On August 9th, the U.N. appointed Intergovernmental Panel on Climate Change (IPCC) published the first part of the Sixth Assessment Report highlighting the "unequivocal" correlation between human-caused greenhouse gases and global warming of the atmosphere, land, and ocean. The IPCC is considered one of the most credible sources of climate science because the scientists from the 195 countries that make up the panel must agree reports consist of the best available science before publication. Below are a few important takeaways you should know from the recent report:
1. Humans are responsible.
Almost all of the warming that has occurred since pre-industrial times is a result of greenhouse gases largely produced by burning fossil fuels. The effects of climate change can be seen in every region across the globe and the scale of these changes are unprecedented over multiple centuries to thousands of years.
2. The 2 degrees Celcius limit is on life support.
The aim of the 2015 Paris Climate Agreement is to limit global warming to a maximum of 2 degrees Celcius with the goal of not exceeding 1.5 degrees Celcius. The report emphasized that under all scenarios, warming will continue until at least mid-century and if striking emissions reductions are not made 2 degrees will be exceeded.
3. There will be dire long-term ramifications.
According to the IPCC, increased warming leads to changes in the climate system including "increases in the frequency and intensity of hot extremes, marine heatwaves, and heavy precipitation, agricultural and ecological droughts in some regions, and proportion of intense tropical cyclones, as well as reductions in Arctic sea ice, snow cover and permafrost." In addition, there are already irreversible changes in the ocean, ice sheets, and global sea level from past emissions that will occur.
4. However, there is some hope!
While not completely ruled out, outcomes including ice sheet collapse, sudden ocean circulation changes, the simultaneous occurrence of some extreme events, and substantially greater warming than predicted are of low likelihood.
5. Changes in emissions are essential to limit global warming.
At least net zero CO2 emissions and a decrease in other greenhouse gases are needed to curb global warming. A large decrease in CH4 emissions predominately from aerosol pollution would also have a significant effect on curbing global warming. If greenhouse gas emissions are radically reduced and maintained at low levels, discernible differences in surface temperatures would emerge within approximately 20 years.
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