German Chancellor, Angela Merkel is due to address the US Congress in a speech later today. Merkel is only the second German Chancellor to be given this honour. The first was West Germany’s Chancellor, Konrad Adenauer in 1957. Ahead of the November 9th celebrations in Berlin, marking the fall of the wall, she will thank the US for backing German unification.It is Merkel’s first visit to America since starting her second term. Meeting with President Obama, she is expecting to discuss a range of issues including Afghanistan and Iran. But the focus of talks will be climate change. Merkel will urge the US to take concrete measures to stop global warming.