The global climate agreement is now officially in force. Parties to the treaty will work under this framework to prevent catastrophic global warming. But what's in the Paris Agreement, and can it achieve its goal?
Cheering in Paris: Participants celebrate having reached an agreement at the climate summit a year ago
This Friday (04.11.2016), the United Nations agreement on climate change has come into force. As of that day, 97 countries have ratified it - among them the largest worldwide greenhouse gas polluters: the United States, China, the European Union and India.
Ratification in such a short time by so many countries has been considered historical, and represents a turning point in climate policy.
What is the objective of the agreement?
The stated goal of the agreement is to limit global warming to 2 degrees Celsius (3.6 degrees Fahrenheit) or ideally 1.5 degrees Celsius.
For the 1.5-degree goal, emission of greenhouse gases would have to decrease very quickly. The greenhouse gas carbon dioxide is released during combustion of fossil fuels and in deforestation. This is the main gas responsible (72 percent) for the greenhouse effect.
In order to limit global warming to a maximum of 2 degrees, coal, oil and gas must be mostly phased out as energy sources by 2050 - to achieve the 1.5 degree target, this would need to happen even earlier.
The greenhouse gases methane and nitrous oxide (N2O) constitute about a quarter of global warming, and are released primarily due to industrial agriculture.
Methane is produced in the stomachs of cows and sheep, and nitrous oxide through fertilization of cropland. Lower meat and milk production and lower fertilization would help reduce emissions.
Reforestation helps to reduce greenhouse gases, since trees remove CO2 from the air and bind it back into woody material.
However, international air traffic and shipping are not included in the Paris climate agreement. The share of air traffic in the greenhouse effect is currently more around 5 percent. And as all forecasts predict rising air traffic, this share could increase.
The share of international shipping traffic toward global greenhouse gas emissions is about 3 percent.
To what have countries committed themselves?
With the UN climate change agreement, also known as the Paris Agreement, all states that are party to the treaty will undertake to limit their emission of greenhouse gases. In the run-up to the Paris conference, they handed drafts for their climate goals.
These vary depending on the country and state of development: For instance, the EU has committed to reducing greenhouse gas emissions by 40 percent compared to 1990 levels by 2030. The United States pledged a reduction of 26 to 28 percent by 2025, compared to 2005.
Countries such as Morocco and China have also committed to halting an increase in emissions - both countries are heavily investing in renewable energies. Climate conference host Morocco wants renewable electricity to make up 52 percent in its electricity mix by 2030. China's goal is to reach peak greenhouse gas emissions by 2030.
The main causes of climate change can be traced back to industrialized countries. From 2020 onwards, these countries would have to pay $100 billion (92 billion euros) annually into the so-called Green Climate Fund for poorer countries, to allow them to build out clean energy systems and set climate protection measures.
In order to limit global warming to 1.5 or 2 degrees, according to the United Nations Framework Convention on Climate Change (UNFCCC), countries' reduction targets submitted to date are not sufficient.
Even if all targets were achieved, according to calculations by the Potsdam Institute for Climate Impact Research (PIK), the Earth temperature would probably rise by 2.4 to 2.7 degrees by the end of this century.
However, the Paris Agreement also includes a hard-fought review mechanism, whereby countries are able to increase "ambition" every five years.
What's at stake?
With a temperature increase of 1.5 degrees Celsius, some coral reefs could still survive, and sea levels would probably rise by "only" 40 centimeters by 2100, according to PIK.
But a temperature increase of 2 degrees could mean the end of coral reefs. Droughts, extreme storms and crop failure are further consequences.
According to PIK calculations, with a 2-degree global temperature increase, by 2100 sea levels would be about 50 centimeters higher than today, and through ongoing ice melt from 1.5 to 4 meters higher by 2300.
This would have devastating consequences for coastal regions around the world. The Netherlands, Bangladesh, Venice, New York, Tokyo, Sydney, Mumbai and London would all be hard hit.
Today, 46 million people live in areas less than a meter above sea level.
Turning point for the planet?
But according to climate researchers' forecasts, the agreed climate goals could still be reached - with the required ambition.
Rapid ratification of the Paris climate agreement by many countries is seen as a watershed for global climate policy. "The Paris Agreement will ultimately prove to be a turning point for our planet," Barack Obama has said.
The UN's Executive Secretary for Climate Change Patricia Espinosa believes the agreement is also a cornerstone for sustainable change.
"It lays the foundation for a transformation that will lead to a world very different from the one we know now," Espinosa told DW.
A quick end to the use of fossil fuels, a successful global transition to clean energy technologies, and far greater energy efficiency are among the primary challenges. But the UNFCCC is optimistic that in the years to come, there will be a worldwide trend toward further climate protection.