Earth Is Still in an Ice Age, but That Does Not Mean Modern Global Warming Is Not a Concern

September Earth is technically still in a long-term ice age, even though humans live during a relatively warm interglacial period. This geological fact has increasingly featured in discussions about the planet’s climate history, but it does not by itself contradict evidence of modern human-driven warming.

Scientists distinguish between the planet’s long-term geological climate state and changes occurring over decades or centuries. Earth has experienced repeated glacial and interglacial cycles during the Quaternary period, while the present Holocene epoch began approximately 11,700 years ago.

Earth Remains in a Long-Term Ice Age

In geological terminology, an ice age is a period when permanent ice exists on Earth’s surface. The planet’s current ice-age state began millions of years ago, with major Northern Hemisphere glaciations developing much later.

Today, enormous ice sheets remain in Antarctica and Greenland, together with glaciers in mountain regions. Their existence means Earth has not entered a completely ice-free greenhouse climate.

The distinction is important, however. Being in an ice age does not mean global temperatures cannot rise substantially. Geological climate states operate over timescales vastly longer than the period of modern industrial development.

The Holocene Is a Relatively Warm Interglacial

Modern civilization developed during the Holocene, a comparatively warm interval between major glacial periods.

During the Last Glacial Maximum, roughly 20,000 years ago, extensive ice sheets covered large areas of the Northern Hemisphere. Global temperatures were considerably lower than during the Holocene.

The transition from glacial conditions to the current interglacial involved natural changes in Earth’s orbit, greenhouse gases, ice sheets and other components of the climate system.

These natural mechanisms remain important to understanding Earth’s climate history. They do not, however, automatically explain the rapid warming observed during the industrial era.

Modern Warming Has a Different Timescale

NASA notes that natural influences such as changes in solar activity and Earth’s climate system continue to operate, but their effects are too small or too slow to explain the rapid warming observed in recent decades. Satellite observations and ground-based measurements are used to monitor greenhouse gases, temperatures, oceans, ice and other climate indicators.

NASA’s current carbon-dioxide indicator reports atmospheric CO₂ at about 428 parts per million in August 2026 and states that the long-term increase is primarily associated with human emissions, particularly fossil-fuel use.

CO₂ Can Promote Plant Growth — But the Picture Is Complex

One part of the argument about rising carbon dioxide has a genuine scientific basis.

Higher atmospheric CO₂ can increase photosynthesis and stimulate plant growth under suitable conditions. A NASA-supported study using satellite observations found significant greening across a substantial portion of Earth’s vegetated areas, with CO₂ fertilization identified as an important contributor.

However, this does not mean that increasing CO₂ universally improves agricultural production or ecosystems.

NASA explains that plant responses also depend on water, nutrients, temperature and other environmental conditions. The CO₂ fertilization effect can diminish as other factors limit plant growth.

Consequently, increased vegetation and the climate impacts of rising greenhouse gases can occur simultaneously.

Ice Sheets and Sea-Level Rise

The presence of large ice sheets is another important part of Earth’s climate story. Antarctica contains an enormous volume of frozen water, and changes in the Antarctic and Greenland ice sheets can affect global sea levels.

The IPCC assesses that global mean sea level will continue rising during the 21st century. Its AR6 assessment gives likely 2100 sea-level increases ranging from approximately 0.28–0.55 metres under SSP1-1.9 to 0.63–1.01 metres under SSP5-8.5, relative to 1995–2014.

The IPCC also emphasizes that ice-sheet and ocean responses continue over centuries to millennia. Therefore, the fact that some major ice changes occur slowly does not mean their eventual consequences are limited to only a few millimetres of sea-level rise.

What About 5°C Warming?

The claim that projections of extreme warming have simply been abandoned is not supported by current IPCC assessments.

The IPCC evaluates multiple emissions pathways rather than making a single prediction. Its assessments include both lower-emissions pathways and high-emissions scenarios. Under the very high-emissions SSP5-8.5 pathway, the IPCC’s assessed global temperature increase for the late 21st century remains substantially higher than under low-emissions pathways.

Importantly, 5°C by 2050 is not the standard IPCC projection. Temperature increases of that magnitude are associated with much longer-term scenarios, particularly toward the end of the century, rather than being an expected global average by 2050.

A More Complete Picture

The scientific evidence therefore supports several facts simultaneously.

Earth is indeed in a long-term ice-age state. Humans developed during a relatively warm interglacial period. Atmospheric CO₂ can stimulate photosynthesis and has contributed to observed global vegetation greening. At the same time, rising greenhouse-gas concentrations warm the climate, and climate impacts vary substantially between regions and ecosystems.

NASA’s observations show both sides of this complex system: satellites detect increasing vegetation in many regions, while also monitoring warming, sea-level changes, ice loss and atmospheric greenhouse gases.

The central scientific question is therefore not whether Earth is technically in an ice age, but how rapidly the climate is changing, what is driving that change, and what its consequences will be for different societies and ecosystems.

Understanding Earth’s deep climatic history provides valuable context, but geological ice-age cycles operate on timescales very different from the rapid changes observed during the industrial era.