Glossary | Climate Lexicon P

carbon-connect AG Climate Glossary with common technical terms, abbreviations and explanations on the topics of the environment, climate protection and CO2 compensation.

Paris Agreement

The Paris Agreement is an international agreement signed in December 2015 at the 21st United Nations Conference on Climate Change (COP 21) in Paris. The agreement aims to limit the increase in average global temperature to well below 2 degrees Celsius and possibly as low as 1.5 degrees Celsius compared to pre-industrial levels in order to prevent the worst effects of climate change.
The agreement calls for countries to regularly revise and improve their greenhouse gas emission reduction contributions (NDCs) to ensure ambitious climate action. It also calls for support for developing countries to transition to sustainable development and facilitate adaptation to climate change.
The agreement entered into force on November 4, 2016 and has been ratified by almost all countries to date.


Permafrost forms in areas where the temperature stays below 0 degrees Celsius for many years. The area covered by permafrost in the Northern Hemisphere makes up about 24% of the landmass. This is an area of about 23 million km2.

pH Value

The pH value is a measurement of the acidic or basic character of water or a solution. Pure water has a pH value of 7 (neutral). Acidic water has a pH value of less than 7, and a pH of over 7 is considered basic. Lemon juice has a pH of 2.4 (acid), pure water a value of 7 (neutral), and bleach a pH value above 12 (alkaline).


The abbreviation ppm is a measurement for concentration and stands for "parts per million". In 2015, the concentration of carbon dioxide in the atmosphere was about 400 ppm. In other words, there were about 400 parts of CO2 per million air particles.