The laws of physics will always try to balance in nature. This means that a change somewhere will cause an impact somewhere else. This consequence is central in our understanding of the climate system.
The most fundamental is the energy balance, which forms the basis of life on earth. In the full version of the energy balance is very complicated, but we can also simplify it to create the required understanding. For really it’s a simple equation:
Received solar energy = Used energy + Earth’s radiation back to the space.
The solar energy received is almost constant, so the change must be seen on the right side. This is about the radiation from the Earth to space, which is prevented by the atmosphere’s greenhouse gases, and as we pour more and more greenhouse gases into the atmosphere, less energy will be sent into space. This means that there is more energy for use – and that is the key point. For the energy we have is used for a variety of purposes: warming of the seas, ice melting, air heating, weather, life, etc. – but the distribution of the energy used in the different areas is not the same all the time.
Therefore, the rule of balance is so important to understand. The earth has always lived with that balance, and right now in these years, more energy will be used with all the consequences it has. That is why there is more energy for warming and weather – so it’s not wrong to assume that the weather will be stronger as more energy is available.
Another point where the balance is important is the ocean currents which are very important for the exchange of energy between the equator and the poles. For Northern Europe, the Gulf Stream is central for the relatively mild climate here. But the driving force for the Gulf Stream is also created by a balance where the so-called deepwater pump is important. It is created by the hot salt surface water from the Caribbean, which drives north of Scotland and further north west of Norway to Sea of Greenland. Here it has been cooled and is therefore heavier, why it descends to the bottom and turns back towards Equator. This circulation is called AMOC Atlantic meridional overturning circulation.
A whole new study points out that the flow has weakened partly due to the warming of the sea and partly due to the meltdown from Greenland’s ice cap. Both parts will make the water less heavy and therefore the deepwater pump will weaken. The study was performed by Stefan Rahmstorf from the Potsdam Institute. He says that the strength of AMOC has weakened and has not been so weak in 1600 years. But he also says that it is impossible to say whether the weakening continues and if the balance at some point tends to change the Gulf Stream significantly.
But Rahmstorf emphasizes that the risks grow as the temperature rises, so it is important to take this study with an enhanced effort for a more ambitious Paris agreement.
This is therefore another reason for progress at COP24 in Katowice in Poland in December. The clock is ticking and the time is not with us.
But let me emphasize that when we are so worried about climate change, it is due to concern for ourselves – humanity. Earth and nature will survive this climate change as it has survived others and much stronger changes.