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Chinese Study Puts Sun In Frame For Global Warming

05.06.2014
05.06.2014 17:42 Age: 2 yrs

New research by scientists from China's space weather laboratory and press released by the news service of the American Association for the Advancement of Science states that solar activity has a non-negligible forcing on the temperature change of the Earth. This research is certain to be seen as controversial as it implies that natural factors have had a greater influence on global warming than IPCC models have suggested.

Click to enlarge. The global wavelet coherence between sunspot number and the anomalies of the Earth's averaged surface temperature. Courtesy: authors and Science China Press.

Click to enlarge. The global wavelet coherence between Total Solar Irradiance and the anomalies of the Earth's averaged surface temperature. The resonant periodicities of 21.3-year (21.5-year), 52.3-year (61.6-year), and 81.6-year are close to the 22-year, 50-year, and 100-year cycles of solar activity. Courtesy: authors and Science China Press.

Click to enlarge. This shows comparisons between the 11-year running averaged Total Solar Irradiance (TSI) and the temperature (T) anomalies of the Earth (global, land, ocean). Courtesy: authors and Science China Press .

 

Research from China published in a peer reviewed Chinese language journal claims that there is a strong correlation between solar output and the warming of the Earth and implies that the climate models used by the Intergovernmental Panel on Climate Change (IPCC) may have "underestimated" the impact of natural factors on climate change.

The recent study claims to demonstrate the existence of significant resonance cycles and high correlations between solar activity and the Earth's averaged surface temperature during centuries, according to an accompanying press release. The press release also claims that a peer reviewer of this paper stated "this work provides a possible explanation for the global warming".

This is a controversial claim and flies in the face of evidence presented by the IPCC and accepted by many climate scientists that increases in atmospheric carbon dioxide (CO2) have been the main factor driving up global temperatures in the industrial age.

The press release states: "climate models of IPCC seem to underestimate the impact of natural factors on the climate change, while overstate that of human activities". It adds that the study "implies that the "modern maximum" of solar activity agrees well with the recent global warming of the Earth. A significant correlation between them can be found".

The research by Dr. Zhao Xinhua and Dr. Feng Xueshang from Chinese state space weather laboratory is published in the peer reviewed journal Chinese Science Bulletin. The paper is written in Chinese with an English language abstract.

In their English language abstract (see below) the authors state: “During the past 100 years, solar activities display a clear increasing tendency that corresponds to the global warming of the Earth (including land and ocean) very well. Particularly, the ocean temperature has a slightly higher correlation to solar activity than the land temperature. All these demonstrate that solar activity has a non-negligible forcing on the temperature change of the Earth on the time scale of centuries.”

This research goes to the heart of the issue of the importance of the sun in climate change and also the issue of the so called sensitivity of the climate to changes in atmospheric CO2 levels. The implication of the research is that the sensitivity of the climate to increases in CO2 is less than that assumed in IPCC model forecasts and therefore that the sun plays a far greater role in influencing climate change than previously acknowledged.

The IPCC's AR5 science report published in September 2013 states: "Nonetheless, there is a high confidence that 21st century solar forcing will be much smaller than the projected increased forcing due to GHGs."

 

Here is the press release issued by the EurekAlert service of the AAAS. Note that Figure 1 referred to below is made up from the top two pictures on the right. And figure 2 referred to below is the bottom picture.

Has solar activity influence on the Earth's global warming?

A recent study demonstrates the existence of significant resonance cycles and high correlations between solar activity and the Earth's averaged surface temperature during centuries. This provides a new clue to reveal the phenomenon of global warming in recent years.

Their work, entitled "Periodicities of solar activity and the surface temperature variation of the Earth and their correlations" was published in CHINESE SCIENCE BULLETIN (In Chinese) 2014 No.14 with the co-corresponding authors of Dr. Zhao Xinhua and Dr. Feng Xueshang from State key laboratory of space weather, CSSAR/NSSC, Chinese Academy of Sciences. It adopts the wavelet analysis technique and cross correlation method to investigate the periodicities of solar activity and the Earth's temperature as well as their correlations during the past centuries.

Global warming is one of the hottest and most debatable issues at present. The Intergovernmental Panel on Climate Change (IPCC) claimed that the release of the anthropogenic greenhouse gases contributed to 90% or even higher of the observed increase in the global average temperature in the past 50 years. However, the debate on the causes of the global warming never stops. Research shows that the current warming does not exceed the natural fluctuations of climate. The climate models of IPCC seem to underestimate the impact of natural factors on the climate change, while overstate that of human activities. Solar activity is an important ingredient of natural driving forces of climate. Therefore, it is valuable to investigate the influence of solar variability on the Earth's climate change on long time scales.

This innovative study combines the measured data with those reconstructed to disclose the periodicities of solar activity during centuries and their correlations with the Earth's temperature. The obtained results demonstrate that solar activity and the Earth's temperature have significant resonance cycles, and the Earth's temperature has periodic variations similar to those of solar activity (Figure 1).

This study also implies that the "modern maximum" of solar activity agrees well with the recent global warming of the Earth. A significant correlation between them can be found (Figure 2).

As pointed out by a peer reviewer, "this work provides a possible explanation for the global warming".

End of press release.

Abstract

Based on the well-calibrated systematic measurements of sunspot numbers, the reconstructed data of the total solar irradiance (TSI), and the observed anomalies of the Earth’s averaged surface temperature (global, ocean, land), this paper investigates the periodicities of both solar activity and the Earth’s temperature variation as well as their correlations on the time scale of centuries using the wavelet and cross correlation analysis techniques. The main results are as follows. (1) Solar activities (including sunspot number and TSI) have four major periodic components higher than the 95% significance level of white noise during the period of interest, i.e. 11-year period, 50-year period, 100-year period, and 200-year period. The global temperature anomalies of the Earth have only one major periodic component of 64.3-year period, which is close to the 50-year cycle of solar activity. (2) Significant resonant periodicities between solar activity and the Earth’s temperature are focused on the 22- and 50-year period. (3) Correlations between solar activity and the surface temperature of the Earth on the long time scales are higher than those on the short time scales. As far as the sunspot number is concerned, its correlation coefficients to the Earth temperature are 0.31-0.35 on the yearly scale, 0.58-0.70 on the 11-year running mean scale, and 0.64-0.78 on the 22-year running mean scale. TSI has stronger correlations to the Earth temperature than sunspot number. (4) During the past 100 years, solar activities display a clear increasing tendency that corresponds to the global warming of the Earth (including land and ocean) very well. Particularly, the ocean temperature has a slightly higher correlation to solar activity than the land temperature. All these demonstrate that solar activity has a non-negligible forcing on the temperature change of the Earth on the time scale of centuries.

Citation

Periodicities of solar activity and the surface temperature variation of the Earth and their correlations by ZHAO X H, FENG X S.Chin Sci Bull (Chin Ver), 2014, 59: 1284, doi: 10.1360/972013-1089

Read the abstract in English and get the open access Chinese language paper here.

Source

News release issued by the EurekAlert service of the AAAS here.


Note: this story was updated with additional material at 19.40 on 5 June 2014.