A growing body of work is leading to the conclusion that it may be nearly impossible to prevent global temperatures from rising more than 1.5 degrees Celsius (or 2.7 degrees Fahrenheit) because we are simply not reducing emissions quickly enough. By some estimates, the current level of emissions will lock in that large a gain within the next few years. At that point, the only way to reverse the effects is to remove carbon dioxide from the atmosphere, where it otherwise will stay for hundreds to thousands of years.