La charla sobre el cambio climático me hizo pensar.

This is a very common Spanish structure.

Hacer + infinitive means to make someone do something, to cause someone to do something, or sometimes to lead someone to do something.

In your sentence:

• La charla = the thing causing the action
• hizo = made / caused
• me = the person affected
• pensar = the action that resulted

So the pattern is:

[thing/person causing it] + hacer + indirect object pronoun + infinitive

Examples:

• Me hizo reír. = It made me laugh.
• Nos hizo cambiar de opinión. = It made us change our minds.
• Te hizo pensar. = It made you think.

This structure is extremely natural in Spanish.

Me tells you who was made to think.

It is an object pronoun, and in this construction it works like this:

• me = me
• te = you
• le = him / her / you (formal)
• nos = us
• os = you all (used in Spain)
• les = them / you all (formal)

So:

• La charla me hizo pensar. = The talk made me think.
• La charla nos hizo pensar. = The talk made us think.

In Spanish, these pronouns normally go before the conjugated verb, which is why you get me hizo, not hizo me.

Hizo is the preterite of hacer, and it is used for a completed event in the past.

Here, the speaker is referring to one specific talk and its effect as a finished event.

• me hizo pensar = it made me think

Other tenses would change the meaning:

• me hace pensar = it makes me think
  used for a present or general effect

• me hacía pensar = it was making me think / it used to make me think
  more ongoing, habitual, or backgrounded

• me ha hecho pensar = it has made me think
  often used when the effect still feels connected to the present

So hizo fits well if the speaker is talking about a particular talk as a finished past event.

Because after hacer in this causative structure, the second verb stays in the infinitive.

So Spanish says:

• me hizo pensar
• me hace pensar
• me hará pensar

not:

• me hizo pensé
• me hizo pensando

This is normal after hacer when it means make/cause someone to do something.

Compare:

• Me hizo llorar.
• Me hizo sonreír.
• Me hizo reflexionar.

The tense is carried by hacer (hizo), and the second verb remains in its base form (pensar).

Not always. In Spanish, me hizo pensar can be quite natural and does not necessarily sound forceful.

Depending on context, it can mean:

• it made me think
• it got me thinking
• it made me reflect
• it prompted me to think

So it can be softer than literal English made me sometimes sounds.

That is why this expression is very common when reacting to talks, books, films, or comments:

• Esa película me hizo pensar.
• Lo que dijo me hizo pensar.

It often suggests reflection, not literal pressure or force.

Sobre here means about or on the topic of.

So una charla sobre X is a very common way to say a talk about X.

Other possibilities exist:

• una charla acerca del cambio climático
  also correct, a bit more formal

• una charla del cambio climático
  possible in some contexts, but less straightforward here

For this kind of topic label, sobre is one of the most natural choices.

You will see it a lot with nouns like:

• un libro sobre historia
• un documental sobre arte
• una conferencia sobre salud mental

Spanish often uses the definite article with concepts that English may leave bare.

Here, el cambio climático refers to the known concept climate change, so the article sounds natural and standard.

Compare:

• el cambio climático
• la educación
• la tecnología
• la economía

English often drops the article in these cases, but Spanish usually does not.

So sobre el cambio climático is the normal form.

Not exactly.

In Spain, charla usually suggests a talk that is somewhat informal, accessible, or conversational in tone. It can still be educational or public, but it often sounds less formal than conferencia.

Roughly:

• charla = talk, chat, talk/session
• conferencia = lecture, conference talk, more formal presentation

So:

• una charla sobre el cambio climático
  sounds natural for a school talk, public talk, outreach event, etc.

• una conferencia sobre el cambio climático
  sounds more formal or academic

In Spain, charla is very common in everyday use.

The pronoun placement is important.

With a conjugated verb, the object pronoun normally goes before the verb:

• me hizo pensar
• te hizo pensar
• nos hizo pensar

So hizo me pensar is not correct.

You can sometimes change the order of larger chunks of the sentence for emphasis:

• La charla sobre el cambio climático me hizo pensar.
  neutral, standard order

• Me hizo pensar la charla sobre el cambio climático.
  possible, but more marked or literary

The original sentence is the most neutral and natural version.

Because pensar on its own can mean to think in a broad sense, especially to reflect.

So me hizo pensar means something like:

• it made me think
• it made me reflect

If you want to say what you were thinking about specifically, Spanish often adds en:

• Me hizo pensar en el futuro.
• Me hizo pensar en mis hábitos.
• Me hizo pensar en cómo vivimos.

So:

• me hizo pensar = general reflection
• me hizo pensar en... = it made me think about...

Yes, and it is very natural.

But there is a small nuance:

• me hizo pensar = made me think, got me thinking
• me hizo reflexionar = made me reflect, caused deeper reflection

Reflexionar can sound a little more deliberate or thoughtful.
Pensar is broader and more everyday.

So both are good, but they are not always identical in tone:

• La charla me hizo pensar.
  very common, natural, broad

• La charla me hizo reflexionar.
  slightly more formal or introspective

You just change the pronoun.

Examples:

• La charla te hizo pensar. = The talk made you think.
• La charla le hizo pensar. = The talk made him/her/you-formal think.
• La charla nos hizo pensar. = The talk made us think.
• La charla os hizo pensar. = The talk made you all think.
  This os form is especially important in Spain.
• La charla les hizo pensar. = The talk made them/you-all-formal think.

If you are learning Spanish from Spain, os is worth noticing because it is used for you all in informal situations.