If humanity does not control greenhouse gas emissions, we risk moving the earth's climate to a state comparable to that of 50 million years ago.
This is according to a new study, which showed that human activity reversed the long-term cooling trend that has taken place since the Eocene era, when the planet was warm and largely free of ice.
In about 20 years, the researchers say the climate could return to something much like that of the Middle Pliocene, a period that existed more than 3 million years ago – and by 2150 we can get the climate click back 50 million years ago.
A new study showed that human activity reverses the long-term cooling trend that has taken place since the Eocene era, when the planet was warm and largely free of ice. File photo
According to the disturbing new report published in the Proceedings of the National Academy of Sciences, the man-made turnaround has taken place in only two centuries, making the fastest changes ever seen.
While human and animal ancestors lived on Earth during the Eocene and the Pliocene, it is unclear how the contemporary species will deal with the accelerated changes.
& # 39; When we think about the future in terms of the past, where we are going, that is an unknown territory for human society & # 39 ;, says lead author Kevin Burke, who performed the work while graduating from the University of Wisconsin-Madison.
We are moving towards very drastic changes in an extremely fast time frame and reversing the planet in a matter of ages. & # 39;
In the study, the researchers investigated data on the geological past of the earth to see how different epochs are in line with future climate projections from the fifth assessment report of the Intergovernmental Panel on Climate Change.
During the Pliocene, about 3 million years ago, the temperatures were 3.2-6.5 degrees Fahrenheit (1.8 to 3.6 degrees C) warmer than they are now, says the team.
And during the eocene the temperatures on earth were on average 13 degrees warmer than today.
Previous research has shown that high atmospheric carbon dioxide levels are likely to be crucial in maintaining the high temperatures of the early eocene
If humanity does not control greenhouse gas emissions, we risk bringing the earth's climate back to a state similar to that of 50 million years ago. Fossil fish from the Eocene era are shown
The team also looked at the Last Interglacial (129-116 thousand years ago), the Middle Holocene (6000 years ago), the pre-industrial era (before 1850 1850) and the beginning of the 20th century.
We can use the past as a yardstick to understand the future, which is so different from everything we have experienced in our lives & # 39 ;, paleo-ecologist John & # 39; Jack & # 39; Williams, professor of geography at the University of Wisconsin-Madison.
& # 39; People have a hard time projecting how the world will be in five or ten years.
& # 39; This is a tool to predict – how we follow those paths and use deep geological analogues from Earth's history to reflect on changes over time. & # 39;
Researchers looked at the future climate scenarios as predicted by Representative Concentration Pathway 8.5 (RCP8.5) and RCP4.5, which represent the future climate without limitation of greenhouse gases, and with moderate reductions, respectively.
They also used the Hadley Center Coupled Model version 3, the Goddard Institute for Space Studies Model E2-R and the Community Climate System Model.
WHY ARE CLIMATE MODELS DIFFICULT TO PRESENT?
The biggest problem with climate models is uncertainty.
In particular, something that has the measure & # 39; equilibrium character sensitivity & # 39; is called, scientists turned to headaches.
This is a very influential measure that describes how much the planet will heat up as carbon dioxide doubles and the Earth's climate adapts to the new state of the atmosphere.
Studies have found a wide range of possibilities for this important measure – somewhere between 1.5 and 4.5 ° C, with 3 ° C.
Most scientists try to limit ECS by looking at historical warming.
Over the past 25 years, the UN Intergovernmental Panel on Climate Change (IPCC), the ultimate authority in the field of climate science, has settled on a probable & # 39; range from 1.5 ° C to 4.5 ° C (2.7 ° F to 8.1 ° F).
Reheating less than 1 ° C is highly unlikely & # 39; and more than 6 ° C becomes very unlikely as & # 39; & # 39; considered, the panel concluded.
Some scientists dispute this, however.
The study showed that the climate on Earth could resemble the Middle Pliocene in 2030 (under RCP8.5) or 2040 (under RCP4.5).
If emissions continue, as predicted with the RCP8.5 model, global warming would continue until the earth begins to look like the eocene around the year 2100.
By 2150 these conditions would be further cemented worldwide.
The team also found new climatic conditions that could not be seen in the past, particularly in East and Southeast Asia, North Australia and the US coastal states.
With mitigation efforts, the researchers say that we can limit the effects to a minimum.
& # 39; The further we move away from the Holocene, the greater the potential that we come from safe business premises & # 39 ;, says Williams.
In about 20 years, the researchers say the climate could return to something much like that of the Middle Pliocene, a period that existed more than 3 million years ago – and by 2015 we might have the climate click 50 million. years ago. File photo
In the more than 20 to 25 years that I work in the field, we have assumed the expectation of climate change, to detect the effects, and now we see that it causes damage.
"People die, property is damaged, we see more intense fires and more intense storms that can be attributed to climate change.
& # 39; There is more energy in the climate system, leading to more intense events. & # 39;
The researchers say that the findings have serious consequences for the future of life on earth.
We have seen great things happen in the history of the earth – new species have evolved, life persists and species survive. But many species will be lost and we live on this planet, "Williams said.
& # 39; These are things to worry about, so this work shows us how we can use our history and the history of the earth to understand changes today and how we can best adapt. & # 39;