Summary: The Climate Emergency assumes that climate change is an existential threat to humanity. Climate scientist Cliff Mass examines the evidence for that theory.
“Is global warming an existential threat?”
Probably not, but it’s still a serious issue.
By Cliff Mass at Weather and Climate, 12 August 2019.
During the recent presidential debate, a number of candidates suggested that global warming represents an existential threat to mankind, and thus requires dramatic and immediate action. Governor Jay Inslee has been particularly generous in the use of this term {details here}, but he is not alone. Kamala Harris, Cory Booker, Bernie Sanders, and Elizabeth Warren have said similar things, as have several media outlets and environmental interest groups.
Some also claim that the window for action on climate change is closing. Jay Inslee suggests that the next president will be the last able to take effective steps. Others suggest 10 or 12 years.
Are these existential threat claims true?
An existential threat is one that threatens the very existence of mankind. Something that is simply a challenge or an inconvenience is not an existential threat. An existential threat must have the potential to undermine the very viability of human civilization.
As described below, global warming is a serious problem and its impacts will be substantial – but in no way does it seriously threaten our species or human civilization. And with reasonable mitigation and adaptation, mankind will continue to move forward – reducing poverty, living healthier lives, and stabilizing our population.
What do current climate models tell us? These models are run under specific scenarios of emission of CO2 and other greenhouse gases (see figure). In one, RCP8.5, we simply continue doing what we are doing, with escalating use of coal and oil and little use of renewable energy. Many believe this scenario is too pessimistic.
Editor’s note: for more about RCP8.5, see these.
• Is our certain fate a coal-burning climate apocalypse? No!
• “Is RCP8.5 an impossible scenario?” by climate scientist Judith Curry.
Much more reasonable is RCP 4.5, which has modestly increased emissions through 2040, declining after 2050. I suspect this one will be closer to reality.
The implication of these emissions on global temperature is shown below based on a collection of climate models (CMIP-5). Under the extreme scenario, the earth warms by about 4°C (7.2°F), but for the reasonable one (RCP4.5), global warming is about 2°C (3.6°F). This warming will not be uniform, being greater in the polar regions, less over the eastern oceans.
You will note the temperature rise in RCP 4.5 is relatively steady through around 2045 and then gradually plateaus. No sharp transitions, no falling off of a cliff, no sudden catastrophes.
I have run a large collection of high-resolution climate simulations over the Northwest, driven by the aggressive RCP 8.5 scenario. As shown for Seattle’s mean annual temperature below {click to enlarge}, there is a steady rise, again with no sudden changes that would be hard to adapt to. Most NW folks will want to purchase an air conditioner for summer, but there is no threat to our existence, and winters will be more pleasant.
Look at economic projections.
First, let’s check the conclusions of the highly respected Intergovernmental Panel on Climate Change (IPCC), which provides a consensus view of scientists and nations. Their analysis (SR15, Chapter 3) quoted a paper by Yohe 2017 (open copy) that found a U.S. GDP loss of 1.2% per degree of warming, So with a 2°C global warming associated with RCP4.5, we are talking about a 2.4% loss of national income in 2100. Not a 2.4% loss from today’s levels, but 2.4% less of the substantially greater income in 2100.
What about the recently released Fourth National Climate Assessment, a document heavily cited by the U.S. environmental community? Their analysis is that the damage to the U.S. economy in 2100 would be about a 1% loss (see below) This is not a 1% loss from the current U.S. gross domestic product (GDP), but a 1% loss of the substantially great GDP in 2100. We will be much richer in 2100, and will lose 1% of our GDP because of global warming. That would not be the end of civilization.
William Nordhaus, who won a Nobel Prize in economics for his study of the economic impacts of climate change, examined a large number of studies regarding the impacts of global warming on the world’s economy (see below). He and his co-author (A Moffat) found that a 2°C increase in global temperatures would result in 0-1% damage to the world economy in 2100. Doubling the warming would only increase the damage to around 3%. Again, no existential threat. {See the paper here. Click the graph to enlarge.}
Reading these numbers and considering the many reports backing them up, there clearly is no existential threat to either the U.S. or mankind from global warming, leaving one to wonder why are so many politicians, environmental activists, and lots of media are spreading this existential threat line.
And the above studies are not considering the potential for major technical breakthroughs in energy generation (e.g., fusion), renewables energy sources, or carbon removal from the atmosphere (sequestration). I believe that such advances are inevitable but underestimated, just as no one in 1950 expected that 2000 would bring personal computers and cell phones.
You also have to wonder whether scientists, politicians, and environmental folks really believe the existential threat warnings they throw around. Many talk the talk, but few walk the walk.
Presidential candidates with little chance of securing the nomination are flying across the country, leaving enormous carbon footprints. Climate scientists fly more for work and pleasure than most. Many environmentalists oppose nuclear power, one of the technologies that could produce massive carbon-free energy. And several local Washington State environmental groups opposed a revenue-neutral, bipartisan carbon tax initiative (I-732).
Global warming is a real issue and we are going to slowly warm our planet, resulting in substantial impacts (e.g., less snowpack in the Cascades, increased river flooding in November, drier conditions in the subtropics, loss of Arctic sea ice). But the world will be a much richer place in 2100 and mankind will find ways to adapt to many of the changes. And there is a good chance we will develop the technologies to reverse the increasing trend in greenhouse gases and eventually bring CO2 concentrations down to previous levels.
Global warming does not offer an existential threat to mankind. Politicians and decision-makers only undermine their credibility and make effective action less likely by their hype and exaggeration. Their unfounded claims of future catastrophe prevent broad national consensus and hurt vulnerable people who are made anxious and fearful. And just as bad, all this end of the world talk results in folks turning away from the issue, both out of fear and from an intuition that a lot of hype is going on.
Climate change is an existential threat. There is no Planet B for us. At our house party in Lebanon, NH this weekend, I talked about how we need to protect our environment—and my new ideas to protect public lands is a step in that direction. pic.twitter.com/tjAgPC1puq
— Elizabeth Warren (@ewarren) April 16, 2019
This is a follow-up to the previous post by Professor Mass:
Another climate scientist speaks out against the hysteria.
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About Cliff Mass
Cliff Mass is a Professor of Atmospheric Sciences at the U of Washington, and leads their Mesoscale Analytics and Forecasting Group. See his home page at the U Washington website, his Wikipedia entry. and his website. He is the author of The Weather of the Pacific Northwest
For More Information
Ideas! See my recommended books and films at Amazon.
If you liked this post, like us on Facebook and follow us on Twitter. For more information about this vital issue see the keys to understanding climate change, and especially these …
- Important: climate scientists can restart the climate change debate – & win.
- Focusing on worst-case climate futures doesn’t work. It shouldn’t work.
- The IPCC gives us good news about climate change, but we don’t listen.
- Roger Pielke Jr.: the politics of unlikely climate scenarios.
- A look at the workings of Climate Propaganda Inc.
- Scary but fake news about the National Climate Assessment.
- Did the IPCC predict a climate apocalypse? No.
- Sad but important truths from an eminent climate scientist.
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To learn more about the state of climate change see The Rightful Place of Science: Disasters & Climate Change
