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Climate Change 2021 Report

Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6)

“Those who are least responsible for climate change are often those that will suffer the most”


The IPCC is an extension of the United Nations and was started in 1988. Their main job is to provide scientific assessments related to climate change to policy makers world-wide. They provide options for mitigating the of effects as well as most likely outcomes for the various scenarios studied. This article is a summary of their latest report.


The report I pulled from is a 41 page summary of a 1,300-page study designed to bullet point information for policy makers. For the sake of this article, I focus on increasing global temperatures, extreme weather, and sea level rise as they are more digestible topics. I will be largely quoting highlights from the report or otherwise paraphrasing the information. My commentary is unquoted and meant to break through the scientific jargon.


Let’s get this out of the way. “Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years. In 2019, atmospheric CO2 concentrations were higher than at any time in at least 2 million years and concentrations of CH4 and N2O were higher than at any time in at least 800,000 years. Natural drivers (non-human factors) changed global surface temperature by only 0°C to 0.1°C in this time.” In other words, this is not a natural process of the earth. Humans are the cause of climate change and its effects are happening right now.


Global Temperature Increases


“Some recent hot extremes observed over the past decade would have been extremely unlikely to occur without human influence. It is virtually certain that heatwaves have become more frequent and more intense across most land regions since the 1950s”. The graphic below shows the intensity of an average increase in global temperature’s effect on artic temperatures. Warming is “projected to amplify permafrost thawing of land ice and of Arctic sea ice in the north pole”. This is because not all warming is created equal. 2 ºC of warming globally is actually closer to 5 ºC - 7 ºC in the arctic.

You will see common benchmarks listed throughout this article. Namely 1.5 ºC, 2 ºC, and 4ºC. These scenarios are shown in the image above and will be discussed in more detail in the next section.


The figures below show the global temperatures over the previous 2000 years. The graph on the right is simply the same information, but shown over a more recent time period so the dramatic increase in temperature can be seen more clearly. The green line represents the warming which would have occurred naturally, while the yellow area is the observed average global temperature increase observed since the 1970s (around 1.2 ºC so far).


Extreme Weather Events (A Compounding Effect)


Before this topic can be discussed further, we need to discuss the 5 different scenarios explored by the IPCC study. The graphs below show 5 simulations they ran under best case, most likely cases, and worst-case scenarios. The various colored boxes each represent 1 of the 5 scenarios. Each box is the range of possible values, while the line is the average and most likely result.


SSP1-1.9 (light blue) was the best-case scenario in which we kept global temperatures from rising to 1.5ºC. One of the major take-aways from this report is that it is now considered impossible to keep global temperatures from rising below this goal. Therefore, SSP1-2.6 (the dark purple box) is the current best-case scenario of 2ºC of warming. Dark red is the worst case in which we simply continue emitting greenhouse gases as we are now.

The image above depicts all 5 scenarios as they relate to our greenhouse gas consumption over the coming decades. By continuing our current emission trajectory without any major changes, we will see a global temperature increase of almost 2.5ºC by 2050. The historical data proves every ton of CO2 emissions directly contributed to an increase in global warming.


What the graph above fails to show is the danger of each increase of 0.5ºC. This is the compound effect of global warming. “Human influence has increased the chance of compound extreme events. There will be an increasing occurrence of some extreme events unprecedented in the observational record with additional global warming, even at 1.5°C of global warming.” This phenomenon is described below.

“With every additional increment of global warming, changes in extremes continue to become larger. For example, every additional 0.5°C of global warming causes an even greater increase in extreme events.” 10-year events are simply extreme weather events that used to occur around every 10 years. The global temperature has already increased by 1°C, meaning these events are now 2.8 times more likely to occur. (This has clearly been the case with extreme wildfires and hurricanes over the past few years).


Again, the previous goal of 1.5°C of warming is now considered unreachable. Therefore, the now hopeful goal of 2°C means these 10-year events are 5.6 times more likely to occur. In other words, a 10-year event will soon become a 2-year event under optimistic circumstances. Worse even, 50-year extreme weather events will be 13.9 times more likely at just 2°C of warming. This equates to once in a generation extreme temperature events soon occurring in less than a decade. This will be catastrophic in terms of droughts, wildfires, and agricultural losses.


Furthermore, “the proportion of intense tropical cyclones (categories 4-5) and peak wind speeds of the most intense tropical cyclones are projected to increase at the global scale. Continued global warming is projected to further intensify the global water cycle, including its variability, for precipitation and the severity of wet and dry events, with implications for mass flooding and drought”.


Sea Level Rise


“The global mean sea level has risen faster since 1900 than any preceding century in at least the last 3000 years. The ocean has also warmed faster over the past century than it has in the previous 11,000 years. Ocean warming has accounted for 91% of the global heating seen thus far. Land warming, ice loss and atmospheric warming accounting for the other 9%.”


The reason ocean warming has accounted for 91% of global warming thus far is the ocean’s ability to absorb greenhouse gases which would have otherwise stayed in the atmosphere. All of this CO2 absorbed by the ocean will soon result in the complete destruction of all coral reefs on the planet among other issues.

This problem goes beyond coral reefs. The ocean (and land) can no longer absorb as much CO2 as it used to. The dark blue bar in the image above (the best-case scenario at 2°C of warming) shows that between the land and the ocean, only 65% of greenhouse gases can be absorbed. This means there is going to be a dramatic increase in the amount of greenhouse gases in the atmosphere over the coming 3 decades. Even worse, if we cannot meet this goal, and the global temperatures increase even further, we could see an increase of over 60% of all greenhouse gases emitted to stay in our atmosphere. This will cause enormous public health issues.


Essentially, our oceans cannot take much more. What we have already put it through gives us a terrifying projection on sea level rise. An increase of 2ºC will result in 3 meters (10 feet) of sea level rise. For the worst-case scenario, they expect 10 –15 m (over 40 feet) rise.


“Even if global net negative CO2 emissions were to be achieved and sustained, many changes due to past greenhouse gas emissions are irreversible for centuries to millennia. Especially changes in the ocean, ice sheets and global sea level.”


Essentially, the ocean will rise no matter how effective we are at reducing CO2 emissions moving forward. This has enormous implications for where we will house an ever-increasing human population. The video below details the repercussions of this housing crisis and I highly suggest watching it now.

Some Good News


This article has been pretty doom and gloom so far. However, not every detail in the report was negative. I won't go into the science due to time, just know the findings listed below are a BIG deal and you are free to look them up yourself if you are curious.

  • The IPCC believes the melting of permafrost in the arctic will not result in the release of massive amounts of methane. (Methane is 84 times more powerful than CO2 when it comes to global warming).

  • The Atlantic Meridional Overturning Circulation (AMOC) is a giant current of water circulating throughout most of the world's oceans. We now think that the changes we will come to see are reversible as long as we do not let warming get too out of hand.


Final Thoughts


“Limiting human-induced global warming to a desired level requires reaching at least net zero CO2 emissions, along with strong reductions in other greenhouse gas emissions. Strong, rapid and sustained reductions are necessary to reach these goals.” One of the scariest pieces of information from the entire document details our window for success.


WE HAVE 7 - 12 YEARS TO MAKE A DRASTIC CHANGE

After this amount of time, an increase of only 2°C will likely be impossible.


I want to thank you for making it so far. This will likely be the most dense article I ever write for the website. That being said, it will probably also be one of the most important. This has been a lot of information, so take a break and breathe. Before you go, I want to be sure to leave on a positive note.

For more information on the IPCC report you can check out the podcast “Code Red for the Planet – Today Explained” or a number of other resources provided on this website. Be sure to read other articles published thus far and subscribe to the site for future updates. I’ll be sure to dive into what policies can be done in the future, but for those who would like to explore solutions now, check out this video.


All information and figures were collected from the IPCC Climate Change 2021 Summary for Policy Makers. Please follow the link if you would like to read the original 41-page document.


It's not too late, we just need to act now.

All the best,


-Nick Engler

Cut Your Carbon Footprint Founder and Head Writer

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