What are you implying? Scientists can't make stars either, but they can make models describing stars and make new observations about these stars that test the validity of these models. Plenty of climate models have been disproven by this exact way. What has been remarkably consistent is that man-made greenhouse gases are causing climate change. For example, models predict that man-made global warming would cause the stratosphere to cool, which is exactly what they measured. By contrast, increased solar activity would have also heated up the stratosphere.