Level of scientific understanding
The Level of Scientific Understanding (LOSU) is a framework utilized by the Intergovernmental Panel on Climate Change (IPCC) to evaluate and communicate the reliability of climate science. Given the complexity and vastness of Earth's climate system, achieving absolute certainty in measurements is virtually impossible. Therefore, the IPCC employs a dual assessment system that combines the strength of evidence supporting various climate influences—such as greenhouse gases and aerosols—with the degree of consensus among scientists. This results in a classification system that ranges from high to very low understanding, aiming to clarify the current state of knowledge without implying unwarranted precision.
The significance of LOSU lies in its ability to convey the intricacies and challenges inherent to climate science, which includes factors like the dynamic nature of the climate and the political landscape surrounding climate policy. This approach acknowledges that scientific consensus is crucial in the evolution of ideas, while also allowing for ongoing debate and scrutiny. Ultimately, LOSU serves as a tool to provide both the public and policymakers with informed estimates regarding climate change, emphasizing the importance of using the best available science and data to address these pressing global issues.
Level of scientific understanding
Definition
The Intergovernmental Panel on Climate Change (IPCC) is a scientific body that represents a hybrid of science and government. Its members strive for maximum reliability in their measurements, but they are keenly aware of the virtual impossibility of reaching that goal. Earth’s climate is simply too vast a system to allow for carefully controlled experiments. Rather than ignore the problem, IPCC workers have designed a compromise system that specifies the degree to which workers in the field are confident of the validity of reported data. A level of scientific understanding (LOSU) designation is applied to assessments of each of the influences on the Earth’s temperature. These factors include the greenhouse gases (GHGs), aerosols, mineral dust, and contrails.
Each of the radiative forcing factors is given an assessment of A to C depending on the evidence supporting it and an assessment of 1 to 3 for the degree of consensus among climate scientists. LOSU is assigned on the basis of these two evaluations. The terms used are high, medium, medium-low, low, and very low. This scale and its terminology were deliberately chosen to avoid confusion with the measures of confidence associated with statistics. IPCC reports clearly state that such statistical precision is not possible in the present state of climate science. The LOSU designation is designed to avoid the unwarranted impressions of understanding.
Significance for Climate Change
Central to all scientific discussions is the reliability of the measurements that are used to support one’s position. In the case of climate change or global warming, there are a number of extremely complex issues seldom encountered in scientific studies. These include the size of the system being studied; the constant changes undergone by that system; the large number of scientists conducting partial studies, each of whom has a particular objective; the lack of power to demand that specific procedures be followed; and so on. By contrast, scientists are accustomed to designing experiments with particular objectives and carrying them out under carefully controlled conditions. Added to these difficulties is the obvious necessity of collecting enormous amounts of data on a worldwide scale and attempting to draw from them meaningful leads for further investigation.
These problems pale in comparison to the realization that these scientific studies are conducted in a highly charged political arena. Imagine a range of scientists with little training and personal sympathies or antipathies toward policymakers presenting tentative conclusions to officials with little scientific background, and perhaps even a jaundiced view of civilians who never have to stand for reelection. Even assuming both groups earnestly desire to benefit humanity, it is clear that differences of viewpoint will often lead to discord over the appropriate strategies and tactics.
Those who disagree with a general position on global warming argue that science must not involve consensus and that the LOSU is therefore fatally flawed. This conclusion is based on a red herring and a profound lack of knowledge of the history of science. The most important reason for publication of the outcome of scientific experimentation is to allow other scientists to fulfill their obligation to question any new proposal. This is how new ideas are tested through peer review. The normal outcome of this process is debate over the validity and utility of that idea, and it inevitably leads to a mixture of acceptance, reservation, and rejection. It was long after John Dalton had proposed the atomic hypothesis that the majority of chemists accepted the existence of atoms. Even after an idea becomes textbook science and is accepted by nearly everyone, at least as a working hypothesis, it may still be modified or rejected when the consensus is broken. A consensus existed that the inert elements did not form compounds, until it was shown that they do. Science depends on consensus at every stage of its evolution.
With these technical and political problems in clear view, the IPCC has sought to bring common sense to bear on its mission. Nowhere is this effort clearer than in the LOSU approach. By considering both the strength of the evidence offered by scientists and the degree of acceptance it obtains from the scientific community, the group offers the public and the policymakers its best estimate of the real-world situation. It has been said that the only simple systems are those that have not yet been studied. It appears clear to informed people, scientists, and policymakers that the problems of climate change must be resolved using the best ideas and technology available. The level of scientific understanding represents a useful approach to evaluating and disseminating the current state of this aspect of climate science.
By the 2010s and 2020s, the global community of climate scientists had reached an overwhelming consensus on climate change. At least 97 percent of climate scientists agreed that climate change was occuring and that human actions were the primary driving factor.
Bibliography
Forster, P., et al. “Changes in Atmospheric Constituents and in Radiative Forcing.” In Climate Change, 2007: The Physical Basis, edited by S. D. Solomon et al. New York: Cambridge University Press, 2008.
Haley, James, ed. Global Warming: Opposing Viewpoints. San Diego, Calif.: Greenhaven Press, 2002.
Silver, Jerry. Global Warming and Climate Change Demystified. New York: McGraw-Hill, 2008.
"Understanding Climate Change." Government of Australia, 2024, www.dcceew.gov.au/climate-change/policy/climate-science/understanding-climate-change. Accessed 21 Dec. 2024.