{"id":463941,"date":"2026-08-19T03:40:20","date_gmt":"2026-08-19T10:40:20","guid":{"rendered":"https:\/\/climatescience.press\/?p=463941"},"modified":"2026-08-19T03:40:22","modified_gmt":"2026-08-19T10:40:22","slug":"milankovitch-cycles-the-last-glacial-period-and-why-earth-is-still-in-an-ice-age","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=463941","title":{"rendered":"Milankovitch Cycles, the Last Glacial Period, and Why Earth Is Still in an Ice Age"},"content":{"rendered":"\n
\"\"
AI generated by Grok<\/figcaption><\/figure>\n\n\n\n

The Last Ice Age most commonly refers to the Last Glacial Period (LGP; also called the last glacial cycle), which lasted from roughly 115,000 to 11,700 years ago. This was the most recent major cold phase within the broader Quaternary glaciation (an ongoing icehouse climate that began about 2.58 million years ago).<\/strong><\/p>\n\n\n\n

Earth is still technically in an ice age <\/strong>today because large ice sheets persist in Antarctica and Greenland<\/strong> (and smaller glaciers elsewhere). <\/p>\n\n\n\n

The current warm phase is an interglacial called the Holocene<\/strong>.<\/p>\n\n\n\n

Timeline<\/strong><\/p>\n\n\n\n

Start:<\/strong> After the Last Interglacial (Eemian)<\/strong>, cooling and ice growth began around 115,000 years ago<\/strong>.<\/p>\n\n\n\n

Last Glacial Maximum (LGM):<\/strong> The peak of ice extent and coldest conditions, generally placed between about 26,500\u201319,000 (or 26,000\u201320,000) years ago. Ice covered roughly 8% of Earth\u2019s surface (versus ~3% today), including vast sheets over northern North America (Laurentide), northern Europe\/Scandinavia (Fennoscandian\/Weichselian), and parts of Asia, plus expanded mountain glaciers and Antarctic ice.<\/p>\n\n\n\n

Global conditions at LGM:<\/strong> Average temperatures were about 6 \u00b0C (11 \u00b0F) cooler than the 20th-century average (with much larger cooling at high latitudes). Sea levels were roughly 120\u2013125 meters (about 400 feet) lower because water was locked up in ice, exposing continental shelves and creating land bridges such as Beringia (between Siberia and Alaska).<\/p>\n\n\n\n

Deglaciation and end:<\/strong> Warming began after the LGM. A temporary return to colder conditions (the Younger Dryas, ~12,900\u201311,700 years ago<\/strong>) interrupted the recovery. The LGP and Pleistocene epoch formally ended around 11,700 years ago with the start of the Holocene.<\/p>\n\n\n\n

Glacial advances and retreats were not perfectly synchronous worldwide; some regional ice masses peaked earlier or later.<\/p>\n\n\n\n

Glacial-interglacial cycles are primarily driven by Milankovitch cycles<\/strong>\u2014slow, predictable changes in Earth\u2019s orbit and axial tilt that alter the distribution of solar radiation, especially in the Northern Hemisphere. These are amplified by feedbacks involving atmospheric CO\u2082 levels, ice-albedo effects (more ice reflects more sunlight), ocean circulation, and vegetation changes. The end of the last glacial period involved rising CO\u2082 (released from the Southern Ocean and other sources) that helped drive global warming and ice melt.<\/p>\n\n\n\n

Impacts<\/strong><\/p>\n\n\n\n

Geography and environment:<\/strong> Lower sea levels created land bridges that enabled migrations of animals and humans (e.g., into the Americas). Many modern landscapes were shaped by glacial erosion and deposition (moraines, lakes, fjords). Climate was generally colder and drier in many regions, with expanded deserts and different vegetation zones.<\/p>\n\n\n\n

Life:<\/strong> Cold-adapted megafauna (woolly mammoths, woolly rhinos, etc.) thrived in some areas but many went extinct near the end of the period, coinciding with climate change and the spread of modern humans. Humans expanded across continents during this time.<\/p>\n\n\n\n

Sea level and coastlines:<\/strong> The post-LGM rise of ~120 and meters flooded shelves, isolating islands and reshaping coastlines over thousands of years.<\/p>\n\n\n\n

In short, when people say \u201cthe last Ice Age,\u201d they usually mean the cold, icy world of the Last Glacial Period that peaked ~20,000\u201326,000 years ago and transitioned into our current interglacial climate around 11,700 years ago. <\/p>\n\n\n\n

The larger Quaternary ice age continuum continues today.<\/strong><\/p>\n\n\n\n

_____________________________________________________________________________________<\/p>\n\n\n\n

Quaternary glaciation (also called the Quaternary Ice Age or Pleistocene glaciation) <\/strong>is the current and ongoing icehouse climate state on Earth. It began approximately 2.58 million years ago<\/strong> at the start of the Quaternary Period and continues today.<\/p>\n\n\n\n

It is defined by the repeated expansion and contraction of large continental ice sheets, primarily in the Northern Hemisphere, alternating with warmer interglacial periods.<\/p>\n\n\n\n

Because permanent ice sheets still exist on Antarctica and Greenland<\/strong>, geologists consider the Quaternary glaciation to be ongoing. We are currently in a warm interglacial phase known as the Holocene (which began ~11,700 years ago).<\/p>\n\n\n\n

It forms the most recent (and still active) part of the broader Late Cenozoic Ice Age<\/strong>, which started earlier (~34 million years ago) when permanent ice first developed on Antarctica.<\/p>\n\n\n\n

Within the Quaternary glaciation:<\/strong><\/p>\n\n\n\n