Category Archives: Risks of climate change

Even if we don’t know if the magnitude is large, can we afford to be wrong?

What “Don’t Look Up” really tells us

The movie Don’t Look Up has been getting “two thumbs up” from a certain political segment for speaking to truth in their view. An existential threat from a comet is used metaphorically to describe the resistance to the import of climate change risk. After watching the film I have a somewhat different take away that speaks a different truth to those viewers who found the message resonating most. Instead of blaming our political system, we should have a different take away that we can act on collectively.

Don’t Look Up reveals several errors and blind spots in the scientific and activist communities in communicating with the public and influencing decision making. The first is a mistaken belief that the public is actually interested in scientific study beyond parlor room tricks. The second is believing that people will act solely based on shrill warnings from scientists acting as high priests. The third (which isn’t addressed in the film) is failing to fully acknowledge what people see that they may lose by responding to these calls for change. Instead these communities should reconsider what they focus on and how they communicate.

The movie opens with the first error–the astronomers’ long winded attempt to explain all of the analysis that went into their prediction. Most people don’t see how science has any direct influence on their lives–how is digging up dinosaurs or discovering the outer bounds of the universe relevant to every day living? It’s a failure of our education system, but we can’t correct to help now. Over the last several years the message on climate change has changed to highlight the apparent effects on storms and heat waves, but someone living in Kansas doesn’t see how rising sea levels will affect them. A long explanation about the mechanics and methods just loses John Q. Public (although there is a small cadre that is fascinated) and they tune out. It’s hard to be disciplined with a simple message when you find the deeper complexity interesting, but that’s what it will take.

Shrill warnings have never been well received, no matter the call. We see that today with the resistance to measures to suppress the COVID-19 pandemic. James Hansen at NASA first raised the alarm about climate change in the 1980s but he was largely ignored due to his righteousness and arrogance in public. He made a serious error in stepping well outside of his expertise to assert particular solutions. The public has always looked to who they view as credible, regardless of their credentials, for guidance. Academics have too often assumed that they deserve this respect simply because they have “the” credential. That much of the public views science as mysterious with little more basis than religion does not help the cause. Instead, finding the right messengers is key to being successful.

Finally, and importantly overlooked in the film, a call to action of this magnitude requires widespread changes in behaviors and investments. People generally have worked hard to achieve what they have and are risk averse to such changes that may severely erode their financial well-being. For example, as many as 1 in 5 private sector jobs are tied to automobiles and fossil fuel production. One might extoll the economic benefits of switching to renewable electricity but workers and investors in these sectors are uncertain about their futures with no clear pathways to share in this new prosperity. Without addressing a truly valid means of resolving these risks beyond the tired “retraining” shibboleth, this core and its sympathizers will resist meaningful change.

Effecting these solutions likely require sacrifice from those who benefit from these changes. Pointing to benefit-cost analyses that rely on a “faux” hypothetical transaction to justify these solutions really is no better than the wealthy asserting asserting that they deserve to keep most of their financial gains simply because that’s how the market works. Compensating owners of these assets and making what appears to be inefficient decisions to maintain impacted communities may seem unfair for a variety of reasons, but we need to overcome our biases embedded in our favored solutions to move forward.

What to do about Diablo Canyon?

The debate over whether to close Diablo Canyon has resurfaced. The California Public Utilities Commission, which support from the Legislature, decided in 2018 to close Diablo by 2025 rather than proceed to relicensing. PG&E applied in 2016 to retire the plant rather than relicense due to the high costs that would make the energy uneconomic. (I advised the Joint CCAs in this proceeding.)

Now a new study from MIT and Stanford finds potential savings and emission reductions from continuing operation. (MIT in particular has been an advocate for greater use of nuclear power.) Others have written opinion articles on either side of the issue. I wrote the article below in the Davis Enterprise addressing this issue. (It was limited to 900 words so I couldn’t cover everything.)

IT’S OK TO CLOSE DIABLO CANYON NUCLEAR PLANT
A previous column (by John Mott-Smith) asked whether shutting down the Diablo Canyon nuclear plant is risky business if we don’t know what will replace the electricity it produces. John’s friend Richard McCann offered to answer his question. This is a guest column, written by Richard, a universally respected expert on energy, water and environmental economics.

John Mott-Smith asked several questions about the future of nuclear power and the upcoming closure of PG&E’s Diablo Canyon Power Plant in 2025. His main question is how are we going to produce enough reliable power for our economy’s shift to electricity for cars and heating. The answers are apparent, but they have been hidden for a variety of reasons.
I’ve worked on electricity and transportation issues for more than three decades. I began my career evaluating whether to close Sacramento Municipal Utility District’s Rancho Seco Nuclear Generating Station and recently assessed the cost to relicense and continue operations of Diablo after 2025.
Looking first at Diablo Canyon, the question turns almost entirely on economics and cost. When the San Onofre Nuclear Generating Station closed suddenly in 2012, greenhouse gas emissions rose statewide the next year, but then continued a steady downward trend. We will again have time to replace Diablo with renewables.
Some groups focus on the risk of radiation contamination, but that was not a consideration for Diablo’s closure. Instead, it was the cost of compliance with water quality regulations. The power plant currently uses ocean water for cooling. State regulations required changing to a less impactful method that would have cost several billion dollars to install and would have increased operating costs. PG&E’s application to retire the plant showed the costs going forward would be at least 10 to 12 cents per kilowatt-hour.
In contrast, solar and wind power can be purchased for 2 to 10 cents per kilowatt-hour depending on configuration and power transmission. Even if new power transmission costs 4 cents per kilowatt-hour and energy storage adds another 3 cents, solar and wind units cost about 3 cents, which totals at the low end of the cost for Diablo Canyon.
What’s even more exciting is the potential for “distributed” energy resources, where generation and power management occurs locally, even right on the customers’ premises rather than centrally at a power plant. Rooftop solar panels are just one example—we may be able to store renewable power practically for free in our cars and trucks.
Automobiles are parked 95% of the time, which means that an electric vehicle (EV) could store solar power at home or work during the day and for use at night. When we get to a vehicle fleet that is 100% EVs, we will have more than 30 times the power capacity that we need today. This means that any individual car likely will only have to use 10% of its battery capacity to power a house, leaving plenty for driving the next day.
With these opportunities, rooftop and community power projects cost 6 to 10 cents per kilowatt-hour compared with Diablo’s future costs of 10 to 12 cents.
Distributed resources add an important local protection as well. These resources can improve reliability and resilience in the face of increasing hazards created by climate change. Disruptions in the distribution wires are the cause of more than 95% of customer outages. With local generation, storage, and demand management, many of those outages can be avoided, and electricity generated in our own neighborhoods can power our houses during extreme events. The ad that ran during the Olympics for Ford’s F-150 Lightning pick-up illustrates this potential.
Opposition to this new paradigm comes mainly from those with strong economic interests in maintaining the status quo reliance on large centrally located generation. Those interests are the existing utilities, owners, and builders of those large plants plus the utility labor unions. Unfortunately, their policy choices to-date have led to extremely high rates and necessitate even higher rates in the future. PG&E is proposing to increase its rates by another third by 2024 and plans more down the line. PG&E’s past mistakes, including Diablo Canyon, are shown in the “PCIA” exit fee that [CCA] customers pay—it is currently 20% of the rate. Yolo County created VCEA to think and manage differently than PG&E.
There may be room for nuclear generation in the future, but the industry has a poor record. While the cost per kilowatt-hour has gone down for almost all technologies, even fossil-fueled combustion turbines, that is not true for nuclear energy. Several large engineering firms have gone bankrupt due to cost overruns. The global average cost has risen to over 10 cents per kilowatt-hour. Small modular reactors (SMR) may solve this problem, but we have been promised these are just around the corner for two decades now. No SMR is in operation yet.
Another problem is management of radioactive waste disposal and storage over the course of decades, or even millennia. Further, reactors fail on a periodic basis and the cleanup costs are enormous. The Fukuyama accident cost Japan $300 to $750 billion. No other energy technology presents such a degree of catastrophic failure. This liability needs to be addressed head on and not ignored or dismissed if the technology is to be pursued.

Electric vehicles as the next smartphone

In 2006 a cell phone was portable phone that could send text messages. It was convenient but not transformative. No one seriously thought about dropping their landlines.

And then the iPhone arrived. Almost overnight consumers began to use it like their computer. They emailed, took pictures and sent them to their friends, then searched the web, then played complex games and watched videos. Social media exploded and multiple means of communicating and sharing proliferated. Landlines (and cable) started to disappear, and personal computer sales slowed. (And as a funny side effect, the younger generation seemed to quit talking on the phone.) The cell phone went from a means of one-on-one communication to a multi-faceted electronic tool that has become our pocket computer.

The U.S. population owning a smartphone has gone from 35% to 85% in the last decade. We could achieve similar penetration rates for electric vehicles (EVs) if we rethink and repackage how we market EVs to become our indispensable “energy management tool.” EVs can offer much more than conventional cars and we need to facilitate and market these advantages to sell them much faster.

EV pickups with spectacular features are about to be offered. These EVs may be a game changer for a different reason than what those focused on transportation policy think of–they offer households the opportunity for near complete energy independence. These pick ups have both enough storage capacity to power a house for several days and are designed to supply power to many other uses, not just driving. Combined with solar panels installed both at home and in business lots, the trucks can carry energy back and forth between locations. This has an added benefit of increasing reliability (local distribution outages are 15 times more likely than system levels ones) and resilience in the face of increasing extreme events.

This all can happen because cars are parked 90-95% of the time. That offers power source reliability in the same range as conventional generation, and the dispersion created by a portfolio of smaller sources further enhances that availability. Another important fact is that the total power capacity for autos on California’s road is over 2,000 gigawatts. Compared to California’s peak load of about 63 gigawatts, this is more than 30 times more capacity than we need. If we simply get to 20% penetration of EVs of which half have interconnective control abilities, we’ll have three times more capacity than we would need to meet our highest demands. There are other energy management issues, but solving them are feasible when we realize there will not be a real physical constraint.

Further, used EV batteries can be used as stationary storage, either in home or at renewable generation to mitigate transmission investments. EVs can transport energy between work and home from solar panels.

The difference between these EVs and the current models is akin to the difference between flip phones and smart phones. One is a single function device and the we use the latter to manage our lives. The marketing of EVs should shift course to emphasize these added benefits that are not possible with a conventional vehicle. The barriers are not technological, but only regulatory (from battery warranties and utility interconnection rules).

As part of this EV marketing focus, automakers should follow two strategies, both drawn from smart phones. The first is that EV pick ups should be leased as a means of keeping model features current. It facilitates rolling out industry standards quickly (like installing the latest Android update) and adding other yet-more attractive features. It also allows for more environmentally-friendly disposal of obsolete EVs. Materials can be more easily recycled and batteries no longer usable for driving (generally below 70% capacity) can be repurposed for stand-alone storage.

The second is to offer add on services. Smart phone companies have media streaming, data management and all sorts of other features beyond simple communication. Automakers can offer demand management to lower, or even eliminate, utility bills and appliance and space conditioning management placed onboard so a homeowner need not install a separate system that is not easily updated.

AB1139 would undermine California’s efforts on climate change

Assembly Bill 1139 is offered as a supposed solution to unaffordable electricity rates for Californians. Unfortunately, the bill would undermine the state’s efforts to reduce greenhouse gas emissions by crippling several key initiatives that rely on wider deployment of rooftop solar and other distributed energy resources.

  • It will make complying with the Title 24 building code requiring solar panel on new houses prohibitively expensive. The new code pushes new houses to net zero electricity usage. AB 1139 would create a conflict with existing state laws and regulations.
  • The state’s initiative to increase housing and improve affordability will be dealt a blow if new homeowners have to pay for panels that won’t save them money.
  • It will make transportation electrification and the Governor’s executive order aiming for 100% new EVs by 2035 much more expensive because it will make it much less economic to use EVs for grid charging and will reduce the amount of direct solar panel charging.
  • Rooftop solar was installed as a long-term resource based on a contractual commitment by the utilities to maintain pricing terms for at least the life of the panels. Undermining that investment will undermine the incentive for consumers to participate in any state-directed conservation program to reduce energy or water use.

If the State Legislature wants to reduce ratepayer costs by revising contractual agreements, the more direct solution is to direct renegotiation of RPS PPAs. For PG&E, these contracts represent more than $1 billion a year in excess costs, which dwarfs any of the actual, if any, subsidies to NEM customers. The fact is that solar rooftops displaced the very expensive renewables that the IOUs signed, and probably led to a cancellation of auctions around 2015 that would have just further encumbered us.

The bill would force net energy metered (NEM) customers to pay twice for their power, once for the solar panels and again for the poor portfolio management decisions by the utilities. The utilities claim that $3 billion is being transferred from customers without solar to NEM customers. In SDG&E’s service territory, the claim is that the subsidy costs other ratepayers $230 per year, which translates to $1,438 per year for each NEM customer. But based on an average usage of 500 kWh per month, that implies each NEM customer is receiving a subsidy of $0.24/kWh compared to an average rate of $0.27 per kWh. In simple terms, SDG&E is claiming that rooftop solar saves almost nothing in avoided energy purchases and system investment. This contrasts with the presumption that energy efficiency improvements save utilities in avoided energy purchases and system investments. The math only works if one agrees with the utilities’ premise that they are entitled to sell power to serve an entire customer’s demand–in other words, solar rooftops shouldn’t exist.

Finally, this initiative would squash a key motivator that has driven enthusiasm in the public for growing environmental awareness. The message from the state would be that we can only rely on corporate America to solve our climate problems and that we can no longer take individual responsibility. That may be the biggest threat to achieving our climate management goals.

Drawing too many conclusions about electric vehicles from an obsolete data set

The Energy Institute at Haas at the University of California published a study allegedly showing that electric vehicles are driven about only one-third of the average standard car in California. I responded with a response on the blog.

Catherine Wolfram writes, “But, we do not see any detectable changes in our results from 2014 to 2017, and some of the same factors were at play over this time period. This makes us think that newer data might not be dramatically different, but we don’t know.“

A recent study likely is delivering a biased estimate of future EV use. The timing of this study reminds me of trying to analyze cell phone use in the mid-2000s. Now household land lines are largely obsolete, and we use phones even more than we did then. The period used for the analysis was during a dramatically changing period more akin to solar panel evolution just before and after 2010, before panels were ubiquitous. We can see this evolution here for example. Comparing the Nissan Leaf, we can see that the range has increased 50% between the 2018 and 2021 models.

The primary reason why this data set is seeing such low mileage is because is almost certain that the vast majority of the households in the survey also have a standard ICE vehicle that they use for their extended trips. There were few or no remote fast charge stations during that time and even Tesla’s had limited range in comparison. In addition, it’s almost certain that EV households were concentrated in urban households that have a comparatively low VMT. (Otherwise, why do studies show that these same neighborhoods have low GHG emissions on average?) Only about one-third of VMT is associated with commuting, another third with errands and tasks and a third with travel. There were few if any SUV EVs that would be more likely to be used for errands, and EVs have been smaller vehicles until recently.

As for copurchased solar panel installation, these earlier studies found that 40% or more of EV owners have solar panels, and solar rooftop penetration has grown faster than EV adoption since these were done.

I’m also not sure that the paper has captured fully workplace and parking structure charging. The logistical challenges of gaining LCFS credits could be substantial enough for employers and municipalities to not bother. This assumption requires a closer analysis of which entities are actually claiming these credits.

A necessary refinement is to compare this data to the typical VMT for these types of households, and to compare the mileage for model types. Smaller commuter models average less annual VMT according to the California Energy Commission’s vehicle VMT data set derived from the DMV registration file and the Air Resources Board’s EMFAC model. The Energy Institute analysis arrives at the same findings that EV studies in the mid 1990s found with less robust technology. That should be a flag that something is amiss in the results.

Vegetation maintenance the new “CFL” for wildfire management

PG&E has been aggressively cutting down trees as part of its attempt to mitigate wildfire risk, but those efforts may be creating their own risks. Previously, PG&E has been accused of just focusing numeric targets over effective vegetation management. This situation is reminiscent of how the utilities pursued energy efficiency prior to 2013 with a seemingly single-minded focus on compact fluorescent lights (CFLs). And that focus did not end well, including leading to both environmental degradation and unearned incentives for utilities.

CFLs represented about 20% of the residential energy efficiency program spending in 2009. CFLs were easy for the utilities–they just delivered steeply discounted, or even free, CFLs to stores and they got to count each bulb as an “energy savings.” By 2013, the CPUC ordered the utilities to ramp down spending on CFLs as a new cost-effective technology emerged (LEDs) and the problem of disposing of mercury in the ballasts of CFLs became apparent. But more importantly, it turned out that CFLs were just sitting in closets, creating much fewer savings than estimated. (It didn’t help that CFLs turned out to have a much shorter life than initially estimated as well.) Even so, the utilities were able claim incentives from the California Public Utilities Commission. Ultimately, it became apparent that CFLs were largely a mistake in the state’s energy efficiency portfolio.

Vegetation management seems to be the same “easy number counting” solution that the utilities, particularly PG&E, have adopted. The adverse consequences will be significant and it won’t solve the problem in the long. Its one advantage is that it allows the utilities to maintain their status quo position at the center of the utility network.

Other alternatives include system hardening such as undergrounding or building microgrids in rural communities to allow utilities to deenergize the grid while maintaining local power. The latter option appears to be the most cost effective solution, but it is also the most threatening to the current position of the incumbent utility by giving customers more independence.

Calculating the risk reduction benefits of closing Germany’s nuclear plants

Max Aufhammer at the Energy Institute at Haas posted a discussion of this recent paper reviewing the benefits and costs of the closure of much of the German nuclear fleet after the Fukushima accident in 2011.

Quickly reading the paper, I don’t see how the risk of a nuclear accident is computed, but it looks like the value per MWH was taken from a different paper. So I did a quick back of the envelope calculation for the benefit of the avoided consequences of an accident. This paper estimates a risk of an accident once every 3,704 reactor-operating years (which is very close to a calculation I made a few years ago). (There are other estimates showing significant risk as well.) For 10 German reactors, this translates to 0.27% per year.

However, this is not a one-off risk, but rather a cumulative risk over time, as noted in the referenced study. This is akin to the seismic risk on the Hayward Fault that threatens the Delta levees, and is estimated at 62% over the next 30 years. For the the German plants, this cumulative probability over 30 years is 8.4%. Using the Fukushima damages noted in the paper, this represents $25 to $63 billion. Assuming an average annual output of 7,884 GWH, the benefit from risk reduction ranges from $11 to $27 per MWH.

The paper appears to make a further error in using only the short-run nuclear fuel costs of $10 per MWH as representing the avoided costs created by closing the plants. Additional avoided costs include avoided capital additions that accrue with refueling and plant labor and O&M costs. For Diablo Canyon, I calculated in PG&E’s 2019 ERRA proceeding that these costs were close to an additional $20 per MWH. I don’t know the values for the German plants, but clearly they should be significant.

“Making the perfect the enemy of the better” for a carbon tax

In an opinion article published on Utility Dive, Kenneth Costello argues that adopting a carbon tax would be a mistake. As he says, “(i)nstead of a carbon tax, why not give more consideration to adaptive strategies, which can evolve over time in response to new information?” His arguments make several key errors and underestimate the political will required to deliver his preferred option.

We need not rely on the social cost of carbon (SCC) to set a tax. Instead of using a benefit-cost approach implied by the SCC, we can use a cost-effectiveness approach by setting the tax to achieve an expected amount of greenhouse gases reduction. This is really no different than how we conduct most of our private transactions–we don’t directly weigh the monetary benefits of buying a new car against its costs–we decide what type of car that we want and then spend the money to buy that car. We may not achieve the mythical “positive net benefits” using such a strategy, but the the truth is that benefit-cost analysis is problematic in the context of climate change, as Martin Weitzmann among others pointed out.

We have a good idea of how increased prices that would result from a carbon tax impact demand, contrary to Costello’s assertion. We have seen that over and over with changes in gasoline and electricity prices in the last half century. (One paper found that the early CAFE standards did not affect automobile fleet fuel economy until gas prices fell in 1984.) We can adaptively manage a carbon tax (which also can be implemented as a global trade tariff framework) to steer toward our emissions reduction target.

Costello instead proposes that we focus solely on climate adaptation by hardening our infrastructure and other measures. This illustrates a lack of understanding of the breadth of the expected impacts and the inability of a large segment of the world’s population to undertake such mitigation without a large wealth transfer. Further, such adaptation focuses largely on the direct impacts to humans and ignores the farther ranging ones on our global environment. Those latter effects, such as ocean acidification and melting of the tundra, can lead to catastrophic outcomes that cannot be readily adapted to, no matter what is spent. And there other effects that that we may not even know about. Focusing so narrowly on what might be adaptive strategies will lead to a gross underestimation of the costs to adapt.

Finally, Costello overestimates the political barriers to implementing and managing a carbon tax and overestimates the political will to implement adaptation strategies. Contrary to his assertion, environmental groups such as EDF and NRDC have been at the forefront of using prices and taxes to regulate environmental pollutants. (I have worked for several of them on such proposals.) Yes, politicians want to avoid taxes, but that reflects the more general problem of wanting to avoid any hard choices. And we only need to look at the state of the U.S. infrastructure to see how difficult it is to persuade the political system to make the investments that Costello recommends. This will be a tough road either way, but the carbon tax option cannot be simply dismissed based on Costello’s analysis.

 

Nuclear vs. storage: which is in our future?

Two articles with contrasting views of the future showed up in Utility Dive this week. The first was an opinion piece by an MIT professor referencing a study he coauthored comparing the costs of an electricity network where renewables supply more than 40% of generation compared to using advanced nuclear power. However, the report’s analysis relied on two key assumptions:

  1. Current battery storage costs are about $300/kW-hr and will remain static into the future.
  2. Current nuclear technology costs about $76 per MWh and advanced nuclear technology can achieve costs of $50 per MWh.

The second article immediately refuted the first assumption in the MIT study. A report from BloombergNEF found that average battery storage prices fell to $156/kW-hr in 2019, and projected further decreases to $100/kW-hr by 2024.

The reason that this price drop is so important is that, as the MIT study pointed out, renewables will be producing excess power at certain times and underproducing during other peak periods. MIT assumes that system operators will have to curtail renewable generation during low load periods and run gas plants to fill in at the peaks. (MIT pointed to California curtailing about 190 GWh in April. However, that added only 0.1% to the CAISO’s total generation cost.) But if storage is so cheap, along with inexpensive solar and wind, additional renewable capacity can be built to store power for the early evening peaks. This could enable us to free ourselves from having to plan for system peak periods and focus largely on energy production.

MIT’s second assumption is not validated by recent experience. As I posted earlier, the about to be completed Vogtle nuclear plant will cost ratepayers in Georgia and South Carolina about $100 per MWh–more than 30% more than the assumption used by MIT. PG&E withdrew its relicensing request for Diablo Canyon because the utility projected the cost to be $100 to $120 per MWh. Another recent study found nuclear costs worldwide exceeded $100/MWh and it takes an average of a decade finish a plant.

Another group at MIT issued a report earlier intended to revive interest in using nuclear power. I’m not sure of why MIT is so focused on this issue and continuing to rely on data and projections that are clearly outdated or wrong, but it does have one of the leading departments in nuclear science and engineering. It’s sad to see that such a prestigious institution is allowing its economic self interest to cloud its vision of the future.

What do you see in the future of relying on renewables? Is it economically feasible to build excess renewable capacity that can supply enough storage to run the system the rest of the day? How would the costs of this system compare to nuclear power at actual current costs? Will advanced nuclear power drop costs by 50%? Let us know your thoughts and add any useful references.

Our responsibility to our children

UN-CLIMATE-ENVIRONMENT-GRETA THUNBERG

Greta Thunberg’s speech at the UN has sparked a discussion about our deeper responsibilities to our future generations. When we made the huge effort to fight World War II, did we ask “how much will this cost?” We face the same existential threat and should make the same commitment. We can do this cost effectively, and avoid making most stupid decisions, but asking whether this effort is worth it is now beyond question. We will have to consider how to compensate those who have invested their money or their livelihoods in activities that we now recognize as damaging to the climate, and that will be an added cost to the rest of us. (And we may see this as unfair.) But we really have no choice.

J. Frank Bullit posted on “Fox and Hounds” a sentiment that reflects the core of opposition to such actions:

What if the alarmists are wrong, yet there is no counter to the demands of enacting economic and energy policies we might regret?”

So our energy costs might be a bit more than it would have otherwise, but we get a cleaner environment in exchange. And even now, renewable energy sources are competing well on a dollar to dollar basis.

On the other hand, if the “alarmists” are correct, the consequences have a significant probability of being catastrophic to our civilization, as well as our environment. We all have insurance on our houses for events that we see as highly unlikely. We pay that extra cost on our house to gain assurance that we will recover our investments if such unlikely events occur. These are costs that we are willing to accept because we know that the “alarmists” have a point about the risks of house fires. We should be taking the same attitude towards climate change assessments. It’s not possible to prove that there is no risk, or even that the risk is tiny. And the data trends are sufficiently consistent with the forecasts to date that the probabilities weigh more towards a likelihood than not.

Unless opponents can show that the consequences of the alarmists being wrong are worse than the climate change threat, we have to act to mitigate that risk in much the same way as we do when we buy house insurance. (And by the way, we don’t have another “house” to move to…)