In the first programme Greta travels through North America on her way to a UN climate conference in Chile. To understand the impact of climate change she stops at three key locations that reveal how the planet is changing. In the Canadian Rockies she learns how a small change in temperature has allowed an insect infestation to kill nearly half the trees in one of its most famous national parks. She visits a glacier that’s melting faster than models predict and discovers the cause is partly due to soot from forest fires falling on it.

As the world is bought to a standstill by the COVID-19 pandemic, Greta has to put her plans on hold. She visits a tree plantation to learn how the age of a forest has an impact on whether or not it can take carbon dioxide from the atmosphere. Then, having recovered from Covid-19, Greta also explores what lessons can be learned from the international response to the pandemic.