Formal pairs suit Writing Task 2. Neutral ones work anywhere. Informal ones belong in Speaking.
1.tackle climate change
formaltake strong, direct action to deal with climate change
No single country can tackle climate change alone, so international agreements are essential.
Strong Task 2 verb. Tackle also works with pollution, poverty and unemployment.
2.reduce carbon emissions
formallower the amount of carbon dioxide released into the air
Taxing aviation fuel would push airlines to reduce carbon emissions.
Cut and lower also collocate with emissions; decrease is less natural here.
3.renewable energy sources
formalsources of power that do not run out, such as wind and solar
Many governments now subsidise renewable energy sources such as wind and solar power.
Use the full phrase once, then renewables in later sentences to avoid repetition.
4.burn fossil fuels
neutraluse coal, oil or gas to produce energy
Most power stations still burn fossil fuels, which is the main cause of global warming.
Burn is the natural verb; use fossil fuels in the plural.
5.environmental degradation
formalthe gradual damage of land, air and water
Rapid industrial growth has led to serious environmental degradation in many developing regions.
An academic noun phrase for Writing. In Speaking, damage to the environment sounds more natural.
6.deplete natural resources
formaluse up resources so that little is left
If consumption continues at this rate, we will deplete natural resources that took millions of years to form.
Exhaust is a formal alternative.
Avoid: finish natural resources → deplete natural resources
7.protect endangered species
neutralkeep animals and plants at risk of dying out safe
Stricter hunting laws are needed to protect endangered species such as tigers and rhinos.
Endangered describes the species; extinct means it has already gone.
8.destroy natural habitats
neutralruin the places where wild animals and plants live
Clearing forests for farmland destroys the natural habitats of thousands of species.
Habitat loss is the noun form for a more concise sentence.
9.pose a threat to
formalbe a danger to something
Plastic waste poses a serious threat to marine life.
Add serious, major or growing before threat for emphasis.
Avoid: give a threat to → pose a threat to
10.raise awareness of
neutralmake more people understand an issue
Schools can raise awareness of environmental issues from an early age.
Raise is transitive, so it takes an object; rise does not.
Avoid: rise awareness about → raise awareness of
11.take urgent action
formalact quickly because a problem is serious
Governments must take urgent action before the damage becomes irreversible.
Take collocates with action; make does not.
Avoid: make urgent action → take urgent action
12.cause irreversible damage
formalharm something so badly that it cannot be repaired
Oil spills can cause irreversible damage to coastal ecosystems.
Do damage is also correct; make damage is not.
Avoid: make irreversible damage → cause irreversible damage
13.sustainable development
formaleconomic growth that does not harm the environment for future generations
Developing countries need support to pursue sustainable development rather than copying polluting industries.
A common Task 2 theme phrase. Use it when you discuss growth and the environment together.
14.single-use plastics
neutralplastic items thrown away after one use, such as straws and bags
Several countries have banned single-use plastics in supermarkets.
Keep the hyphen in single-use.
15.extreme weather events
formalfloods, droughts, heatwaves and storms that are unusually severe
Scientists link the rise in extreme weather events to a warming climate.
More precise than bad weather in an essay.
16.carbon footprint
neutralthe amount of carbon dioxide a person or activity produces
Flying less is one of the quickest ways to cut your carbon footprint.
Reduce, cut and shrink all collocate with carbon footprint. Works in both Speaking and Writing.