to support Skeptical Science
iPhone app Download	Android app Download
Nokia app Download

	It's the sun
	Climate's changed before
	There is no consensus
	It's cooling
	Models are unreliable
	Temp record is unreliable
	It hasn't warmed since 1998
	Ice age predicted in the 70s
	We're heading into an ice age
	Antarctica is gaining ice
	View All Arguments...

Latest Posts

• Climate change: Water vapor makes for a wet argument
• Carbon dioxide equivalents
• How we know an ice age isn't just around the corner
• Urban Heat Islands: serious problem or holiday destination for skeptics?
• The surprising result when you compare bad weather stations to good stations
• The empirical evidence that humans are causing global warming
• Sea level rise: the broader picture
• Human CO2: Peddling Myths About The Carbon Cycle
• Why we can trust the surface temperature record
• Ocean acidification threatens entire marine food chains
• Comparing volcanic CO2 to human CO2
• Can humans affect global climate?
• Climate Models: Learning From History Rather Than Repeating It
• Arctic sea ice... take 2
• Hansen etal hit a Climate Home Run -- in 1981
• Station drop-off: How many thermometers do you need to take a temperature?
• Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
• Pakistan flood: many more will die unless more aid is delivered quickly
• Medieval Warm Period: rhetoric vs science
• Weather vs Climate: Watch the waves, miss the turning of the tides
• University of Western Australia Open Day 2010
• The main culprit in mid-century cooling
• Dust-Up On Mars: Should Martians Be Sceptical of Global Warming?
• What caused early 20th Century warming?
• The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
• How climate skeptics misunderstand past climate change
• 1934: the 47th hottest year on record
• The Strange Case of Albert Gore, Inconvenient Truths and a Man in a Powdered Wig
• What were climate scientists predicting in the 1970s?
• Can't We At Least Agree That There Is No Consensus?

Archives

How do volcanoes drive climate?

What the science says...

Volcanoes emit sulfate aerosols which reflect incoming sunlight, cooling the planet. A large volcanic eruption such as the Pinatubo eruption in 1991 can have a global cooling effect of 0.1°–0.3°C for several years (Robock 1994, Zielinski 2000).

However, mega-eruptions or a series of eruptions can have a cooling effect that take decades to wear off, giving a perceived warming effect. Zielinski 2000 studies past volcanoes, particularly over the past few centuries:

Zielinksi concluded "the lack of any climatically effective volcanism in the period 1920s to early 1950s undoubtedly contributed to the overall warm conditions during those decades." (Zielinski 2000).

This is confirmed by Hegerl 2003 who found that "early 20th century
warming is attributed to a composite of greenhouse warming, an uncertain contribution from solar forcing, and a recovery from a previous period of heavy volcanism".

Similarly, Bertrand 1999 found that "the lack of volcanism during the period 1925-1960 could account, at least partly, for the observed warming trend in this period". Bertrand was investigating the effect of solar and volcanic influence on climate and concluded "these are clearly not sufficient to explain the observed 20th century warming and more specifically the warming trend which started at the beginning of the 1970s".

In short, a lack of volcanic activity had some part in temperature rise over the first half of the 20th century. However, it has had little to no part in the modern global warming trend that began in the 1970's. On the contrary, relatively frequent volcanic activity in the late 20th century may have masked some of the warming caused by CO2.

Printable Version  |  Link to this page

Link to this page