News•November 18, 2015

U.S. Agencies Agree: October Was Crazy Warm

On the heels of the news from NASA that October’s global temperature this year spiked more than any other month in 135 years, virtually assuring that 2015 will be the warmest year on record, the National Oceanic and Atmospheric Administration announced Wednesday that their data showed similarly remarkable numbers.

How temperatures across the globe ranked for October 2015.
Credit: NOAA

The arresting October heat is a sign of both the steady upward march of global temperatures from warming as well as the strong El Nino boosting global heat this year.

By NASA’s calculations, October was more than 1°C, or nearly 2°F, above the 1951-1980 average for the month — the biggest departure for any month in their archives and the first time any month has exceeded a full degree Celsius. NOAA put the departure at 0.98°C (or 1.76°F) compared to the 20th century average. This was also the highest departure in NOAA’s records, extending back 136 years. The small differences are due to the slightly different ways the two agencies treat the data, though overall their estimates are in broad agreement.

This was the sixth month in a row this year that had set a global monthly temperature record, NOAA said in their release. In total, eight months this year have been the warmest for their specific month.

An El Nino that is expected to rival the strongest events on record is providing significant heat, with ocean temperatures in parts of the tropical Pacific reaching a record level recently. El Nino years tend to be warmer than years in which Pacific waters are colder than normal, called a La Nina, or when they are in a neutral state.

But La Nina years of recent decades have been warmer than previous El Nino years, a sign of the overall background rise in global temperatures because of the excess heat trapped in the atmosphere from the accumulation of greenhouse gases like carbon dioxide.

With only two months left in the year, there is a 99.9 percent chance that 2015 will best 2014 as the warmest year on record, according to Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, which keeps their temperature records.