The global climate has never been as warm as it is today in the past 24,000 years; the current increase is indeed unprecedented over the entire period. This is the result of a new analysis that extends the famous hockey stick diagram significantly into the past. While the team mainly confirms existing assumptions, thanks to the inclusion of geographical differences it comes to the conclusion that there has not been a slight slowdown in the past millennia, which has been assumed in some cases. Instead, there has been a steady warming trend for nearly 10,000. The most recent acceleration, however, is much more massive.
No intermittent cooling
An old and the new temperature curve (in blue)
(Image: Osman et.al)
Like Matthew Osman’s group from the University of Arizona now explained, the most recent temperature curves, which go back to the last ice age, are several years old. In different versions, they show the famous “hockey stick”, especially at the end, a long, relatively straight line with a strong upward deflection at the end. Depending on the method, there was a slight cooling or a slight warming after the rapid increase in temperature after the Ice Age. Your new curve now goes back 24,000 years and consists of data points every 200 years. The cooling in the most recent Ice Age was followed by sharp increases in temperature and finally a flattening 10,000 years ago. In the end it goes up rapidly.
In order to confirm the unprecedented man-made climate change, the researchers have therefore combined two methods. They used underwater sediments to reconstruct past temperatures in various places on earth. They admit that this is no more perfect than resorting to climate models. Only the combination of both methods was able to exploit the strengths of both. This made it possible to identify regional differences in the past. World maps based on this show that the climate has been warming regionally at different rates over the past decades. It has also been confirmed that greenhouse gases and the retreat of the ice sheets are driving this warming.
Only when the interval changes at the end does the current global warming and its extent become visible.
(Image: Osman et.al)
Your work, which is now in the US science magazine Nature has appeared, End a debate about whether it was warmer in the meantime after the last Ice Age than it is today, the team is convinced. Another research group had already come to this conclusion at the beginning of the year, at the time using a different method. Together, the two works would leave little room for doubt as to the assumption that the Holocene was a period of slow global warming until a few hundred years ago, Samantha Bova of San Diego State University explained to ArsTechnica. Comes from her and her colleagues the other work.
(mho)
