Transcription
Among the climate cognizanti, there's a running joke about the Al Gore effect because every time he's giving a lecture about the alleged dangers of a warming globe, it's snowing. The reason it's a joke, of course, is because the snow happens one or two days. It's weather, whereas climate is the long-term average of weather. So I beg your sympathy for this talk as I suffer through the inverse of the Al Gore effect.
Let me start by telling you what I'm not going to do. I'm not going to tell you that the climate isn't changing. I'm also not going to tell you that humans aren't influencing the climate. We are. And I'm not going to tell you that it doesn't matter because it does. But what I am going to tell you is that there is a gap, a very significant gap between what climate science actually says and what you've been told it says. And that gap has driven decisions that are damaging this country and many others.
I've spent 50 years in science as a professor at Caltech, as chief scientist at BP here in London, and as under secretary for science at the US Department of Energy in Washington. I've studied climate science, not just the summaries of the assessment reports. So, what I am going to tell you is what the science actually says.
Let's start with what we know. The global temperature has gone up by about 1.3 degrees C since 1900. That's real. It's measured. It's unambiguous. And human activity has contributed to that warming. But here's what else has happened over those same 120 years. The global population has quintupled and the economy has increased roughly 25-fold. Life expectancy increased by 50 years during that same time. And deaths from extreme weather, hurricanes, floods, droughts, extreme heat fell by about 95%.
Let's see. We can't get the slide to advance. There we go. The deaths have gone down. That decline isn't despite the warming. It's alongside it. And in part because of the prosperity and resilience enabled by energy. It reflects what human ingenuity and economic development actually do. They make societies more resilient, more adaptable, better able to cope with whatever nature delivers.
Now, the IPCC, the UN body that synthesizes the world's climate science, doesn't dispute any of this. In fact, its most recent assessment is considerably more hedged than the public discourse implies. There are no clear global trends in hurricane frequency or in intensity. Drought signals are mixed and highly regional. The headlines and the science are just not the same.
document. Here in Britain, I'd ask you to hold one number in mind. In a typical year, cold-related deaths outnumber heat-related deaths by more than 20 to one. It's right up there on a parliamentary website. A warming UK is not obviously a more dangerous UK, and anyone telling you otherwise is not giving you the full picture.
So what does science say about the future? To answer that, we need good models for how the climate is going to respond to growing influences. And we need to make assumptions about future emissions. Let me start with the models. The current generation, the ones that feed into IPCC assessments and from there into policy, have sensitivities to carbon dioxide that range from 1.8° to 5.6°, a factor of three. That's not a rounding error. It's instead a telling reflection about how much we don't yet understand about the climate system. If your weather app gave you a forecast anywhere between 18° and 56° for next Tuesday, you wouldn't plan your week around it.
Now, the scientific community has been working to narrow that range by testing models against what we can actually observe. And what they found is that many of the most sensitive models, the ones projecting the greatest warming, produce temperatures that don't match the observations over the past century. They run too hot. And as a result, those models have been de-weighted quietly and without the corrected headlines that should have followed.
And then there's the question of the scenarios, what will future emissions be? The most alarming projections, those that underpin the language of existential threat, are built on a scenario called RCP 8.5. This scenario assumed that global coal use would quintuple five times by the end of this century to levels unrelated to any credible energy forecast. Even the scenario's original lawsuits have distant themselves from treating it as a baseline. Yet, it remains the scenario most used in the studies that make the news and most referenced by politicians and commentators as business as usual.
When you constrain the models to those that perform well against observations and you use scenarios that reflect plausible energy trajectories, you find a warming by 2100 of between 2° and 3° with a median of 2.2°. Remember, we've already seen 1.3 degrees since 1900, during which time humanity has flourished like never before. That additional warming warrants serious attention, but it is not the apocalypse. And that caveat matters enormously for how we respond.
Let me tell you about a number you almost certainly haven't seen in a newspaper. This is from the IPCC's own working group to report, the one that deals with impacts. It shows the estimated effect on the global GDP of some amount of warming at two and a half or three degrees of warming. The central estimate is a reduction of global GDP by 1 to 5%. That's a few percent of GDP spread across 80 years of economic in growth in a world that will on current trajectories be dramatically richer than it is today. To be clear, this is a real cost, but it's equivalent to losing only one or two years of growth over the next 80 years.
Public debates hardly ever touch on the central question. How do the costs of our climate policies compare to the climate impacts that we're expecting to avoid? In other words, is it worth it? How did the public understanding of climate science become so different from the science itself? The journey from an IPC assessment to a political speech involves three stages of compression. And in each one, there's ample opportunity to introduce bias. First, the full scientific report, thousands of pages full of ranges, caveats, and genuine uncertainty. Then there's the summary for policymakers. Shorter, more definitive, negotiated line by line by government delegates with the uncertainties minimized and the worst cases emphasized. Then media and political communication where the remaining caveats disappear and the uncertainty becomes confidence. When you make a photocopy, you lose detail at random. This process does not. At each days, the findings that get dropped are the ones that would temper alarm, and the framings that survive are those that heighten alarm.
The costs of that misrepresentation are not abstract. They show up in your rising bills and your declining industries. Britain now has the highest electricity prices in the developed world. Energy-intensive industries face higher input costs that their competitors in Asia and North America do not. Britain is paying more for energy while making a negligible reduction in global emissions. That's not a strategy. It's a self-imposed handicap. If I had one of the members of the government there, my first question would be, "What do you think you're doing?"
I spent my career Thank you. I spent my career inside the scientific establishment. I believe in what science can do when it functions as it should. When hypotheses are tested, when dissent is engaged rather than dismissed, when uncertainty is communicated honestly. What I've seen happen in climate science over the past two decades does not meet that standard. And I think it's time to say so clearly because there is a cost for getting this wrong.
The fiscal costs are real. Hundreds of billions committed to an energy transition constrained not by technology or political will but by the laws of physics and economics with negligible measurable effect on the global emissions curve. Those resources could instead build flood defenses, the heat-resistant infrastructure we need, the energy access in the developing world that genuine adaptation requires.
The energy costs are real. Reliable, affordable energy, the foundation of everything that we've been discussing at this conference, has been treated as a problem to be solved rather than a foundation to be secured.
The industrial costs are real. We've exported emissions and livelihood and called it progress.
And the cost to science itself are real. Researchers who raised legitimate questions about model reliability, about scenario plausibility, about the gap between what the science established and what was being claimed in its name were not answered. They were labeled deniers as a career weapon rather than an honest engagement. I've watched it happen to colleagues of integrity and distinction. This is not how science works. It's how science fails.
But the cost I find hardest to accept. The one that should trouble everybody in this room is what we've done to the young people. A generation has been told in schools, by governments, by institutions that they were raised to trust that they face an existential threat. That the planet may be uninhabitable in their lifetimes. That the future should be dreaded rather than treated as a possibility. The data do not support that message. The IPCC does not support that message. If you read it carefully, we have given an entire generation anxiety instead of agency, fear instead of facts. And I think that's the most serious harm of all because it's the hardest to undo.
In closing, I'm not angry that people took climate change seriously, but I am angry that taking it seriously became a reason to stop thinking clearly. And it's true. It's really true. Environmental stewardship is a genuine observation obligation, but it's not in conflict with abundant, reliable, affordable energy. In fact, it requires energy. The countries that will be most successful in managing whatever climate future arrives are not those that have impoverished themselves in advance. They'll be those that remained rich, innovative, and adaptable.
Science requires doubt. Policy requires honest trade-offs. And democracy requires accurate information. All three have been ills served. and the consequences are visible, measurable, and still mounting. The good news is that none of this is beyond correction. The serious informed conversation can in fact must be had and it's increasingly being had in forums like this one. That's the mindset shift. It begins with insisting on the truth. Thank you.