We Need To Do More – Global Warming Will Likely Exceed the 1.5-Degree Limit

Global Warming Earth Climate Change Concept

The 1.5 degree Celsius threshold of global warming refers to the maximum temperature increase above pre-industrial levels that the international community has agreed to strive to limit warming to, as outlined in the 2015 Paris Agreement. This target is considered more ambitious than the previous goal of limiting warming to 2 degrees Celsius and is seen as necessary in order to avoid the worst impacts of climate change, such as more frequent and severe heatwaves, droughts, and storms, as well as rising sea levels and disruptions to ecosystems.

It is expected that global warming will exceed the threshold established in the 2015 Paris Agreement, though it is uncertain to what extent this will occur.

According to new research from scientists at the Department of Energy’s Pacific Northwest National Laboratory, the University of Maryland, and the U.S. Environmental Protection Agency, current climate pledges are insufficient to achieve the goals of the 2015 Paris Agreement, and it is likely that global warming will surpass the 1.5 degree Celsius limit.

The research suggests that the only way to minimize the extent of this overshoot is for countries to adopt more ambitious climate pledges and decarbonize their economies at a faster pace. This will help to reduce the amount of time that the planet spends in a warmer state.

While exceeding the 1.5-degree limit appears inevitable, the researchers chart several potential courses in which the overshoot period is shortened, in some cases by decades. The study was published recently published in the journal Nature Climate Change.

“Let’s face it. We are going to breach the 1.5 degrees limit in the next couple of decades,” said corresponding author and PNNL scientist Haewon McJeon. “That means we’ll go up to 1.6 or 1.7 degrees or above, and we’ll need to bring it back down to 1.5. But how fast we can bring it down is key.”

PNNL researchers Gokul Iyer and Yang Ou, authors of the new study, unpack their findings Credit: Sara Levine | Pacific Northwest National Laboratory

Every second shaved off the overshoot translates to less time courting the most harmful consequences of global warming, from extreme weather to rising sea levels. Forgoing or delaying more ambitious goals could lead to “irreversible and adverse consequences for human and natural systems,” said lead author Gokul Iyer, a scientist alongside McJeon at the Joint Global Change Research Institute, a partnership between PNNL and the University of Maryland.

“Moving fast means hitting net-zero pledges sooner, decarbonizing faster, and striking more ambitious emissions targets,” said Iyer. “Every little bit helps, and you need a combination of all of it. But our results show that the most important thing is doing it early. Doing it now, really.”

During COP26 in 2021, the same research team found that the then updated pledges could substantially increase the chance of limiting warming to 2 degrees Celsius over pre-industrial levels. In their new paper, the authors take an additional step in answering the question of how to move the needle from 2 to 1.5 degrees.

“The 2021 pledges don’t add up to anywhere near 1.5 degrees—we are forced to focus on the overshoot,” said PNNL scientist Yang Ou, who co-led the study. “Here, we’re trying to provide scientific support to help answer the question: What type of ratcheting mechanism would get us back down and below 1.5 degrees? That’s the motivation behind this paper.”

The Paths Forward

The authors model scenarios—27 emissions pathways in total, each ranging in ambition—to explore what degree of warming would likely follow which course of action. At a base level, the authors assume that countries will meet their emissions pledges and long-term strategies on schedule.

In more ambitious scenarios, the authors model how much warming is limited when countries decarbonize faster and advance the dates of their net-zero pledges. Their results underscore the significance of “ratcheting near-term ambition,” which entails rapid reductions in carbon dioxide emissions from all sectors of the energy system, immediately and through 2030.

If countries uphold their nationally determined contributions through 2030 and follow a two percent minimum decarbonization rate, for example, global carbon dioxide levels would not reach net zero this century.

Taking the most ambitious path outlined, however, could bring net-zero carbon dioxide emissions by 2057. Such a path, the authors write, is marked by “rapid transformations throughout the global energy system” and the scaling up of “low-carbon technologies like renewables, nuclear energy, as well as carbon capture and storage.”

“The technologies that help us get to zero emissions include renewables, hydrogen, electric cars, and so on. Of course, those are important players,” said Iyer. “Another important piece of the puzzle is the technologies that can remove carbon dioxide from the atmosphere, like direct air capture or nature-based solutions.”

The most ambitious scenarios outlined in their work are meant to be illustrative of the pathways on offer. But the central takeaway remains clear throughout all modeled scenarios: if 1.5 degrees is to be reattained sooner after we warm past it, more ambitious climate pledges must come.

Reference: “Ratcheting of climate pledges needed to limit peak global warming” by Gokul Iyer, Yang Ou, James Edmonds, Allen A. Fawcett, Nathan Hultman, James McFarland, Jay Fuhrman, Stephanie Waldhoff and Haewon McJeon, 10 November 2022, Nature Climate Change.
DOI: 10.1038/s41558-022-01508-0

The study was funded by the U.S. Environmental Protection Agency.

11 Comments on "We Need To Do More – Global Warming Will Likely Exceed the 1.5-Degree Limit"

  1. Howard Jeffrey Bender, Ph.D. | January 7, 2023 at 7:00 am | Reply

    Governments keep bragging about the steps they’re taking, but they’re not even baby steps. My dramatic novel “Gaia’s Climate Challenge – Giving Humans Their Last Chance” has some real possible solutions and you can read it for free, one chapter a week, on Mastodon #climatechange. Next week will be chapter 7. Enjoy, or not.

  2. Gemini Musings | January 7, 2023 at 7:47 am | Reply

    The point of the scientific method is to prove a hypothesis. If “X” amount of CO2 reduction is hypothesized to lower global temps, then the addition of “Y” CO2 should raise global temps.

    If reducing CO2 is so difficult, then reverse the experiment design, develop a model that would predict global temperature rise based on CO2 addition then run that experiment. For example, what would be the predicted temps if atmospheric CO2 were 500 ppm? 1,000 ppm? 1,500 ppm? 5,000 ppm?

    The plan would be to pump CO2 into the atmosphere until the desired PPM was reached (wonder how much CO2 that would take and could it even be produced), then maintain that PPM level over some fixed period of time, and record temperatures. Adjust and repeat.

    And not to worry about survival; studies have shown CO2 levels have been that high on planet Earth over the millennia, so just re-creating history. Wonder if dinosaurs would come back?

    Or could it be, the warmer the earth gets, the more it off-gases CO2? Henry’s Law?

    Thus far, none of the actual data has come close to the models’ predictions; there is still ice on the poles and NYC is not under water.

    • Yes, people will survive, but most likely the world will be wracked by wars, mass migration, poverty, hunger and disease.

      The other unknown is how many people will survive? Perhaps if we follow your plan the number of people will be reduced by 90%

    • Arctic ice does not directly contribute to sea level rise; current predictions say that by 2035 the North Pole will be ice free by 2035 unless we can limit warming to 1.5 C or less, which seems unlikely. Today is 2023, still 12 years to go. With warming of 2 C or less, we will have an average sea level rise of about 6 inches by 2100, also not today, and not enough to flood New York. With 3 C, we will have 5 feet by 2300 or earlier; then yes, NY will be at least that much under water.

  3. No. Stop.
    “We Need To Do More – Global Warming Will Likely Exceed the 1.5-Degree Limit” is not news or journalism, it’s activism. Report the facts. Don’t tell anyone what to do. You don’t know what to do.

    Doing more is accelerating the problem. Besides natural gas fracking, nothing has made a dent in CO2 emissions. Insane net-zero calculations are used to see battery-vehicles reducing emissions by forgetting entirely about emissions mining for and manufacturing them, creating the energy powering them, and ignoring their rapid degradation by pretending you’ll drive an 20-year-old electric car when most won’t last 8. The article repeats “renewables, hydrogen, electric cars” as the answer; fossil fuels generate your car’s electricity at pathetically low efficiency (coal->turbines->transmission->DC conversion->battery charge->storage, so many losses), they electrolyze water into hydrogen for you below 80% efficiency, and they manufacture and maintain any ‘renewable’ capture devices you use. They just load massive emissions up front, for short lifespans, spewing more carbon elsewhere to make up for pathetically high losses of energy creating electricity versus just burning a fuel directly in a simpler car.

    If you do activism, you need to have the answers. You don’t have the answers, so report the facts, all of them, so an informed reader can decide.

    • Perhaps the climate scientists who wrote the paper know more about this topic than you? To say we need to do more is just common sense at this point. We all need to be activists. Individual readers cannot decide what governments should do.

      The idea that EVs consume emit more CO2 than ICEs is a debunked myth. A combustion engine in a car is extraordinarily inefficient compared to an electric motor; generating electricity, even by burning coal, emits less CO2 overall, The reason is that generators operate at higher temperatures and get almost the theoretical maximum of 40% efficiency, compared to a car with about 12-30%. A typical EV gets 77%. As in almost all countries electricity is a mix of solar, wind, nuclear, hydroelectric, geothermal and fossil fuel, EVs are even better. It’s true that there are energy costs in making each type of car, and also mining, refining and transporting gas. At the end of the day, the total climate warming emissions are much much less for EVs.

      Few people drive 20 year old ICEs, otherwise nobody would buy new cars. I agree that hydrogen powered cars make no sense.

      • Hottan Bothred | January 7, 2023 at 1:21 pm | Reply

        An appeal to authority. Climate scientists aren’t engineers. Besides, climate change science is quite new, with a spotty track record unworthy of the authority fallacy. Anyone can handwave an argument away as a debunked myth, even after its corroborated.

        It seems virtually impossible for an electric car to be more efficient than a fossil-fuel powered car. The electric car adds mining and processing and manufacturing batteries, but they share the environmental burden of mining and processing and distribution of fossil fuels. Maybe use some of it to manufacture some renewable energy capture devices, but not many, maybe 12% in the US, and those wind turbines and solar panels degrade in efficiency, say a percentage point yearly. Burning the coal/oil/gas to turn a turbine is at that 40% efficiency max. 2% of the energy generated is lost in the step-up transformer for the grid, then a 5% (USA EIA estimate average) loss in power line transmission. Another 2% in stepping that down near your neighborhood. Another 4-6% loss distributing that power to homes. Now convert that AC in your wall jack to DC using a powersupply, and Tesla doesn’t publish their efficiency but expensive transformers are in the 80% range, so subtract another what, 5 to 35%? Charging batteries require a chemical reaction, approximately 70% efficient. Lithium batteries self-discharge a few percent in 24hr, then 1 to 2% per month. Now calculate the energy loss in running the electric motor, which I agree is very efficient, say 85 to 95%. Every step loses efficiency into generating waste heat; talk about global warming.

        Compare that efficiency, to burning a fossil fuel in the car to turn the wheels instead of a turbine…and that’s all. It’s not as efficient as at the powerplant, but that improves yearly with ICE refinements. You didn’t have to mine/manufacture the heavy batteries, or drive them around everywhere, which don’t get lighter as they discharge, and won’t lose range and need replacement in about 6 years like a Nissan Leaf’s.

        I love the idea of electric cars. I want them to be better so much. Climate change is a real and big problem. Those three things don’t change the reality about the article’s advice. “Do more”, and “Be an activist” sound wonderful, but it depends on what you do and what you advocate. I’m arguing for humility, not authority. I don’t have the answers, I have the questions, so I read SciTechDaily for information, not advocacy. When any authority tells you what to do, question why.

      • “Perhaps the climate scientists who wrote the paper know more about this topic than you?” That is certainly a possibility, but I wouldn’t advise you to bet your next paycheck that your conjecture is correct.

        “… generators … get almost the theoretical maximum of 40% efficiency, compared to a car with about 12-30%. A typical EV gets 77%.”

        77% of 40% is 31%. Even before taking into account all the losses in the system, as detailed by Hottan Bothred, the efficiency of EVs is similar to and ICE. Using Hottan Bothred’s estimates below: 0.40×0.98×0.95×0.98×0.95×0.80×0.70×0.90=0.17=17%
        That puts the overall efficiency of an EV below the mid-range average of an ICE. Apparently, you can cut that in half for Winter usage.

    • Agreed. This article is activism. It’s like trying to draw a correlation saying that SciTechDaily is a California-based publication. Oh wait.

    • “If you do activism, you need to have the answers.”

      It is commonly agreed, even among alarmists, that the Global Circulation Models run warm. Yet, the authors apparently are using such models to make predictions, without even acknowledging, let alone compensating for, the known error. Doing the wrong thing, just to be going through the motions of appearing to do something, can be worse than doing nothing. Despite the frequent claim that “The science is settled,” there are many things that we still don’t know. Those questions need to be answered before moving forward.

  4. I say we should start planning for a complete failure of the war against climate change, you almost knew from the historical actions of humans that they would not solve the problem. So what to do? Start constructing buildings underground, immune from the harsh surface conditions. Take all that “going to live on Mars technology” which we developed, and adapt it for earth survival. The storm is coming.

Leave a comment

Email address is optional. If provided, your email will not be published or shared.