The rainforest visitor attraction near Oxford - the former home of Wyld Court Orchids - was redeveloped in the 1990s and is now home to 700 species of plants and animals. It is run by the Trust for Sustainable Living and works to educate the public about the world's threatened rainforests.
The latest planned exhibit would focus on the rainforests of small island nations such as the Seychelles because they are already feeling the impact of climate change through rising sea levels.
The glasshouse would include mangrove plants, a picture wall showing the coastline, animals such as a monitor lizard or a giant tortoise, and hundreds of butterflies flying around freely (something that is not possible in the other glasshouses due to the free ranging birds and animals).
Educational displays would highlight the importance of these ecosystems and how visitors can help protect them.
The trust needs to raise £56,000 in total to complete the project, with donations matched by the Greenham Common Trust. If sufficient funds are raised the glasshouse will open in spring.