A recent study finds that 14.8% of Americans do not believe in global climate change. This number is roughly in line with what recent survey have found, such as this 2024 Yale study which put the figure at 16%. In 2009, by comparison, the figure was at 33% (although this was a peak – the 2008 result was 21%). The numbers are also encouraging when we ask about possible solutions, with 67% of Americans saying that we should prioritize development of green energy and should take steps to become carbon neutral by 2050. The good news is that we now have a solid majority of Americans who accept the consensus on climate change and broadly support measures to reduce our carbon footprint.

But there is another layer to this study I first mentioned – the methods used in deriving the numbers. It was not a survey. It used artificial intelligence to analyze posts on X (Twitter) and their networks. The fact that the results aligns fairly well to more tried and true methods, like surveys, is somewhat validating of the methods. Of course surveys can be variable as well, depending on exactly how questions are asked and how populations are targeted. But multiple well designed survey by experienced institutions, like Pew, can create an accurate picture of public attitudes.

The advantage of analyzing social media is that it can more easily provide vast amounts of data. The authors report:

We used a Deep Learning text recognition model to classify 7.4 million geocoded tweets containing keywords related to climate change. Posted by 1.3 million unique users in the U.S., these tweets were collected between September 2017 and May 2019.

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What is the potential for climate change policy to affect climate change? I often discuss, here and on the SGU, the science of climate change, and specifically focus on what we can do about it, mostly by reducing our CO2 emissions. Often I get push back explicitly promoting the position that there is nothing we can really do about, so we should just let technology and economics play themselves out. This is the position of the fossil fuel industry, whose opinion on climate change may vary but always concludes with – do nothing. This may take various forms – climate change isn’t real, climate change won’t be bad, it may be happening but it’s not because of human activity, there’s nothing we can do about it anyway, or whatabout China. The one thing all these positions have in common is the ultimate result – do nothing. It’s almost as if some people are starting with that conclusion and then working backward to whatever justification they can defend at the moment.

But often I get questions that reflect genuine confusion about climate change policy – is there anything “we” can really do? The “we” may be us as individuals, or our country, or the world. I do believe the most important thing we can do as individuals, those of us living in democracies, is to be knowledgeable about climate policy and vote for politicians who support good climate policy. If we don’t make it a priority why should we expect our elected leaders to? In a recent Pew survey, 71% of Americans said they thought that policy to address climate change is either a top or important priority. In the same survey 74% of Amercians support US involvement in international efforts to address climate change.

But what is good climate policy? For most people who raise the issue for me the first thing that comes up is subsidies for electric vehicles, almost as if this one policy is the poster-child for climate change action. But this is arguably the least effective and least important climate policy. Subsidies may have been useful a decade ago to kickstart a new industry, but I think we are past that point. Here are some of the policies that can have a significant, even dramatic effect, on future CO2 release. Continue Reading »

There is good evidence that if you want to lose weight, you need to weigh yourself at least weekly. You need the constant feedback of the scale to adjust your behavior. This is a good general principle – having outcome feedback to measure the effect of what you are doing so you can make adjustments. This is the basic concept of many AI learning algorithms. Plug output into input and let it run.

Along these lines, a group of 50 scientists have made a website and report that tracks several useful measures of how the world is doing tackling climate change. They are doing this in part in preparation for the upcoming (and future) IPCC meetings. But it’s also a useful resource for journalists and the public. So – how are we doing? Brace yourself.

One measure they track is the average warming (above pre-industrialized levels) averaged over the last decade running. This helps track one of the primary goals of trying to blunt global warming, keeping peak warming below 1.5 C (2.7 F). In 2019 this average of the previous 10 years was 1.07 C. In 2022, just three years later, this average is up to 1.14 C. My only “note” is that I would put some kind of thermometer or gauge on the website, visually representing current average warming and how close we are getting to 1.5 C. But the numbers tell the tale.

Another way to mark our march toward problematic climate change is known as the carbon budget – how much cumulative CO2 can we release into the atmosphere without pushing warming past 1.5 C? The remaining carbon budget is 250 gigatonnes of CO2. Our current annual rate of CO2 emissions is 41 gigatonnes – so if we stay at the current rate we will exhaust our carbon budget in 2029 – just 6 years. Remember when it was common to report that “we have just 12 years to stop global warming”? That was based on the carbon budget calculation. That’s not really what it means. It’s more accurate to say, we have 12 years, at current CO2 emissions, before we will exceed 1.5 C warming. That figure has now been cut in half, down to 6 years.

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Whenever I write about climate change here, the deniers show up spouting dubious (to say the least) claims. In my opinion, this is a manifestation of a deliberate political strategy, one that we see with other topics. The strategy is to make up blatant lies, or at least claims without the slightest regard for whether or not they are true, and then spread them through ideologically friendly outlets. Sometimes this may involve amplifying claims that emerge from the most extreme “fever swamps” promoting that ideology. Just keep throwing crap against the wall, and some of it will stick. When these notions make their way into the mainstream media, they are quickly debunked. But by then it’s too late – the damage is done. Long after the false claims are soundly refuted, the rank and file believers will still be quoting them. They are now part of the narrative.

This means that for science communicators and skeptics (but also mainstream journalists), we need to have a working knowledge of these common false claims that are circulating, so that we can respond to them quickly when they emerge. One of the reasons I allow such comments to continue in my blog is because that is one of the ways that I can see which claims are circulating. I don’t mind if they come here – we can handle it. Normally I handle the claims in the comments, but occasionally there is a critical mass of nonsense that is more efficiently dealt with by a post. Here are some recent claims.

Volcanoes emit more greenhouse gas than human activity.

This is an old one, but has remarkable persistence. These claims go through a selection process. Claims survive not because they are true, but because they resonate. In this case, the volcano claim fits the overall narrative that meager human activity is nothing compared to the awesome scale of nature. They want to portray the very idea that we can alter the climate as ridiculous.  Fact, however, get in the way of this narrative.

According to the US Geological Survey:

Published scientific estimates of the global CO₂ emission rate for all degassing subaerial (on land) and submarine volcanoes lie in a range from 0.13 gigaton to 0.44 gigaton per year.

That sounds like a lot, but human activity releases 35 gigatons of CO2 each year. That means that human activity releases more than 100 times the CO2 as does all volcanic activity. When I pointed this out in the comments, these easily verifiable scientific facts were dismissed as a liberal conspiracy. Another strategy is to simply shift to another claim, without ever admitting that you were wrong on the first one. In this case just shift over to methane – but that is a loser argument also. Of all the methane released into the atmosphere each year, 60% is due to human causes. All natural sources amount to only 40%, and volcanoes are a minority of that. Most methane on Earth comes from biology.

I do admit it still surprises me when this one is trotted out, because these are easily checkable basic facts. This is a good way to completely squander one’s credibility. I think this says something meaningful about the intellectual process that is being employed by those dedicated to the denial of global warming.

Climate models are simplistic and wrong.

Dismissing climate models is a more complex matter to refute, because this is more than just looking up a couple of numbers. First there is the notion that climate scientists, in producing their models which predict anthropogenic global warming, did not consider natural factors. This is, of course, absurd, and represents non-experts criticizing an entire world-wide community of experts from a profound level of relative ignorance – and doing it with confidence and arrogance. This almost always comes without citations, or by citing only known outliers.

Climate models, from the beginning, have sought to include the latest science available and account for all possible factors. Over the last 50 years climate models have been steadily modified, to account for new scientific data as it comes in. In addition, models have to account for future behavior, such as how much CO2 will the world emit in the future. So they can only give ranges of outcomes based upon explicitly stated assumptions about human behavior in the future. Often models are used to project what will happen under various scenarios – continuing our current trends vs changing course.

One of the best ways to determine how well models predict the climate (how “skillful” they are, in the jargon) is to see how past models predicted later climate change. This has been done multiple time. Here is a 2019 review of 17 climate models. They found:

We find that climate models published over the past five decades were skillful in predicting subsequent GMST changes, with most models examined showing warming consistent with observations, particularly when mismatches between model-projected and observationally estimated forcings were taken into account.

That last bit means the difference between projections of CO2 emissions vs actual CO2 emissions. The bottom line is that the model basically work, and they are continuously getting better as they incorporate the latest science. Computers are also getting more powerful, allowing for more complex climate simulations. But still you will frequently hear things like, “Maybe it’s the sun. All those scientists never thought of that.”

A recent commenter brought up one I had not yet heard – neutrinos warming up the inner Earth and all that heat rising to the surface through ocean vents. The commenter also explicitly states that climate models do not include natural sources of warming. Sure, there is geological sources of heat that affect the climate – and climate scientists are well aware of this factor.  Geothermal ocean heating is a known factor. It has a relatively small magnitude, and there is no reason to think that it has suddenly changed in the last 50 years. But the notion that climate scientists are not away of geothermal heating is just silly.

CO2 causes greening which absorbs excess CO2.

The basic notion that increases in CO2 concentrations in the atmosphere increases plant growth is true. CO2 is an important metabolite for plant growth. But the full story is more complicated, and turning this into a net benefit from climate change is simply not true. The increase in productivity does occur, but also results in a depletion of other nutrients, such as nitrogen, from the soil. It therefore is not sustainable in natural settings (i.e. not farmland where nutrients can be added). Also, plants are not adapted to higher CO2 levels and so they get diminishing returns from higher CO2.

But the main reason this is not a valid argument against the need to mitigate climate change, is that it ignores all the other effects. Increasing temperature and worsening droughts are bad for agriculture. Shifting climate also shifts growing zones away from where they are currently located. Also, the effect on different crops varies. Wheat will benefit, but corn production will drop, while some other crops will see no immediate change. This will be highly disruptive to agricultural infrastructure. Also, as warming continues, the effects of increased temperature and drought will overwhelm any positive effect from CO2.

The notion that plants will simply absorb any excess CO2 is also profoundly naive and just factually incorrect. There is a carbon cycle, which already includes plants absorbing CO2. But plants don’t just sequester CO2, they absorb and emit CO2 in a continuous cycle. The more CO2 there is in the system, the more CO2 there will be in every part of the system (plants, the ocean, the atmosphere, in minerals, etc.). This is already accounted for in climate models.

But sure, we should maximize biomass to help mitigate CO2 release, and stop doing things like cutting down the rainforest. But this is not going to compensate for the 35 billions tons of CO2 humans release every year.

The US is about to pass into law the first real action on climate change in decades. Obviously there is a lot of politics involved, and I don’t want to get sucked into that, but rather I want to discuss the strategy of this approach to mitigating climate change. Here is a summary of the climate-related provisions in the bill. The bill provides tax incentive and grants for states, industry, and individuals to purchase electric vehicles, install green energy, make buildings energy efficient, convert cement, steel, and agricultural industries to more green methods, reduce leaks from methane pipes, and accelerate research in green technologies and manufacturing. Proponents estimate these measures will reduce US carbon emissions by 40% by 2030.

This projected reduction, however, is not compared to zero reduction, but rather what would happen without the bill:

Recent modeling by Rhodium Group highlights the substantial emissions reduction impact of these provisions. Under a business-as-usual scenario, the United States is on track to reduce greenhouse gas (GHG) emissions by between 24% to 35% by 2030 compared to 2005 levels. Should the IRA become law, this would increase to between 31% to 44% by 2030.

So it looks like the provision will produce an additional 10% reduction. Critics would also argue that this is only for the US and therefore as a percental of global GHG emissions, this is small potatoes. In a tradeoff to get support, the bill also would increase leasing for more oil and gas drilling:

“…it requires the U.S. Department of the Interior to lease 2 million acres in federal lands onshore and 60 million acres offshore each year for oil and gas development (or whatever acreage the industry requests, whichever is smaller).”

This has some environmentalists upset (aren’t we supposed to be reducing fossil fuel production). I don’t think they should be. There is a very deliberate strategy to this bill, and I think it is the correct one. At the top level, strategically there are two basic approaches to reducing GHG emissions, or specifically the burning of fossil fuels (which is the major contributor) – either we reduce supply of fossil fuels or we reduce demand. These, of course, are not mutually exclusive, we can do both, but specific measures usually fall into one or the other category.

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One of the challenges of being a science communicator is keeping up to date. About 2.5 million scientific papers are published every year. Most of this is noise, preliminary studies, speculations, etc., but the end result is that most fields of science are constantly changing. This became very concrete for me while writing my next book (shameless plug alert), The Skeptics Guide to the Future, coming out this Fall. A big part of the book is examining cutting edge science and technology and then extrapolating it into the near, midterm, and far future. During the editing process there were constantly science news items that required small updates to the book. In fact I had to ask my editor, after the final submission, if I could please squeeze in one more update, and promised it would be the last one.

If you are not paying obsessive attention to a particular field of science, it’s really difficult to keep completely up to date. There is also a substantial delay, sometimes decades, between changes to the consensus of scientific opinion based on new evidence and when that new consensus filters down to the public’s general consciousness. Sometime the delay is forever, as outdated ideas persist indefinitely. This is especially true if an outdated scientific conclusion has a rhetorical utility, either in marketing a product or promoting a political ideology. We figured out a quarter of a century ago that consuming anti-oxidants were not good for your health, but don’t hold your breath for the supplement industry to alter their promotion of anti-oxidant products.

One idea that has become a standard part of the conversation on climate change is that once CO2 is released into the atmosphere it will cause continued warming for decades. So, the argument goes, even if we stopped all release of greenhouse gases today, full net-zero, the climate would continue to warm for many decades, perhaps a century or longer. That was the scientific consensus, although it was never a very firm one, just the best estimate based on existing evidence. That conclusion, however, started to crack as early as 2008, and by 2020 was updated with new and better science. This is a rare instance of good climate news. In an interview, climate scientist Michael Mann said:

“This really is true,” he said. “It’s a dramatic change in the paradigm that has been lost on many who cover this issue, perhaps because it hasn’t been well explained by the scientific community. It’s an important development that is still under appreciated. It’s definitely the scientific consensus now that warming stabilizes quickly, within 10 years, of emissions going to zero.”

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The Intergovernmental Panel on Climate Change (IPCC) has just produced their sixth report. This report builds on their previous work, and the current version (AR6) is the product of 234 scientists from around the world. This is essentially an update from their previous reports, taking into account all new evidence that has come to light. You can read the full report, or the executive summary for policymakers, or if you want more detail, the technical summary. Many news outlets, like the BBC, have also put out a highlight summary of their own.

I am not going to produce my own summary, just read the executive summary if you want the details. It’s only 39 pages. Instead, I am going to make some general observations.

First, for those who say there is no such thing as consensus in science, you are straight-up wrong. That is a strawman and denialist talking point. The strawman is the ubiquitous talking point that science is not determined by consensus. Of course it isn’t – consensus is determined by the science. The IPCC report is a great example of what consensus in science means – 234 experts pour over all the available evidence and then hash out a joint statement about what that evidence says. Next to each and every point there is a confidence notation, which they quantify – unlikely, likely, very likely, etc., with percentage confidence indicated for each notation. They are acknowledging the uncertainty, which torpedoes another strawman, equating consensus with certainty, or that the science is “settled” or that further research or debate is being shut down. This is all nonsense. The IPCC is simply a list of specific scientific statements, with a summary of the current evidence and degree of confidence.

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There have been many studies coming out recently looking at what it would take to mitigate climate change, and some patterns emerge from these analyses. First it is important to note that a certain amount of climate change has already happened, with 2020 being 1.2C warmer than the average year in the 19th century. More warming is also inevitable, even if we stopped all greenhouse gas emissions today.

The famous “12 years to stop global warming” notion refers to what it would take to stay below 1.5C warming, because below that level we can avoid major outcomes from climate change. That means getting close to net zero by 2030, which is absolutely not going to happen. Failing that the next goal is to stay below 2C warming. For that we likely need to get to net zero by 2050. That is possible, but will be extremely difficult.

One point of clarification that often gets misunderstood – no one is claiming that seriously bad outcomes will happen by 2030 or 2050, just that dangerous levels of warming will become inevitable by then if we don’t drastically reduce our CO2 release. The bad outcomes, like significant ocean level rise, kick in around 2100. This misunderstanding creates the illusion that scientists keep warning about climate change with endless deadlines that keep passing, while the world seems to be doing fine. Don’t be deceived by this. This is like ignoring your health, including warning signs like high cholesterol and high blood pressure, and claiming everything is fine, right up until the day you have a heart attack.

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Of course there are many important issues facing the world, but arguably drastically reducing carbon emissions is near the top of the list. The 2020s is likely to be a pivotal decade for this effort, and will have a dramatic and long lasting effect. The reason for this is that we are nearing the end of our “carbon budget” – the cumulative amount of carbon we can release into the environment without causing warming >1.5C above pre-industrial levels. We are very close to exhausting this budget, and in fact most experts have set their sights on 2C as the goal, believing it is already too late to keep global warming below 1.5C. Without a major effort in this decade, we will miss the more liberal 2C target, we will have exhausted our carbon budget, and it will no longer be possible to avoid serious consequences of global warming. In fact, it’s possible it would then be too lake to stop a cascade of events that will eventually lead to 5-6C of warming through triggering threshold positive feedback events. This may take hundreds of years to play out, but it still may be unavoidable at that point.

This is really the last decade we have to ensure a high probability of avoiding significant global warming by drastically reducing our carbon emissions. This means transforming our energy and transportation sectors into mostly carbon free technology. Industrial emissions will be harder, and require various technological advances, but any such advances there will help as well. This means, at the very least, we have to stop burning fossil fuel. This in turn means electric vehicles (with perhaps some role for hydrogen and biofuel), and an energy infrastructure built on renewable sources (wind, solar, geothermal, hydroelectric) and nuclear with some grid storage. All of this is achievable with current technology, and will reap benefits beyond climate change, such as reduced health care costs and deaths from pollution.

Often, those who push back against the suggestion that we need to make this change to our civilization a priority frame the choice before us as a false dichotomy – the climate vs the economy. More people will be harmed by the economic costs of decarbonization than will benefit from reducing carbon emissions, they claim. Often this strategy is coupled with denial of climate change itself, or unsupported assertions that climate change will not be so bad. They will often point to the most extreme predictions of climate change and argue that the entire field is “alarmist”.

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Psychological research confirms what I have observed anecdotally – that people prefer simple answers to complex ones, and will often settle on a single cause of even complex events. This is why I often jokingly answer questions of, “Is the cause A, B, or C,” with “yes.” That is usually the correct (if unsatisfactory) answer, all of the options are correct to some degree. Assuming there is “one true cause” can also be considered a false choice fallacy, or a false dichotomy.

I most recently did this when asked if the increase in wildfires were are currently experiencing on the West Coast of the US are caused by global warming or bad forest management. The experts agree that both contribute, and a new review of the literature sheds some additional light on this question. The authors reviewed over 100 studies published since 2013. This same group published an earlier review on the causes of the Australian wild fires last year. The conclusion of the new review is that global warming has had an “unequivocal and pervasive” role in increasing the conditions that contribute to wild fires.

As they say, this is not rocket surgery. As the weather gets warmer we are experiencing a greater portion of the year with high temperatures, lower humidity, decreased rain, and increased winds. These are all conditions that contribute to starting and spreading wildfires, making them more likely and more intense when they occur. The result has been the worst fire season on record, with three of the four worst individual fires occurring this year.

Stepping back a bit to the bigger question – is there global warming – this fire season adds to the growing evidence that there clearly is. Average temperatures are increasing with the top 10 warmest years on record all being since 1998, with 2016 being the warmest. It is too early to tell for sure, but 2020 is on track to being one of the warmest years on record as well, and may even break the record as the warmest. Further, global ice is decreasing steadily. Hurricanes are getting stronger. Flooding is increasing. And of course, wild fires are increasing. You could claim that any one of these is a coincidence, or has a separate explanation. But given the totality of evidence, that amounts to little more than special pleading. Climate models predicted all of these things, and they are all happening. Trying to write off each individual item (and others I didn’t mention) may work rhetorically with some, but only when looked at in isolation. The probability that so many events predicted by climate scientists as a result of global warming are actually happening is not some grand coincidence or conspiracy. The Earth is warming.

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