Host: Shamini Bundell

Welcome back to the Nature Podcast. This week, we’ll be hearing about the history of climate change…

Host: Nick Howe

And learning why mandating vaccines should be done carefully. I’m Nick Howe.

Host: Shamini Bundell

And I’m Shamini Bundell.

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Interviewer: Nick Howe

Unless you’ve been living under a rock, you probably know that the climate is warming. Today’s human-induced climate change is relatively novel, but that doesn’t mean that the climate has been stable until now. Here’s climate scientist Raphael Neukom from the University of Bern in Switzerland.

Interviewee: Raphael Neukom

So, that’s always a big question when you look at the media about current climate change – is this extraordinary or has it happened before?

Interviewer: Nick Howe

The earth’s history is in fact littered with pockets of cooler and warmer periods. For example, from around 1300-1850 AD, there is a period known as the Little Ice Age –unsurprisingly, a cooler period. Charuta Kulkarni, a historian from the Open University who’s studied the Little Ice Age, explains that life then was hard.

Interviewee: Charuta Kulkarni

You could have a blend of droughts, colder summers, even winters, years which were continuously colder as compared to the previous years. People could not cope with it.

Interviewer: Nick Howe

A Serbian monk from the 16th century put it simply, writing: “It is terribly cold, my brothers.” So, what caused the variations in the climate in the past and how do they compare to what’s happening now? Well, Raphael and his team have been trying to find out, and this week he is presenting a model of temperatures across the globe for the past 2000 years. But since there aren’t exactly thermometer recordings from 12 AD, to build his model, Raphael looked for what is known as proxy evidence.

Interviewee: Raphael Neukom

Data from natural or human archives. For example, tree rings or lake sediments, marine sediments, ice cores, cores, or also old written documents.

Interviewer: Nick Howe

This proxy evidence can give Raphael information about past climate. For example, in warmer years, trees can grow more and so the tree rings for those years will be thicker – nice. But this isn’t a fool-proof measure. Things like rainfall can also have effects and so Raphael used as much proxy evidence as possible – over 200 records – to average out the variability and build up a clear picture.

Interviewee: Raphael Neukom

And what we found based on this is that earlier warm or cold periods didn’t happen at the same place, at the same time.

Interviewer: Nick Howe

Before 1850, Raphael found that climate warming or cooling was never consistent across the planet. For example, during the Little Ice Age, in some places the coldest period was during the nineteenth century, but for other regions it was several centuries earlier – quite different to what we see today.

Interviewee: Raphael Neukom

For more than 98% of the globe, the warmest multi-decade period actually occurred within the last 100 years, so in the twentieth century, so that’s a really global consistence that we do not observe from the earlier periods.

Interviewer: Nick Howe

Now, on average, the globe is warming everywhere simultaneously. Scott St. George, a researcher who studies the history of climate who didn’t work on this study, thinks we can have confidence in Raphael’s conclusions.

Interviewee: Scott St. George

They’ve really tried to do the reverse estimate in almost every way possible. I think they use about eight or nine discrete methods to combine this jigsaw puzzle of tree rings, lake sediments and ice cores into this global picture of past yearly changes in temperatures. And because they kept coming up with the same answer no matter what the statistical toolbox that they applied, then we can be a little more confident that the results they’re getting are not a reflection of their own personal choice or their own preferred method.

Interviewer: Nick Howe

So according to this study, in the past, the climate warmed and cooled in chunks – a patchwork of local climate change across the globe rather than the global change we see today. The next question is why? There is clear evidence that now, human emissions of carbon dioxide are forcing temperatures higher, but in the past 2,000 years, other things may have been more important. Over longer timescales, the causes of climate shifts are harder to pin down, but in a Nature Geoscience paper also published this week, Raphael looked at shorter durations to get more definitive answers about the causes of past temperature changes.

Interviewee: Raphael Neukom

And there we came to the finding that most important drivers of the global mean prior to industrialisation is actually volcanic eruptions. They tend to cool the climate on large fractions of the globe over multiple decades.

Interviewer: Nick Howe

It’s still unclear what caused longer-term changes such as the Little Ice Age, but it’s possible that volcanic activity played a role. But one thing we can be sure of is that current global warming is unlike anything we’ve seen in the past. Here’s Scott.

Interviewee: Scott St. George

The world that we’re living in today is synchronised in terms of temperature in a way that it hasn’t been for at least the last 2,000 years, and so when we talk about the unusual temperatures and the impact that global warming is having on the planet, it’s not just a question of the Earth overall being warmer, it’s that in a lot of ways, there’s no place to hide from this warming. Everywhere is warming.

Interviewer: Nick Howe

That was Scott St. George of the University of Minnesota in the US. You also heard from Raphael Neukom of the University of Bern in Switzerland and Charuta Kulkarni of the Open University in the UK. You can find Raphael’s papers over at nature.com, along with a News and Views article written by Scott.

Host: Shamini Bundell

Coming up later is the News Chat, where we’ll be finding out about India’s latest mission to the Moon. Now though, it’s the Research Highlights, read this week by Anna Nagle.

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Anna Nagle

Scientists have been making surfaces that can drive droplets of liquid along at high speeds over long distances, even defying gravity. To move a droplet along a material, the researchers modified the charge across the surface. This caused positively charged liquids to be pulled along. In this way, droplets could be propelled up vertical surfaces or even travel upside down. The researchers used this technique to make a small water droplet car. Using four droplets as wheels, they showed that small objects could be transported. They hope that in addition to transporting objects, this technique could have applications in harvesting water or self-cleaning surfaces. Slide on over to that research in Nature Materials.

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Anna Nagle

Love them or hate them, scientists from University College London have found that laugh tracks do make things funnier. They did this by playing 40 groan-inducing jokes to participants and getting them to rate their humour – jokes such as, ‘What does a dinosaur use to pay the bills? Tyrannosaurus cheques!’ The researchers were able to show that the addition of laughter increased the perceived funniness of the joke. Not all laughter is created equal though, as the team were also able to show that genuine spontaneous laughter increased the rating of humour more than the staged chuckles associated with your least favourite comedies. Giggle along with that researcher over at Current Biology.

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Host: Shamini Bundell

It’s hard to overstate just how important vaccines are. The idea is simple – prep the body’s immune system for particular threats – and the impacts of vaccines have been immense. The World Health Organisation estimated that vaccines prevented at least 10 million deaths between 2010 and 2015 alone.

Interviewee: Saad Omer

Well, in a way, we are in the golden age of vaccines.

Host: Shamini Bundell

This is Saad Omer of the Yale Institute for Global Health in the US.

Interviewee: Saad Omer

There have been more vaccines available than before. There are new vaccine technologies that are coming online all the time. But having said that, there’s an asterisk.

Host: Shamini Bundell

And that asterisk is a big one because in spite of these advances, some people are refusing vaccines. When it comes to certain diseases, like measles, vaccines have been so effective that some parents may feel the risk of vaccinating their children outweighs the benefits. As a result, measles rates are rising rapidly. In the first four months of this year, the number of measles infections was more than three times that for the same period the previous year. Saad has written a Comment piece out in this week’s Nature, arguing that overcoming this problem will take more than simply making parents vaccinate their children. Reporter Adam Levy gave him a call.

Interviewer: Adam Levy

Now, something that has been discussed and also tried to turn this around it to mandate vaccines to make it actually necessary that parents vaccinate their children, but there is actually a big variety in what these mandates can look like, right?

Interviewee: Saad Omer

Yeah, you’re absolutely right. Mandates come in various shapes and sizes. For example, all states and D.C. in the US allow exemptions from these mandates for medical reasons, 45 states allow exemptions from these mandates due to non-medical reasons, such as religious only or religious and philosophical reasons. So, there is a whole variety both in terms of how they’re implemented, what are the penalties, and how easy it is to carve out exemptions.

Interviewer: Adam Levy

Now, naively as someone who doesn’t work in this field, I would have thought that the harder you make it to get an exemption the better, but in this Comment piece you’re arguing for a slightly more nuanced approach.

Interviewee: Saad Omer

Yes. For example, in California a few years ago they eliminated all non-medical exemptions to their state level mandate for vaccination, and what we found was there was a bit of a replacement effect. So, there was a higher rate of people filing for medical exemptions, then some parents were seeking home-schooling and other ways of avoiding the implementation of these mandates to them altogether, and so on and so forth. There is a sweet spot that you hit through this approach.

Interviewer: Adam Levy

Are there any actual risks of negative effects from making a mandate too harsh?

Interviewee: Saad Omer

There’s some evidence in that context. For example, this really nice study from Germany looked at this phenomenon and found that people’s perceptions of vaccines, if they have negative perceptions, can become more entrenched if you mandated a vaccine.

Interviewer: Adam Levy

So, what are the alternatives to mandates that should be done either instead or I suppose at the same time as mandates to increase vaccination rates?

Interviewee: Saad Omer

The state of the evidence suggests that, to paraphrase Voltaire or more recently Spiderman, with great power comes great responsibility, and the power of mandates should be exercised with deliberation and maturity and with nuance. But having said that, vaccine hesitancy or non-acceptance due to behavioural reasons are not the only reasons why children are not getting vaccinated. So, mandates work best not in isolation but in conjunction with other interventions. For example, having a nuanced look at the reasons for under vaccinations, using immunisation registries and sending reminders at the population level have been very effective, for example in Australia, and then providing vaccines again in communities is helpful. So, that’s the second step if you are thinking about mandates.

Interviewer: Adam Levy

And do you think that all these approaches could turn around the trend that we’ve seen in vaccine uptake?

Interviewee: Saad Omer

We should approach vaccine policies and vaccine interventions from a perspective that demands evidence, and if you do not tolerate suboptimal evidence in vaccine development science, we should not tolerate suboptimal evidence in vaccine communication science or vaccine policy. We don’t have a choice. I think vaccines have been one of the most significant successes not just for public health and biomedical sciences, I’m not being hyperbolic when I say as a species, and so it would be incredibly sad if we lose some of that progress and so I guess we don’t have a choice but to bring our a-game to addressing some of these issues in vaccine acceptance and science.

Host: Shamini Bundell

That was Saad Omar of the Yale Institute for Global Health in the US. You can find his Comment piece over at nature.com/opinion.

Interviewer: Nick Howe

Finally on this week’s show, it’s time for the News Chat. I’m joined this week by Holly Else, one of the reporters here at Nature. Holly, hi.

Interviewee: Holly Else

Hi.

Interviewer: Nick Howe

Thanks for joining me, and you come to me with breaking news. At the time of recording, the UK has just found out it has a new prime minister.

Interviewee: Holly Else

It does. This literally just happened about an hour ago, so Boris Johnson has been elected as the UK’s new prime minister and he’s going to be the man to pull us out of Europe with Brexit.

Interviewer: Nick Howe

Before we get into what this might mean and the B-word that is Brexit, how did we get here?

Interviewee: Holly Else

So, Theresa May handed in her resignation at the end of May because she couldn’t get parliament to agree on the terms of her Brexit deal and that triggered a leadership contest within the party and Boris Johnson won this morning.

Interviewer: Nick Howe

I guess the question is then, what might Boris Johnson’s leadership mean for Brexit?

Interviewee: Holly Else

He has said that he will deliver Brexit whatever happens by 31st October and that could mean that we’re leaving without a deal, which would obviously be catastrophic for scientists who rely on the European Union for funding and also being able to recruit people from overseas without having to go through protracted visa hoops, for example. Obviously, scientists like to travel to conferences and they do so really easily at the moment as we’re part of the EU. So, those are just some of the things at stake if we left without a deal.

Interviewer: Nick Howe

Okay, and moving away from Brexit as well, has Boris Johnson said anything during the leadership contest about what his plans are for science?

Interviewee: Holly Else

He hasn’t said much. He’s said a bit about the bioeconomy. What people are waiting for him to talk about is this policy that we have in the UK that which was brought in by May, where we’re hoping to spend 2.4% of GDP on research and development by 2027. So, this is a promise that was made and scientists have been eagerly awaiting the details of how that will happen, but that’s kind of got caught up in Brexit machinery where nothing has actually happened about it, and now we don’t know even if Boris Johnson will continue that policy now he’s in power, and that’s obviously money for researchers to do their work every day.

Interviewer: Nick Howe

So, has there been any response from scientists so far?

Interviewee: Holly Else

Well, a bit. Mainly, a lot of the things we’ve already just discussed, but also some people saying that Boris Jonson tends to like sort of big, shiny projects, so he infamously supported the Garden Bridge which was this pedestrian bridge over the Thames which was ill-fated and cost a lot of money but looked very good. And so that could actually be a benefit to science because he’s interested in these really big, shiny projects, so maybe we’ll get a new massive research centre into some area of science which he can tout about all over the world about how great we are.

Interviewer: Nick Howe

Well, I guess we don’t know much at the moment so we’ll have to see what happens with Boris Johnson’s leadership going forwards. Moving onto our second story then, Holly, India are shooting for the moon – what can you tell me about this?

Interviewee: Holly Else

Yeah, so this week they launched a spacecraft with an attempt to reach the surface of the Moon.

Interviewer: Nick Howe

So, what is the aim of this mission to the Moon then?

Interviewee: Holly Else

Well, they’ve tried before and didn’t make it, and this time they obviously want to make it and they’re hoping to land in a little research region of the Moon – the south pole. So, previously, other countries that have landed on the Moon have done so at the equator and so there’s not really much known about this area. As they say, we will be exploring the unexplored.

Interviewer: Nick Howe

So, why are they shooting for the poles?

Interviewee: Holly Else

Well, no one’s ever been there before, for one, and also because it is a pole, it may contain vast amounts of resources like water, oxygen or hydrogen, and that could be really helpful for future exploration of the Moon or even making a Moon base.

Interviewer: Nick Howe

And so, this mission has just launched. When will we know that it’s been successful… or not?

Interviewee: Holly Else

Well, the lander will land on the Moon on 7th September if all goes to plan.

Interviewer: Nick Howe

Well, we’ll have to look Moon-ward on 7th September then. Holly, thanks for joining me. Listeners, if you want to find out more about those stories, head over to nature.com/news.

Host: Shamini Bundell

That’s all for the Nature Podcast this week, but there is just time to tell you about a video I’ve made. It’s all about how virtual reality technology is being used in neuroscience and you get to see me failing to beat a rat in a memory task. Head over to youtube.com/NatureVideoChannel for that. I’m Shamini Bundell.

Host: Nick Howe

And I’m Nick Howe. Thanks for listening.