Q&A: Geosciences Professor Gabriel Vecchi on Extreme Heat

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Gabriel Vecchi's research focuses include climate science and extreme weather events.

Photo: Chris Fascenelli

The world is experiencing another summer of record-breaking heat and extreme weather. In Phoenix, Arizona, temperatures were above 110 degrees every day for nearly a month. Across the country in New Jersey, heat advisories have been issued most weeks on top other extreme weather events of flooding during to torrential rainfalls and poor air quality because of smoke drifting south from Canadian wildfires. Similar patterns have happened across the country.

Some experts are predicting 2023 will be the warmest year on record, due to rising greenhouse gases and climate change (2016 currently holds the record). So, is extreme heat the new normal? Gabriel Vecchi, professor of geosciences and director of the High Meadows Environmental Institute, spoke with PAW about what’s causing the heat, advice for coping with the weather, and the actions people need to take now to make a difference. 

How do we explain this summer’s heat?

Let’s start with what is behind the heat wave in the Southern and Western United States, which is really dramatic. What we’re seeing is pretty characteristic of heat waves at this latitude, which is that you get a heat dome or an area of high pressure in the atmosphere. High pressure tends to be associated with air going down in the atmosphere, and that persists so it doesn’t move from that place. Once you have high pressure, that creates a dry atmosphere that allows the sunlight to come in. Heat waves are often intensified by dry soil, because it causes the air to heat more rapidly.

Although this is a classic heat dome setup, it does not explain why we have had such extreme temperatures across the vast area of the planet for the past few years. To understand that, we have to look at the longer-term record. A key player in all this has been the warming of the planet over the last century in large part due to the increase in greenhouse gases. The last year where the surface of the Earth was colder than the 20th century average was in 1976. When you raise the temperature of the planet and you have these classic heat domes setting up, that ultimately pushes the temperature higher.

The problem with this warming is that it makes it more difficult for the planet to cool and in response the planet has to warm so that it can send the energy it gets from the sun back and the planet doesn't warm uniformly — land warms faster than the ocean. The takeaway is that heat waves have some dominant dynamics, and they're happening over a warmer planet in a particularly warmer land. 

What are the dangers of extreme heat?

Exposure to heat can result in severe health impacts that cause damage to the body. This tends to be mostly in people who are vulnerable, but even relatively healthy people can have pretty severe consequences to heat, including death. Social disruption comes from this when people try to adjust to this warmth to find comfort, and it can stress our power systems when everyone is trying to cool their homes at the same time. Couple this with extreme rain like we’ve had, and our emergency management systems can become strained and forced to choose between addressing crisis A or B. Outdoor work becomes extremely dangerous, but many things that need to happen for our society to function well happen outdoors. How do we manage that? These are at a human social level.

You can start thinking about the consequences to our agriculture and livestock, where most of our livestock have certain temperature ranges where they are most comfortable. Exceeding this on the warm side can result in a reduction of production in, for example, milk and eggs, and at the more damaging end the livestock may die. Similar circumstances can happen for plants.

Challenges to ecosystems and the biodiversity in ecosystems is another example. So, it’s pretty large ranging and the effects can be drawn out in time. Heat waves will generally last a number of days, but the impacts can be felt for a while. These are not trivial issues. Many of us are fortunate enough that we can stay indoors and perhaps use air conditioning, but using AC heats the environment. 

Are there any signs of relief?

I think as we move forward in time, given the role of global warming in changing the statistics of these heat waves, we are going to have to unfortunately find a way to live with them as best as possible. That is a pretty monumental challenge. The people who are under these heat waves right now I think are finding them quite challenging to live with.

The good news is for some places there are strategies to minimize the impact of these heat waves, which can include setting up cooling centers. That said, we can’t cool an entire wheat field. As we start thinking about the remainder of the 21th century where we expect the planet to continue warming, even if we are successful in reducing greenhouse gas emissions, we’re going to have to learn how to produce food in a world with dispersed heat waves. It is going to be a challenge. Now thinking about the energy transition and moving ourselves to renewable energies, one positive note is heat domes and dry air normally come with lots of sunlight, so we can use that to our advantage by capturing that light for solar energy.

What tips or advice can you offer for people to cope with heat?

Firstly, take it seriously. Heat is relatively slow, so the line between discomfort and damage to the body is not clear. Listen to the heat warnings. Check in on each other. Avoid daytime strenuous outdoor activities. Drink plenty of water.  It’s not a sign of vigor and strength to just muscle through a heat wave.

What can we do to address this long-term?

We expect further global warming, but we have some influence over how large that global warming is going to be. How do we keep that level of warming down? The more greenhouse gases we have the more difficult the challenge, the fewer we have the easier the challenge. The amount of warming we get is connected to a concept that is known as cumulative emissions.

So, you can just add up all of the emissions of greenhouse gases that have occurred since the beginning of the Industrial Revolution (1760s), and that tells you how much global warming we have committed to having. There’s nothing we can do about the past, but in 20, 30, 40 years from now a substantial amount of the greenhouse gases that will matter then will have been emitted between today and that time. So, we can make that number smaller if we find a way to do what we want while emitting less carbon.

I think there’s reason to be hopeful because there are real plans being put into place to transition our economy away from fossil fuels in a way that’s not super damaging. There’re some really exciting ideas out there to enhance the way carbon is pulled from the atmosphere. At the local level, it will be crucial to develop better ways to help each other, to organize society, to distribute resources, so that when these heat waves happen they’re perhaps less impactful.

What’s your response to the argument that the Earth experiences warm and cold periods, so this is just a warm period and nothing to really worry about?

There’s a lot to unpack on that. Yes, there have been many warm periods in the past and also many extremely cold periods, but this has been an unusually warm period. If you think about all the things associated with human beings — the pyramids, the Great Wall, the creation of famous art works, etc. — all of that happened in a climate that was essentially within a certain bound that we are now outside of. Oftentimes, when you look at past warm climates and you ask why were they warm, there’s lots of mediating factors, but one of the recurring themes is that warm periods tend to be periods where there are very large greenhouse gas concentrations in the atmosphere, so we know it is an important control on our climate. It’s true that there are cycles, it’s just not relevant to explaining what we're going through. But it does carry lessons for us. 

What’s the main point you hope people take away from experiencing rising temperatures?

I really hope that we don't approach this at the extremes: On the one end being dismissive and on the other being despairing, which can both result in a lack of action. We need to be very serious, but we need to proceed with guarded optimism. Don’t be Pollyannaish, the unicorns aren’t going to come down and save us — it’s us that’s going to save us. Despite the bad that humanity has done, I believe we’ve done more good and this will be one of those cases. What motivates me is thinking about a future in 100 or 200 years where our descendants will look back and say “those people rose up to the challenge.”

Interview conducted and condensed by C.S.