IPCC reports unprecedented, widespread, rapid climate changes due to human influence
Without serious action now, impacts will become more severe and some will be irreversible
A new report by an international team of scientists says climate change is widespread across the globe and the entire climate system. Some of the changes observed are unprecedented across many thousands of years.
“Due to past and future greenhouse gas emissions,” many of the changes “are irreversible for centuries to millennia, especially changes in the ocean, ice sheets and global sea level.”
The report by the Intergovernmental Panel on Climate Change states in dire terms that “It is unequivocal that human influence has warmed the atmosphere, ocean and land” and has caused “widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere.”
United Nations Secretary General Antonio Guterres called the report “a code red for humanity.” He said “The evidence is irrefutable: greenhouse gas emissions are choking our planet and placing billions of people in danger.”
The IPCC, sponsored by the UN Environment Programme, assesses climate science by bringing together the world’s top climate scientists to develop a report based on recent research. The report must be approved by participating countries before publication.
Graphs document extremes we have experienced
The latest report, the sixth in a series dating back to 1988, presents numbers and graphs to match the horrific scenes we have witnessed around the globe, of towns burning or flooded, and of people seeking relief from heatwaves or storms worse than weather we have experienced in the past. And the report also gives us a dire warning: if you think this is bad, in the future it will become even worse—if we do not act now.
As climate research has advanced and computer models have been refined, the IPCC predictions have become ever more ominous. As the Guardian article on the report puts it, the report shows that “the more we know, the worse it looks.”
One area where the science has advanced is the ability to attribute an extreme weather event to human influence. For example, a World Weather Attribution study recently concluded that the extreme heatwave this year in the Pacific Northwest and western Canada was “virtually impossible without human-caused climate change.”
Human-caused warming reached 1 degree C (1.8 degrees F) above preindustrial levels in 2017. The safe goal—to avoid the worst impacts—has been to keep warming to no more than 1.5C (2.7F) above preindustrial levels. At the Paris accords in 2015, that was the aspirational goal, though most of the nearly 200 countries participating failed to even pledge emission reductions sufficient to meet the basic goal of 2C (3.6F).
Without action now, more severe future climate disruptions likely
Allowing warming to reach 2C or more will present major risks to all life systems in the decades ahead, including heat extremes, drought, flooding, heavy precipitation, and other extremes. More than 10 million people globally would be exposed to disruptive sea-level rise. Keeping warming to 1.5C will reduce these risks as well as improve the possibility of sustainable development and efforts to eradicate poverty.
Michael Mann, professor of atmospheric science at Pennsylvania State University, told the Guardian that this latest IPCC report is the last assessment of climate change that can actually influence governmental policy before the 1.5C threshold is exceeded.
“Climate change is now causing amplified weather extremes of the sort we’ve been witnessing this summer – droughts, heatwaves, wildfires, floods, superstorms,” he said. “The impacts of climate change are no longer subtle. We see them playing out in real time in the form of these unprecedented extreme weather disasters.”
In assessing “possible climate futures,” the report projects that, even under low emissions scenario, sea level rise will reach 0.32 – 0.62 meters (a foot to almost two and a half feet) by the end of the century. Higher emissions could cause seas to rise by as much as 1.01 meters (well over three feet) by 2100.
Sea level rise will continue for centuries
“In the longer term”—in the next century and beyond, the report says with high confidence, “sea level is committed to rise for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and will remain elevated for thousands of years.” Seas will rise by about 2 to 3 meters if warming is held to 1.5C and up to 6 meters if warming reaches 2C. Without any reductions in the use of fossil fuels, global warming could reach 5C above preindustrial levels and seas could rise as high as 22 meters.
The IPCC report will play a major role in deliberations by 195 countries at the 26th UN Climate Change Conference of the Parties (COP26) this November in Glasgow, Scotland. The first conference was the Earth Summit in Rio de Janeiro in 1992, which addressed several issues related to climate change, including alternative energy to replace fossil fuels and public transportation to reduce emissions from cars.
The key goal of COP26 will be to hold warming to no more than 1.5C. Scientists say that will require achieving net-zero emissions by 2050—meaning, reaching a balance between emissions we add to the atmosphere and the emissions we remove. The IPCC report warns of a risk of shooting past the 1.5C goal even with significant reductions in emissions, and some scientists question the feasibility of achieving net-zero by 2050. But the International Energy Agency released a report in May that finds that it is possible but will require a major transformation of the global energy system, starting now.
IPCC report puts pressure on COP26 countries to act
Achieving net-zero by mid-century will require ramping up electric vehicles, renewable energy installations, energy efficiency, and large investments in various energy technologies, including carbon capture, according to the IEA report.
Much of the technology necessary to avoid the most catastrophic impacts of climate change is already available but not sufficiently deployed. Renewable energy costs continue to fall, making clean energy often cheaper than energy from fossil fuels.
The IPCC report puts pressure on countries at COP26 to commit to serious action to curb emissions, something most countries have so far failed to do. As Vox puts it, “Climate science has advanced rapidly, but climate action has not.”