The world is on fire, and there are flooding. Experts have just reported that we may not be able to prevent more severe climate change. This should prompt us to look for economic and rapid ways to reduce carbon emissions.Ars Technica. This article originally appeared on Ars Technica. It is a trusted source of technology news, analysis, reviews and other information. Cond Nast, WIRED's parent company owns Ars.A paper that examines the contribution of individual power plants to global emissions has just been published. This is some good news. This study shows that there are many countries that emit carbon dioxide at levels that exceed the global or national averages. The best 5 percent of plants that emit carbon dioxide would be shut down immediately to eliminate 75 percent of electricity-generated carbon dioxide.CARMA RevisitedIt is easy to see power generation as simple, such as "renewables bad, coal good." This statement is true to a certain extent. It also combines all power generation, from "somewhat poor" to "truly awful," into one category. The situation is much more complicated, as a range of research has shown. Different plants can convert fossil fuels into power with different efficiency levels depending on their age. Some plants that are less efficient only come online when there is a high demand. The rest of the year they remain idle and emit no emissions.These factors interact to determine whether a power plant is contributing significantly to the country's emissions or just part of its background noise. We could make a list of the worst power plants and identify them so that we can reduce our carbon output.We did, in fact, emphasize the past tense. Someone had created the Carbon Monitoring for Action database (or CARMA) using data from 2009. Nearly a decade later Don Grant, David Zelinka and Stefania Mitchella of the University of Colorado Boulder used 2018 data for an update of CARMA. This updated provides emissions data that is likely much more current.It was more challenging than you might think. Some countries have detailed data on their emissions at the per-plant level. This data can be easily imported into CARMA. Many other countries do not. These countries were not included in the research. The researchers used everything, from production data from the International Energy Agency to engineering specifications of individual plants.Researchers found that the most significant sources of uncertainty in their data were mostly concentrated in smaller plants. These have the lowest impact on overall emissions. The data for large facilities, which are likely to contribute significantly, is generally very good.The Worst of the WorstNo one should be surprised to learn that coal plants are the worst. The distribution of the most polluting plants may include some surprises. China, for example, is not the country known for its coal production. However, it has one of the worst 10 polluting plants. India and South Korea have two each.China has a lot of plants that aren't particularly bad. This is partly because many of them were built during the same boom in industrialization. There is little variation in efficiency from one plant to the next. However, the US, Germany, Russia, Indonesia and other countries see a lot more variation, so it's likely that they have inefficient plants.The authors looked at the country's pollution levels by examining the top 5 percent of power plants. This was ranked according to carbon emissions. China's worst 5 percent produced about 25% of its total emissions. The US saw the worst five percent of plants produce about 75 percent carbon emissions from the power sector. South Korea saw similar results, while Australia and Germany had roughly the same numbers. Japan, Australia, Germany and Japan each saw their worst 5 per cent of plants account for about 90 percent of carbon emissions from their power sector.