The two-degree target aims to limit global warming to below 2 degrees. The ambition got introduced at COP16 in Cancun, Mexico. However, it is most famous as a part of the Paris Agreement, which is the international agreement to keep global warming below 2 degrees.
The Paris Agreement aims to “limit global warming to well below 2, preferably to 1.5 degrees Celsius, compared to pre-industrial levels”. For this to happen, the world must reach a global peak of greenhouse gas emissions as soon as possible.
What does the two-degree target mean?
The climate on Earth is getting warmer than natural following human activities that release greenhouse gases (heating the planet). International targets work against this through efforts like keeping the heating below 2°C. Usually, the temperature rise gets counted from pre-industrial levels – the average temperature before the 19th century and industrialisation. The latter is one of the most significant reasons for global warming today.
Furthermore, the two-degree target is generally about controlling the level of CO2 in the atmosphere. CO2 is the most common greenhouse gas, released through, for example, the burning of fossil fuels. Usually, it gets measured in parts per million – ppm. In detail, a sustainable level of CO2 is 350 ppm. For example, in 2016, there was about 400 ppm in the atmosphere. If the development continues, we will reach 450 ppm between 2030 and 2040.
What happens if there is global warming over two degrees?
It is difficult to predict the exact consequences of different degrees of warming. A small change in any ecosystem can set off chain reactions for many other parts of the planet. Yet, one example that scientists stress is the survival of coral reefs. The two-degree target risks killing 99 % of the world’s reefs. Partly due to this, the Paris Agreement sets its target at 1.5 degrees. There are too many unpredictable risks involved with warming above this.
Furthermore, global warming over two degrees can lead to a large increase in world hunger, as it would reduce harvests worldwide. Sea levels could also rise by about 46 cm, almost half a metre. Today, millions of people live along coasts and low-lying islands. Therefore, such a change would destroy the homes of millions of people. More so, it would create millions of climate refugees across the globe.
Another typical example of global warming is the fast melting of glaciers. This consequence reduces the Earth’s albedo and allows dark seas to absorb even more heat from the sun. Leading to continuous and much faster warming.
The debate on the 2°C target
The debate around the catastrophic consequences of the two-degree target has changed the world’s ambition to a maximum of 1.5°C warming. However, today’s emissions are far away from reaching the goal. Furthermore, many believe even the 2°C target will be difficult to achieve since the emissions are still very high and the policy changes are slow. For example, a study in Nature suggests a 5 % chance of keeping global warming below 2 degrees.
Finally, it is important to remember that staying below 1.5 degrees is significantly better than 2. While two degrees is much better than 3 degrees, and so on.
Example of source: UNFCCC