What sentence is written using a formal style?

Some of the hugest amounts of carbon emissions are created by farmers who don’t follow good farming practices.

I have never been able to understand why so many people cannot grasp the urgency of climate change.

Changes in the world’s climate affect weather patterns, and this increases the frequency of droughts and floods.

I mean, farmers should obviously support climate change action because their farms are at stake.

Changes in the world's climate affect weather patterns, thereby increasing the frequency of droughts and floods.

The sentence written in a formal style is: "Changes in the world’s climate affect weather patterns, and this increases the frequency of droughts and floods."