Learn Hardcore Indonesian: Konferensi internasional tentang iklim itu menarik. - That international conference about climate is interesting.

Konferensi internasional tentang iklim menarik.
This is more general: International conferences about climate are interesting (or an international climate conference is interesting in a non-specific way).

So:

With itu → specific, known conference.
Without itu → more general idea, not a particular one.

Why is there no adalah in Konferensi ... itu menarik? I thought Indonesian used adalah like “to be.”

In Indonesian, when the predicate is an adjective, you usually do not use adalah:

Konferensi itu menarik. ✓
Konferensi itu adalah menarik. ✗ (sounds unnatural in standard Indonesian)

Typical pattern:

Subject + (itu/ini) + adjective
- Film itu bagus. – That movie is good.
- Rumah ini besar. – This house is big.

You mainly use adalah before:

A noun:
- Dia adalah guru. – He/She is a teacher.
A noun phrase:
- Indonesia adalah negara kepulauan. – Indonesia is an archipelagic country.

So here menarik is an adjective, so adalah is not needed.

Why do the adjectives come after the noun in konferensi internasional? Why not say internasional konferensi like in English?

In Indonesian, adjectives normally come after the noun:

konferensi internasional – international conference
kopi panas – hot coffee
buku baru – new book

So the pattern is:

Noun + adjective (Indonesian)
vs.
Adjective + noun (English)

In your sentence:

Konferensi = conference
internasional = international (adjective describing the conference)

So konferensi internasional is the standard, natural word order.

What does tentang mean exactly, and where does it usually go in the sentence?

Tentang means about or regarding. It introduces the topic of something.

Structure:

[Noun] + tentang + [topic]

Examples:

konferensi tentang iklim – conference about climate
buku tentang sejarah – book about history
diskusi tentang politik – discussion about politics

In your sentence:

konferensi internasional tentang iklim
= an international conference about climate

The prepositional phrase tentang iklim follows the noun phrase it describes (just like about climate follows conference in English).

What’s the difference between iklim and cuaca? Could I say tentang cuaca instead?

Iklim and cuaca are different:

iklim = climate
Long-term patterns of weather in a region or globally.
cuaca = weather
Short-term conditions like rain, sun, temperature today or this week.

So:

konferensi internasional tentang iklim
= international conference about climate (climate change, global warming, etc.)

You could say tentang cuaca, but it would change the meaning:

konferensi internasional tentang cuaca
= an international conference about weather (e.g., forecasting storms), not long-term climate patterns.

For discussions like climate change, iklim is the correct word.

What is the difference between menarik and tertarik? Can I say Konferensi itu tertarik?

Menarik and tertarik are related but used differently:

menarik = interesting / attractive (describes the thing)
- Konferensi itu menarik. – That conference is interesting.
tertarik = interested (describes a person/subject who feels interest)
- Saya tertarik pada konferensi itu. – I am interested in that conference.

So:

Konferensi itu tertarik. ✗
This is wrong, because a conference is not the one feeling interest; it creates interest. You must use menarik.

Correct uses:

Konferensi itu menarik. – The conference is interesting.
Saya tertarik dengan konferensi itu. – I’m interested in the conference.

Is konferensi internasional tentang iklim one long noun phrase, or is tentang iklim a separate part of the sentence?

In this sentence, the whole chunk konferensi internasional tentang iklim functions as one noun phrase (the subject).

Structure:

konferensi – head noun
internasional – adjective modifying konferensi
tentang iklim – prepositional phrase giving more detail about the konferensi

So the breakdown is:

[Konferensi internasional tentang iklim itu] – subject
[menarik] – predicate (adjective)

All of that before menarik is one big “who/what” that the sentence is about.

How would I say “International climate conferences are interesting” (in general, not just one specific conference)?

To express a general statement about conferences of that type, you’d typically drop itu and often also make the subject a bit more generic:

Konferensi internasional tentang iklim menarik.
= International climate conferences are interesting. (general statement)

Indonesian doesn’t mark plural with -s like English, so konferensi can mean conference or conferences depending on context.

If you want to make the plurality more explicit, you can say:

Konferensi-konferensi internasional tentang iklim menarik.
(reduplication indicates plural, but in many contexts it’s not necessary.)

Could I say Konferensi internasional tentang iklim itu sangat menarik? Where do intensifiers go?

Yes, that is natural and correct:

Konferensi internasional tentang iklim itu sangat menarik.
= That international conference about climate is very interesting.

Intensifiers like sangat, sekali, cukup, agak typically come:

Before the adjective:
- sangat menarik – very interesting
- cukup menarik – quite interesting
Or after the adjective (for some words like sekali):
- menarik sekali – very interesting (lit. interesting once, but idiomatic)

So you can say:

Konferensi itu sangat menarik.
Konferensi itu menarik sekali.

Is this sentence formal, informal, or neutral? Would people say this in everyday conversation?

The sentence:

Konferensi internasional tentang iklim itu menarik.

is neutral and perfectly natural in both spoken and written Indonesian.

It’s not slangy or overly casual.
It’s also not very formal or bureaucratic.

You could hear or read it:

In everyday conversation:
“Menurut saya, konferensi internasional tentang iklim itu menarik.”
In simple written texts, news, or reports.

To make it slightly more formal, someone might add details (e.g., sangat menarik, or specify the name and date of the conference), but the core structure is already fine for most situations.