IPCC Climate Change Report 2021 (AR6) Key Takeaways
Every 6-7 years, the Intergovernmental Panel on Climate Change (IPCC) compiles the latest and greatest climate change research in one huge report. The newest report (AR6 - the sixth assessment report) is hot off the presses, so I'm diving in. In this article, I discuss the most important quotes from the IPCC's Summary for Policymakers.
"A.1 It is unequivocal that human influence has warmed the atmosphere, ocean and land. Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred."
What it means: Basically, our average global temperature is rising because of human activity. As the average global temperature increases, the characteristics of our air, water and land are changing along with it. Climate change is here and it's happening! If you want a more detailed breakdown of how and why climate change is happening, NASA is a great resource.
Why it matters: Coming from scientists, this statement is huge. Scientists rarely speak with such certainty because it's hard to "unequivocally" know anything based on research. Science can suggest or demonstrate that theories might be facts, but science cannot prove facts. From an objective perspective, it is very impressive that scientists are so confident humans are causing climate change. From a subjective perspective, it's downright scary.
"A.4 Improved knowledge of climate processes, paleoclimate evidence and the response of the climate system to increasing radiative forcing gives a best estimate of equilibrium climate sensitivity of 3°C with a narrower range compared to AR5."
What it means: Since the panel's last climate report in 2016, they've improved their estimating skills. They now expect our climate to warm about 3 degrees Celcius (compared to the average temperature before industrialization, around 1900) before we get a handle on the situation.
Why it matters: Knowing how much our average temperature will rise is crucial because different temperature changes will yield very different Earths. It might not sound like much, but 3 degrees Celcius is an extreme change for our climate. With 3 degrees of warming, many more species will go extinct; we'll have more powerful and more frequent flooding, drought and heatwaves; our oceans will be more acidic; more ice will melt; we will lose more money; and more people will die. If you want a more numeric breakdown, Carbon Brief is a great resource! Knowing how much our temperature will change can help us prepare for the planetary changes to come.
"B.1 Global surface temperature will continue to increase until at least the mid-century under all emissions scenarios considered. Global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades.
B.1.1 The last time global surface temperature was sustained at or above 2.5°C higher than 1850–1900 was over 3 million years ago (medium confidence)."
What it means: Our global average temperature would continue to increase even if we stopped all greenhouse gas emissions now because our atmosphere takes some time to warm after greenhouse gases are released. We already knew this, but it's good to remind everyone that the planet is destined for more warming no matter what we do. If our planet warms more than 2.5 degrees Celcius, it will be the hottest it has been in 3 million years.
Why it matters: THREE. MILLION. YEARS. is a very long time and we should all be alarmed. It is terrifying that we're approaching virtually unprecedented planetary circumstances. However, B.1 suggests that there is still a sliver of time to limit our warming. We (*ahem* policymakers and corporations) have to act quickly and thoughtfully to cut emissions if we want to mitigate the effects of climate change.
"B.5 - Many changes due to past and future greenhouse gas emissions are irreversible for centuries to millennia, especially changes in the ocean, ice sheets and global sea level."
What it means: Many of the changes that have happened in the last few decades or will happen in the upcoming decades would take centuries to millennia to revert. Climate change has already created lasting changes over a relatively short time.
Why it matters: This stood out to me because although it's not the flashiest fact about climate change, it is super important to understand. Climate change is causing practically irreversible changes. Our current action or inaction will change the face of our Earth for hundreds or thousands of years to come.
"C.3 Low-likelihood outcomes, such as ice sheet collapse, abrupt ocean circulation changes, some compound extreme events and warming substantially larger than the assessed very likely range of future warming cannot be ruled out and are part of risk assessment."
What it means: Doomsday-esque scenarios could happen. Our planet could warm out of control, causing unlivable changes in our air, water and land. It is unlikely that these scary things will happen, but we cannot rule them out.
Why it matters: It could become unimaginably challenging to live on our planet and that is very (very, very) scary. Obviously, we need to make changes to mitigate climate change, but we also need to prepare for worst-case scenarios. Preparing for these scenarios means bolstering infrastructure, hiring and heeding the advice of disaster preparedness professionals, getting to know our neighbors, creating "go bags" and becoming more familiar with basic survival skills. An all-out natural disaster is very unlikely to occur, but we would be wise to prepare.
"D.1 From a physical science perspective, limiting human-induced global warming to a specific level requires limiting cumulative CO2 emissions, reaching at least net zero CO2 emissions, along with strong reductions in other greenhouse gas emissions. Strong, rapid and sustained reductions in CH4 emissions would also limit the warming effect resulting from declining aerosol pollution and would improve air quality."
What it means: Scientifically, in order to limit climate change, we have to reduce our greenhouse gas emissions.
Why it matters: We know how to mitigate climate change, and we have the tools to do it: reducing our greenhouse gas emissions is the name of the game. This is important because although climate change is big and scary, we know exactly how to stop it. This knowledge should give you hope and make you angry. Policymakers and large corporations know how to save our planet; they just aren't doing it. At this point, it's just a matter of taking action on the science.
"D.2 - Scenarios with very low or low GHG emissions (SSP1-1.9 and SSP1-2.6) lead within years to discernible effects on greenhouse gas and aerosol concentrations, and air quality, relative to high and very high GHG emissions scenarios (SSP3-7.0 or SSP5-8.5). Under these contrasting scenarios, discernible differences in trends of global surface temperature would begin to emerge from natural variability within around 20 years, and over longer time periods for many other climatic impact-drivers (high confidence)."
What it means: Depending on how our world develops socially, we will release different amounts of greenhouse gases. To demonstrate various possible social circumstances, the IPCC created five potential social paths called Shared Socioeconomic Pathways (SSPs). These scenarios range from working together to improve sustainability and well-being worldwide to staying socially stagnant to becoming highly nationalistic and materialistic. Depending on which path we take, our world could look very different and we could begin to see these differences within the next 20 years.
Why it matters: If we can work towards equality, expand education and become socially ~better~ overall, our climate future could be brighter than anticipated. This point gives me a bit of hope because I like to believe that our world is heading toward a better social future. We don't have much time to bring about these social changes, but we have a little. We have to take advantage of the present moment to create large-scale social and environmental changes!