Human Limits
Back when 80-foot-long ocean dinosaurs swam the seas, and T-Rexes and Triceratops roamed the land we walk on today, Earth was a hot, hot place to live. During this Mesozoic Era – from about 250 to 66 million years ago – atmospheric CO2 levels were about 16 times higher than they are today, creating a “greenhouse climate” with average temperatures 6 to 9 degrees warmer than they are today.
Illustration: DW
Scientists believe that methane from the burps and farts of dinosaurs—similar to those of cows today—contributed to global warming at the time. But the main reason was that the supercontinent Pangaea was slowly starting to drift and break apart. This eventually led not only to the creation of the continents as we know them today, but also to climate change.
The movement of entire landscapes and continents caused massive volcanic eruptions that spewed climate-damaging gases into the atmosphere, warming the planet. It also led to acid rain, ocean acidification, and a fundamental change in the chemistry of land and water, triggering a mass extinction that paved the way for the rise of the dinosaurs.
Today, we are still a long way from the temperatures that turned the planet into a hothouse during the Mesozoic Era. But by burning fossil fuels like coal, oil and gas at unprecedented rates, humans have already warmed the planet by 1.1 degrees Celsius above pre-industrial levels.
As a result, ecosystem health is deteriorating faster than ever, with serious implications for people as well as land, forest and marine ecosystems around the world. Scientists say the average duration of drought in Central America will increase by five months at 1.5 degrees Celsius, by eight months at 2 degrees Celsius and by 19 months at 3 degrees Celsius.
They also say the world will hit 3 degrees Celsius by the end of the century if greenhouse gas emissions continue unchecked, leading to unprecedented floods, storms, rising sea levels and extreme heatwaves. Scientists are therefore talking about the climate crisis as an existential threat to humanity.
Why are dinosaurs still alive?
And back to the dinosaur story. The fact that these massive animals coped so well with the climate in which they lived was largely due to one decisive factor: time.
Although atmospheric CO2 concentrations were extremely high during the Mesozoic, they rose very slowly. While intense volcanic activity took millions of years to warm the planet by a few degrees, by burning fossil fuels, humans have radically changed the climate within two centuries.
Dinosaurs could live in very hot environments, but that was because they had time to adapt and had better tolerance limits - things that humans currently lack. Photo: DW
Slower warming gives nature a chance to adapt, says Georg Feulner of the Potsdam Institute for Climate Impact Research (PIK). “Animals that don’t like the heat can move to higher latitudes, such as towards the poles. Or they can adapt through evolutionary processes.”
But he added that extreme heat could make certain animals uninhabitable “because there are simply physiological limits to animals and humans.” Dinosaurs were apparently much healthier and more resilient than humans. In fact, hundreds of thousands of people die worldwide each year from extreme heat.
And history shows that the five mass extinctions the planet has seen so far have all involved extreme warming or ice ages of the planet, as well as changes in chemical cycles in the seas or on land.
For example, an asteroid impact 67 million years ago created a huge dust cloud and caused violent volcanic eruptions around the world, darkening the sky and cooling the climate dramatically. This strong and relatively rapid cooling gave us little time to adapt and marked the end of the age of dinosaurs. Overall, 76% of species became extinct at that time.
In a mass extinction, at least three-quarters of species disappear over a period of about 3 million years. Some scientists, looking at the current rate of extinction, think we are in the midst of a sixth mass extinction. It is estimated that at least 1 million of the 8 million known species are at risk of disappearing forever in just the next few decades. Many scientists believe the real number could be much higher.
Therefore, to avoid the fate of humans like dinosaurs and millions of other species in the past, humans must do everything possible to prevent the earth from warming rapidly, and it is estimated that it will require an investment of hundreds of billions of dollars each year so that humans can adapt to an increasingly hot climate in the future.
Mai Van (according to DW)
Source
Comment (0)