"We must tackle this existential challenge, and we can not wait until every last person on Earth has been convinced of the scientific proof", said Dr Merkel, who cut her political teeth chairing talks that eventually lead to the Kyoto Agreement.
"I'd like to emphasize for the German government that President Erdoğan is an important guest for us and we welcome his participation in the G20 summit", Seibert said. Gabriel says those requests must be handled on a case-by-case basis, according to German law.
Speaking after meetings with her counterparts from France, Italy, the Netherlands, Spain and Norway, and EU representatives, Merkel said Thursday she "regrets" the USA decision but that the European G-20 participants are "united" in their support for the agreement.
"We are telling Turkey that we are convinced that such an appearance in Germany is not possible", he said during a visit to Russian Federation, citing provisions in Germany's constitution as justification.
Germany will deny permission for Turkish President Recep Tayyip Erdogan to address Turks at a rally when he visits for the upcoming Group of 20 meeting in Hamburg, Germany's foreign minister said Thursday.
Erdogan made his last appearance before supporters in Germany in May 2015. It wasn't clear whether permission would be granted.
Germany has also warned Turkey not to bring Turkish security agents who were charged for violent scuffles in Washington last month.
German parliamentarians have been briefed about the measure.
This decision caused great concerns and discontent among Turkish authorities and opposition.
Speaking to the Bundestag, the lower house of parliament, Ms. Merkel criticized the US for abandoning the Paris climate accord and warned of hard talks. "We have constitutional justification for doing this", he said.
Merkel stressed in a speech to the German parliament Thursday that the European Union stands fully behind its commitment to the agreement.
With her strident Bundestag rhetoric, coloured in part by September's looming federal election, the German leader signalled she is not interested in a lowest common denominator agreement.
Steffen Seibert, spokesman for Chancellor Angela Merkel, told a government news conference he had no information indicating that Erdogan would not attend the G20 summit next week in Hamburg.
Ahead of preparatory talks on Friday in Berlin with European G20 leaders and EU officials, the chancellor warned Mr Trump that Europe would not be dragged down by United States unilateral trade and climate policies.