Ira Helfand is an emergency medicine physician and co-president of International Physicians for the Prevention of Nuclear War (IPPNW), which won the Nobel Peace Prize in 1985. Arun Mitra is a surgeon working in the city of Ludhiana, India and co-president of IPPNW. Tilman Ruff is a public health and infectious diseases physician and also serves as co-president of IPPNW. The opinions expressed in this commentary are their own. View more opinion at CNN.

(CNN) As doctors responding to this crisis, the past few weeks have been filled not just with treatment and crisis management but with frustration. Frustration because the Covid-19 pandemic did not just "sneak up on us." Public health experts have been warning us for decades; we simply chose not to listen.

The Trump administration has been rightly criticized for its epically inept response to this crisis. First, the administration disbanded two groups that were supposed to deal with pandemics within the White House National Security Council and the Department of Homeland Security in 2018. Second, President Donald Trump ignored the warnings from the intelligence community on a potential pandemic as early as January. And, consistently, this administration has downplayed the seriousness of the crisis and the need to take decisive action to contain the epidemic.

However, this catastrophic short-term failure is only part of the story.

For decades, experts have been telling us that it was not a question of "if" but only a question of "when" the next great pandemic would strike. As early as 1992, an Institute of Medicine report drew attention to this danger. And as a more recent report by the World Health Organization observed, "few doubt that major epidemics and pandemics will strike again, and few would argue that the world is adequately prepared."

Despite these clear warnings, world leaders failed to prepare, and the general public did not mobilize to make them take action. It is not possible to prevent the emergence of new pathogens capable of causing a global pandemic, but it is possible to prepare an adequate response to these diseases when they do emerge. We didn't, and now the world is paying a terrible price.

In the middle of a pandemic, like the one we're going through now, it's hard to imagine things could've been even worse. We could've been afflicted by a different and much more devastating kind of virus with a much higher mortality rate. It could've been even more contagious than Covid-19. The next pandemic, and there will be others, may, in fact, be more intense. We can and must learn from this disaster and prepare better for future outbreaks.

If there is one lesson we can learn from this crisis it is this: When the experts tell us the sky is going to fall if we don't take action, we better take action or the sky really may fall.

And we must apply this lesson to the two other existential threats that humanity faces: the climate crisis and the growing danger of a nuclear war.

In the case of the climate crisis, the warnings from the scientific community could not be clearer. If we don't stop relying on fossil fuels and achieve net zero carbon emissions by 2050, we are dooming the planet and our children to a climate catastrophe that will render large portions of the planet uninhabitable, displace hundreds of millions of people and cause human suffering on an unimaginable scale.

These warnings are widely known , and they have spurred action by governments and individuals across the planet, like the 2015 Paris Agreement . But the action taken so far has consistently fallen short of what the experts tell us we need to do, and so we continue on a path to a totally preventable disaster.

In relation to the danger of a nuclear war, the warnings have been equally clear, though they have received much less attention. Former Secretary of Defense William Perry has said repeatedly that we are closer to a nuclear war than we were during the Cold War. The expert panel at the Bulletin of the Atomic Scientists, which includes 13 Nobel laureates, assessed that "the international security situation is now more dangerous than it has ever been." This year, they set their iconic Doomsday Clock to 100 seconds to midnight -- or a potential global catastrophe -- the closest to planet-wide apocalypse that it has ever been.

The healthcare community is buckling under the strain of the current pandemic; it would collapse if even a single nuclear bomb were used against an urban target.

A nuclear war, even a limited nuclear war, would be a disaster for the entire planet. Climate and medical scientists have warned that a war between India and Pakistan could cause enough abrupt climate disruption to drastically reduce food production around the world. This would trigger a global famine that would put up to billions at risk and almost certainly end modern civilization. A large-scale nuclear war between the US and Russia would kill hundreds of millions in an afternoon and trigger a nuclear winter that would kill the vast majority of the human race.

Recognizing this danger, 122 nations around the world voted in 2017 to adopt the Treaty on the Prohibition of Nuclear Weapons (TPNW) requiring the elimination of these weapons. Yet, despite the warnings, the nuclear armed states have actively opposed the treaty and are all engaged in expensive programs to upgrade their nuclear arsenals.

Get our free weekly newsletter Sign up for CNN Opinion's new newsletter. Join us on Twitter and Facebook

We may be able to prevent the emergence of some new pathogens, but for most we can only prepare. But we can actually prevent the looming climate disaster and a fatal nuclear war. We need to move with all possible speed to eliminate further release of greenhouse gasses, and the nine nuclear armed states need to join the TPNW and promptly negotiate a verifiable, enforceable, timebound plan to eliminate their nuclear arsenals.

If we listen and take the experts' warnings seriously, we can avoid these calamities. If we don't, the sky may really fall. We will survive this pandemic, and if we learn from it, perhaps Covid-19 will save the world.