Posted on 31 August 2024 by Guest Author, John Mason

Skeptical Science is partnering with Gigafact to produce fact briefs — bite-sized fact checks of trending claims. This fact brief was written by Sue Bin Park from the Gigafact team in collaboration with John Mason. You can submit claims you think need checking via the tipline.

Is recent global warming part of a natural cycle?

While natural cycles explain some historical periods of climate change, the current one is due to human activity.

Solar energy reaching the Earth varies regularly over thousands of years with "Milankovitch cycles" in the planet's orbital path, tilt, and wobble. As an example of "external forcing", they affect the total energy present in Earth's climate system.

But those cycles are in a cooling phase and cannot explain recent warming. Man made greenhouse gasses can.

Shorter-term cycles ("internal variability"), like the El Nino Southern Oscillation, merely move energy around within the climate system. In warm El Nino years, heat is released from the oceans to the atmosphere. In cooler La Nina years, the reverse occurs.

However, even La Nina years are getting warmer. 2022 was the warmest La Nina year on record and the 5th warmest year globally. This runs counter to natural cycles contributing to current global warming.

Go to full rebuttal on Skeptical Science or to the fact brief on Gigafact

This fact brief is responsive to conversations such as this one.

Sources

National Oceanic and Atmospheric Administration What is Attribution?

NASA Why Milankovitch (Orbital) Cycles Can’t Explain Earth’s Current Warming

Geophysical Research Letters The recent global warming hiatus: What is the role of Pacific variability?

About fact briefs published on Gigafact

Fact briefs are short, credibly sourced summaries that offer “yes/no” answers in response to claims found online. They rely on publicly available, often primary source data and documents. Fact briefs are created by contributors to Gigafact — a nonprofit project looking to expand participation in fact-checking and protect the democratic process. See all of our published fact briefs here.