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Climate Change 2021: The Physical Science Basis

Access to new UN report on global warming and climate change added to PMWL

10 August 2021 – Washington, DC, USA – Access to a new resource has been added to the PM World Library related to solving global problems.  The resource titled “Climate Change 2021: The Physical Science Basis”, is the sixth and most recent IPCC assessment addressing the most up-to-date physical understanding of the climate system and climate change.

According to the report, climate change is widespread, rapid, and intensifying, and some trends are now irreversible, at least during the present time frame. The report, prepared by 234 scientists from 66 countries, highlights that human influence has warmed the climate at a rate that is unprecedented in at least the last 2,000 years.  In 2019, atmospheric CO2 concentrations were higher than at any time in at least 2 million years, and concentrations of methane and nitrous oxide were higher than at any time in the last 800,000 years.

Global surface temperature has increased faster since 1970 than in any other 50-year period over a least the last 2,000 years. For example, temperatures during the most recent decade (2011–2020) exceed those of the most recent multi-century warm period, around 6,500 years ago, the report indicates. Meanwhile, global mean sea level has risen faster since 1900, than over any preceding century in at least the last 3,000 years. The document shows that emissions of greenhouse gases from human activities are responsible for approximately 1.1°C of warming between 1850-1900, and finds that averaged over the next 20 years, global temperature is expected to reach or exceed 1.5°C of heating.

The UN Secretary-General António Guterres said the Working Group's report was nothing less than "a code red for humanity. The alarm bells are deafening, and the evidence is irrefutable". He noted that the internationally-agreed threshold of 1.5 degrees above pre-industrial levels of global heating was "perilously close. We are at imminent risk of hitting 1.5 degrees in the near term. The only way to prevent exceeding this threshold, is by urgently stepping up our efforts, and persuing the most ambitious path.

The Intergovernmental Panel on Climate Change (IPCC) is the international body for assessing the science related to climate change. The IPCC was set up in 1988 by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation

PM World provides information about global problems in order to educate readers and promote the application of modern project management to help solve those problems.  We support all efforts to save the planet and improve the lives of more people. Working together, we can make a difference.

To access this resource, go to, select “Addressing Climate Change”, scroll down to resource. Free access to all but please consider registering if you have not done so.  Free Trial membership provides free access to everything in the library for 30 days.