Learn Hardcore Spanish (Spain): En la carrera tenemos una asignatura optativa sobre cambio climático. - In the degree program we have an elective subject on climate change.

In this sentence, en la carrera means “in the degree programme / in the degree we’re studying” (for example, in my Law degree, in my Engineering degree, etc.), not a physical race and not “career” in the English sense.

In Spain, people often say:

hacer una carrera = to do a university degree
¿Qué carrera estudias? = What are you studying at university?

Why is it la carrera and not mi carrera?

Spanish often uses the definite article (el/la) where English would use a possessive (my/our), especially when the context is shared or obvious.

Here, the speaker is probably talking to classmates or about their own studies, so la carrera is understood as “our degree / the degree (we’re doing)”. Saying:

En la carrera tenemos…

sounds natural, like “On the degree (program), we have…”.

You can say en mi carrera if you really want to emphasise that it’s my degree and not someone else’s, but it’s not necessary in a typical context where everyone knows which degree you’re talking about.

What is the difference between carrera, grado, curso, and asignatura in Spain?

Roughly:

carrera
Your whole university degree (Law, Medicine, Engineering, etc.).
- Estoy estudiando la carrera de Medicina.
grado
More formal/modern term for an undergraduate degree (Bologna system). Universities use it a lot in official names:
- Grado en Física = Bachelor’s Degree in Physics.
  In everyday speech, many people still just say carrera.
curso
Depends on context:
- At university or school: year/level:
  Estoy en segundo curso. = I’m in second year.
- Also: a course (e.g. a short language course):
  Voy a hacer un curso de francés.
asignatura
A subject / module / class that is part of your studies:
- Tengo cuatro asignaturas este semestre.

So in the sentence, en la carrera = in the degree, and una asignatura = one subject (one component of that degree).

What exactly is asignatura? Is it the same as materia or clase?

All three can be related to “subject / class”, but they aren’t used in exactly the same way:

asignatura
The standard word for an academic subject or module in a curriculum:
- asignatura obligatoria = compulsory subject
- asignatura optativa = optional subject
materia
More like subject area / material. It can overlap with asignatura, but sounds a bit more general or academic:
- materias científicas = scientific subjects/fields
  In everyday speech about what you study at school or uni, asignatura is more common.
clase
Means:
- a lesson/session: Tengo clase a las 10.
- sometimes informally, the subject: No me gusta la clase de mates.
In your sentence, asignatura is the most natural choice, because we’re talking about a specific module in the degree plan.

Why is it una asignatura optativa and not una optativa asignatura?

In Spanish, most descriptive adjectives (colour, shape, type, etc.) normally go after the noun:

asignatura interesante
coche rojo
película aburrida

So optativa (optional) comes after asignatura:

una asignatura optativa = an optional subject

Putting it before the noun (una optativa asignatura) sounds wrong or at least very unnatural here.

Note: in everyday speech in Spain, people often shorten it and say:

una optativa (literally “an optional (one)”)

because asignatura is understood:
En la carrera tenemos una optativa sobre cambio climático.

Why is optativa feminine?

Adjectives in Spanish agree in gender and number with the noun they describe.

asignatura is feminine singular (la asignatura).
Therefore, the adjective optativo must also be feminine singular: optativa.

Compare:

un libro optativo (masculine singular)
dos libros optativos (masculine plural)
una asignatura optativa (feminine singular)
dos asignaturas optativas (feminine plural)

Why do we say tenemos una asignatura instead of hay una asignatura?

Both tener and haber (hay) can translate to English “have”/“there is”, but they’re used differently:

tenemos una asignatura optativa…
= we have an optional subject…
Focus on the group (we) possessing or having that subject in our degree plan.
hay una asignatura optativa…
= there is an optional subject…
More impersonal: just states that such a subject exists.

In this context, since you’re talking about your degree and what it includes for you, tenemos feels more natural in Spanish. It underlines that we, in this degree, have that module.

Can I say sobre el cambio climático? Why is there no el here?

Yes, you can say sobre el cambio climático, and it’s perfectly correct.

The difference is subtle:

sobre cambio climático
More like “about climate change in general”, treating cambio climático as a general concept. In Spanish, with some abstract or general concepts, the article can be dropped:
- estudios sobre cambio climático
- información sobre educación infantil
sobre el cambio climático
Also common. The article el makes it feel a bit more like a specific, known phenomenon (the climate change we all talk about), but in practice, both versions are very close in meaning here.

Both are acceptable; style and personal preference decide. In many contexts, Spaniards naturally say sobre el cambio climático, but dropping el is not wrong.

Could I say una asignatura optativa de cambio climático instead of sobre cambio climático?

You could, but it sounds less natural in this context and slightly shifts the nuance.

sobre cambio climático
Literally “about climate change” – focuses on the topic or content of the subject. This is the most typical way to say it.
de cambio climático
Literally “of climate change”. It can work, but it sounds a bit like you’re labelling the subject by type rather than simply stating its topic. In many ears, asignatura de cambio climático feels a little heavier or less idiomatic than asignatura sobre cambio climático.

So, sobre is the best, most natural preposition for “on/about [topic]” here.

Is cambio climático always singular? Could it be plural?

Normally, when we talk about the global phenomenon, we use the singular:

el cambio climático = climate change (as a general, global process)

You might see a plural cambios climáticos in texts talking about various separate climate changes in geological history or different types of changes, but in everyday language, when people say cambio climático, they mean the single global phenomenon, so it’s singular.