NOAA data.

In the JMA data set, which analyzes similar temperature records but processes them differently than NOAA and NASA do, this October beat October 2014 by 0.34 degrees Fahrenheit, or 0.19 degrees Celsius. According to NASA, though, this October beat October of last year by 0.32 degrees Fahrenheit, or 0.19 degrees Celsius.

According to the JMA, this was the largest temperature departure from average for any month so far this year.

The JMA information shows October was unusually mild throughout areas of the Northeast, Central, and South Pacific Ocean, the Indian Ocean, much of North America, parts of Asia, and most of Europe — as well as all of Australia, Africa and the Middle East.

The warmth in the Central Pacific is related to a strong El Niño event that is characterized by unusually mild ocean temperatures along the equator, from the central Pacific to the west coast of South America.

Global average surface temperature anomalies through October 2015, showing where 2015 as a whole is likely to end up. Image: NASA GISSTEMP

El Niño events cause changes in weather patterns around the world by altering the way heat is distributed throughout the oceans and atmosphere. They also tend to boost global average temperatures higher, in addition to the effects of long-term manmade global warming.

The NOAA has found a 97% chance that 2015 will break the all-time calendar year temperature record for the planet. On Tuesday, Gavin Schmidt, who directs NASA's Goddard Institute of Space Studies in New York, said it is now 99% likely that 2015 will set a calendar year temperature record.

Probability that 2015 will be a record warm year now 99.9% based on Jan-Oct GISTEMP data. pic.twitter.com/glfKYAha3X — Gavin Schmidt (@ClimateOfGavin) November 17, 2015

According to NASA, the January through October period ranks as the warmest such period in its 136 years of record-keeping, with a temperature anomaly of 0.82 degrees Celsius, or 1.45 degrees Fahrenheit. This beats global average temperature anomalies for the same period last year, which was 0.76 degrees Celsius, or 1.37 degrees Fahrenheit above average.

For the year as a whole, global average surface temperatures are likely to reach 1 degree Celsius, or 1.8 degrees Fahrenheit, above preindustrial temperatures for the first time, according to the UK Met Office, NOAA and now NASA as well.

Even 2014, which was the previous record-holder for the warmest year in recorded history, did not eclipse this symbolic, but important, boundary.

Global average surface temperature anomalies for the warmest years in NASA's data set. Image: NASA GISS

The 1-degree mark means that the world is already halfway to the internationally agreed warming target of 2 degrees Celsius (3.6 degrees Fahrenheit), above preindustrial levels. Since the stated goal of the Paris Climate Summit, which kicks off on Nov. 30, is to craft an agreement that will limit global warming to the 2-degree target or lower, it's clear that diplomats do not have an easy task before them.

In fact, the assessments produced to date show the planet will likely exceed the 2-degree threshold, at least for a period of time, even if the Paris agreement puts stringent emissions limits in place that are rigorously enforced.