Jeffrey Sachs is one of the most popular economists in the world for his books on poverty and globalization, which are based on his research at Columbia University and his advisory work for the United Nations on how to combat climate change and achieve sustainable development. The 67-year-old was recently in Madrid, where the temperature had soared to 41ºC (105ºF), precisely to talk about this issue: how we are lagging in the fight against global warming. Instead of focusing on the war in Ukraine, he says, we should address the real priorities. In the Spanish capital, he took part in an event organized by the Spanish Network for Sustainable Development.

You have come to Madrid in the middle of a heatwave and are experiencing extreme heat directly. How do you feel?
It’s hot, yes, but in some places, it’s deadly. There were 50ºC days in parts of India this spring. It’s also a sign of how much human activity has already warmed the planet. We know that on average Earth is warmer now than at any time in the past 10,000 years. We know that we are about to exceed the 1.5-degree limit that we agreed to in Paris. We’re on an extremely dangerous path. The advantage now is there is scientific clarity about what to do. We have to decarbonize the energy system fast by mid-century. And the second piece of good news is that the technology to do that has come down in cost 100-fold. So it’s actually perfectly reasonable to do what we need to do. So the question for humanity is, are we perfectly reasonable or not?

And will we be?
That is the struggle: our rationality. Warming threatens to destroy the rainforest, which is close to a tipping point. Many species are going to the edge or to extinction. Many ecosystems are collapsing. So this isn’t how hot we feel walking outside. This is changing the way the Earth in its entirety is working. The so-called ocean circulation is slowing down. There are so many risks and tipping points. The melting of the sea ice in the Arctic means that the planet rather than reflecting sunshine from the ice, absorbs the sunshine into the ocean. The melting of the permafrost is another tipping point because it could release huge amounts of methane and carbon dioxide that were stored under the ice. In a short period of time, we’re changing the planet in ways that we don’t even recognize. When scientists are telling you every day at Columbia University: ‘This is worse than we thought, Mr. Sachs. It’s accelerating, it’s dangerous!” It’s enough to make you a nervous wreck.

A few years ago you said that meeting the Sustainable Development Goals (SDGs) was the equivalent of conquering the Moon in the Kennedy era. But we are not reaching that moon.
The greatest challenge is having our minds clear enough to do the right thing. We don’t lack the solutions. We don’t lack the need. We don’t even lack the basic values. But we are so constantly distracted and falling into our worst impulses. Now it’s war in Europe. What a tragedy and a waste of time! We could have negotiated with Russia and avoided this war. But we’re so bad at speaking with each other and now it’s devastating. So many people dying, so much destruction, so much migration, so much waste of money. My government just voted for $40 billion of emergency aid for Ukraine. If I had ever said $40 billion for sustainable development, I would have been laughed out of Washington. ‘How could we waste that money, Mr. Sachs?’ But for war, they do it. This is the confusion. It’s a kind of primitive thinking.

Do you really think the war could have been avoided?
Absolutely. NATO kept enlarging to the east and especially into the highly sensitive Black Sea region. [Then UN Secretary General] Kofi Annan asked me in 2000 to advise the UN on the SDGs. But then 9/11 came and the US said now we’re going to have a global war on terror. I thought at that moment: ‘This is stupid.’ Do we really have to invade Afghanistan? Iraq? Topple the Syrian regime? Libya? Is this really a good idea? Well, they did all that. And where were the Millennium Development Goals [international development goals established by the UN for the year 2015] after all that fighting, all of those trillions of dollars that the United States wasted on these wars? Well, the Millennium Development Goals were left behind.

So there’s always an excuse to avoid taking action.
There is something wrong with the American political system. And in our human nature. We’re ready to fight, but find it extremely hard to cooperate. We’re ready to throw weapons and lives in a fight. But investment in peace and development is highly controversial. It doesn’t make sense. But that’s the way it is.

Has capitalism failed?
Capitalism means a lot of different things. It’s a big term that includes social democracy and pure market capitalism. This in particular has failed many times, because it leads to so many social inequalities and environmental crises. Not only does the market not address these problems, it exacerbates them. But removing the market as the Soviet Union did is a disaster. So what we’re looking for is something that is mixed. That is an economy that has markets, government, civil society and a set of clear ethics. And it should be environmentally sustainable. Social democracy works much better than the Anglo-Saxon market model.

In any case, we have seen that global markets are more powerful than governments.
Well, there are many more complications in that. For a long time, we debated this within the so-called Western world and now we are confronting a lot more models. The way China thinks about these issues is really quite different. Sub-Saharan Africa is a whole different set of challenges, and a long legacy of the colonial era which left so much of the continent without even the basics of infrastructure and education. In an interconnected world, we need a tremendous amount of global cooperation in order to be able to ensure that every region of this planet finds its place, its role and its path to a decent life. It’s what I’ve worked on for decades. There’s not any part of the world that isn’t worrying about this set of issues. But unfortunately, the “us versus them” mentality is so deeply built into our politics and our psyches, that the idea of global cooperation is viewed with a lot of suspicion.

If we fail to meet the SDGs, what will the world look like in 25 years?
There are many kinds of risks and you can’t predict how the danger will manifest. In sub-Saharan Africa, poverty is extreme, climate change is extraordinarily dangerous and at the same time, the population is rising very fast. What is it going to mean for Europe when there are three billion people in Africa living in hugely unstable conditions and in the European Union, fewer than 500 million people? We need to be thinking ahead so that we don’t have to answer that question in the end. We should be investing today, right now. The EU’s highest priority should not be the war in Ukraine, which should be settled at the negotiating table, not by increasing the military budget, but by ensuring that every child in Africa is in school right now. It doesn’t cost very much, but it would change the future of the world. If the children are in school, there’s going to be an economy in Africa, there’s going to be jobs. That’s the most important thing right now.