Generated Summary
This document is a report from the World Resources Institute, summarizing key findings from the IPCC’s 2021 Climate Report. It examines the current state of global climate change, emphasizing the urgency of action to limit warming to 1.5 degrees C. The report highlights the impacts of extreme weather events, the scientific understanding of climate change, and the need for transformational changes to avoid catastrophic outcomes. The analysis includes scenarios of both ambitious action and high-emissions pathways, with a focus on the actions required to reach net-zero emissions and mitigate the effects of climate change. The report underscores the role of governments, businesses, and investors in addressing the climate crisis and the potential benefits of a sustainable future. It explores the effects of climate change across different regions of the globe and emphasizes the need to prepare for more dangerous and costly impacts.
Key Findings & Statistics
- The IPCC Working Group I sixth assessment report indicates the world will likely reach or exceed 1.5 degrees C (2.7 degrees F) of warming within the next two decades.
- Under a high-emissions scenario, the IPCC finds the world may warm by 4.4 degrees C by 2100.
- If aggressive action is taken, the temperature rise can be limited to 1.6°C by mid-century and reduced to 1.4°C by 2100.
- If a high-carbon pathway is followed, temperatures could climb to 2.4°C by mid-century and reach 4.4°C by 2100.
- The report notes that the world has a limited carbon budget of only 400 gigatonnes of carbon dioxide (GtCO2) as of the beginning of 2020.
- Recent global emissions levels of 36.4 GtCO2 per year, this amounts to about 10 years before we exhaust the budget.
- In the scenarios studied by the IPCC, there is a more than 50% chance that the 1.5 degrees C target is reached or crossed between 2021 and 2040.
- Under a high-emissions scenario, the world reaches the 1.5 degrees C threshold even more quickly (2018-2037).
- If the world takes a carbon-intensive pathway (SSP5-8.5), global warming could climb to 3.3-5.7 degrees C (5.9-10.3 degrees F) higher than pre-industrial levels by the end of the century.
- The report shows that the concentration of carbon dioxide is unmatched for at least 2 million years.
- Glacial retreat is unmatched for 2,000+ years.
- The last decade has been warmer than any period for approximately 125,000 years.
- Sea level rise is faster than any prior century for 3,000 years.
- Summer Arctic ice coverage is smaller than anytime in the last 1,000 years.
- Ocean warming is faster than at any time since the end of the last ice age.
- Ocean acidification is at its highest level in 2 million years.
- At 3 degrees C (5.4 degrees F) and 5 degrees C (9 degrees F), respectively, projections suggest an eventual near-complete loss of the Greenland Ice Sheet and complete loss of the West Antarctica Ice Sheet.
- The report indicates that extreme heat (which has become at least twice as likely as a result of human-induced climate change) was a key driver of the recent fires in Australia.
- Human activities contributed to 84-90% of marine heatwaves since at least 2006.
Other Important Findings
- The report highlights how extreme weather events, such as wildfires, floods, and heatwaves, are becoming more frequent and intense.
- It emphasizes that limiting warming to 1.5 degrees C requires significant reductions in emissions this decade.
- The report notes the crucial role of ambitious emissions cuts to prevent the worst climate impacts.
- It outlines the need for global GHG emissions decline from the 2020s onwards and net-zero GHG emissions by mid-century.
- It suggests that the changes already seen are unprecedented in recent history and will affect every region of the globe.
- The report also mentions that achieving the 1.5 degrees C target will require managing trade-offs and that transformation can lead to better-quality jobs and health benefits.
- The science of attribution linking extreme events to human-induced warming is becoming more sophisticated, thanks to greater observational data and advanced models.
- The report emphasizes the importance of carbon removal strategies to compensate for emissions.
- The report highlights the impacts of climate change, with enormous human and economic costs that far outweigh the costs of action.
Limitations Noted in the Document
- The report focuses on the climate impacts and mitigation strategies.
- It acknowledges the potential for tipping points, such as sea level rise due to collapsing ice sheets or ocean circulation changes, but notes that the likelihood of these increases with greater warming.
- The IPCC notes that the climate system will not immediately respond to carbon removal.
- Some impacts, such as sea level rise, will not be reversible for at least several centuries even after emissions fall.
- The report is based on the IPCC’s assessment, which is subject to the limitations inherent in climate modeling and the availability of data.
- The report acknowledges the complex nature of climate change impacts, including the interactions between different factors and the uncertainties associated with these interactions.
Conclusion
The IPCC’s 2021 Climate Report provides a stark reminder of the urgent need for action to address climate change. The document emphasizes that the world is already experiencing the effects of warming, with more dangerous and costly impacts expected in the future. The window to limit warming to 1.5 degrees C is closing, making this decade critical. To achieve this goal, transformational changes are required across all sectors, involving ambitious emissions cuts and the transition to net-zero emissions by mid-century. The report underscores the significance of government, business, and investor actions and highlights the potential for a safer, more sustainable future. The findings indicate that while there is a chance to limit warming, it requires collective action. The report also warns that the impacts of climate change will continue to mount and compound as emissions increase, underscoring the need for immediate and decisive action. It is essential to act quickly to avoid the most catastrophic outcomes.