WASHINGTON — The Nobel Prize-winning U.N. panel on climate change put to rest any remaining sophistry over whether a “safe” temperature guardrail exists: It’s life or death for much of life on the planet as soon as 2040.
Nothing can protect the world against all of the most dangerous projections for global warming, the United Nations’ Intergovernmental Panel on Climate Change, or IPCC, concluded in a major report.
The IPCC reported on the difference between allowing the world to warm by another half-degree or 1 degree Celsius, drawing on the work of almost 100 authors, 1,000 reviewers and 6,000 studies.
Amid a record year of heatwaves, droughts and other human-affected climate impacts, the IPCC said even the most optimistic scenarios for lowering global greenhouse gases in line with the 2015 Paris Agreement on climate change will have serious repercussions for the planet and future generations.
“Every extra bit of warming matters, especially since warming of 1.5 degrees Celsius or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems,” Hans-Otto Pörtner, a German scientist who co-chairs one of IPCC’s main working groups, said in a statement.
The report found a half-degree Celsius less warming would cause fewer deaths and illnesses and 0.1 meters less sea rise, and it would halve the number of people who lacked fresh water. Substantially fewer heatwaves and droughts would result, it said, and the world’s coral reefs might survive.
Limiting the global average temperature increase to 1.5 degrees Celsius would avert 150 million premature deaths over the 21st century. For starters, the report said the global economy must become “carbon neutral” by 2050. That would mean forcing a sharply downward curve in carbon dioxide emissions to the atmosphere starting in 2020.
“There is no definitive way to limit global temperature rise to 1.5 above pre-industrial levels,” the report said. “Global warming is likely to reach 1.5 degrees Celsius between 2030 and 2052 if it continues to increase at the current rate.”
International negotiators in 2010 sought to limit warming to 2 degrees Celsius above pre-industrial times. That changed in the Paris Agreement, which committed the world to “holding the increase in the global average temperature to well below 2 degrees Celsius above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 degrees Celsius above pre-industrial levels.”
Since the world has already warmed by 1 degree Celsius from pre-industrial levels, even these most favorable scenarios mean only a difference of a half-degree. So if all nations were to meet their goals under the Paris Agreement, the planet would warm another half-degree or 1 degree Celsius.
Avoiding some of the worst damage will require the world economy to be transformed in ways that have “no documented historic precedent,” the panel said in its 728-page report. Greenhouse gases must come to a full stop by mid-century to limit global warming to another half-degree Celsius.
The report said the planet is on track to cross the threshold of 1.5 degrees Celsius above pre-industrial levels by as early as 2030, bringing the risk of catastrophic climate change marked by floods, extreme drought, wildfires and food shortages for hundreds of millions of people.
One of the report’s key contributors, Mark Howden, director of Australian National University’s Climate Change Institute, said he sees wide impacts for human health, regional economies and the global environment.
“To limit temperature change to 1.5 degrees we have to strongly reduce carbon dioxide emissions,” he said. “They have to decline about 45 per cent by 2030 and they have to reach zero by 2050. We’re not on track. We’re currently heading for about 3 degrees to 4 degrees of warming by 2100.”
To avoid that, the world must all but eliminate the use of coal for electricity within a little more than two decades, IPCC said. Carbon taxes as high as $27,000 a ton by 2100 will probably be needed.
— IPCC (@IPCC_CH) October 6, 2018
First, the bad news
The panel’s climate scientists warned it may be nearly impossible to ward off some of the most damaging projected effects of global warming by keeping rising temperatures in check this century. Politically, that would require a massive turnaround.
Some of the worst effects from coastal flooding, such more damaging storms and stronger heat waves, will be hardest on the world’s poor: a rise in disease and displacement, lost jobs and livelihoods, more expensive food, scarcer freshwater supplies.
The IPCC’s new report was mandated with the adoption of the Paris Agreement. The panel was asked to assess the most up-to-date scientific findings about the damage that 1.5 degrees Celsius of global warming will cause, and to compare this with the damage that 2 degrees Celsius will cause. Delegates to a weeklong IPCC meeting at Incheon, South Korea approved the report.
The historic Paris Agreement, signed by 195 nations, took effect in 2016. It has been ratified by 181 nations so far, but more than a tenth of all global greenhouse gas emissions come from nations that did not join the treaty, notably Russia, Turkey and Iran, all heavy producers or users of fossil fuels.
U.S. President Donald Trump announced in 2017 that he would withdraw the United States from the agreement. But one of its provisions bars any nation that signed it from giving a one-year notice of departure until at least November 4, 2019. This means none of the signatories, including the United States, can exit until November 4, 2020 — exactly one day after the next U.S. presidential election.
The Trump administration denies the science of human-caused climate change and wants to increase coal-burning in the United States, the second-biggest greenhouse gas emitter behind China. The world’s seventh-biggest emitter, Brazil, was on the brink of electing far-right candidate Jair Bolsonaro as its new president. Like Trump, he plans to withdraw his nation from the climate treaty.
Climate impacts are already occurring and the new @IPCC_CH report says it will be much worse at 2°C than previously projected. In order to avoid much of the loss and risk, we must limit warming to 1.5°C: https://t.co/i9zbva36GT #SR15 pic.twitter.com/EkdbrYqKEO
— Climate Nexus (@ClimateNexus) October 8, 2018
Despite its grim message, IPCC’s report aimed to strengthen the global response to climate change by spreading a sense of urgency and prodding nations to commit to more ambitious goals.
Doing more will require clean energy and transportation alternatives. Nations will not only have to move away from fossil fuels but also find ways to reduce carbon dioxide already emitted into the atmosphere, through so-called carbon capture and sequestration.
The world needs to achieve “rapid and far-reaching” changes in energy, land use, city and industrial design, transportation and building use, the report said, while emissions of greenhouse gases other than carbon, such as methane, will also have to decrease.
“The report has sent a very clear message that if we don’t act now and have substantial reductions in carbon dioxide emissions over the next decade, we are really making it very challenging to impossible to keep warming below 1.5 degrees,” said Jim Skea, a Scottish scientist who co-chaired an IPCC working group.
“Limiting warming to 1.5 degrees Celsius is possible within the laws of chemistry and physics,” he told a news conference about the report, “but doing so would require unprecedented changes.”