In astronomy one aberrant observation is enough to completely revolutionize the field or destroy a previously esteemed view. It's not based on melting pot models and so a single mistake indicates something is wrong, perhaps fundamentally wrong. Consider that decades before relativity was discovered we knew very well that something was very broken because Mercury's expected orbit was off by 1/100th of a degree per century.

By contrast, how would you propose falsifying a climate model? Each decade or so we gain another chunk of data we can use to try to trial predictions of the past and, to date, they've done quite abysmally except in the most broad sense of a longterm gradual increase in temperatures. For instance from 2001 and 2010 the warming slowed to 0.11C per decade. [1] For the 17 years before then was 0.17C. There was not a single model that predicted this and, in spite of a number of after the fact hypotheses for that apparent decline, there is still no decisive answer. In a science that was more heavily dependent upon testing, this would be a ground-shaking event. But it's effect on climate science has been relatively minimal.

[1] - https://www.scientificamerican.com/article/did-global-warmin...