You have likely seen Greta Thunberg on TV or the internet this week. She testified before the US Congress and the United Nations. She is remarkably consistent in referring policy and law makers to an IPCC report.
First, who is the IPCC? The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. The IPCC was created to provide policymakers with regular scientific assessments on climate change, its implications and potential future risks, as well as to put forward adaptation and mitigation options.
The report that Ms. Thunberg references can be found here: https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15_SPM_version_report_LR.pdf
The 2018 report is a comprehensive summary of the science behind climate change, potential impacts and an assessment of the risks.
I encourage you to read the summary and see why Ms. Thunberg is pleading with policy and law makers to read the report.