Why has Earth got hotter now than it was 100,000 yrs ago?

As scorching heat grips large areas of the Earth, many people are trying to put the extreme temperatures into context and asking: When was it ever this hot before? Globally, 2023 has seen some of the hottest days in modern measurements, but what about farther back, before weather stations and satellites?
Some news outlets have reported that daily temperatures hit a 100,000-year high.As a paleoclimate scientist who studies temperatures of the past, I see where this claim comes from, but I cringe at the inexact headlines.
While this claim may well be correct, there are no detailed temperature records extending back 100,000 years, so we don’t know for sure.
Here’s what we can confidently say about when Earth was last this hot. This is a new climate state. Scientists concluded a few years ago that Earth had entered a new climate state not seen in more than 100,000 years.
Earth was already more than 1 degree Celsius (1.8 Fahrenheit) warmer than preindustrial times, and the levels of greenhouse gases in the atmosphere were high enough to assure temperatures would stay elevated for a long time.
Even under the most optimistic scenarios of the future – in which humans stop burning fossil fuels and reduce other greenhouse gas emissions – average global temperature will very likely remain at least 1 C above preindustrial temperatures, and possibly much higher, for multiple centuries.
This new climate state, characterized by a multi-century global warming level of 1 C and higher, can be reliably compared with temperature reconstructions from the very distant past.
Without rapid and sustained reductions in greenhouse gas emissions, the Earth is currently on course to reach temperatures of roughly 3 C (5.4 F) above preindustrial levels by the end of the century, and possibly quite a bit higher. At that point, we would need to look back millions of years to find a climate state with temperatures as hot.