THE IPCC 2021 REPORT
A summary of the UN report, including quotes and some of the positives
The IPCC 2021 report on climate change- a major UN scientific report- has warned that the climate is changing in unprecedented ways due to human activity. This report comes before the COP26 in Glasgow, which will be essential in agreeing coordinated action to reverse climate change. Rising temperatures, rising sea levels, increased heavy rainfall, and agricultural droughts are all increasingly likely in every region on Earth. The landmark study states that “it is unequivocal that human influence has warmed the atmosphere, ocean and land”.
SolarisKit has prepared a summary of this report.
RISING TEMPERATURES
Due to intensifying carbon dioxide concentrations in the atmosphere, the global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years. Compared to the average temperature in 1850-1900, the Earth’s global surface temperature has increased by around 1.1°C. This level is not believed to have been reached in the last 125,000 years, around the time of the last ice age.
Changes in global surface temperature relative to 1850-1900
The report uses emissions scenarios to show the impact of continuing global warming, some more likely than others, yet all scenarios point towards the same conclusion: the 1.5°C global warming limit is likely to be reached between 2021 and 2040. In the moderate emissions scenario, which follows the same trajectory we are on with little changes, average global temperatures would be likely to rise by 2.1–3.5 °C. This being only the moderate scenario, it could be much worse if significant actions are not taken. It is still possible to limit global warming to 1.5 °C, but only if there are “immediate, rapid and large-scale reductions of all greenhouse gases”.
RISING SEA LEVELS
September Arctic sea ice area
Figure SPM.8, panel b)
Since 1900, the global mean sea level has risen faster than over any preceding century in at least the last 3000 years. Global warming has caused sea levels to rise, and it is “virtually certain” that they will continue to do so this century. If emissions continue without any action, the melting of Antarctic ice sheet could cause a rise in sea levels to over a metre in 2100, and 15 metres by 2500.
As the climate has warmed, this has led to increased sea level rise due to ice loss on land and thermal expansion (water expands as it warms). The report explains that 50% of the sea level rise during 1971– 2018 is due to thermal expansion; ice loss from glaciers contributed 22%, ice sheets 20% and the remaining 8% due to changes in land water storage. Ice sheet loss is also a huge issue, as the rate of ice sheet loss is said to have increased by a factor of four between 1992–1999 and 2010–2019. The sobering fact mentioned is that “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.” This does not mean we should stop trying to make a positive environmental impact where we can.
EXTREME WEATHER
HEATWAVES
Human-induced climate change has led to and will continue to lead to an increase in extreme weather. Extreme weather means that there are observed changes in extremes such as heatwaves, heavy precipitation, droughts, and tropical cyclones, among others.Since the 1950s, the report states that it is “virtually certain” that hot extremes (including heatwaves) have become more frequent and more intense across most land regions on Earth.
Figure SPM.6
Conversely, cold extremes (including cold waves) have become less frequent and less severe. Both factors are stated to be “extremely unlikely” to occur without human influence on the climate system. Marine heatwaves have doubled in frequency since the 1980s.
RAINFALL
Figure SPM.6
We are “very likely” to experience clearly discernible increases in the intensity and frequency of heavy precipitation- amongst all other types of changes in extreme weather- for every additional 0.5°C of global warming. Globally, daily precipitation events are projected to intensify by about 7% for each 1°C of global warming.
By 2081-2100, the average annual global land precipitation is projected to increase by 0–5% under the very low GHG emissions scenario,1.5-8% for the intermediate GHG emissions scenario and 1–13% under the very high GHG emissions scenario; relative to 1995-2014. Where some regions have become wetter, others have become drier.
AGRICULTURAL & ECOLOGICAL DROUGHTS
A warmer climate will intensify very wet and very dry weather, which will lead to flooding and droughts. Various regions in world such as southwest Africa and the Mediterranean region have already been seriously impacted by severe drought. If global warming reaches 2°C or above, we should expect heatwaves and long-term droughts to occur simultaneously. Extreme heat, coupled with droughts, are also likely to lead to an increasing number of wildfires, to add to the worst July on record for wildfires since satellite records began since 2003. It should be noted that this is at least since 2003, and it is likely that it may have been for longer ago.
QUOTES
“Recent changes in the climate are widespread, rapid, and intensifying, and unprecedented in thousands of years.”
“Unless there are immediate, rapid, and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5°C will be beyond reach.”
“It is indisputable that human activities are causing climate change, making extreme climate events, including heatwaves, heavy rainfall, and droughts, more frequent and severe.”
“Climate change is already affecting every region on Earth, in multiple ways. The changes we experience will increase with further warming.”
“There’s no going back from some changes in the climate system...
...however, some changes could be slowed and others could be stopped by limiting warming.”“To limit global warming, strong, rapid, and sustained reductions in CO2, methane, and other greenhouse gases are necessary...
...this would not only reduce the consequences of climate change but also improve air quality.”
SUMMARY
The first IPCC report in 1990 concluded that human-caused climate change would soon become evident. Since then, with more data and better models, the evidence is “overwhelming” that the climate has changed, and that human activities are the principal cause of that change. This IPCC report is considered the strongest ever made, with all data pointing in one direction: climate change is the result of humanity.
The importance of bettering the 1.5°C threshold cannot be understated and failing to do so may have serious consequences. The COP26 will prove to be a monumental event in history: drastic action will be needed to reverse the damage already caused.
THE POSITIVES
By removing carbon dioxide from the atmosphere, we could reverse some of the effects of climate change. Removal of carbon dioxide could reverse some aspects of climate change, but only if deliberate removals are larger than emissions. The report states that we could see a variety of changes. Firstly, within just a few years, the increase in global surface temperature would start to reverse. Secondly, we could see permafrost thawing reverse within decades; the acidification of the deep ocean would take centuries to reverse. Finally, the sea level rise, would take from centuries to millennia to reverse. This shows that we can reverse some of the damage caused with rapid and permanent action.