What could 2 degrees C of warming do to life on Earth?

How will a global temperature rise of 2, rather than 1.5 degrees C, affect the planet?
21 May 2018

Interview with 

Professor Rachel Warren, University of East Anglia


"The Blue Marble" is a famous photograph of the Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of about 29,000 kilometres (18,000 mi). It shows Africa, Antarctica, and the Arabian Peninsula.


Imagine being told that 50% of the area you live in is about to become uninhabitable? How would you react? Most probably with alarm. But the reality is that, according to a new study out this week, many species around the world, and possibly us too, are potentially facing this very problem, unless we take measures to curb climate change much more seriously. Izzie Clarke spoke to University of East Anglia climate scientist and author of the study Rachel Warren. They began by looking at what the Paris Agreement commits over 190 nations to achieve...

Rachel - The actual wording is to “reduce warming to well below 2 degrees, and to pursue efforts to limit the warming to 1½ degrees”. We wanted to see what the effect on biodiversity was of limiting global warming to 1½  rather than 2 degrees, because the previous studies had only looked at 2 degrees and above and there was very little work on 1½ degrees.

What we found was that the geographic ranges of species would fall greatly when the climate warms. We counted the proportion of species that we studied that would lose more than half their range. And we found that at 2 degrees,18 percent of insects, 16 percent of plants, and 8 percent of backboned animals would lose more than half their range. But, at 1.5 degrees C, that is reduced a lot to 6 percent of insects, 8 percent of plants, and 4 percent of vertebrates.

Izzie - So if we can reach that 1.5 degrees Celsius rather than 2, it’s a much better scenario for our wildlife and plants?

Rachel - That’s right, absolutely yes.

Izzie - Are we on track to even reach this?

Rachel - No we're not. And if temperatures were to rise by 3 degrees, actually our study estimates that 49 percent of the insects would  lose more than half of their climatic range. Now that would have very far-reaching ecological consequences.

Izzie - Gosh. So 50 percent of insects would lose 50 percent of where they live, essentially?

Rachel - Right, exactly. The places where species are going to be happy living are going to move across the Earth’s surface. And when that happens, some of those spaces if you imagine it’s like a shadow. That shadow moves across a continent and it reaches a coastline and falls off, or it reaches the top of a mountain and disappears. So that’s one reason why we see these ranges shrinking. The other reason is because the species can’t move to keep up and, in particular, we are concerned about  pollination. So the three groups of insects that are particularly important for pollination, which includes the bees of course, are amongst those that are at the highest risk.

Izzie - How many species were you looking at and how can you predict all of this in the first place?

Rachel - Okay. Well we looked at 31,000 species of insects.

Izzie - Gosh, that’s a lot.

Rachel - Yes, yes. And the reason we were able to do this is because there’s this wonderful organisation called the Global Biodiversity Information Facility, and that database allows us to associate the present day climate with the present day places where the species are found. Then we use a computer model to calculate how likely the species is to be there where that particularly preferred type of climate moves to geographically in the future.

Izzie - What are the implications of a study like this? What can we do now; what happens next?

Rachel - I think the key message is that if we want to avoid these kinds of consequences, countries would need to decide to do more to reduce their emissions so that we actually attain the objective of the Paris Agreement. Things that the average person can do is to get on your bike and cycle wherever possible rather than driving down to the local shop, and try to buy energy efficient appliances, recycle as much as possible. So, basically, just try to reduce your footprint and your energy consumption.


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