Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cosmic rays do not explain global warming

17.12.2008
A new study supports earlier findings by stating that changes in cosmic rays most likely do not contribute to climate change.

It is sometimes claimed that changes in radiation from space, so-called galactic cosmic rays, can be one of the causes of global warming. A new study, investigating the effect of cosmic rays on clouds, concludes that the likelihood of this is very small.

The study "Cosmic rays, cloud condensation nuclei and clouds – a reassessment using MODIS data" was recently published in the journal Atmospheric Chemistry and Physics. A group of researchers from the University of Oslo, Norwegian Institute for Air Research (NILU), CICERO Center for Climate and Environmental Research, and the University of Iceland, are behind the study.

Unlikely that cosmic rays affect warming
There are scientific uncertanties about cosmic rays and cloud formation. Some researchers have claimed that a reduction of cosmic rays during the last decades has contributed to the global temperature rise. The hypothesis is that fewer cosmic rays causes fewer cloud droplets and reduced droplet size, and that this again causes global warming, since reduced cloud droplets would reflect less energy from the sun back to space. However, the researchers who stick to this hypothesis find little support amongst colleagues.

“According to our research, it does not look like reduced cosmic rays leads to reduced cloud formation”, says Jon Egill Kristjansson, a professor at the University of Oslo.

This result is in line with most other research in the field. As far as Kristjansson knows, no studies have proved a correlation between reduced cosmic rays and reduced cloud formation.

Kristjansson also points out that most research shows no reduction in cosmic rays during the last decades, and that an astronomic explanation of today’s global warming therefore seems very unlikely.

Studied solar outbreaks
Kristjansson and his collegaues have used observations from so-called Forbush decrease events: Sudden outbreaks of intense solar activity that lead to a strong reduction of cosmic rays, lasting for a couple of days. The researchers have identified 22 such events between 2000 and 2005.

Based on data from the space-borne MODIS instrument, the researchers have investigated whether these events have affected cloud formation. While previous studies have mainly considered cloud cover, the high spatial and spectral resolution of the MODIS data also allows for a more thorough study of microphysical parameters such as cloud droplet size, cloud water content and cloud optical depth.

No statistically significant correlations were found between any of the four cloud parameters and galactic cosmic rays.

“Reduced cosmic rays did not lead to reduced cloud formation, either during the outbreaks or during the days that followed. Indeed, following some of the events we could see a reduction, but following others there was an increase in cloud formation. We did not find any patterns in the way the clouds changed”, Kristjansson explains.

By focusing on pristine Southern Hemisphere ocean regions, the researchers examined areas where a cosmic ray signal should be easier to detect than elsewhere.

Supports other recent work
Joanna Haigh from Imperial College London has also studied possible links between solar variability and modern-day climate change.

“This is a careful piece of work by Jon Egill Kristjansson that appears to find no evidence for the reputed link between cosmic rays and clouds," she commented to BBC.

“It's supporting other recent work that also found no relationship," Haigh added.

Petter Haugneland | alfa
Further information:
http://www.cicero.uio.no
http://www.atmos-chem-phys.net/8/7373/2008/acp-8-7373-2008.html

More articles from Studies and Analyses:

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

nachricht A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Bodyguards in the gut have a chemical weapon

20.01.2017 | Life Sciences

SF State astronomer searches for signs of life on Wolf 1061 exoplanet

20.01.2017 | Physics and Astronomy

Treated carbon pulls radioactive elements from water

20.01.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>