Terrestrial warming and cooling: Either or both?

The main focus of the journal Temperature is on the interactions between temperature and life; in fact, the journal’s motto is: “Temperature is life!” [1]. In agreement with this focus, Temperature has been covering some biologically relevant aspects of climate change. One of Temperature’s Editorial Board members, Camille Parmesan, participated in the Intergovernmental Panel on Climate Change (IPCC); together with the former US Vice-President Al Gore, the panel was awarded the Nobel Peace Prize in 2007 “for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change.” In the first volume of Temperature, Camille Parmesan published an essay about her fascinating journey in science [2]. In the same issue, Robyn Hetem and her colleagues published a comprehensive review on responses of large mammals to climate change [3]. Lučka Kajfež Bogataj, another IPCC participant, coauthored two articles published in Temperature [4,5]. One of these articles [5] is an editorial introducing HEAT-SHIELD, a European Union-funded inter-sectoral research project aimed at shielding the population from the increasing frequency and magnitude of heat events.

A main direction of modern research on climate change and of IPCC activities involves studies using modeling and connecting terrestrial temperatures to carbon dioxide levels. Cumulatively, these studies suggest that air temperatures on our planet are generally (“on average”) increasing, which has been linked to rising carbon dioxide. Of course, the carbon dioxide-based approach to understanding climate change is not the only one. Recently, the journal Scientific Reports published a paper by Valentina Zharkova et al. [6], in which the authors focus on the fact that terrestrial temperatures are affected by activity of the Sun and, according to the research presented in the paper, closely correlate with the total solar irradiance. Extrapolating these correlations into the future, the authors predict that “ … substantial temperature decreases are expected … to occur in 2020–2055 and 2370–2415” [6]. Wait a minute, is the Earth currently warming or cooling? Or is it exhibiting a long-term warming trend with some short-term cooling occurring on top of it?

In addition to the scientific intrigue, it is also puzzling to me how the Editors of Scientific Reports handled the Zharkova et al. [6] article. After the article passed peer review and was published, it received critical comments on the journal’s website (the so-called post-publication peer review), and the Editors retracted the paper. In the retraction notice, the Editors explained that the retraction was based on a scientific error [6], and the retraction was accepted by one of the four authors of the retracted work. While different publishers and journals have different policies, it is rather unusual to retract a paper based on an error – not on any misconduct. Errors in published papers are typically corrected in errata. If all scientific papers containing honest errors were retracted, not too many would be left for us to read! It is also important to note that, in the Zharkova et al. case, the alleged error did not seem to interfere with the analyses presented in the “main” portion of the paper, and neither did it change the authors’ main conclusion.

Zharkova’s work, her provocative predictions, and the retraction of her article received a lot of attention in the media, including mainstream newspapers such as the Washington Post and Guardian. I thought the readers of the journal Temperature would be interested in hearing from Professor Valentina Zharkova, first-hand. I invited her to write an editorial and to explain, in layman’s terms, to us – biologists and physicians – what her work says about the thermal future of our planet. You can read Valentina Zharkova’s thoughts on this topic in this issue of Temperature [7]. I hope Temperature readers agree that we need more original approaches to research, more discussion, and more effort to explain our ideas to others, especially across disciplines. Errors happen, and this is fine. Different studies – all arguably imperfect – lead to different conclusions, and this is fine too.