we can observe the climate changing on ALL THE PLANETS IN THE SOLAR SYSTEM, AT THE SAME TIME.

No we can't.

Be serious. How much information do you think we have about the climate of Jupiter? Or Venus? Or even Mars?

We know a few things like the facts that Mars has seasons and Jupiter's Red Spot is a storm, and we have a reasonably good idea of the average temperatures of the planets but not enough to say we can observe their climate changing.

What even counts as climate on Saturn? Or Neptune?

Neptune was discovered only about 180 years ago, and for most of that time we knew literally nothing about either the weather conditions or climate on the planet. (As opposed to what we know now, which is one fifth of fuck all.) It takes Neptune 165 years to go around the sun so we've only known about it's existence for barely more than one of its years, and you think that we're such experts about Neptunian global climate that we could even tell whether it was changing or not? Get the fuck out of here, you're dreaming.

In any case, regardless of what's happening on other planets, what's happening on earth is the same plus even more because of the near doubling of CO2 in the atmosphere. Since pre-industrial times, we've added roughly 780 billion tonnes of CO2 into the atmosphere, as well as other greenhouse gases such as methane.

So even if there was some small component of solar heating and cooling (which usually goes in cycles of about 22 years) there has been a massive trend added to that tiny cycle.

CC u/Death_By_Democracy