The report points to Green House Gas (GHG) emissions as being the main driver of global warming. Each of the last four decades have been successively hotter than any decade that preceded it since 1850, and the changes in climate are already affecting every inhabited region, with increases in the frequency of concurrent heatwaves and droughts on a global scale, fire weather, and flooding.

Statistics which enable future climate predictions in The Physical Science Basis, alerts us that unless serious reductions in CO2, and other GHG emissions are made in the coming decades, the global surface temperature will exceed 2ºC during the 21st Century. Every additional 0.5ºC of global warming will exasperate the intensity and frequency of changes in the climate system, including hot extremes, heavy precipitation and droughts (to name a few).

The report highlights the necessity of the limitation of CO2 emissions. If global net negative CO2 emissions were to be achieved and sustained, the subsequent global surface temperature increase would gradually be reversed. In fact, measures implemented in 2020 to reduce the spread of COVID-19 resulted in a temporary, but nonetheless, detectable effect on improvement in air quality. However, these improvements are not sufficient. If we aim for a future consisting of low GHG emissions, it will strongly limit the intensity of climate risks.

Although not all projected climate change related losses and damages can be eliminated, near-term mitigations that limit global warming close to 1.5ºC would significantly reduce impacts. The risks and vulnerability to the climate are being reduced through the adjustment and adaptation of existing systems, but their effectiveness depends on governance and decision-making processes. If current GHG emissions do not rapidly decline, climate resilient development prospects are increasingly limited.

At least 170 countries are now including adaptation in their climate policies and planning processes, which has the capability of producing an array of benefits such as agricultural productivity, health and well-being, food security and biodiversity conservation.

Net anthropogenic GHG emissions (i.e., emissions originating from human activity) have increased since 2010 across all major sectors globally, with an increasing share of these emissions being attributed to cities. Without strengthened policies, GHG emissions are expected to rise from 2025 and lead to an average global warming of 3.2ºC.

Various sectors from industrial, energy, transport, and urban areas can induce mitigation strategies to increase resource efficiency. The adoption of new production processes, carbon management, reducing and changing material consumption, use of sustainable biofuels and low-emission hydrogen, changes in the use of infrastructure and socio-cultural change are just a few mentioned.

This report emphasises how imperative it is that we strive to achieve and sustain global net zero GHG emissions. Mitigation strategies such as transitioning from fossil fuels to very low, or zero, carbon energy sources, and deploying carbon dioxide removal (CDR) methods are essential to combating climate change.

Currently these CDR methods are practiced in the form of afforestation, reforestation, improved forest management, agroforestry and soil carbon sequestration.

Governance of climate through laws, strategies and institutions supports mitigation by providing frameworks where policies can be developed and implemented, such as the Paris Agreement. The engagement of civil society actors, political actors, businesses, youth, labour, media, indigenous peoples and local communities will build on an effective and equitable climate governance by influencing political support for mitigation and policy outcomes.

International cooperation is a critical enabler for achieving ambitious climate change mitigation goals. The UNFCCC, Kyoto Protocol, and Paris Agreement are supporting rising levels of national ambition and encouraging development and implementation of climate policies.