Century-long trend of global ocean warming identified

Oct 29, 2012

One of the largest sources of uncertainty in reconstructing the warming of the past century stems from problems with historical ocean temperature records. Inconsistencies in method or technology or gaps in observation caused by two world wars mean that long-term records of sea temperature need to be interpreted with care.

Drawing on two historical sets of observations—one of the and the other of the upper 20 meters (66 feet) —Gouretski et al. find that the 20th century saw a long-term trend of ocean warming. The two data sets were mostly collected independently, using different tools and techniques, and were subjected to different post processing. The authors suggest that, owing to the distinct ways in which the data were gathered, the presence of a similar trend could mean that it is not a spurious finding.

Before the middle of the twentieth century, were predominantly measured from water collected in ships' engine rooms. At the end of World War II, bucket-collected water became the tool of choice, a shift that caused a sharp dip in measured temperatures. Instrumental biases from subsequent (and earlier) shifts in technology were accounted for to varying degrees. Drawing from a number of databases, the authors compiled more than 7 million subsurface temperature profiles, together with 244 million measurements from the International Comprehensive Ocean Atmosphere Data Set, representing observations back to 1900.

The authors find that sea surface and upper 20 meters (66 feet) temperatures generally tracked each other throughout the study period, though were higher than those of the subsurface. Both records show warming from 1900 to 1945, a decrease until the mid-1970s, and then a return to warming. Additionally, the authors find that, on average, the upper 400 meters (1,312 feet) of the warmed by 0.5 degrees Celsius (0.9 degrees Fahrenheit) to 0.6 degrees Celsius (1 degree Fahrenheit) from 1900 to 2000.

Explore further: Remnants of Tropical Depression Peipah still raining on Philippines

More information: Geophysical Research Letters, doi:10.1029/2012GL052975, 2012

add to favorites email to friend print save as pdf

Related Stories

June Earth's hottest ever: US monitors

Jul 15, 2010

Last month was the hottest June ever recorded on Earth, the US National Oceanic and Atmospheric Administration said Thursday, amid global climate warming worries.

Ocean height indicator of climate

Oct 07, 2005

U.S. and Canadian authors say an index of sea surface heights gathered by satellites could be a useful indicator of long-term climate cycles.

France has had hottest year since 1900

Dec 27, 2011

This year was the hottest in France since the start of the 20th century, Meteo France said Tuesday, with average national temperatures 1.5 degrees Celsius warmer than the norm.

Sea temperatures around Japan hit record high

Sep 10, 2010

Japan, which has just endured its hottest summer on record, said Friday it had also last month recorded the warmest sea temperatures since it started gathering comparable data 25 years ago.

Reanalyses find rising humidity in the Arctic

Jul 06, 2012

(Phys.org) -- Direct, reliable observations of atmospheric conditions stretch as far back as the mid seventeenth century, with otherwise consistent records being punctuated by periodic updates in methods, practitioners, and ...

Recommended for you

New study outlines 'water world' theory of life's origins

1 hour ago

(Phys.org) —Life took root more than four billion years ago on our nascent Earth, a wetter and harsher place than now, bathed in sizzling ultraviolet rays. What started out as simple cells ultimately transformed ...

Agriculture's growing effects on rain

22 hours ago

(Phys.org) —Increased agricultural activity is a rain taker, not a rain maker, according to researchers at Pacific Northwest National Laboratory and their collaborators at the University of California Los ...

User comments : 0

More news stories

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

Patent talk: Google sharpens contact lens vision

(Phys.org) —A report from Patent Bolt brings us one step closer to what Google may have in mind in developing smart contact lenses. According to the discussion Google is interested in the concept of contact ...

Tech giants look to skies to spread Internet

The shortest path to the Internet for some remote corners of the world may be through the skies. That is the message from US tech giants seeking to spread the online gospel to hard-to-reach regions.

Wireless industry makes anti-theft commitment

A trade group for wireless providers said Tuesday that the biggest mobile device manufacturers and carriers will soon put anti-theft tools on the gadgets to try to deter rampant smartphone theft.