You may have seen posters that state that by the year 2050, there will be more plastic in our oceans than fish. We are still in the year 2019. So, how can can marine analysts make predictions about 2050? There could be multiple ways of doing so. Perhaps they just assume that plastic is added without any cleanup, or perhaps they just use the current rate of increasing plastic pollution, or they might have applied another kind of algorithm.
The essence of this statement is that by arriving at a number (such as the year 2050), they can spread awareness about increasing marine plastic pollution. By stating that there will be more plastic than fish, they can get the attention of the masses and encourage them to get working now. People dread the worst; if you throw an alarming situation at them, they are more likely to react (in the suggested way).
Similarly...