Over two thousand years .. unprecedented rise in global temperatures

The Little Mohammed Al Gharbi

Researchers in two new studies have found that global warming since the mid-20th century is the first climate phenomenon to extend to all regions of the world in the last 2,000 years.

The researchers have shown that all the previous climate changes that occurred during this period, such as the ice age small did not turn into global phenomena as previously thought scientists.

The Roman period, which lasted until the fifth century AD, the period of the cold dark ages (between 450 and 950 AD), and the small ice age (sixteenth to early nineteenth century), the most famous climatic events in Europe and the North Atlantic and the surrounding .

Wrong idea
Old climate scientists believed that these events had a global impact on all continents and oceans, and they expected to find evidence of these climate changes in ancient climate records around the world, but the findings of scientists in two new studies disprove this belief.

The first study was published on July 24, 2019 in the journal Nature, in which researchers from the United States, Switzerland, Spain and Norway took part, testing the prevailing notion of climate scientists that there were simultaneous periods of cold and warmth in all regions on Earth.

The researchers calculated annual temperatures between the first year of 2000 and 2000 using a climate database covering all continents and oceans.

Analysis of these data showed the absence of any strong global climate impact in the pre-industrial period. Every year until 1850, nearly a tenth of the Earth's surface area increased at temperatures above the average, Overall average heat.

Regional phenomena
The researchers also observed that known climatic periods, such as the small ice age, emerged only through data when average temperatures were calculated for decades, and even then there was not a single climatic trend covering all regions at the same time.

Instead, after drawing the chronological order of the periods of peak warming or cold in each of the areas covered by the test, the researchers found that the climatic events previously thought to have covered the entire surface of the planet were in fact purely regional phenomena consistent with natural climate variability .

But it was quite different with the current warming, which seemed very homogeneous at the global level in a very different way from the global disparity that had taken place over the past 2,000 years, says Nathan Stegger of Columbia University in the United States and lead author of the study.

The second study was done by the 2K network, a global initiative to study climate change over the past two thousand years and published in NatureJoines on the same day as the other study.

This group examined the rate of change of global mean temperatures at different time scales using the same data set in the first study. It also tried to identify the factors that led to these changes, and their results were consistent with the findings of the Stegger team.

Warming is the first global phenomenon
Scientists found that changes in global temperatures before the start of the industrialization era were mainly affected by major volcanic eruptions, with relatively little greenhouse effect.

Again, the picture was quite different with the onset of the Industrial Revolution, where warming rates had risen since the mid-20th century to all levels recorded over the previous two millennia.

Although none of the studies examined the specific drivers of current global warming, the fact that the current warming period is characterized by its global reach and the high average temperature at an unprecedented rate during the previous two millennia suggests that the abnormal cause behind this phenomenon is human activity.