Greta Thunberg first heard about global warming when she was 8 years old and she was very troubled by it. She was 15 when she started a school strike. Greta led protests at home in Sweden and abroad, and soon began speaking to groups including the World Economic Forum, the British and European parliaments, and the United Nations Climate Action Summit and Conferences. She has received many awards for her efforts. Greta has an autism spectrum disorder, known as Asperger's syndrome, which she calls her superpower because it helps her strongly focus her attention on climate change. She continues to work to get countries to decrease emissions, and she has inspired so much awareness and activism that the result is known as the "Greta Effect."