In the 3,000-pag 234 scientists identified warming as responsible for sea-level rise and more extreme weather events in the latest report published on 9 August 2021 by the Intergovernmental Panel for Climate Change (IPCC) Working Group 1.  The report is the first major review of the science of climate change since 2013 and it signifies that scientists are observing changes in the Earth’s climate in every region and across the whole climate system.  Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of years, and some of the changes already set in motion – such as continued sea level rise – are irreversible over hundreds to thousands of years.

The report was released the same week that California experienced its largest single wildfire, the hottest ever temperature in Europe was recorded in Sicily at 48.8 degrees, fires ripped through Greece, and the Chinese province of Sichuan saw flash flooding. These coinciding events couldn’t be ignored, and the report’s key findings echoed eerily among the international community.

The IPCC’s sixth assessment report could not have come at a better time to keep policy makers accountable. In a few months, the 26th United Nations Climate Change Conference (COP26) will be held in Glasgow and this report will set the backdrop to the diplomatic commitments and negotiations. This new avalanche of climate science irrefutably shows the role of human activity in climate change, and the immediacy of action required avoiding the worst of what’s to come.

The United Nations Secretary-General António Guterres said this report is a “Code Red for Humanity” (“Code Red” is one of several military slang terms that refers to a form of extrajudicial punishment — a type of punishment that’s carried out without a court’s oversight or any form of legal approval).  He noted that the internationally-agreed threshold of 1.5 degrees above pre-industrial levels of global heating was perilously close. We are at imminent risk of hitting 1.5 degrees in the near term. The only way to prevent exceeding this threshold is by urgently stepping up our efforts, and perusing the most ambitious path.

Here is a graph, illustrating change in average global temperature:

Here is a graph, illustrating An Average Rise in Sea Level:

Here is another graph, illustrating How the World could get Warmer:

Here are the key points of the report:

  • Global surface temperature was 1.09C higher in the decade between 2011-2020 than between 1850-1900;
  • The past five years have been the hottest on record since 1850;
  • The recent rate of sea level rise has nearly tripled compared with 1901-1971;
  • Human influence is “very likely” (90%) the main driver of the global retreat of glaciers since the 1990s and the decrease in Arctic sea-ice; and
  • It is “virtually certain” that hot extremes including heatwaves have become more frequent and more intense since the 1950s, while cold events have become less frequent and less severe

It’s critical to understand that climate change is not just about temperature. Climate change is bringing multiple different changes in different regions – which will all increase with further warming. These include changes to wetness and dryness, to winds, snow and ice, coastal areas and oceans. For example:

  • Climate change is intensifying the water cycle. This brings more intense rainfall and associated flooding, as well as more intense drought in many regions;
  • Climate change is affecting rainfall patterns. In high latitudes, precipitation is likely to increase, while it is projected to decrease over large parts of the subtropics. Changes to monsoon precipitation are expected, which will vary by region;
  • Coastal areas will see continued sea level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion. Extreme sea level events that previously occurred once in 100 years could happen every year by the end of this century;
  • Further warming will amplify permafrost thawing, and the loss of seasonal snow cover, melting of glaciers and ice sheets, and loss of summer Arctic sea ice;
  • Changes to the ocean, including warming, more frequent marine heatwaves, ocean acidification, and reduced oxygen levels have been clearly linked to human influence. These changes affect both ocean ecosystems and the people that rely on them, and they will continue throughout at least the rest of this century; and
  • For cities, some aspects of climate change may be amplified, including heat (since urban areas are usually warmer than their surroundings), flooding from heavy precipitation events and sea level rise in coastal cities.

Here are the following five future impacts that the report projected:

  • Temperatures will reach 1.5C above 1850-1900 levels by 2040 under all emissions scenarios;
  • The Arctic is likely to be practically ice-free in September at least once before 2050 in all scenarios assessed;
  • There will be an increasing occurrence of some extreme events “unprecedented in the historical record” even at warming of 1.5C;
  • Extreme sea level events that occurred once a century in the recent past are projected to occur at least annually at more than half of tidal gauge locations by 2100; and
  • There will be likely increases in fire weather in many regions.

It’s no secret that carbon dioxide (CO2) is the most important of Earth’s long-lived greenhouse gases. It absorbs less heat per molecule than the greenhouse gases methane or nitrous oxide, but it’s more abundant and it stays in the atmosphere much longer. Increases in atmospheric CO2 are responsible for about two-thirds of the total energy imbalance that is causing Earth’s temperature to rise.

The question is – Can temperature rise be kept below 1.5°C?

According to IPCC:

  • 1.1°C the increase in temperature since pre-industrial times;
  • 40bn tonnes roughly amount of CO2 humanity emits every year; and
  • 2,400bn tonnes CO2 humans have emitted to date.

The answer is: 500bn tonnes more would leave only a 50-50 chance of staying under 1.5°C.

Nepean, Ontario, Canada 04 October 2021