Antinuclear

Australian news, and some related international items

Weather expert explains: greenhouse gases, not solar flares, the major cause of global warming

solar changes have been far too small to explain the dramatic warming of the Arctic that has been observed.

Other patterns of change provide a means of distinguishing between solar warming and greenhouse warming…..Climate does vary naturally. We can’t stop the climate system changing, but we can avoid loading the dice heavily in favour of rapid warming of the climate system.

There’s always the sun: solar forcing and climate change,  THE CONVERSATION, 20 July 2011Karl Braganza, Manager, Climate Monitoring at The Bureau of Meteorology“…..A popular argument against the enhanced greenhouse effect, or a human influence on climate, has emerged:

“We don’t doubt that climate changes, the climate is always changing”. 

The climate always changes, especially when pushed

If climate is unstable, how does it follow that climate is insensitive to increasing carbon dioxide?

Further, if the climate system is naturally sensitive to a range of different influences, how does that make artificially doubling a (naturally occurring) atmospheric constituent a consequence free action?

The specious reasoning can be placed into context by choosing another example.

“Southern Australia is a fire prone region, and wild fires occurred naturally, long before human occupation of the continent.

“Ergo, humans cannot have any appreciable affect on the incidence or magnitude of modern day fires.”

The climate system does indeed change naturally, on a range of different timescales. However, natural climate variability during human history has been small in comparison to recent observed change and very small in comparison to future, projected changes.

Clearly, this statement has little credence. Humans have greatly impacted on fire regimes across Australia, for many thousands of years.

Importantly, natural changes don’t just happen by magic. Natural forces act to push climate in a particular direction. The climate system itself doesn’t care if the push is natural or human in origin, it just feels the push……

Sunspot cycles can have a slight impact on global mean temperature and might even have a subtle affect on weather patterns. However to date, scientists have not found that sunspots have a regular and profound influence on the climate system…..

Some of the patterns of change associated with solar forcing are similar to greenhouse gas driven changes, such as more rapid warming of the Arctic. However when the pace of change is also factored in, solar changes have been far too small to explain the dramatic warming of the Arctic that has been observed.

Other patterns of change provide a means of distinguishing between solar warming and greenhouse warming.

Perhaps the best pattern to investigate the role of the sun on the climate system is the temperature of the upper atmosphere known as the stratosphere.

If solar energy increases, so too should the temperature of the stratosphere.

Years of study have now confirmed that the upper atmosphere is cooling, and that this cooling is consistent with both global increases in carbon dioxide and decreases in stratospheric ozone in the southern hemisphere.Conversely, increasing greenhouse gases should cool the stratosphere, as they change the way long-wave radiation is absorbed and re-emitted through the atmosphere.

Climate does vary naturally. We can’t stop the climate system changing, but we can avoid loading the dice heavily in favour of rapid warming of the climate system.On average, solar forcing has been in relative decline in recent decades, and global temperatures have continued to warm……..

Reducing greenhouse gases is therefore not about “controlling climate”.Rather, it’s about avoiding an uncontrolled experiment on the climate system.

http://theconversation.edu.au/theres-always-the-sun-solar-forcing-and-climate-change-1878

July 20, 2011 - Posted by | climate change - global warming |

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