Earth from space by DonkeyHotey
Post Format

The climate has always changed

It’s 2023 and there are still people who don’t accept climate change. They might say they do, like they’ll say of course they accept climate change, the climate has always changed. But that’s not what we generally mean when we talk about climate change. We’re talking about the climate change that’s happening now, caused by human emissions of greenhouse gases and that poses a serious threat to human societies. That’s the climate change some people still don’t accept.

Does it matter? These are a small and dwindling group of people so can’t we just ignore them the way we ignore flat earthers and creationists? Perhaps, but I just need to get this off my chest.

This “the climate has always changed” response is the one I hear most often. You can’t refute it. Of course the climate has always changed. Is anyone saying it hasn’t? Do the people who say this think anyone believes the climate was completely stable until we started burning fossil fuels? Everyone’s heard of the ice ages, and we know it was much hotter than now than when the dinosaurs were around.

The people who say “the climate has always changed” are I think defending themselves against being told they don’t believe in climate change or that they’re climate change deniers. They’re implying that since the climate has changed in the past without human influence it is most likely changing for similar reasons now. Most people don’t know why the climate changed in the past, why we’ve had ice ages and inter-glacials and hothouse earths. Some may have heard of natural cycles the planet goes through. The idea that the changes we’re now seeing are just part of a natural cycle may seem more plausible than the idea that the exhausts from our puny little cars are warming the planet. Clearly the eco-zealots have jumped on that idea because they hate cars and they want to take away our freedoms and tell us what to do and make us pay more taxes. This climate change business is just an excuse.

Ah, but the warming we’re seeing now is unprecedented. It’s warming extremely rapidly and there is no known natural driver of that warming, but we’ve long known that carbon dioxide is a greenhouse gas, we’ve even observed the warming effect it has on other planets. We can measure the radiation hitting the Earth and what’s being radiated back out into space. There’s an energy imbalance. Whatever the complexities of the climate system, it’s a closed system. If more energy enters a closed system than leaves it, it’s going to heat up. We can also see that radiation is being absorbed at exactly those wavelengths we’d expect to see absorption if the warming were due to an increased concentration of carbon dioxide in the atmosphere. The way the planet is warming matches what we’d expect to see from an enhanced greenhouse effect.

Blah blah blah. Boring. They told us the polar bears were going to all die but there are more polar bears now, and I hear the coral reefs are doing fine and it’s a bit chilly here so we could do with some global warming!

Maybe what’s boring is accepting what the experts tell us. Far more fun to imagine they’re all part of some globalist conspiracy, and if you’re an anti-globalist, that’s going to sit far more comfortably with your ideology. If you accept there are global problems such as climate change that require international cooperation you’re accepting there needs to be some degree of globalism.

If your vision is of a world of independent nation states doing purely what’s in their own national interests, unencumbered by international laws and treaties, anything that appears to require international laws and treaties may seem like a threat. 

Solution aversion

This is the idea that when we don’t like what we think are the solutions to a problem we have a tendency to minimise or outright deny the problem. If you think the proposed solution to climate change is ever more government regulation but you’re someone who generally opposes government regulation, particularly when that regulation is going to negatively impact your lifestyle or bank balance, then denying the problem may be preferable to changing your ideology. 

Do those who say “the climate has always changed” really think climate scientists aren’t aware of that? Does the fact that the climate has always changed, mostly without human activity, mean there must be some natural driver to the current warming? Or that the current warming is probably natural? If so, we have to ask what it is that’s causing the planet to warm.

I find it hard to come up with a response that isn’t offensive when someone says “the climate has always changed” so usually I end up not responding at all. Either they’re being disingenuous, using a devious rhetorical trick to avoid being called a climate denier when they know full well that no one, at least no climate scientist, is unaware of the fact that the climate has always changed, or they’re assuming those who accept the reality of climate change are extremely ignorant and imagine the Earth’s climate was completely stable and unchanging until humans started burning fossil fuels.

In April US Representative Marjorie Taylor Greene said

You’re going to tell me that back in the ice age, how much taxes did people pay, and how many changes did governments make to melt the ice? The climate is going to continue to change.

The assumption here appears to be that if there have in the past been climate changes that weren’t caused by human activity, the current climate change cannot have been caused by human activity. That’s like someone accused of murder pleading not guilty despite the bloody knife sticking out of the victim’s back with their fingerprints and DNA all over it along with several witnesses and CCTV footage. “People have always died, your honour.”

But it’s not really though, is it? This isn’t a serious argument, it’s a more a way of taking the piss, which makes it hard to respond to. The actual argument being made is hiding underneath “the climate has always changed.” That is that because the climate has always changed, there are natural forces changing the climate, and because those natural forces whatever they are have changed the climate in the past, they’re probably also responsible for any changes it may be undergoing now.

If they were to say that explicitly, like if Marjorie Taylor Greene were to say

My hypothesis is that the dominant forcing behind the current warming of the Earth’s climate is natural, not anthropogenic.

Then you could ask her what specific natural forcing she was talking about. Is solar irradiance increasing? Or is it orbital forcing, wobbles of the Earth’s axis and its orbit? That last one has been the cause of the planet going into and coming out of ice ages. They’re known as Milankovitch Cycles and they’re pretty well understood. If the Milankovitch Cycles were the only driver of the Earth’s climate we would now be in a very gradual cooling phase, heading towards the next ice age in around 50,000 years.

Getting into specifics

Richard Tice, leader of the Reform party and campaigner against net zero, did get into some specifics over what might be causing climate change in a recent debate with meteorologist Jim Dale. “We all agree the climate has changed for billions of years. It always will,” he said.

My point is, anybody that suggests that you can stop climate change, I believe is misinformed, deeply misinformed. Of course man made CO2 has an impact. There is a serious scientific debate as to what percentage that is and what you do about it.

No one is actually saying you can stop climate change in its tracks, but anyway… If only a small proportion of the warming is caused by our emissions of greenhouse gases then he’s right, cutting emissions wouldn’t make much difference.

Look, climate change is caused by solar variability, by sea level, oscillation by volcanic activity.

He’s right about solar irradiance, that does have an impact on our climate, but mostly a relatively minor impact and in recent decades, when we’ve seen significant warming, there has been no upward trend in solar irradiance. According to NASA

The Sun can influence Earth’s climate, but it isn’t responsible for the warming trend we’ve seen over recent decades. […] One of the “smoking guns” that tells us the Sun is not causing global warming comes from looking at the amount of solar energy that hits the top of the atmosphere. Since 1978, scientists have been tracking this using sensors on satellites, which tell us that there has been no upward trend in the amount of solar energy reaching our planet.

So Tice is wrong on his first suggested cause. How about the second? Sea level. He’s saying sea level causes climate change? Is he just getting cause and effect mixed up? Sea level rise is an effect that’s caused by a warming planet, resulting from the melting of the ice sheets. Reduced ice cover reduces the Earth’s albedo: ice reflects solar radiation back into space whereas open sea absorbs that radiation, so ice cover has an impact on the Earth’s energy balance but this is a positive feedback, a result of a warming planet.

How about his third suggested cause? Oscillation by volcanic activity. If by that he just means volcanic activity, then yes, volcanic activity can have an effect on the Earth’s climate. The Mount Pinatubo eruption in 1991 pumped a load of sulphur dioxide into the atmosphere which caused the Earth’s surface to cool over the following three years. Volcanic eruptions also pump a load of carbon dioxide into the atmosphere and carbon dioxide, being a greenhouse gas, would result in warming. But, according to the US Geological Survey

All studies to date of global volcanic carbon dioxide emissions indicate that present-day subaerial and submarine volcanoes release less than a percent of the carbon dioxide released currently by human activities 

So, if you accept that the carbon dioxide released by volcanoes can cause the planet to warm, you have to also accept that the carbon dioxide released by human activities can cause the planet to warm times a hundred.

It’s interesting he says “oscillation by volcanic activity” rather than just “volcanic activity”. Does throwing in the word oscillation there just make his assertion sound more sciencey?

A serious scientific debate

Tice suggests there is a serious scientific debate into what percentage of the observed warming is caused by man made CO2 and on that he’s right, but there are virtually no climate scientists who think that percentage is anywhere near zero, or even who think it’s less than 50%. According to the IPCC’s fifth assessment report, human emissions and activities have caused around 100% of the observed warming since 1950. Their best estimate is that 110% of the observed warming was caused by human emissions and activities. How can that be? 110%! It sounds like nonsense but simply means that if there had been no human activity and no human emissions there would have been no warming at all but rather there would have been a slight cooling.

Similarly, the recent US fourth national climate assessment found that between 93% to 123% of observed 1951-2010 warming was due to human activities.

Whether you think the figure is closer to 93% or closer to 123% depends largely on what you think the climate would be doing if humans hadn’t been doing what we’ve been doing. There is however widespread agreement that the main driver of the current warming is down to us humans and therefore what we choose to do in the coming decades will make a significant difference.

A serious political debate

If we’re to have a serious political debate over what we should do in the coming decades, we need to agree on a shared set of facts. The IPCC’s latest assessment report states

Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1°C above 1850-1900 in 2011-2020.

In other words, there is not a serious scientific debate over whether or not human activities have caused global warming. The debate now is political. It’s over what we should do about this. One thing we should not do is deny it’s happening, which is exactly what those who say the climate has always changed are doing, or at the very least trying to cast doubt and create uncertainty.

It’s worth considering those figures the IPCC quotes. A rise of just over one degree in just over one century doesn’t sound like much, but when we emerged from the last ice age the planet warmed five degrees over a period of 10,000 years. That’s about 0.05°C per century and that was one of the sharpest changes in temperature since the dawn of humanity. So it’s not just the fact that it’s warming now that requires explanation – and just waving yours hands and chanting natural causes does not count as an explanation – but it’s the astonishing rate of the warming. Set aside all the evidence that this warming is unnatural and just compare it with previous climate changes. Does this look natural?

The problem with “the climate has always changed” is that it fails to spell out what the speaker is really trying to get across. If everyone agrees the climate has always changed, why bother saying it? If you want to make the claim that most of the observed warming over the past century has a natural cause then make that claim, spell out what natural processes you think are responsible and provide evidence to support your hypothesis.

That’s what makes “the climate has always changed” so effective. It allows the speaker to cast doubt on the fact that our emissions of greenhouse gases are the primary driver of the observed warming without actually pinning them down to any definite claim they could then be asked to defend. They have to be pinned down. When someone comes out with “the climate has always changed”, ask them what point they’re making. What do they conclude from the fact that the climate has always changed?

Does the fact that the climate has changed naturally in the past mean that the current statistically significant warming of the planet cannot have been caused by human activity?

if the climate had hardly changed during the course of the Earth’s history (despite variable incoming solar radiation and changing amounts of CO2 in the atmosphere), then we would conclude that there are strong stabilizing feedbacks in the climate system

Stefan @ RealClimate

The fact that the climate has changed in the past shows that our planet’s climate is not that stable, that it’s sensitive to changes such as the concentrations of greenhouse gases in the atmosphere and that rather than there being strong stabilising feedbacks there are instead amplifying feedbacks. For instance, the polar icecaps reflect a lot of solar radiation back into space, making the planet cooler than it would otherwise be. The melting of those icecaps in the summer months means much of that solar radiation, rather than being reflected will be absorbed by the ice-free sea and land.

A serious political argument has to delve into the science, at least when the science is being challenged. That often takes time, so in a culture where these debates are had in a five or ten minute slot on a TV show, or in an exchange of tweets it tends not to happen.

In the cases of Marjorie Taylor Greene and Richard Tice, they’re both using “the climate has always changed” argument as a way to argue against action to reduce carbon emissions. Marjorie Taylor Greene opposes carbon taxes whilst Richard Tice opposes net zero. If climate change is not primarily caused by our emissions there’s less of an imperative to enact legislation that reduces those emissions. However, if climate change is primarily caused by our emissions, which it is, and if it poses a significant threat to our societies, which it does, then the argument has to be about how we can cut emissions, not whether we should.

A serious political debate needs to be based on reality. We can debate how best to cut emissions, how to do it fairly, what to replace fossil fuels with, but we should not be debating the reality that makes those emissions cuts necessary. That’s not to say people shouldn’t have freedom of speech. Flat earthers, evolution deniers and climate deniers have every right to speak their minds, but we shouldn’t be taking them seriously. They are not serious people.