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Green, sustainable, resource-saving - you've probably come across all these terms before.
In the supermarket, for example, or when shopping online.
The main reason why adjectives are so popular with companies is that they make a good impression, but say little in concrete terms.
Who defines what is »green«, what is really »sustainable« and when can a product boast of »resource-saving« production?
The criteria for this are often completely unclear, or so complicated that hardly any consumer climbs through.
There is a similar threat in the area of climate protection: recently, various actors in political Berlin, for example, have been claiming that they are pursuing a Paris-compatible policy.
One is then “on a 1.5 degree path”, for example.
But what does that mean exactly?
And can that be checked?
The answer is yes.
But it's not that easy.
The total amount of carbon dioxide emitted since the beginning of industrialization largely determines the extent of global warming.
That's because most of the warming is caused by CO₂, and CO₂ stays in the atmosphere for a very long time — sometimes tens of thousands of years.
A maximum of 500 billion tons to prevent the worst
Because global warming depends on the total - i.e. cumulative - amount of emissions, each climate target means a certain residual amount that we can still emit.
This is the global emissions budget, which can be found in the Intergovernmental Panel on Climate Change reports.
According to the latest report from this year, we can still emit around 500 billion tons of CO₂ from the beginning of 2020 in order to remain below 1.5 degrees with a 50 percent probability (PDF ).
By 2020, humanity has already emitted 2,400 billion tons, with an uncertainty of plus or minus ten percent.
Since around 40 billion tons of CO₂ are currently emitted per year, mankind would have used up this budget in 10 years from now if the emissions were constantly high, with a linear decrease in 20 years.
According to the Intergovernmental Panel on Climate Change (IPCC), emissions should therefore be halved worldwide by 2030 (see graphic).
The concept of the carbon budget is similar to that of a financial budget that shrinks by the day - and nature punishes overspending relentlessly with disaster and human suffering.
Graphic:
Future emission paths according to IPCC - where we are with the current climate policy in the world, and which paths lead to 1.5 or 2 degrees warming.
The exciting question now is: What does this mean for Germany?
In the Paris Agreement, all countries committed to efforts to limit warming to 1.5 degrees.
We are already at 1.2 degrees of global warming and have passed the stable temperature range of the Holocene.
In Paris, however, it was left to the individual countries to define their own contribution to 1.5 degrees.
Germany at the forefront on a global scale
The agreement speaks only vaguely of the "common but differentiated responsibility of the states," meaning the greater responsibility of the rich industrialized countries.
In terms of cumulative CO2 emissions, Germany ranks sixth of all (around 200) countries in the world, behind the USA, China, Russia, Brazil and Indonesia, all of which of course have a much larger population.
We are among the world's most responsible countries for the increasingly dangerous destabilization of the global climate.
The German Advisory Council on the Environment (SRU) has been calculating for some time what a fair share of the Federal Republic of the global remaining budget would be, whereby assumptions about a fair distribution of the budget naturally have to be made.
The SRU makes assumptions that are favorable to us and therefore regards the figures as an upper limit.
Latest result: Germany is only entitled to 3.1 billion tons of CO2 emissions from 2022, for a 50:50 chance of keeping warming below 1.5 degrees.
At the current level of emissions, this budget would last only four years.
With a linear reduction, at least until 2031 - but for this to happen, emissions would have to fall around twice as fast as previously provided for in the German Climate Protection Act.
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Of course, the climate only cares about the total emissions of all countries - if some emit more, this can be compensated for by the fact that others emit less.
Of course, we cannot simply trust that others will literally pull the coals out of the fire for us.
But you can agree on such deals with partners – as is also the case within the EU with common climate goals.
We can benefit from this in Germany, as there are countries in the EU with significantly lower per capita emissions than ours.
For the 1.5 degree target with a linear reduction, the EU would therefore only have to reach zero emissions in 2039 and not already in 2031.
Unfortunately, even the current EU targets are not sufficient to make this – and thus a fair contribution to compliance with 1.5 degrees.
Therefore, according to the new calculations of the environmental council, not only Germany should strive for more ambitious climate goals, but also advocate stronger EU goals, which the European Parliament also voted for.
And above all, of course, it is important to actually stick to the emission budget associated with a decided reduction path.