Part 2: Is global warming caused by humans? And is it even a bad thing?

The short answer to both questions is: Yes! But let’s dive a little deeper and understand why global warming is a bad thing and how we know we humans caused it.

How do we know that the climate change is caused by humans?

  • burning fossil fuels emits greenhouse gases
  • deforestation destroys natural carbon sinks
  • livestock emits greenhouse gases (e.g. methane)
  • many processes in the industry, e.g. cement production emit greenhouse gases

Since the greenhouse effect is very well understood, we can calculate how much global warming the accumulated greenhouse gas emissions of humans causes. There is no doubt at all within the scientific community that climate change is 100% man-made.

This is confirmed by the 2021 assessment of the Intergovernmental Panel on Climate Change (IPCC). For those of you who don’t know what the IPCC is, it is an international body that assesses the scientific evidence on climate change. Every few years, it publishes a new assessment. Each assessment is written by hundreds of climate scientists who study thousands of scientific papers. It is basically the most trusted source on climate change there is. In their 2021 assessment, they explicitly state that 100% of the climate change currently observed is human-caused. The following two figures from the current assessment illustrate this fact:

Simulated and observed climate change. Source
The human factor in global warming. Source

What are the consequences of global warming?

  1. Increasing weather extremes such as heat, droughts, extreme precipitation (i.e. floods), and stronger tropical storms
  2. Sea level rise
  3. Massive loss of biodiversity and ecosystems
  4. Food and water scarcity
  5. Spread of infectious diseases

In this article, I will not go into detail about why all these things will happen. That will become clear in the following parts of this series of articles. The severity of each example depends on the degree of heating. The following figure from the 2021 IPCC assessment shows the frequency and intensity of weather extremes we can expect at different levels of global warming. As we can see, both the frequency and intensity of these events will increase dramatically as temperatures rise.

Projected changes in weather extremes. Source

These climate impacts may lead to numerous deaths, mass migration and international conflicts, and eventually the end of our civilization. Climate protection is therefore not a nice-to-have, but essential for our survival. In case you’re wondering where our current trajectory will take us in the long term: It is beyond the 4°C scenario, mainly because of tipping points. I’ll end this article with quotes of 2 very respected climate scientists:

Professor Johan Rockström, the head of one of Europe’s leading research institutes, warned in 2019 that in a 4°C-warmer world it would be “difficult to see how we could accommodate a billion people or even half of that … There will be a rich minority of people who survive with modern lifestyles, no doubt, but it will be a turbulent, conflict-ridden world”.
Professor Hans Joachim Schellnhuber, one of the world’s leading authorities on climate change, said that if we continue down the present path “there is a very big risk that we will just end our civilization. The human species will survive somehow but we will destroy almost everything we have built up over the last two thousand years.” (Source)

Back to the overview of articles on the climate crisis.

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