Professor Ed Hawkins, University of Reading: Impacts of climate change

Tim Hughes: So next up, we have Professor Ed Hawkins from the University of Reading talking about the impacts of climate change. Over to you, Ed.

Ed Hawkins: Good morning, everyone. So, first of all, thank you very much for all being part of this amazing process. We appreciate your giving up a lot of time to be here. So as Joe's just described, we've understood the basics of the greenhouse effect for a very long time. The basic physics and chemistry of our atmosphere means that if we add more greenhouse gases to the atmosphere, it will warm up. Of this we're certain. So we understand the theory, if we add greenhouse gases to the atmosphere, it will warm up, and that is what our thermometers also tell us. So, as Joe described, we have thermometer measurements covering the planet. We can reconstruct our global temperatures back to about 1850. And so those measurements show that if we start at 1850, so one strike represents one year. The blue colours represent cold years, the red stripes represent hot years. So starting in 1850, we see mainly cold years, and as we go forward through time up to the present day, the stripes get redder and darker, showing that the planet is warming up and that rise has accelerated in the last 40 or 50 years or so. We are changing the climate. Now, we've warmed the planet by about 1, 1.1 degrees so far. That may not sound like very much, and on a day like today if you walk outside, you may not feel the difference between 8 degrees or 9 degrees outside. But when we average that over the planet, that has very severe consequences. So we're gonna start, about some of those consequences in the Arctic. But first of all, I should note that what we're seeing here this warming of our climate, is happening everywhere. It's happening in every country, and it's happening over the oceans as well.

So, we have satellite measurements over the Arctic. We've looked down on the North Pole since about 1979 from satellite, and over that time we've watched the sea ice. Over that time, we've watched the sea ice slowly decline over time. It wobbles around from year to year, but over time, over the last 40 years, we've lost about 40% of the sea ice cover in the summer over the Arctic. And of course, that 1 degree rise in global temperatures is actually about 2 degrees in the Arctic, and that means that there's more opportunity for ice to melt. And so that's what we're seeing. We're seeing the consequences of a warming planet on the sea ice. And this is also the natural world telling us that something is happening. The natural world is responding. It's telling us the same stories as our thermometers. We're seeing the changing seasons as the natural world responds. We're seeing wildlife respond to the warming planet, and we're seeing the ice respond as well. We are warming the planet. And as well as the sea ice retreating and getting thinner, we're also seeing the melting of Greenland, for example. Greenland is losing water at a rate of three Olympic sized swimming pools every single second. That's a lot of water entering the ocean and causing sea levels to rise. We'll come back to sea level in a moment. And this, of course, this melting in the Arctic and warming of the Arctic has consequences for those who live in the Arctic, people, and the wildlife who live there and are used to the climate of the past, and we're pushing them outside the climate of the past and making them live in a new climate in which they may not be adapted to.

There are other consequences as well. I'm sure you won't have missed the bushfires in Australia over the last couple of months, and this photograph was taken by a firefighter having to think about how to deal with this inferno in front of him. Because the reasons for the bushfires in Australia are many and they're complex, and at the heart of it is actually some unusual weather conditions which has led to some very hot weather and some very dry conditions. You can see the grass and the photo is very dry. Many of these areas have been in drought for the last three years, which has meant the area's very dry and very flammable, coupled with the unusual weather conditions has meant that fires have been likely. So, the fires would have happened without climate change. But climate change has made it worse, because we have warmed the climate, we've warmed the temperatures in Australia, this event was hotter than it would otherwise have been, which has meant the fires are worse than they would have bean without climate change. It's also possible, likely, in fact, that we've affected the weather patterns around Australia and dried out some of the parts of Australia where these bushfires are happening. When we warm the planet, we shift the atmosphere's circulation, and so storms go in slightly different directions than they would otherwise have done, and so over the last 40 or 50 years, parts of Australia which have experienced these bushfires have shown quite a strong drying out as well. So there's many different ways in which climate change can affect these events that would have happened anyway, but we are making these events worse than they would otherwise have been. How about closer to home? So is Joe described, we have thermometer measurements all over the world, and we have some very long records. For example, from Oxford. So in Oxford we have temperature measurements. So someone has measured the temperature every single day in Oxford, at the same place since 1814, every single day. So we can look back over those 200 years and see how temperatures had changed in Oxford. Again, the same stripes we see going from 1814 on the left to 2019 on the right. The blue years are the cold years, red years are hot years. And again, we can see the pattern of our warming climate even at the scale of a single thermometer based in one town in the UK. Climate change is here and now.

Interestingly, the very dark stripes we see, they're volcanic eruption years. So we know there are some big volcanic eruptions in 1815 and in the 1830's and in the 1880's, which we can see cooling the climate in Oxford, for example. But at the end, we can see that there's very strong warming signal. As our climate has warmed, we're seeing the temperature rise everywhere across the UK and in every country around the world. So what does that mean for us in the UK? So if we think about the recent heat waves that we've had in 2018 and 2019, we had some very hot weather as well. Similar to Australia, what we see is that the hot weather caused hot temperatures, but the temperatures were hotter than they would otherwise have been without climate change. We've added extra extra heat to those events. We're making them warmer than they would otherwise have been. In 2018, we saw big problems in our railways and our roads because they're not used to dealing with this amount heat all the time. And so our infrastructure isn't necessarily adapted to the conditions that were pushing our climate into, and that is causing the consequences.

Also in the UK, I think one of the main risks for the UK from a warming climate is probably flooding. So this picture is from 2015. We had some very severe floods in Somerset. I'm sure many of you remember, this picture is of a flooded village back then. Climate again, this event has many and varied complex reasons for occurring, but ultimately it comes down to how much rain fell from the sky. So for this event, we had lots of storms coming across the Atlantic and hitting the UK as we do every every winter. There's nothing particularly unusual about any of those individual storms. They all dropped their rain in the same place, which caused a lot of the flooding. So how has climate change affected an event like this? Because we're living In a warmer world, the atmosphere can hold more moisture. Again it's very simple physics. A warmer atmosphere holds more moisture, more water, so when we get a storm dumping a lot of rain it actually rains more than it would otherwise have done. So we're seeing more rain than would have occurred in the same storms 100 years ago, so that they were getting more rain, potentially leaving more flooding at events like this. That is how climate change is affecting us, as people and our ecosystems, it's by making extreme weather events worse, and the impacts of those events worse.

So, the world faces very different risks depending on where you live. There are a whole load of risks that you might think about the consequences of our warming world. I've discussed some of them already, so we are likely to - well we will experience and are experiencing more heat waves. We'll also see more floods, as I've described already. I've discussed sea level rise. The sea levels around the globe have already risen by about 25 centimetres or so, and they will continue to rise for centuries as the planet continues to warm, mainly due to melting of ice from say Greenland and Antarctica, but also the fact that as the oceans are warming, sea water expands as it gets warmer and so takes up more space in the ocean causing sea levels to rise. So those are the main two reasons why sea levels are rising, which means also that when we get storms, say hurricanes or typhoons or storms hitting the U.K, it means that when those storms hit the coast, the sea level is higher. So the water that's coming from the storm surge, as those waves break over the coast, the water's already higher. And so we get more flooding on the coasts as well.

Many of these risks are from the fact that we change our climate. We're shifting our climate out of what we're used to experiencing. So ecosystems and wildlife are adapted to living in a particular climate, and so if we're pushing the climate outside what they used to experiencing, that's gonna cause consequences. They'll want to move to another location, perhaps, but there may be nowhere to move to, and so that would cause consequences for them. Our infrastructure here in the UK and anywhere is adapted to the weather and the climate that were used to experiencing in the past. We need to think about how we adapt our infrastructure for the future to make it capable of dealing with future hot temperatures and more flooding.

We're also seeing that the fact that as we're adding more carbon dioxide to the atmosphere, some of that carbon dioxide has been absorbed by the ocean and actually turns into carbonic acid in the ocean. So we're actually seeing the oceans getting slightly more acidic through time as well. And that has consequences on wildlife living the ocean; corals and other species as well. The corals for example, in Australia, you may have seen have been struggling recently partly due to this ocean acidification, but also due to the fact that getting very hot temperatures and the coals are not used to experiencing those hot temperatures and so bleach and die. So large parts of the Great Barrier Reef had some very large problems in the last couple of years as temperatures have hit record highs.

So those are ones that we're very confident about, and there are other impacts that we may be slightly less confident about. So we might imagine that climate change adds to increased risks in certain areas. Many of these impacts are happening in vulnerable countries, and so if you are changing the climate, you may be making farming particularly difficult in a particular area leading to potentially people moving away, because they can't grow the crops that they used to experiencing. So migration is one thing that we think about. Climate change is what we call a risk multiplier: it adds to the risk that already happened due to the weather conditions. We're seeing glaciers been melting across the world, which means that many regions which are used to living off the melt water from glaciers will no longer have a water supply. For example, once the glaciers have gone. There are many and numerous different ways in which climate change is affecting how people will live on the risks that they face. In the UK we"lll have think about our infrastructure and potentially we'll see different diseases coming to the UK. These are all things that we worry about, we're less certain about, but they're potential risks that way will face. As Joe said, I think the UK, we built the Industrial Revolution. James Watt invented the efficient steam engine in the 1780s, which kick started the Industrial Revolution, which has been a great thing for a science and technology and medicine and how we live our lives. But now we're seeing the side effects of that development, and these are all the risks that we face now because of that development that we've experienced, and I think the UK has a great opportunity to be part of the next revolution. To try and tackle these risks, and reduce risks all across the world. Thank you.

Tim Hughes: Thank you very much, Ed. So, same again, I'm just going to give you a couple...