This UK online course in gardening, may be of interest:

https://www.futurelearn.com/experttracks/gardening-for-beginners-the-basics-and-beyond

It is provided in conjunction with the BBC Gardening magazine.

There are also many courses on nature and the environment, including climate change. A good place to explore what is on offer, is:

https://www.futurelearn.com/subjects/nature-and-environment-courses