Dinosaurs lived on a scorching planet — why can't humans?

Back in the times when 25-meter-long ocean dinosaurs swam the seas and the T-Rex and Triceratops roamed the ground we walk today, Earth was a hot place to live. Very hot. During this Mesozoic Era — from about 250 to 66 million years ago — the concentrations of CO2 in the atmosphere were around 16 times higher than now, creating a "greenhouse climate” with temperatures on average six to nine degrees warmer than today. 

Scientists assume that methane from dinosaurs burping and farting — similar to cows today — contributed to global warming at the time. But the main reason was that the supercontinent of Pangaea was slowly starting to drift and break apart. Not only did this ultimately lead to the creation of the continents as we know them today, but it also led to a changing climate.

The movement of entire landscapes and continents caused enormous volcanic eruptions that spewed climate-damaging gases into the atmosphere, thereby heating the planet. It also led to acid rains, acidification of the ocean and a radical change in the chemical compositions on land and in the water, causing a mass extinction that paved the way for the rise of the dinosaurs.

Were dinosaurs adapting better?

Today we are still a long way from the kind of temperatures that made the planet a hothouse during the Mesozoic Era. However, by burning fossil fuels such as coal, oil and gas at unprecedented levels, humans have already warmed the planet by 1.1 degrees Celsius over pre-industrial levels.

As a result, ecosystem health is deteriorating faster than ever before, with dramatic impacts for people as well as land, forest and marine ecosystems across the world. Scientists say the average duration of drought in Central America will increase by five months with 1.5 degrees of warming, by eight months at an increase of 2 degrees and by 19 months should temperatues rise to an additional 3 degrees.

They also say the world will reach that 3-degree mark by the end of the century if greenhouse gas emissions continue unchecked, leading to unprecedented floods, storms, sea level rise and extreme heat waves. Scientists therefore speak of the climate crisis as an existential threat to humans. 

The fact that the dinosaurs coped well with the climatic conditions in which they lived is mainly due to one decisive factor: time.

Although CO2 concentration in the atmosphere was extremely high back in the Mesozoic Era, it rose very slowly. While it previously took mighty volcanic activity and millions of years to warm the planet by several degrees, by burning fossil fuels, humans have managed to radically change the climate within two centuries.

Georg Feulner of the Potsdam Institute for Climate Impact Research (PIK) said a slower pace of warming gives nature the chance to adapt. "Animal species that don't love the heat can move to higher latitudes, towards the poles for example. Or they can also adapt through evolutionary processes."

He said as long warming occurs slowly and its impacts don't hit a highly technical civilisation with existing infrastructure, it has largely not been a big problem thus far.

But he added that extreme heat could render given regions uninhabitable for certain animal species "because there are simply certain physiological limits for animals and humans."  Every year, hundreds of thousands die worldwide because of extreme heat.

Even dinosaurs get problems when things go too fast

For humans to adapt to a warmer planet and the extreme storms, floods, droughts and heat waves that higher temperatures promise to bring, it would require a global investment of more than $300 billion (€272 billion) by 2030 alone.  Billions more are needed for the energy transition to stop continued runaway heating. History shows that the five great mass extinctions the planet has so far witnessed were all connected to radical heating or cooling of the planet, as well as changes in the chemical cycles in the sea or on land. 

For example, the impact of an asteroid 67 million years ago created an enormous cloud of dust and caused violent volcanic eruptions all over the world, darkening the sky and radically cooling the climate. This drastic and comparatively rapid cooling left little time for adaptation and spelled the end of the dinosaur era. Overall, 76% of species became extinct at that time.

In a mass extinction, at least three quarters of all species disappear within about 3 million years. Some scientists, looking at current extinction rates, think we are in the midst of a sixth mass extinction. In the next few decades alone, it is estimated that at least one million out of eight million known species are in danger of disappearing forever. Many scientists believe that the real numbers could be much higher.

This article was originally published in German.