Image: Marcio Jose Sanchez/Associated Press
Earth just went through its second-warmest April on record, according to preliminary NASA data.
This comes on the heels of the fourth-warmest March, and continues a streak of more than 29 years of global temperatures above the 20th century average. The trend has been tied to manmade global warming, with some contributions from natural climate variability.
According to NASA, the planet's average March temperature was 59.56 degrees Fahrenheit, which was 1.26 degrees Fahrenheit above the average temperature from 1951 to 1980. Only April 2010 exceeded last month's global average surface temperature, with 1998 coming in third.
The National Oceanic and Atmospheric Administration (NOAA) maintains global temperature records that often differ slightly from NASA's, and could lead to an April 2014 ranking that's slightly differently when its global temperature report comes out in a few days.
NASA's preliminary monthly rankings can change as new data comes in, with a relatively high uncertainty concerning an individual month's ranking.
Global temperature departures from average for April 2014.
Regardless of the exact ranking, it's clear that warm temperature anomalies during April were centered across eastern Russia, including much of Siberia, as well as western Europe, northern Africa and the Middle East. In fact, the only large areas with cooler-than-average temperatures during April were across the Midwest U.S., and Canada's Hudson Bay. Record-high levels of Great Lakes ice remained throughout the month as the winter reluctantly, and ever so slowly, yielded to spring in this region.
For the cold season in the Northern Hemisphere, which runs from November through April, all of Europe and Asia had above average temperatures, compared to the 1951 to 1980 average, NASA data shows. The largest temperature departures from average occurred across Siberia and Alaska, as well as the North Pacific Ocean.
Global average temperature departures from average for November through April of 2013-14.
Over the long term, temperatures during the Northern Hemisphere cool season have been warming significantly, in keeping with global temperature trends during other seasons.
Trend in global average surface temperatures during the Northern Hemisphere cool season, between 1900 and 2014. Grey areas indicate missing data.
New NOAA data released on Tuesday found that for the U.S. only, April was a wetter-than-average month but had near average temperatures.
The U.S. had an average temperature for the month of 51.7 degrees Fahrenheit, NOAA says, which was 0.7 degrees Fahrenheit above the 20th century average, ranking near the middle among all Aprils in the 120-year period of record.
If an El Niño event develops this summer or early fall — as is currently forecast — it could boost global average temperatures to record levels later this year and in 2015. El Niño events, which are characterized by unusually mild ocean waters in the central and eastern tropical Pacific Ocean, add heat to the atmosphere and can alter weather patterns from California to eastern Africa.