Question: If climate change causes the oak leaves to be bigger won't the tree be able to take in more carbon dioxide for photosynthesis? Won't this help the environment?

Anna Gardner answered on 12 Jun 2019: last edited 12 Jun 2019 1:26 pm

Yes this is a great question! One that is taking researchers over 12 years to understand so far.

There are many types of forest in the world (tropical, desert, conifer, mediterranean) and so far studies have only been on younger trees.
Young trees (like young people!) grow at a faster rate than old people and so we cannot compare the results we have found in the young trees to older trees. As most of the forests in the whole world are old (ancient!) trees- we have to study older trees to get more accurate results.
If there is more carbon dioxide (due to climate change) the leaves might grow (via the process of photosynthesis) bigger or more of them. However, this might only happen for two or three years. This is because growing reqiures other things like nutrients (such as nitrogen) from the ground and lots of water. This could mean that after a few years, the tree has used up all of those nutrients from the ground and cannot grow any faster or bigger.

In summary, more carbon dioxide (from climate change) might mean our plants could grow bigger to start with, but due to other limitations like nutrients (or water) they will just be back to growing at the same rate. This is important because many people think that plants will be able to easily adapt, which might not be the case. Plants have taken millions of years to evolve and the rate climate change is increasing faster than then can evolve.

It has been suggested that climate change might lead to drier soils with less nutrients. This might be very bad when we need to grow lots of food to help with our planets growing populations of humans. Some studies have found that even though the extra carbon dioxide has helped our plants grow bigger (like wheat plants grown for making bread), but the plants produce less wheat with less nutrients. This means we get smaller bread!. So bigger plants does not always mean better for the environment. I hope this helps with your question.