(ORDO NEWS) — We are currently witnessing global warming. The average temperature on the planet has already increased by more than 1 degree Celsius compared to the pre-industrial period.
And this is not the limit – according to scientists, humanity is unlikely to be able to stop this process at even 1.5 degrees Celsius.
But the current global warming is anthropogenic, that is, caused by the activities of mankind.
However, it is known that the climate on the planet was constantly changing even before the industrial revolution – in the history of the Earth there were both ice ages and periods of strong warming.
For example, Greenland two million years ago was a really green island with a rich ecosystem. But what period would it be now, If climate was not affected by human activity?
According to scientists, the Earth should have cooled and approached the ice age, but not everyone agrees with this opinion.
How scientists learn about past climates
To answer the question of what the natural climate should be like now, scientists need to know what the average temperature on our planet was in the past.
According to paleoclimatologists who study the climate in antiquity, data for the last 6,000 years are especially important.
Therefore, the attention of many researchers is riveted to this time period. But scientists could not come to a consensus, because the data are too contradictory.
How do scientists even know about the climate that was on Earth thousands of years ago?
Of course, no thermometers existed several thousand years ago, as well as written archives. Therefore, paleoclimatologists have to study indirect indicators.
For example, one of them is the growth rings of trees – the wider they are, the higher the temperature was where they grew. The ice of ancient glaciers also contains climate data.
In addition, scientists draw conclusions from tiny shells found in the sediments of the bottom of lakes and oceans, since their chemical composition during life changes depending on temperature.
Based on the combination of all these indicators, scientists can draw fairly accurate conclusions about the climate in a given period of time.
However, there is one “but” that prevents scientists – all of the above indirect indicators, as a rule, are unevenly distributed over the planet and in time.
This makes it difficult to reconstruct changes in global temperatures.
Ice age or global warming?
Proxy studies show that there was less ice on the planet 6,000 years ago than in the 19th century (at the last moment before the industrial revolution that caused the planet to warm).
In addition, the Earth had more vegetation cover. This suggests that the planet was darker, which means it absorbed more heat.
But over time, the Earth began to cool, as a result of which the temperature dropped by 0.7 degrees Celsius.
But climate modeling shows a very different result – as societies based on agriculture developed over the millennia after the retreat of the ice sheets in the Northern Hemisphere, the amount of carbon dioxide in the atmosphere increased. This means that climate warming began long before the industrial period.
How do scientists know about the content of carbon dioxide in the atmosphere thousands of years ago? Its composition was preserved in the air bubbles of ancient ice. But what was the real situation?
Climate models based on atmospheric, biosphere, and hydrosphere data do not appear to be entirely accurate.
For example, an experiment with a climate model that included data on vegetation on Earth showed results similar to those obtained by scientists based on proxy indicators.
From this we can conclude that the Earth was still cooling, which to some extent compensated for human intervention in the climate.
However, at the moment the situation with global warming is still much worse than previously thought. Therefore, one cannot count on natural cooling.
—
Online:
Contact us: [email protected]
Our Standards, Terms of Use: Standard Terms And Conditions.