Scientists project that global temperatures are likely to increase by an average of about 1.5 to 2 degrees Celsius (approximately 2.7 to 3.6 degrees Fahrenheit) by the end of the century if substantial efforts to reduce greenhouse gas emissions are not made. In more extreme scenarios, if current trends continue without significant intervention, temperatures could rise by 4 degrees Celsius (7.2 degrees Fahrenheit) or more.
A projected increase of 20 degrees Fahrenheit is generally considered unlikely and would have catastrophic effects on ecosystems, weather patterns, and human populations. It's important to rely on peer-reviewed climate models and reports from organizations like the Intergovernmental Panel on Climate Change (IPCC) for accurate assessments of future temperature changes.