Les émissions sont trop élevées.

In French, you usually need an article before a plural noun in a general statement.

So French says:

• les émissions = the emissions / emissions in general

Even when English would often just say emissions, French normally keeps the article.

Compare:

• Les émissions augmentent. = Emissions are increasing.
• Les prix sont élevés. = Prices are high.

So les is the normal choice here.

Because the noun is talking about emissions as a general category or total amount made up of many emissions.

French often uses the plural where English also does:

• les émissions
• les températures
• les dépenses

The singular l’émission usually means the emission or, in another common meaning, a TV/radio program depending on context. Here, les émissions clearly means emissions in the environmental sense.

Yes, émission is feminine: une émission.

You can tell in this sentence because both the article and adjective agree with it:

• les = plural article
• émissions = plural noun
• élevées = feminine plural adjective

A lot of nouns ending in -ion are feminine in French, and émission follows that pattern.

Sont is the they are form of the verb être.

The subject is les émissions, which is third-person plural, so the verb must also be plural:

• les émissions sont

This is the same pattern as:

• Les prix sont élevés.
• Les maisons sont grandes.

So sont is simply the correct plural form of être.

This is a very important difference.

• très élevées = very high
• trop élevées = too high

Trop means there is an excess, more than is acceptable or desirable.

So:

• Les émissions sont très élevées. = The emissions are very high.
• Les émissions sont trop élevées. = The emissions are too high.

If the meaning shown to the learner is too high, then trop is exactly right.

Because the adjective must agree with émissions, which is feminine plural.

The base adjective is élevé. Its forms are:

• masculine singular: élevé
• feminine singular: élevée
• masculine plural: élevés
• feminine plural: élevées

Since émissions is feminine plural, the correct form is élevées.

This kind of agreement is a basic rule in French adjectives.

French does not always use the same adjective that English uses.

For measurements, levels, amounts, prices, temperatures, rates, and emissions, French very often uses élevé rather than haut.

So you commonly get:

• des prix élevés
• une température élevée
• un taux élevé
• des émissions élevées

Haut is more often used for physical height or position, though it also has figurative uses in some expressions.

So Les émissions sont trop élevées sounds natural, while trop hautes would usually not be the standard choice here.

They help show pronunciation and spelling.

• é is pronounced like the ay sound in say, but shorter and cleaner.
• In émissions, the first é tells you the word starts with that sound.
• In élevées, both é letters are pronounced clearly.

So:

• émissions ≈ ay-mee-syon
• élevées ≈ ay-luh-vay

The accents are part of the correct spelling and should not be omitted in normal writing.

A careful pronunciation is roughly:

lay zay-mee-syon son tro ay-luh-vay

A few useful points:

• les émissions has a liaison: the s in les links to the vowel at the start of émissions, sounding like z
• sont is pronounced roughly like son with a nasal vowel
• trop ends with a pronounced p
• élevées ends with the ay sound

So:

• les émissions → lay-zay-mee-syon
• sont trop élevées → son tro ay-luh-vay

In more careful or formal speech, some speakers may also make a liaison between sont and élevées, but the most important one for learners here is les émissions.

Yes. That would simply mean The emissions are high.

Adding trop makes the sentence stronger and more specific:

• Les émissions sont élevées. = The emissions are high.
• Les émissions sont trop élevées. = The emissions are too high.

So trop adds the idea of excess.

Here trop modifies the adjective élevées, so it goes directly before it:

• sont trop élevées

That is the normal word order in French:

subject + verb + adverb + adjective

Compare:

• Le prix est trop élevé.
• Les températures sont trop basses.
• Ces chiffres sont trop faibles.

So placing trop before élevées is exactly what you should expect.

Yes. Émission is a word with more than one meaning.

Common meanings include:

• emission in the environmental or technical sense
• broadcast / program / show in radio or television

For example:

• Les émissions de CO₂ = CO₂ emissions
• une émission de télévision = a television program

In your sentence, the adjective élevées strongly suggests the environmental meaning, not TV shows.

You would change the noun, article, verb, and adjective to singular:

• L’émission est trop élevée.

Changes:

• les → l’
• émissions → émission
• sont → est
• élevées → élevée

This shows how French agreement works across the whole sentence.