GENEVA – Climate change is widespread, rapid and intensifying according to the latest Intergovernmental Panel on Climate Change (IPCC) report released August 9, which also identified humans as an “unequivocal” influence on the warming of the planet. The IPCC’s Sixth Assessment Report is the most up-to-date assessment on how global warming will change the world in coming decades. United Nations Secretary-General Antonio Guterres called it “a code red for humanity.”
“We have known for decades that the world is warming,” said Panmao Zhai, co-chair with IPCC’s Working Group I (WG1) at the release of the IPCC WG1’s contribution to the Sixth Assessment Report, ‘Climate Change 2021: The Physical Science Basis.’ “Recent changes in the climate are widespread, rapid and intensifying. Some of the changes we see today are unprecedented in thousands of years or never seen before.”
We have already seen 1.1° Celsius warming since the preindustrial era, from the 1850s to 1900. Each of the last four decades has successively been the warmest since the late 1800s, said Mr. Zhai. Some of the effects of this—extreme droughts, heat waves and rainfalls and catastrophic flooding—will continue to worsen for the next 30 years while melting ice sheets and rising sea levels will continue for at least 2,000 years. Carbon dioxide (CO2) concentrations in the atmosphere are higher than at any time during the past two million years and the rate of sea level rise has roughly doubled since 2006.
Further warming in the coming decades is expected. Under all the five potential climate futures presented in the report, the world will reach 1.5° Celsius warming and sooner than previously expected. “What is clear from this report,” said co-chair Valerie Masson-Delmotte, “is that unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5° Celsius will be beyond reach.”
However, if we rapidly reduce greenhouse gas emissions and if we can reach global net zero CO2 emissions by around 2050, it is extremely likely that we can keep global warming below 2° Celsius, she said. “If we do this, it is more likely than not that temperatures will gradually decline to below or around 1.5° Celsius by the end of this century, with a temporary overshoot of no more than 0.1° Celsius.”
We will reach 2° Celsius of global warming by the middle of this century if global greenhouse gas emissions remain around current levels in the coming decades, which means greater changes in the climate. “Every additional half degree of warming will cause increases in the frequency and the intensity of heat extremes, heavy precipitation and drought,” said Ms. Masson-Delmotte.
At 2°C of global warming, heat extremes would more often reach critical thresholds. Extreme rainfall events will intensify by about seven percent for each additional degree of global warming. “Future further changes depend on future human influence,” she said.
“It is indisputable that human activities are causing climate change, making extreme climate events, including heat waves, heavy rainfall and droughts, more frequent and severe,” said Mr. Zhai.
Previous IPCC climate reports have not specifically identified human influence on climate change. What’s different is that scientists now have a more advanced understanding of the connections between greenhouse gas emissions and the rise in global average temperature, the change to weather and to climate we are seeing around the world.
A total of 234 authors and review editors from 65 countries assessed more than 14,000 scientific publications from the previous decade for the Climate Change 2021 report. The review process considered more than 78,000 reviews. The report was approved by 195 countries.
Mr. Zhai explained, “In this report, we looked at all the atmospheric gases that affect the climate. We confirmed that human caused emissions of greenhouse gases are the main driver of global warming. We can see clearly how much warming comes from CO2, methane and other greenhouse gases. We can also assess the influence of pollution particles, called aerosols, which have an overall cooling effect. This cooling effect partly masks the warming from the greenhouse gases. We also looked at all the natural factors that can affect the climate. We took into account how natural climate variability moderates human caused change on regional scales with little effect on global warming at a central scale.”
Many of the changes set in motion by human caused climate change are slow processes, said Ms. Masson-Delmotte. “These long-lasting changes for the most part affect the planet’s frozen regions (the cryosphere) and the oceans. Changes in ice sheets, deep ocean temperature, and acidification will continue for centuries to thousands of years, meaning that they are irreversible in our lifetime and will continue for generations to come. There’s no going back from some changes in the climate system.”
The good news is that these irreversible changes could be slowed down with rapid, strong and sustained reductions in emissions and other changes can be stopped in greenhouse gas emissions are deeply reduced, Ms. Masson-Delmotte said.
“This report reaffirms that there is a near linear relationship between the cumulative amount of emissions of CO2 in the atmosphere from human activity and the extent of observed and future warming,” said Ms. Masson-Delmotte. This means that the only way to limit global warming is to reach net zero CO2 emissions at the global scale.
“The wide-ranging IPCC report has unquestionable international implications,” said Canada’s Minister of Environment and Climate Change Jonathan Wilkinson in a statement. “But it also matters here at home. Canada is warming at nearly twice the global rate. Parts of western and northern Canada are warming at three times the global average. Scientists have made a clear link between climate change and more frequent and powerful weather events, including heat waves, wildfires, flooding and sea ice loss.”
“The report makes clear that we find ourselves at a critical time for international climate action. The science shows it is vital that countries do more to address climate change, maintaining their pursuit of the Paris Agreement goal of limiting global warming to 1.5° Celsius, and doing so on a faster timeline,” he stated. “Canada has joined more than 120 countries—including all G7 countries—to commit to achieving net-zero emissions by 2050. The recently passed Canadian Net-Zero Emissions Accountability Act turns Canada’s net-zero goal into law. Reaching net-zero emissions is what the IPCC report reiterates the world must achieve if we are to keep 1.5°C within reach.”
Minister Wilkinson pointed to Canada’s revised target under the Paris Agreement to reduce greenhouse gas emissions by 40 to 45 percent below 2005 levels by 2030, on the path to net zero, announced in April 2021. He also noted the federal government’s commitment of climate finance investments to help developing nations, having doubling its previous contribution to $5.3 billion over the next five years.
Climate Action Tracker (CAT), an independent science analyst produced by two research organizations (Climate Analytics and New Climate Institute), has been tracking climate action since 2009. CAT tracks progress towards the globally agreed aim of holding warming well below 2°C and pursuing efforts to limit warming to 1.5°C by quantifying and evaluating climate change mitigation commitments and assesses whether countries are on track to meeting those. The latest rating for Canada, dated September 2020, showed Canada to be on track for a likely temperature increase between two and three degrees Celsius during this century. The rating is ‘insufficient.’
Canada submitted its updated Nationally Determined Contribution (NDC) in July 2021, which remained unchanged from its domestic reduction target announced in April 2021. Canada refers to the target as a reduction of ‘at least’ 40 to 45 percent below 2005 levels, suggesting that it could go beyond this level. “While the ‘at least’ 40 to 45 percent is an improvement, Canada would need to reduce its own emissions by at least 54 percent below 2005 levels by 2030 for its national emissions to be 1.5°C compatible,” according to CAT. “Canada does not have sufficient policies in place to meet its updated domestic target and will need to adopt further measures.”
Inger Anderson, executive director of United Nations Environment Programme, thanked report scientists and added, “You’ve been telling us for over three decades about the dangers of allowing the world to warm. The world listened, but it didn’t hear. The world listened, but it did not act strongly enough and as a result, climate change is a problem that is here now. Nobody is safe and it’s getting worse faster. We must treat climate change as an immediate threat just as we must treat the connected crisis of nature and biodiversity loss and pollution and waste as immediate threats.”
Climate change exacerbates already grave risks to biodiversity and natural managed habitats, she said, and ecosystem degradation damages nature’s ability to reduce the force of climate change.
Governments need to make their net zero plan an integral part of their Paris Agreement commitments, said Ms. Anderson, and every country, business and citizen needs to do their part.
“We can’t undo the mistakes of the past but this generation of political and business leaders, this generation of conscious citizens, can make the systemic changes that will stop the planet warming, help everyone adapt to the new conditions and create a world of peace, prosperity and equity,” she said. “Climate change is here now but we are also here now. And if we don’t act, who will?”