And for better or worse, the world won't have a shortage of those anytime soon.

Throughout this series, we've covered many of the areas where these challenges lie and how engineers are making their mark.

But we've only just skimmed the surface!

While we couldn't get to them all, one thing is certain: the future landscape of engineering will be very different from what we see today.

[Theme Music]

From the tiny to the large, we've seen engineering in action to deliver drugs, build bridges, and shore up skyscrapers.

In general, the kinds of problems that engineers solve depend on what we want and need.

Farms, factories, cities, and homes all rely on energy production, civil infrastructure, and communication networks for their basic functions.

Society will continue to need those in some form in the future, which is why a lot of focus is put into these fields of engineering.

But new engineering specialties are also popping up all the time.

In the last decade, the demand for smartphones has driven huge developments in electrical and computer engineering.

The industry is working on improving the designs of components like processors and finding cheaper ways of producing them.

In other words, economic factors can play a big role in what fields engineers end up working in and what sorts of jobs are available to them.

But in the 21st century, there are challenges facing the world that go beyond economics, with implications for our very existence!

The environment is changing more radically than ever.

There are entirely new threats to our infrastructure.

Healthcare and sanitation have the potential to save hundreds of millions of lives.

Although engineering has improved the average quality of life to the best it's ever been,

big challenges like these need to be addressed if humanity is going to keep thriving.

To outline some of these problems, the US National Academy of Engineering, or NAE,

has consulted with engineers, scientists, and technologists to create a set of Grand Challenges for Engineers in the 21st century.

These goals address some of the most essential global issues in both big and small ways.

Broadly speaking, they focus on sustainability, security, health and general quality of life.

It all starts with sustainability, or making sure our planet stays a place where we can live.

To heal the environment and keep humanity safe, we need to engineer a future that looks very different from our past.

To prevent further damage from the burning of fossil fuels, we need to develop cleaner methods for energy production.

Engineers are already working to make solar panels more efficient and investigate the possibility of power plants that use nuclear fusion.

But producing power isn't the only way we're warming the planet.

Modern agriculture uses lots of artificial fertilizers to increase food production.

Unfortunately, only some gets absorbed into living things like crops; much of the rest escapes to the atmosphere as nitrogen oxide.

There, it acts as a greenhouse gas, trapping in heat and deepening the effects of climate change.

Worse still, some returns to Earth in the form of acid rain.

To address these problems, engineers need to find ways of stopping nitrogen from leaking out of the food production process.

Stopping the release of nitrogen oxide is essential for managing the nitrogen cycle that supports the Earth's ecosystem.

And that may mean designing new methods of applying fertilizer, or processing organic waste into more environmentally-friendly alternatives.

But it's too late to just change what we do in the future.

To fix the warming planet, we need to reverse the effects of greenhouse gases.

That's the goal behind carbon sequestration, which aims to take carbon dioxide out the atmosphere and store it safely away.

The good news is, sequestration is already possible!

There are chemical reactions for capturing CO2, like the kind used to add fizz to soda.

The huge challenge is to scale up that technology to remove billions of tonnes of it from the atmosphere in a way that's economically viable.

A good start would be capturing carbon dioxide as it is released from fossil fuel-based energy plants.

The smokestacks in coal-powered plants could be altered to absorb greenhouse gases at the source.

And once we can prevent its release or take it out of the atmosphere, we'll need a way to store that CO2.

Engineers are working on finding places, like deep within porous rock formations, where all that carbon could be put away.

While preventing environmental ruin is a huge task, there are other risks engineers need to plan for in the future.

While civil engineering has provided a lot of infrastructure needed to support our daily lives, not enough work has gone into maintaining it.

Old structures and outdated transportation systems are in need of modernization to make them safer and more reliable.

As part of these efforts, engineers in the UK are sending electromagnetic waves through the ground

to locate buried objects like pipes and cables that are part of the current communication and plumbing networks.

This will allow engineers to map them out and improve waste treatment facilities and telephone networks,

making those systems more resilient against potential catastrophes.

Sadly, the risks posed to infrastructure aren't just because of negligence.

As the world becomes more connected, systems like power grids are increasingly coordinated using networks of computers.

Unfortunately, that makes them more vulnerable to attacks from hackers!

In 2015, hackers managed to disrupt the power grid in Ukraine, temporarily cutting off the supply of electricity to 230,000 residents for several hours.

If attacks like this continue to escalate in scale, they could threaten important services like hospitals and firefighters.

To prevent hackers from attacking critical infrastructure,

computer engineers are developing solutions to ensure that only trusted operators can access the systems that control them.

That involves developing more secure software,

and even implementing new hardware like fingerprint scanners to make sure only a few designated people can make changes.

They can also organize vulnerable computer systems to operate on networks that are entirely disconnected from the internet,

so hackers have a harder time accessing them in the first place.

But big threats to infrastructure aren't just restricted to cyberspace!

Although nuclear weapons haven't been used in warfare since World War II,

there's always the chance that a malicious group could turn stolen nuclear material into an improvised bomb.

To prevent this, engineers are developing ways to monitor and track the radioactive elements used in places like energy plants, hospitals, and research facilities.

For example, devices could be designed that measure the radioactivity near nuclear reactors, giving an indication of the amount of material inside.

If that level drops suddenly and without explanation, it could alert investigators that a theft has occurred.

Now, this all kinda sounds like the future of engineering is just preventing terrible things from happening.

But the good news is that engineering is also an active, positive force for improving lives.

Because of the incredible pace at which technology has advanced, engineering can make huge strides in the fields of health and sanitation.

We saw a way to provide better access to clean water in the context of engineering design, which is vital for sanitation and preventing the outbreak of disease.

But there are lots of ways engineers could help treat diseases, too.

The tools of genetic engineering, for example, give us new ways to create medicine, such as specially-designed enzymes that produce cancer drugs more efficiently.

Some recent advances like CRISPR might even allow doctors to treat patients based on their DNA and eliminate certain diseases entirely.

And as we saw with biodevices, new hardware is being developed to work within the body for medical diagnoses and monitoring.

The data that those devices collect, like blood pressure and heart rate, could be used to alert doctors immediately when something goes wrong.

Grouped across many patients, this data could also be used to investigate and predict healthcare trends, a field called health informatics.

Engineers will play an enormous role in designing the systems that collect, transmit, and even analyze that data.

As well as personalizing healthcare, engineering can develop other kinds of tools that are tailored to individuals, like those used in education.

Many current resources, including videos like this one, are aimed at a broad audience.

In the future, though, resources could be designed to change the style and depth of information they provide based on an individual student's strengths and preferences.

Imagine an online textbook that could automatically elaborate on topics you didn't get the first time around,

or digital flashcards that adapt to test you on the things you forget most often.

New hardware, like virtual or augmented reality headsets, could even provide simulated environments for students to learn and experiment in.

Software engineers will be key to bringing these sorts of tools into classrooms and homes.

Of course, similar technologies could be applied to every aspect of our lives to allow our thoughts and personalities to influence our environments.

But to do that, we'd need to understand the brain a lot better than we do now.

Understanding the human brain is one of the biggest scientific challenges there is.

Doing so would allow us to develop new medical and psychiatric treatments.

Modeling computer systems on the design of the human brain could also give us entirely new ways of solving problems.

You've probably heard of the progress being made in fields like artificial intelligence.

The goal is to construct systems with problem-solving capabilities similar to the kind humans have,

such as driving cars or recognizing tumours in X-ray scans.

So far, we can only crudely mimic how brain cells are connected.

Understanding how the brain works more completely could help us replicate some of its remarkable abilities.

On this front, engineers are developing new hardware to assist in making scientific discoveries, like infrared sensors that measure brain activity.

This helps us to understand how physical changes like blood flow and electrical impulses correspond to the act of thinking.

And determining that could help us better model individual parts of the brain and improve our efforts at artificial intelligence.

From brains to biofuels, it's clear that engineers have lots of ways to impact the future.

Despite the challenges laid out by the NAE, the truth is that engineering rarely goes the way we predict.

Few people would have thought that less than 70 years would separate the flight of the first airplane from our first steps on the Moon.

The development of technology, and the challenges that come with it, are still big questions on the horizon.

But what we can say is that whatever the future holds,

the problem solving skills and fundamental ideas provided by engineering will put you in a good spot to take a crack at them yourself.

Because that's really what engineering is all about – using bright ideas to tackle big challenges!

And we hope this series has put you on the path to do just that.

Crash Course Engineering is produced in association with PBS Digital Studios.

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Crash Course is a Complexly production and this episode was filmed in the Doctor Cheryl C. Kinney Studio with the help of these wonderful people.

And our amazing graphics team is Thought Cafe.