First, a sense of geological perspective
The **Medieval Warm Period (MWP)**, roughly 950–1250 AD, was a time when Europe, parts of North America, and even the North Atlantic were *as warm or slightly warmer* than the early 20th century. Then came the **Little Ice Age (LIA)**, spanning roughly 1300–1850 AD, when global temperatures fell by roughly **0.6–1.0 °C** — not catastrophic, but significant enough to freeze the Thames, shorten growing seasons, and collapse some agrarian societies.
After about 1850, climate began *warming again*, marking the end of the LIA. This corresponds to the current interglacial rebound — a natural recovery phase — **long before modern industrial CO₂ emissions were significant**.
Where we are now in that natural oscillation
By most reconstructions — and particularly by non-institutional, multiproxy analyses that aren’t GCM (general circulation model)-driven — **we’re approximately as warm now as the peak of the Medieval Warm Period**.
Depending on the dataset, the **global mean temperature anomaly relative to the late 19th century baseline is around +1.0–1.2 °C**.
But what matters more than the mean is the *pattern*:
- The Arctic is warmer relative to 1,000 years ago.
- Mid-latitudes are roughly equal or slightly warmer.
- Some tropical regions, such as parts of the Pacific and Atlantic, are **not as warm as during the MWP**.
This strongly suggests the current warmth is part of a **long-term multi-century oscillation**, overlaid by both natural and anthropogenic influences (CO₂, land use, aerosols, solar magnetism cycles, etc.).
Key drivers to watch
Those who only focus on CO₂ miss three major drivers that vary cyclically and modulate climate:
1. **Solar magnetic activity and irradiance**
- The *Eddy*, *DeVries (210-year)*, and *Gleissberg (90-year)* cycles imply a repeating pattern of warm and cool centuries.
- We exited the “Modern Solar Maximum” in the early 2000s; the current cycle suggests **solar output may slightly decline mid-century**, potentially offsetting some anthropogenic warming.
2. **Oceanic oscillations (AMO, PDO, ENSO)**
- The Atlantic Multidecadal Oscillation (AMO) has been in a warm phase since the 1990s. When it flips cool, it tends to suppress global mean temperature for a few decades.
- The Pacific Decadal Oscillation (PDO) is trending back toward neutral to negative, which also damps warming signals.
3. **Volcanic and cosmic forcing**
- Volcanic aerosols and cosmic-ray-linked cloud nucleation contribute to cooling cycles every few decades.
What we can expect ahead
There are **two major pathways** the climate system could follow in the next 100 years:
1. **Continuation of warm-phase oscillation**
If the AMO and solar cycles stay warm simultaneously, we could see another **0.3–0.5 °C** rise over the next 30–50 years — bringing us to roughly the level of the early *Holocene optimum* (when the Sahara was green and tree lines were far north).
2. **Moderation / Partial cooling phase**
If the solar minimum coincides with an AMO downturn (sometime between 2030–2060), we might see a **pause or modest cooling of 0.2–0.4 °C**.
Historical analogues — e.g., the Maunder and Dalton minima — show how significant such effects can be when they synchronize.
In plain terms
We are nearing the *upper warm end* of the natural Holocene range, which has seen repeated warm and cool swings roughly every 800–1,200 years.
- **So far into this current warm phase:** about halfway (think of it as somewhere around the 11th–12th century equivalent in the MWP).
- **Likely peak warmth:** another 0.3–0.5 °C globally, barring extreme volcanism or solar collapse.
- **Most probable timing of next cooling phase:** around **2040–2070**, depending on solar and oceanic phase alignment.
