Context : Earth is currently on course to reach temperatures of roughly 3°C above preindustrial levels by the end of the century.
- Current global heatwave raises curiosity about past extreme temperatures.
- Modern data shows 2023 as one of the hottest years recorded.
- Claims of 100,000-year high lack precise evidence due to limited historical temperature records.
Here’s what we can confidently say about when Earth was last this hot.
State of New Climate
- Scientists concluded Earth entered a new climate state not seen in 100,000 years based on a climate assessment report published by the IPCC in 2021.
- Climate scientists Nick McKay and Darrell Kaufman discussed this conclusion in a recent scientific journal article.
- Earth’s temperature was already more than 1°C (1.8°F) warmer than preindustrial times.
- Greenhouse gas levels in the atmosphere were high, ensuring prolonged elevated temperatures.
- In the most optimistic future scenarios with reduced greenhouse gas emissions, global temperature will likely stay at least 1°C above preindustrial levels.
- This elevated temperature could persist for multiple centuries and may even increase further.
- The new climate state exhibits global warming of 1°C and higher, lasting for multiple centuries.
- This state allows for reliable comparison with temperature records from the distant past.
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How we estimate past temperature?
- Sediment-based records are valuable for reconstructing past global temperatures.
- However, they have limitations due to sediment mixing by currents and burrowing organisms.
- Short-term temperature spikes may be blurred in the records.
- The precise timeline for each record is unknown, leading to cancellation of fine-scale fluctuations.
- Comparing long-term past temperatures with short-term extremes is challenging for paleoclimate scientists.
Hottest in 100,000 years?
- Earth’s average global temperature fluctuates between glacial and interglacial conditions in cycles lasting about 100,000 years.
- These cycles are driven by slow and predictable changes in Earth’s orbit.
- Greenhouse gas concentrations in the atmosphere also play a role in these temperature fluctuations.
- Currently in an interglacial period, starting about 12,000 years ago, marked by ice sheet retreat and increased greenhouse gas levels.
- The interglacial period began approximately 12,000 years ago.
- Global temperatures might have peaked around 6,000 years ago during this period.
- According to the IPCC report, the temperature increase likely did not exceed 1°C at that time.
- Last glacial episode lasted about 100,000 years; no evidence of reaching preindustrial baseline.
- Previous interglacial period peaked around 125,000 years ago; evidence of warmer temperatures.
- Long-term average temperature likely no more than 1.5°C (2.7 F) above preindustrial levels.
Now what?
- Without rapid and sustained greenhouse gas emission reductions, Earth may reach temperatures around 3°C (5.4 F) above preindustrial levels by the century’s end.
- We would need to look back millions of years to find a similarly hot climate state.
- The Pliocene epoch, when Earth’s climate supported the rise of agriculture and civilization, might be comparable.
Hottest in 100000 years?,Hottest in 100000 years?
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