Sweden's Climate Act, passed in 2017, aims for net zero greenhouse gas emissions by 2045. The Act was based on a proposal from a committee with members from all political parties, despite criticism from business and unions. The committee learned from each other and international policies, leading to a consensus and innovative proposal. This shows that joint learning on complex climate issues can lead to ambitious outcomes, and policy diffusion between countries can raise ambitions. Having a framework climate act can support more ambitious sectoral laws, and dismantling arguments against action is crucial for adopting stricter climate policies.