Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Greenhouse gases likely drove near-record U.S. warmth in 2006

Greenhouse gases likely accounted for over half of the widespread warmth across the continental United States in 2006, according to a new study that will be published 5 September in Geophysical Research Letters, a publication of the American Geophysical Union.

Last year's average temperature was the second highest since recordkeeping began in 1895. The team found that it was very unlikely that the 2006 El Nino played any role, though other natural factors likely contributed to the near-record warmth.

When average annual temperature in the United States broke records in 1998, a powerful El Nino was affecting climate around the globe.

Scientists widely attributed the unusual warmth in the United States to the influence of the ongoing El Nino. El Nino is a warming of the surface of the east tropical Pacific Ocean.

The research team, led by Martin Hoerling at the National Oceanic And Atmospheric Administration (NOAA) Earth System Research Lab in Boulder, Colorado, also found that greenhouse gas increases in Earth's atmosphere enhanced the probability of U.S. temperatures breaking a record in 2006 by approximately 15-fold compared to pre-industrial times. The authors also estimate that there is a 16 percent chance that 2007 will bring record-breaking warmth.

"We wanted to find out whether it was pure coincidence that the two warmest years on record both coincided with El Nino events," Hoerling said. "We decided to quantify the impact of El Nino and compare it to the human influence on temperatures through greenhouse gases."

Preliminary data available in January 2006 led NOAA to place that year as the warmest on record. In May 2007, NOAA revised the 2006 ranking to second warmest after updated statistics showed the year was .08 F cooler than 1998. The annual average temperature in 2006 was 2.1 F above the 20th Century average and marked the ninth consecutive year of above-normal U.S. temperatures. Each of the contiguous 48 states reported above-normal annual temperatures, and for the majority of states, 2006 ranked among the 10 hottest years since 1895.

Using data from 10 past El Nino events observed since 1965, the authors examined the impact of El Nino on average annual U.S. surface temperatures. They found a slight cooling across the country. To overcome uncertainties inherent in the data analysis, the team also studied the El Nino influence using two atmospheric climate models.

The scientists conducted two sets of 50-year simulations of U.S.
climate, with and without the influence of El Nino sea-surface warming.
They again found a slight cooling across the nation when El Nino was present.
To assess the role of greenhouse gases in the 2006 warmth, the researchers analyzed 42 simulations of Earth's climate from 18 climate models provided for the latest assessment by the Intergovernmental Panel on Climate Change (IPCC). The models included greenhouse gas emissions and airborne particles in Earth's atmosphere since the late 19th century and computed their influence on average temperatures through 2006. The results of the analysis showed that greenhouse gases produced warmth over the entire United States in the model projections, much like the warming pattern that was observed last year across the country.

For a final check, the scientists compared the observed 2006 pattern of abnormal surface temperatures to the projected effects of greenhouse-gas warming and El Nino temperature responses. The U.S. temperature pattern of widespread warming was completely inconsistent with the pattern expected from El Nino, but it closely matched the expected effects of greenhouse warming.

"That attribution was not confirmed at the time," says Hoerling.
"Now we have the capability, on the spatial scale of the United States, to better distinguish natural climate variations from climate changes caused by humans."

The research was supported by NOAA's office of Global Programs.

Notes for Journalists
Journalists and public information officers of educational and scientific institutions (only) can receive a PDF copy of this paper (a pre-publication copy subject to final editing of any article listed as "in press") by sending a message to Jonathan Lifland at

Please provide your name, the name of your publication, and your phone number.

"Explaining the record US warmth of 2006"
Martin Hoerling, Jon Eischeid, Xiaowei Quan, Taiyi Xu, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA.
Hoerling, M., et al. (2007), Explaining the record US warmth of 2006, Geophys. Res. Lett., 34, In Press, doi:10.1029/2006GL0030643.
Contact information for authors:
* Martin Hoerling, +1 303 497-6165 or
* Jon Eischeid, +1 303 497-5970 or
* Quan Xiaowei, +l 303 492-5961 or
* Taiyi Xu, +1 303 497-6343 or

Jonathan Lifland | AGU
Further information:

More articles from Earth Sciences:

nachricht Ice shelf vibrations cause unusual waves in Antarctic atmosphere
25.10.2016 | American Geophysical Union

nachricht Enormous dome in central Andes driven by huge magma body beneath it
25.10.2016 | University of California - Santa Cruz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>